proceedings meeting society neurological dublin, 5-9

10
Journal of Neurology, Neurosurgery, and Psychiatry 1995;59:651-660 Proceedings of the 127th Meeting of the Society of British Neurological Surgeons, Dublin, 5-9 September 1995 LOSS OF HETEROZYGOSITY IN SPORADIC CORTICAL DYSPLASIA FOR DNA MARKERS IN THE REGION OF THE TUBEROUS SCLEROSIS (TSC1) GENE ON CHROMOSOME 9Q34 M Farrell, A Greene, T Sepp, PS Mischel, HV Vinters. Beaumont Hospital, Dublin, Ireland, Cambridge University, UK and UCLA Medical Center, Los Angeles, CA, USA Background-Neurohistological similarities between cortical dysplasia (CD) and tuber- ous sclerosis (TSC) have given rise to the hypothesis that CD is a forme tuberous scle- rosis of TSC. Hamartomas, including a cor- tical tuber, from cases of TSC show loss of heterozygosity (LOH) for DNA markers in the region of the TSC gene on chromosome 16pl3-3.' Other TSC hamartomas show allele loss for DNA markers in the region of the TSC1 gene on chromosome 9q34.2 These data are consistent with the hypothe- sis that both the TSC1 and TSC2 genes act as tumour or growth suppressors, according to Knudson's theory. On this basis, the lesions seen in TSC may occur occasionally in a patient who does not have TSC, as an isolated finding due to two somatic gene inactivity mutations. In some cases, the inactivating mutation may be large enough to remove genetic material in the region of the TSC gene, giving rise to LOH. Objectives-To determine if there were genetic similarities between CD and TSC. Methods-DNA extracted from paraffin- embedded normal brain and from CD brain obtained from three non-TSC patients dur- ing neocortical surgical resections for intra- ctable epilepsy was analysed. Polymorphic dinucleotide repeat DNA markers were analysed by PCR, using normal DNA and DNA from CD as templates. The DNA markers analysed spanned the region of the known TSC2 gene, and the as yet uncloned TSC1 gene. Results-One of the three CD tissues showed LOH in the region of the TSC1 gene. No LOH was found in any of the tis- sues for markers flanking the TSC2 gene. Conclusion-There is preliminary evidence that CD may arise as a result of inactivation of both somatic alleles of a TSC gene, anal- ogous to a somatic "localised" form of TSC. (PSM and HVV are supported by NS 28383). 1 Green AJ, Smith M, Yates JR. Loss of het- erozygosity on chromosome 16pl3-3 in hamartomas from tuberous sclerosis patients. Native Genetics 1994;6:193-6. 2 Green AJ, Johnson PH, Yates JR. The tuber- ous sclerosis gene on chromosome 9q34 acts as a growth suppressor. Hum Mol Genet 1994;3: 1833-4. CYTOKINE EXPRESSION IN ANTERIOR PITUITARY ADENOMAS LN Tripathy, B Mathew, SL Atkin, MC White. Department of Neurosurgery, Hull Royal Infirmary, Department of Medicine, University of Hull, Hull, UK Objective-To investigate cytokine expres- sion in human pituitary adenomas. Design-Tumour tissue collected sequen- tially was examined blindly without prior knowledge of the clinical diagnosis, which was determined retrospectively. Subjects-Tumour tissue was collected from 17 clinically confirmed patients with pituitary adenoma during their surgery. Outcome measures-Determination of the presence or absence of cytokine expression in each of the tumours. Results-IL8 was expressed in all tumours. TGFfl1, TGFfl2, and TGF#3 were expressed in 16, 11, and 13 of the 17 adeno- mas respectively. IL2, IL5, and IL7 were not expressed in any tumour. Sporadic expression of ILl al/I, IL4, IL6, and TNFocfl occurred independently of the tumour type. Conclusions-Pituitary adenomas express a wide profile of cytokines and an understand- ing of their overexpression or underexpres- sion may lead to novel endocrine treatment options in the future. INVESTIGATION, MANAGEMENT, AND TREATMENT OUTCOME IN NINE CHILDREN AND ADOLESCENTS WITH CUSHINGS' DISEASE, AFTER TRANSPHENOIDAL SURGERY JS Norris, A Weber, AB Grossman, PN Plowman, GM Besser, MO Savage, F Afshar. Department of Neurosurgery, The Royal London Hospital, Whitechapel, London, UK Cushings' syndrome in childhood is extremely rare and a proportion will have Cushings' disease as a cause. A total of 177 new cases of Cushings' syndrome were referred to this supraregional endocrine unit during the period from 1978 to 1993, and only 12 (6-8%) were children. Nine (5-1%) of these (five boys, four girls; age range 7-6-17-8 years) were found to have Cushings' disease. This constitutes 8-2% of the overall experience of 1 10 cases (all ages) of Cushings' disease requiring surgery from 1984 to 1994. Treatment modalities included surgery and pituitary radiotherapy. These were per- formed by the senior surgeon and radiother- apist in all cases. Six of the nine children required surgery alone, with the remaining three needing adjuvant radiotherapy. To date seven are completely cured, with two in remission. Cases of persisting Cushings' dis- ease were all successfully treated by external beam radiotherapy. The results confirm that the services of a specialised paediatric neuroendocrine unit and an experienced neurosurgeon and radio- therapist offer these children the best chance of cure. FLOW CYTOMETRIC EVALUATION AND K167 LABELLING OF OLIGODENDROGLIOMAS: IS INTRAOPERATIVE ASSESSMENT OF PROLIFERATING TUMOUR A POSSIBILITY? K Seex, J Nicoll, P Stanton, R Rampling, G Cruickshank. Departments of Neurosurgery and Neuropathology, Institute Neurological Sciences, Glasgow, Department of Surgery, Glasgow Royal Infirmary, and Beatson Oncology Unit, Western Infirmary, Glasgow, UK Aims-The improved excision of focal brain tumours is associated with increased sur- vival. Morphological imaging does not allow this objective to be realised, as such tech- niques do not allow imaging of the true pro- liferative zone. It is possible that real time flow cytometry coupled to the product of the CUSA might allow improved excision by directed aspiration of growing tumour. This study sets out to investigate S phase fraction (SpF) DNA analysis as a method of identify- ing proliferating tumour by comparison of SpF analysis, with Ki67 indices from a ret- rospective sample of oligodendrogliomas. Subjects-Fifty patients producing 63 biopsies (1977-90). Methods-Original histology was reviewed and the grading updated. Ki67 immunohis- tochemistry was performed, and the labelling index (LI) evaluated by a stratified counting technique, centred on the most active tissue areas. Flow cytometric profiles were performed, and ploidy and (SpF) cal- culated. Results-LI and flow cytometry correlated unreliably with the histological grade, but better with survival. The LI (median 3-5% 0-35%) correlated well with the SpF (median 5-8% 1-4-27%). Flow cytometry showed a 53% diploid population and a 47% aneuploid/tetraploid population. Conclusions-In oligodendrogliomas con- ventional histology is poor at predicting pro- liferative potential. The correlation between Ki67, SpF and outcome suggests that real- time flow cytometric analysis might allow a more directed and more effective approach to the operative removal of proliferating tumour. ENDOSCOPIC MANAGEMENT OF PINEAL REGION TUMOURS HB Coakham, I Pople, DR Sandeman. Department of Neurosurgery, Frenchay Hospital, Bristol, UK Objective-The wide variety of pineal region tumours require different management strategies which are best determined by biopsy. Early treatment of hydrocephalus is usually necessary. A method of endoscopic biopsy and third ventriculostomy has been developed which achieves both these objec- tives. Design and subjects-Fifteen patients pre- sented with obstructive hydrocephalus due to pineal masses between 1983 and 1995. Via a coronal burr hole a rigid solid lens neuroendoscope was passed freehand and a biopsy taken. Recently a flexible fibrescope was also used. Third ventriculostomy was performed using diathermy and a Forgharty balloon catheter. Results-Histology obtained in all cases: pineoblastoma two, pineocytoma two, ger- minoma four, teratoma four, astrocytoma one, carcinoma two. Biopsy was misleading in one case. Ventriculostomy was successful 651 on October 1, 2021 by guest. Protected by copyright. http://jnnp.bmj.com/ J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.6.651 on 1 December 1995. Downloaded from

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Page 1: Proceedings Meeting Society Neurological Dublin, 5-9

Journal ofNeurology, Neurosurgery, and Psychiatry 1995;59:651-660

Proceedings of the 127th Meeting of the Society of BritishNeurological Surgeons, Dublin, 5-9 September 1995

LOSS OF HETEROZYGOSITY IN SPORADIC

CORTICAL DYSPLASIA FOR DNA MARKERS IN

THE REGION OF THE TUBEROUS SCLEROSIS

(TSC1) GENE ON CHROMOSOME 9Q34M Farrell, A Greene, T Sepp, PS Mischel,HV Vinters. Beaumont Hospital, Dublin,Ireland, Cambridge University, UK andUCLA Medical Center, Los Angeles, CA,USA

Background-Neurohistological similaritiesbetween cortical dysplasia (CD) and tuber-ous sclerosis (TSC) have given rise to thehypothesis that CD is a forme tuberous scle-rosis of TSC. Hamartomas, including a cor-

tical tuber, from cases of TSC show loss ofheterozygosity (LOH) for DNA markers inthe region of the TSC gene on chromosome16pl3-3.' Other TSC hamartomas showallele loss for DNA markers in the region ofthe TSC1 gene on chromosome 9q34.2These data are consistent with the hypothe-sis that both the TSC1 and TSC2 genes actas tumour or growth suppressors, accordingto Knudson's theory. On this basis, thelesions seen in TSC may occur occasionallyin a patient who does not have TSC, as an

isolated finding due to two somatic gene

inactivity mutations. In some cases, theinactivating mutation may be large enoughto remove genetic material in the region ofthe TSC gene, giving rise to LOH.

Objectives-To determine if there were

genetic similarities between CD and TSC.Methods-DNA extracted from paraffin-

embedded normal brain and from CD brainobtained from three non-TSC patients dur-ing neocortical surgical resections for intra-ctable epilepsy was analysed. Polymorphicdinucleotide repeat DNA markers were

analysed by PCR, using normal DNA andDNA from CD as templates. The DNAmarkers analysed spanned the region of theknown TSC2 gene, and the as yet unclonedTSC1 gene.

Results-One of the three CD tissuesshowed LOH in the region of the TSC1gene. No LOH was found in any of the tis-sues for markers flanking the TSC2 gene.

Conclusion-There is preliminary evidencethat CD may arise as a result of inactivationof both somatic alleles of a TSC gene, anal-ogous to a somatic "localised" form of TSC.(PSM and HVV are supported by NS28383).

1 Green AJ, Smith M, Yates JR. Loss of het-erozygosity on chromosome 16pl3-3 inhamartomas from tuberous sclerosis patients.Native Genetics 1994;6:193-6.

2 Green AJ, Johnson PH, Yates JR. The tuber-ous sclerosis gene on chromosome 9q34 actsas a growth suppressor. Hum Mol Genet1994;3: 1833-4.

CYTOKINE EXPRESSION IN ANTERIORPITUITARY ADENOMASLN Tripathy, B Mathew, SL Atkin, MCWhite. Department of Neurosurgery, HullRoyal Infirmary, Department of Medicine,University of Hull, Hull, UK

Objective-To investigate cytokine expres-sion in human pituitary adenomas.

Design-Tumour tissue collected sequen-

tially was examined blindly without priorknowledge of the clinical diagnosis, whichwas determined retrospectively.

Subjects-Tumour tissue was collectedfrom 17 clinically confirmed patients withpituitary adenoma during their surgery.

Outcome measures-Determination of thepresence or absence of cytokine expressionin each of the tumours.

Results-IL8 was expressed in all tumours.TGFfl1, TGFfl2, and TGF#3 were

expressed in 16, 11, and 13 of the 17 adeno-mas respectively. IL2, IL5, and IL7 were

not expressed in any tumour. Sporadicexpression of ILl al/I, IL4, IL6, and TNFocfloccurred independently of the tumour type.

Conclusions-Pituitary adenomas express a

wide profile of cytokines and an understand-ing of their overexpression or underexpres-sion may lead to novel endocrine treatmentoptions in the future.

INVESTIGATION, MANAGEMENT, ANDTREATMENT OUTCOME IN NINE CHILDREN

AND ADOLESCENTS WITH CUSHINGS' DISEASE,AFTER TRANSPHENOIDAL SURGERY

JS Norris, A Weber, AB Grossman, PNPlowman, GM Besser, MO Savage, FAfshar. Department of Neurosurgery, TheRoyal London Hospital, Whitechapel,London, UK

Cushings' syndrome in childhood isextremely rare and a proportion will haveCushings' disease as a cause. A total of 177new cases of Cushings' syndrome were

referred to this supraregional endocrine unitduring the period from 1978 to 1993, andonly 12 (6-8%) were children. Nine (5-1%)of these (five boys, four girls; age range

7-6-17-8 years) were found to haveCushings' disease. This constitutes 8-2% ofthe overall experience of 1 10 cases (all ages)of Cushings' disease requiring surgery from1984 to 1994.Treatment modalities included surgery

and pituitary radiotherapy. These were per-formed by the senior surgeon and radiother-apist in all cases. Six of the nine childrenrequired surgery alone, with the remainingthree needing adjuvant radiotherapy. Todate seven are completely cured, with two inremission. Cases of persisting Cushings' dis-ease were all successfully treated by externalbeam radiotherapy.The results confirm that the services of a

specialised paediatric neuroendocrine unitand an experienced neurosurgeon and radio-therapist offer these children the best chanceof cure.

FLOW CYTOMETRIC EVALUATION AND K167LABELLING OF OLIGODENDROGLIOMAS: ISINTRAOPERATIVE ASSESSMENT OFPROLIFERATING TUMOUR A POSSIBILITY?K Seex, J Nicoll, P Stanton, R Rampling, GCruickshank. Departments of Neurosurgeryand Neuropathology, Institute NeurologicalSciences, Glasgow, Department of Surgery,

Glasgow Royal Infirmary, and BeatsonOncology Unit, Western Infirmary,Glasgow, UK

Aims-The improved excision of focal braintumours is associated with increased sur-vival. Morphological imaging does not allowthis objective to be realised, as such tech-niques do not allow imaging of the true pro-liferative zone. It is possible that real timeflow cytometry coupled to the product of theCUSA might allow improved excision bydirected aspiration of growing tumour. Thisstudy sets out to investigate S phase fraction(SpF) DNA analysis as a method of identify-ing proliferating tumour by comparison ofSpF analysis, with Ki67 indices from a ret-rospective sample of oligodendrogliomas.

Subjects-Fifty patients producing 63biopsies (1977-90).

Methods-Original histology was reviewedand the grading updated. Ki67 immunohis-tochemistry was performed, and thelabelling index (LI) evaluated by a stratifiedcounting technique, centred on the mostactive tissue areas. Flow cytometric profileswere performed, and ploidy and (SpF) cal-culated.

Results-LI and flow cytometry correlatedunreliably with the histological grade, butbetter with survival. The LI (median 3-5%0-35%) correlated well with the SpF(median 5-8% 1-4-27%). Flow cytometryshowed a 53% diploid population and a47% aneuploid/tetraploid population.

Conclusions-In oligodendrogliomas con-ventional histology is poor at predicting pro-liferative potential. The correlation betweenKi67, SpF and outcome suggests that real-time flow cytometric analysis might allow amore directed and more effective approachto the operative removal of proliferatingtumour.

ENDOSCOPIC MANAGEMENT OF PINEALREGION TUMOURSHB Coakham, I Pople, DR Sandeman.Department of Neurosurgery, FrenchayHospital, Bristol, UK

Objective-The wide variety of pineal regiontumours require different managementstrategies which are best determined bybiopsy. Early treatment of hydrocephalus isusually necessary. A method of endoscopicbiopsy and third ventriculostomy has beendeveloped which achieves both these objec-tives.

Design and subjects-Fifteen patients pre-sented with obstructive hydrocephalus dueto pineal masses between 1983 and 1995.Via a coronal burr hole a rigid solid lensneuroendoscope was passed freehand and abiopsy taken. Recently a flexible fibrescopewas also used. Third ventriculostomy wasperformed using diathermy and a Forghartyballoon catheter.

Results-Histology obtained in all cases:pineoblastoma two, pineocytoma two, ger-minoma four, teratoma four, astrocytomaone, carcinoma two. Biopsy was misleadingin one case. Ventriculostomy was successful

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in 5/5 cases. Appropriate definitive treat-ment was then carried out according to cur-rent protocols.

Conclusions-The neuroendoscope is avaluable instrument in the initial manage-ment of pineal tumours. The combined useof rigid and flexible endoscopes through acommon sheath is our current recommenda-tion.

1 Fukushima T, Ishijima B, Hirakawa K,Hakamura N, Sano K. Ventriculofiberscope:a new technique for endoscopic diagnosisand surgery. J7 Neurosurg 1973;38:251-6.

2 Griffith HB. Techniques of fontanelle and per-sutural ventriculoscopy and endoscopic ven-tricular surgery in infants withhydrocephalus. Childs Brain 1975;1:359-93.

AN AUDIT OF INTRINSIC BRAIN STEMTUMOURS PRESENTING AT GREAT ORMONDSTREET HOSPITAL FOR CHILDREN BETWEEN1980 AND 1990B Chitnavis, WFJ Harkness, RD Hayward.Great Ormond Street Hospital for Children,Great Ormond Street, London, UK

Objective-To analyse the presentation,pathology and long term prognosis of brainstem tumours in children.Methods-Thirty paediatric patients with

brain stem tumours presenting at GreatOrmond Street Hospital between 1980 and1990 were reviewed. The factors evaluatedincluded age at presentation, duration ofsymptoms before presentation, examinationfindings, radiology, operative intervention,history, adjuvant treatments, and duration ofsurvival after diagnosis.

Results-The study was a retrospectiveanalysis of 30 patients (19 girls and 11 boys)with brain stem tumours, aged 1 week to 14years (mean 5 years). Symptoms manifesteda mean of five months before diagnosis. Thesite of involvement was pontine in 20patients, midbrain in four patients,medullary in three patients, and extensive intwo patients. MRI was available in 24patients and CT in all patients. Histologywas obtained in 11 patients; two at surgeryto debulk the tumour, eight through burrhole biopsies, and one through cytologicalanalysis of CSF. Four were malignantgliomas, six were low grade gliomas, andone a PNET. Twenty six patients receivedradiotherapy, six patients were givenchemotherapy in addition, four patientsreceived neither. Eight patients requiredshunting for hydrocephalus. Median survivaltime after diagnosis was nine months; sixpatients remain alive.

Conclusion-The prognosis for intrinsicbrain stem tumours remains poor with six of30 patients surviving more than five years.Future improvements are unlikely to be sur-gical and work continues to find an effectivechemotherapeutic regime to accompanyradiotherapy.

THE HAEMODYNAMIC EFFECT OF VASOSPASMON THE CIRCLE OF WILLISJG Rowe, A Thomas, A Molyneux, JVByrne, CBT Adams, B Rajagopalan. MRCSpectroscopy Unit, John Radcliffe Hospitaland Departments of Neurosurgery andNeuroradiology, Radcliffe Infirmary,Oxford, UK

Objective-To investigate how proximalvasospasm affects cerebrovascular resistance.

Methods-Mean arterial pressures (MAP)were measured around the circle of Willis, inpatients undergoing endovascular treatmentof aneurysms. Seven patients hadvasospasm, 20 did not. Values are mean ±SD.

Results-Without vasospasm pressure gra-dients were small. The MAP at the anteriorcommunicating artery (ACoA) origin was 97(3)% of the extracranial carotid, and at themiddle cerebral artery (MCA) bifurcation94 (7)%. Without vasospasm < 5% of thecerebrovascular resistance arose at the circleof Willis. Pressure gradients increased withproximal vasospasm, 82 (6)% and 74 (10)%of extracranial carotid MAP being transmit-ted to the ACoA origin and MCA bifurca-tion. On average threequarters of theresistance still arose distally, and pressuresmeasured at these points (65 (13) mm Hgand 57 (18) mm Hg respectively) wereabove the lower limit of autoregulation, sug-gesting that proximal vasospasm alone wasinsufficient to compromise blood flow. Asflow decreased less than vessel lumenal area,transcranial Doppler velocities should beincreased. This was confirmed in fourpatients.

Conclusions-The modest effect of proxi-mal vasospasm on cerebrovascular resistancehas implications for the development ofischaemia after subarachnoid haemorrhage,and for the use of angiography in guidingtreatments for vasospasm, such as angio-plasty.

ARTERIOVENOUS MALFORMATIONS INCRITICAL AREAS OF THE BRAIN:MICRONEUROSURGICAL EXCISION: THE GOLDSTANDARD IN CURRENT TREATMENT?SA O'Laoire. Department of Neurosurgery,Mater Private Hospital, Dublin 7, Ireland

Materials and methods-Fifty six patientswho had AVMs in eloquent areas of cortexor deep brain, or were of large multiterritor-ial size were excised using microsurgicaltechniques between June 1981 andNovember 1989. Single stage surgery wasused in 44 cases, and deliberate surgicalstaging in 10 cases. In four cases routinepostoperative angiography disclosed residualAVM, and further treatment was surgical intwo cases and focused radiation in two.Presentation followed haemorrhage in 41cases (73%), progressive neurological deficit(PND) in nine cases (16%), and epilepsy insix cases (1 1%).

Results-Forty three patients made a goodrecovery (77%), seven were fair (13%),three had a poor result (5%), and three died(5%). Three patients developed a new orincreased deficit after surgery (5%), andseven of nine patients who had epilepsy andwho had not bled are free of epilepsy (78%).No new cases of long term epilepsy haveoccurred after surgery (minimum follow upis now five years).

Conclusions-Microsurgical excision ofcerebral AVMs even in critical areas of thebrain has a far better outcome than the nat-ural history of conservatively treated lesions.Surgery should be considered not only afterhaemorrhage, but also in cases presentingwith PND or epilepsy. The non-surgicaltreatments of these lesions require very criti-cal assessment in the light of the results ofmodern microneurosurgery.

ENDOVASCULAR EMBOLISATION OF

INTRACRANIAL ARTERIOVENOUSMALFORMATIONS

P Brennan, AJ O'Dwyer, JP Phillips, JToland. Department of Neuroradiology andNeurosurgery, Beaumont Hospital, Dublin,Ireland

Objective-To clarify the role of endovascu-lar treatment of intracranial arteriovenousmalformations (AVMs).Design-A retrospective review was per-

formed of the patients who underwentendovascular treatment of AVMs.

Subjects-Eighteen patients were includedwithin an 18 month period from January1994 to June 1995. Follow up angiographyand clinical review were performed in allcases.

Results-Four AVMs were completelyobliterated, 14 were partially treated, 10were reduced significantly in size and fourwere considered failures. Subsequently fourpatients underwent curative surgery, oneradiosurgery; two others await radiosurgery,and three await further treatment. Two hadtransient neurological deficits after treat-ment; no patient had rebleeding, and onepatient had a permanent neurological deficit.

Conclusions-Endovascular embolisationhas an important supportive role in treatingAVMs.

1 For AJ, Pelz DM, Lee DH. Arteriovenousmalformations of the brain. Recent results ofendovascular therapy. Radiology 1990;177:51-7.

2 Dawson RC, Tarr RW, Hecht ST, JungressCA, Lundsford LD, Coffey R, Horton JA.Treatment of arteriovenous malformations ofthe brain with combined embolisation andstereotactic radiosurgery; results after 1 and2 years AJNR Am _7 Neuroradiol 1990;1l:857-64.

FACTORS IMPLICATED IN DEATHS FROMSUBARACHNOID HAEMORRHAGE: ARE THEYAVOIDABLE?PJA Hutchinson, H Seeley, PJ Kirkpatrick.Academic Neurosurgical Unit,Addenbrooke's Hospital, Hills Road,Cambridge, UK

Introduction-Although causes of death fromsubarachnoid haemorrhage (SAH) are mul-tifactorial, some are potentially avoidable. Inaddition, poor grading (often considered acontraindication for transfer to neurosurgi-cal departments) in patients may be due tocorrectable factors. By auditing patients whohave died from SAH we have attempted toexplore these possibilities.Methods-The records and CT of 100

patients (mean age 54 8) who died fromSAH were derived from two district generalhospitals and the neurosurgical department(NSD).

Results General: Eighteen of the patientswere considered unsalvagable (WFNSGrade 5, pupils fixed). In the remainder, 57were good grade (WFNS 1-3) of which 38(67%) died of a rebleed (mean day 12-8). Of25 poor grade patients, hydrocephalus wasidentified in seven (28%). In addition, poorresuscitation (seizure control and inadequateintravenous fluids) were considered possiblecontributing factors in 13 (52%) cases.District hospitals: Those transferred arrivedin the neurosurgical department on (mean)day 2-6. Out of 26 deaths (10 good grade)the NSD was not contacted in 13 cases (sixgood grade). Of the eight poor gradepatients correctable factors were identifiedin four (50%).

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Conclusion-Rebleeding was the maincause of death in all grade patients. In addi-tion, possible reversible factors were identi-fied which prompt a more activeneurosurgical role in the management ofpoor grade patients.

THE MANAGEMENT OF LESIONS OF THEDISTAL EXTRACRANIAL INTERNAL CAROTIDARTERYN Patel, RJ Nelson, T Lewis, M Morse.Departments of Neurosurgery, Neuro-radiology, and Radiology, FrenchayHospital, Bristol, UK

Objective-To present the surgical approachto lesions of the distal extracranial internalcarotid artery and to describe the optimalmultidisciplinary management of theselesions.Design-A prospective study of patients

admitted consecutively over a two yearperiod with angiographically confirmedlesions of the suprahyoid segment of theextracranial internal carotid artery.Patients-Ten patients (six men, four

women; mean age 54) with acute or tran-sient cerebral ischaemia due to several dis-eases including atypical atherosclerosis,post-traumatic, iatrogenic, or spontaneousarterial dissection, and aneurysm formation.

Interventions-A combination of open sur-gical techniques including endarterectomy,patch angioplasty, and saphenous veinbypass grafting and endovascular techniquesincluding carotid stenting and balloonangioplasty.Outcome-The management of the arterial

lesion and long term outcome in sevenpatients has been good. One patient had afatal postoperative myocardial infarction,one patient developed fatal postoperativecerebral oedema, and one patient has had arecurrence of a carotid dissection after stent-ing.

Conclusions-Lesions of the distalextracranial carotid artery are unusual andare technically demanding for both the sur-geon and interventional radiologist. Withcareful assessment and planning goodresults may be obtained in most patients.

IDIOPATHIC SYRINGOMYELIA ASSOCIATEDWITH FOCAL SUBARACHNOIDCONDENSATIONS MAKING WEBSCL Mallucci, R Stacey, J Miles, B Williams.Midland Centre for Neurosurgery,Birmingham, and Walton Centre forNeurosurgery, Liverpool, UK

Objective-Ten patients with symptomaticsyringomyelia without commonly recognisedpredisposing factors are reported. They havebeen found to have a focal area of arach-noiditis forming webs, pouches or cysts, andwith blockage of the normal CSF flow.

Patients-Eight men and two women(average age 47 years). All had preoperativeMRI evidence of syringomyelia of whomthree had appearances suggestive of webs.Myelography in eight showed subarachnoidhold up of contrast from below compatiblewith subarachnoid webs.

Results-Eight patients had laminectomiesand division of the obstructing arachnoidwebs (one cyst) and the dura left widelyopen. Five of these had immediate goodimprovement in symptoms and three hadonly mild improvement. Two patients hadshunting procedures (syringosubarachnoidand syringopleural), and both were immedi-ately worse. Delayed follow up was available

in nine patients (average two years), inwhich two patients had recurrence of symp-toms. Postoperative MRI showed collapse ofthe syrinx in eight of nine patients.

Conclusions-Patients with idiopathicsyringomyelia should be investigated formeningeal webs. The treatment of choice islaminectomy and excision of the obstructingarachnoid condensations so as to re-estab-lish normal CSF flow and eliminate the fill-ing mechanism. Their aetiology is unknownand early results of surgery seem good.

FAMILIAL CAVERNOUS MALFORMATIONSRJ Stacey, G Findlay, RV Jeffreys, PHumphrey, TP Enevoldson. Walton Centrefor Neurology and Neurosurgery, Liverpool,UK

The availability ofMRI has greatly increasedthe detection of cavernous malformationsof the CNS in both symptomatic andasymptomatic patients. This has led to therealisation that, in cases where more thanone cavernous malformation is present,there may be a familial component to thedisease. These lesions may also be responsi-ble for previously unexplained neurologicalevents or may even have been previouslyincorrectly diagnosed. A family, spanningthree generations, is reported, in which atleast eight members are affected with anautosomal dominant pattern of inheritance.Each patient presented independently withneurological complications. To date otherasymptomatic family members haverefused to be screened. In all cases multiplecerebral cavernomas were identified. Inaddition, in one case, an associated spinalcavernoma requiring surgery was also seen.In four of the subjects the diagnosis wasconfirmed retrospectively only with theadvent of MRI. In one patient a diagnosis oflow grade glioma had previously beenmade. Only one of the patients has under-gone surgery, with removal of two cerebraland one spinal cavernoma. A review of theliterature shows this to be the largest seriesreported in a single family.

VERTEBROBASILAR ANEURYSMS: AN ANALYSISOF 60 CASESPV Marks, SA Ross. The General Infirmary,Leeds, UK

The results of management of 60 consecu-tive vertebrobasilar aneurysms over a sixyear period have been analysed. Aneurysmswere found at the following sites: basilarbifurcation (30), posterior inferior cerebellarartery (nine), superior cerebellar artery (six),posterior cerebral arteries (seven), basilartrunk (three), anterior inferior cerebellarartery (two), vertebral artery (two), andbasilar origin (one).

Ninety per cent of patients presented withsubarachnoid haemorrhage but in severalcases, the posterior circulation aneurysmwas not responsible for the bleed and wastherefore treated electively. A variety of sur-gical approaches were invoked includingcombined maxillofacial access proceduresand the transoral transclival route. Threeaneurysms were considered inoperable andtwo were subsequently treated by inter-ventional radiology. Four deaths occurred inthe postoperative period and two patientswho were initially grades III and IV on theWFNS scale had poor outcomes. Theremaining patients had good or excellentoutcomes.

LUMBAR DIASTEMATOMYELIA: A MODEL FORTHE NEUROSURGICAL MANAGEMENT OF ALLTYPES OF OCCULT SPINAL DYSRAPHISM?RD Hayward, WFJ Harkness, U Andar.Great Ormond Street Hospital for Children,Great Ormond Street, London, UK

Objectives-To study the type and incidenceof neurological, orthopaedic, and urologicalproblems after both prophylactic surgery andsurgery for progressive symptoms in childrenwith lumbar diastematomyelia.Methods-A retrospective review of

patients seen at this institution over a 20 yearperiod with diastematomyelia in the lumbarregion but no evidence of other dysraphicabnormalities.

Results-Forty four cases out of a total of84 fulfilled the entry criteria. The female/male ratio was 2:1. Of the 33 patients oper-ated on with no evidence of any progressiveclinical problems, only one showed any evi-dence of deterioration during a follow upperiod that ranged from 1-3 to 17 years. Of10 patients operated on because of progres-sive neurological, orthopaedic, and/or uro-logical problems (average age at surgery 6-8years) three improved whereas the remaindershowed no evidence of further deteriorationover a follow up period that averaged 5-7years.

Conclusion-This study of a uniformcohort of patients with occult spinal dys-raphism suggests that their clinical problemscan be divided into two groups-"true" dete-rioration (defined as the loss of a previouslynormal function) and those due to the clini-cal emergence of abnormalities (usually ataround 2 years of age) which had alwaysbeen present but previously disguised by theimmaturity of the nervous system. Thismodel is helpful in the analysis of the resultsof surgery (prophylactic and symptomatic)for other forms of occult spinal dysraphism,such as the lipomeningoceles.

THORACIC DISC HERMIATION:RE-EVALUATION OF THE LATERALPOSTERIOR (HEMILAMINECTOMY ANDMICRODISCECTOMY) APPROACHIH Chaudhry, K Saeed, C Marks, TFBuckley. Neurosurgical Department, CorkUniversity Hospital, Cork, Ireland

Objectives-To assess the value and safety ofthe lateral-posterior (hemilaminectomy andmicrodiscectomy) approach to herniated tho-racic discs.

Design-Retrospective study of 17 patientsoperated on in the unit from 1978 to May1995. Follow up varied from four months to17 years.Subjects-There were 17 patients (6 men,

1 1 women) aged 31 to 61 years.Outcome measures-Pre and postoperative

neurological status were compared.Results-Eleven patients made excellent or

good recoveries, four were fair, one remainedunchanged, and one became worse.

Conclusions-A posterior approach withhemilaminectomy and microdiscectomy isa safe, effective, cost efficient, and less trau-matic procedure for thoracic disc herniation.

TETHERED CORD SYNDROME: RECENTCLINICAL EXPERIENCES Sharif, P Brennan, C Marks, D Allcutt.Departments of Neurosurgery and Neuro-radiology, Beaumont Hospital, CorkUniversity Hospital, Dublin, Ireland

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condition which may be due to fixation andstretching of the spinal cord by intradural orextradural elements. The current manage-ment and its results are controversial. Thirtyseven consecutive patients who were treatedsurgically by two surgeons were reviewed.The mean age at presentation was 10 years(24 girls and 13 boys). Main presentingcomplaints were back and leg pain, foot andspinal deformities, motor and sensorydeficits, and cutaneous manifestation of dys-raphism. Average duration between onset ofsymptoms and surgery was 35 months and86% reported deterioration of symptoms, 32patients had MRI and five had myelograms.Indications for surgery were progressive neu-rological deterioration, primary prophylacticsurgery or as a preliminary to correctivescoliosis surgery, and nine patients had hadprevious spinal surgery. The cord wasuntethered in 31 patients and the filum ter-minale was divided in 16 patients. Therewere no serious complications, two patientshad a CSF leak which was repaired.Adequate postoperative follow up was avail-able in 36 patients, of which 63% subjec-tively improved and 14% showed improvedsigns. There was no deterioration in neurol-ogy in any patient. Our series suggests thatrelease of the cord in patients with tetheredcord syndrome may improve or arrest pro-gression of neurological deterioration. Thusclose follow up and consideration of surgeryfor patients who develop signs of a tetheredcord is recommended.

COLOUR DOPPLER IMAGING IN THEINVESTIGATION OF SHUNT FUNCTIONS Sgouros, P John, AR Walsh, AD Hockley.Childrens Hospital, Birmingham, UK

Objective-To investigate the value ofDoppler sonography in detecting flowthrough ventriculoperitoneal (V-P) shunts.Design-The observation of the normally

invisible CSF flow from the peritoneal endof a V-P shunt during a conventionalabdominal ultrasound examination in one ofour patients led us to try colour Dopplerimaging, using a 10 MHz linear array trans-ducer, which performed spectral and colourcoded Doppler sonography. Further in vitrostudies were performed with a simulatedshunt/ventricular system model, to explorethe limitations of the technique.

Patients-Seventeen patients with V-Pshunts, aged 3 months to 12 years wereinsonated. Twenty examinations were per-formed because two patients had repeatedexaminations before and after shunt revi-sion.

Results-In 13 examinations (65%) CSFflow was identified through the shunt tube.Flow velocities between 5-7 cm/s were mea-sured. No flow was seen in seven examina-tions (35%). Of these, three examinations(15%) were performed before revisions forblocked shunt. In vitro studies demonstratedthat although clear CSF is not ultrasonicallyvisible, the presence of particulate matter,such as choroid plexus debris, can generatea satisfactory Doppler signal with the probeinsonating over the length of the tubing. Inthe presence of clear CSF, turbulence gener-ated at junction points of the shunt systemor at the exit of the peritoneal tube can bevisualised well with Doppler sonography,presumably due to generation of microbub-bles.

Conclusions-This preliminary report sug-gests that colour Doppler imaging mayprove helpful in demonstrating flow through

shunts, although at this stage there wouldseem to be a considerable number of falsenegative results. Further improvements withaquisition techniques could decrease theincidence of false negatives, allow differenti-ation of constant or intermittent flowthrough functioning shunts, and identifyshunt independent patients. If the methodbecomes established, the clinical implica-tions in the management of shunt obstruc-tion are obvious.

THE NON-SURGICAL MANAGEMENT OF CSFSHUNT INFECTIONSEM Brown, EM Jones. Department ofMedical Microbiology, Frenchay Hospital,Bristol, UK

Treating shunt infections with antibioticsalone has consistently yielded cure rateswhich have been significantly lower thanthose achieved with a combination of shuntremoval and antibiotics. A critical evaluationof how patients have previously been man-aged conservatively disclosed several expla-nations for these poor results: inappropriateantibiotics; inadequate dosages; and, mostimportantly, administration by routes whichfailed to produce therapeutic concentrationsin the CSF. This knowledge was used todevise a regimen which would representoptimal non-surgical therapy of shunt infec-tions caused by Gram positive cocci, thepredominant pathogens. Vancomycin,instilled into the ventricles through anOmmaya reservoir, combined with systemi-cally administered rifampicin and, inselected cases, intraventricular gentamicin,all for two weeks, was expected to yield thehighest response rates. To date, 24 episodesof shunt infection in 22 patients have beentreated; three were managed, at least in part,on an outpatient basis. Clinical and bacteri-ological cure rates were achieved in 20 of the24 (83%) episodes, including all 15 causedby coagulase negative Staphylococci; four ofthe five infections caused by staphylococcusaureus failed to respond. After follow upperiods of between six months and morethan eight years, there were no relapses inpatients who were cured, no deaths, and noadverse events attributable to treatment.These results suggest that treatment ofshunt infections caused by bacteria otherthan S aureus according to this regimenyields cure rates which are comparable withthose achieved with conventional manage-ment.

CSF SHUNT INFECTIONS: A REVIEWR Zafar, S Sharif, D Rawluk, E McNamara,E Smyth. Departments of Neurosurgery andMicrobiology, Beaumont Hospital, Dublin,Ireland

Cerebrospinal fluid shunt infection remainsa difficult management problem and in therecent past there have been very little dataconsidering this issue. This study wasundertaken to review the incidence, aetio-logical agents, clinical presentation, andmanagement protocol to facilitate furtherefforts to reduce their occurrence in thefuture. Microbiological data, theatre andpatient case records were reviewed retro-spectively, and 534 operations for shuntinsertion were carried out between January1992 and March 1995. There were the 45cases of microbiologically proved CSF shuntinfections thus yielding an incidence rate of8-4%. Mean age of subjects was 29-6 (range2 to 72) years, 56-5% being males, and

95-5% of infective episodes involved ven-triculoperitoneal shunts. The major indica-tion for insertion being hydrocephalus inassociation with spina bifida. Mean numberof previous shunt revisions in these was two(range 0 to 7), common presenting featureswere pyrexia, leucocytosis, vomiting, andheadache. Overt wound infections wereobserved in 20%. The aetiological agentsbeing Staphylococcus aureus in 55-5% andcoagulase negative Staphylococcus in 37-7%of these episodes. The use of external ven-tricular drainage was employed in 60% andeventually shunts were revised in 86-6%.Antibiotics were used in 91% of cases, 55%being intraventricular. Mean stay in hospitalwas 17 (range 9 to 107) days. The use ofintensive care facilities was employed in15-5% of cases, 8-8% requiring ventilatorysupport for a mean period of 48 hours. It istherefore considered that much more effortneeds to be directed towards prevention ofCSF shunt infection, given the problems ofantibiotic therapy, if the costs incurred bythese potentially lethal complications are tobe limited.

IN VIVO STUDY OF CODMAN MICROSENSORINTRACRANIAL PRESSURE CATHETERSWP Gray, M Gardner, J Gill, F lannotti.Department of Neurological Sciences,Wessex Neurological Centre, SouthamptonGeneral Hospital, Southampton, UK

Objective-To measure the accuracy of anewly developed intracranial pressure (ICP)catheter in which a microsensor is located atthe tip.

Design-All patients had a standard rightfrontal fluid filled subdural catheter systeminserted. In addition, a microsensor catheterwas inserted within the fluid filled subduralcatheter. Finally a separate microsensorcatheter was inserted into the brainparenchyma. A computerised monitoringsystem was used to simultaneously record allthree ICPs. Microsensor drift was recordedat explant.

Patients-Eleven patients requiring ICPmonitoring.

Results-The tissue sensor became dis-lodged and traumatised in two patients.This left nine patients with 36 000 validsimultaneous recordings. Tissue ICP mea-sured by the microsensor catheter washigher than the subdural fluid filled catheterby 2-8 mm Hg (P < 0-001) and the subduralmicrosensor catheter by 1-5 mm Hg (P <0-001). The tissue microsensor catheter gavea superior quality recording with a meanamplitude of 5-5 mm Hg compared with thesubdural sensor (4-4 mm Hg) and the sub-dural fluid catheter (3 mm Hg). Mean sen-sor drift was < 1 mm Hg.

Conclusions-Microsensor tipped cathetersrecord ICP accurately and tissue measure-ments yield a superior recording.

TREATMENT OF HYDROCEPHALUS SHUNTINFECTIONS: BSAC WORKING PARTYRECOMMENDATIONSR Bayston, J De Louvois, E Brown, AHedges, R Johnston, P Lees. UniversityDepartment of Microbiology (InfectiousDiseases), City Hospital, Nottingham, UK

Though the incidence of shunt infectionshas fallen in recent years, they are still amajor problem in the control of hydro-cephalus. The incidence is highest in babies,and reasons for this have been proposed.The commonest causative organisms are

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the coagulase negative Staphylococci. Earlyreports showed clearly that regimens in usefor other staphylococcal infections were inef-fective, and the reasons for this are pharma-cological (related to drug penetration intothe CNS) and microbiological (factors pro-duced by the organisms during infection).All reports of attempts to treat shunt infec-tions without removal of the device haveshown disappointing results.' Vancomycin isthe antimicrobial of choice for treatment ofshunt infections due to Gram positive bacte-ria, and is both safe and effective whenadministered intraventricularly.2 Its activityis enhanced by the addition of rifampicin.The recommendation of the working party isthat, for Gram positive infections, the shuntshould be removed and extemal ventriculardrainage instituted; and that intraventricularvancomycin and either oral or intravenousrifampicin should be given. Recent studieshowever, suggest that this regimen might besuccessful without shunt removal in somecases and the recommendation may need tobe revised. In those patients with a shuntwho develop community acquired meningi-tis due to haemophilus, pneumococcus, ormeningococcus, shunt removal is not neces-sary. For infections due to Gram negativebacilli or candida, the working party recom-mends immediate shunt removal and appro-priate antimicrobial chemotherapy.

1 James HE, Walsh JW, Wilson HD, Connor JD,Bean JR, Tibbs PA. Prospective randomizedstudy of therapy in cerebrospinal fluid shuntinfection. Neurosurgery 1980;7:459-63.

2 Bayston R, Hart CA, Barnicoat M.Intraventricular vancomycin in the treatmentof ventriculitis associated with cerebrospinalfluid shunting and drainage. J NeurolNeurosurg Psychiatry 1987;50:1419-23.

ADULT HEAD INJURIES IN EUROPEANCENTRES: A PILOT STUDYGM Teasdale, G Murray on behalf of theEuropean Brain Injury Consortium.University Department of Neurosurgery,Institute of Neurological Sciences, Glasgow,UK

Objective-To determine the acceptability ofa "core data set" of observations on acutehead injuries and the feasibility of using thisto obtain information in collaborativeresearch in European centres.Design-A two page proforma, containing

60 items of information on demography, clin-ical features, investigation, management, andearly outcome was devised. Centres through-out Europe were invited to submit data onmoderate and severe head injured patientsadmitted from 1 February to 30 April 1995.

Outcome measures-The number of centresresponding, the number of patients reported,and quality and credibility of data.

Results-Reports on more than 750patients have been received from 61 centres.The conformity of data has been high butsome ambiguities have been identified. Themedian age was 37, 73% were men and 50%were road traffic accidents. The median timefrom injury to neurosurgical admission was2-92 hours, and 75% had a severe injury.Clinical data "prehospital" were available in60% of cases; when admitted to neuro-surgery, more than a third had some aspectof the Glasgow coma scale untestable.Results of CT according to the TraumaticComa Databank categories were: I, 12%; II,27%; III, 12%; IV, 3%; 44% had a "mass"lesion evacuated.

Conclusions-The core data proformaswere widely accepted; a large number of

patients were reported in a brief period; thedata were of high quality and credibility andprovide a valuable basis for planning furtherresearch.

'H MAGNETIC RESONANCE SPECTROSCOPY OFACUTE HEAD INJURYD Oluoch-Olunya, B Condon, D Hadley, AWagstaff, GM Teasdale. Department ofNeurosurgery, Beaumont Hospital, Dublin,Ireland, and Departments of ClinicalPhysics, Neuroanaesthesia, andNeurosurgery, Institute of NeurologicalSciences, Glasgow, UK

Introduction-Secondary ischaemic braindamage is exceedingly common in fatal headinjuries, but when this occurs in life isunclear. Cerebral blood flow studies haveshown hypoperfusion, particularly early afterhead injury, but confirmation of ischaemicmetabolic changes has been difficult.Previous 31P magnetic resonance spec-troscopy (MRS), showed a tendency tointracellular alkalosis.' Four cases studied,within 20 hours of injury to seek lactate asan index of anaerobic glycolysis.Methods-The patients were ventilated to

a Paco, of 4-33 (11) kPa and monitoringincluding ICP with MR compatible equip-ment. No untoward events occurred duringMR investigation performed with a Siemens1-5 Tesla system. Spin echo (SE) 1500/135and SE1500/270 'H spectra were collectedfrom two volumes of interest (VOI) identi-fied by imaging (1) adjacent to and (2)remote from maximum focal damage con-sisting of contusions, or acute subduralhaematoma. Three of the patients wereimaged postoperatively.

Results-Lactate was identified as beingpresent if a negative peak at the correctchemical shift position changed from nega-tive on the SE1500/135 to positive on theSE1500/270. Lactate was detectable in allfour VOIs adjacent to the focal lesion; twoof which were greater than the N-acetyl-aspartate, choline or creatine peak areas.There was a smaller lactate peak in two ofthe remote regions.

Conclusion-Intracellular lactacidosis hasnow been demonstrated in the first hoursafter head injury in humans. Further studieswill explore its pathophysiological and thera-peutic implications.

1 Rango M, Lenkinski RE, Alves WM,Gennarelli TA. Brain pH in head injury: animage-guided "P magnetic resonance spec-troscopy study. Ann Neurol 1990;28:661-7.

THE AXONAL CYTOSKELETON IS ALTEREDEARLY IN DIFFUSE HEAD INJURY IN HUMANSMO Fitzpatrick, EA Irving, DI Graham, DDewar. Wellcome Surgical Institute and theInstitute of Neurological Sciences, SouthemGeneral Hospital, Glasgow, UK

Objective-To study the cytoskeleton in dif-fuse axonal injury and to detect specificmarkers of axonal injury.Design-Comparison of the immunoreac-

tivity of the microtubule component of thecytoskeleton in diffuse axonal injury andnormal brain tissue. Cases are age and sur-vival time matched.Specimens-Human postmortem brain tis-

sue with the neuropathological diagnosis ofdiffuse axonal injury (n = 11) and normalbrain tissue (n = 8).

Outcome measures-Monoclonal antibodyimmunohistochemical staining.

Results-There are disturbances in the

cytoskeleton in diffuse axonal injury in thehuman brain. These alterations were moremarked at longer survival times. Changes inthe distribution of the microtubule basedproteins were noted in white matter tracts atsurvival times up to six hours. This morpho-logical appearance may represent an earlystage in axonal pathology. The microtubuleassociated protein, MAP5, was a sensitivemarker of injured axons as early as sevenhours postsurvival.

Conclusions-Alterations in the cytoskele-ton can be detected early in diffuse axonalinjury and may reflect cytoskeletal break-down. These changes progressed with time.Disintegration of the microtubule systeminterferes with axonal function and could beimportant in the cascade of events precedingaxotomy and irreversible neuronal damage.Early markers of axonal injury permit fur-ther investigation of the pathophysiology ofwhite matter damage.

OPTIMISING OXYGEN DELIVERY INNEUROSURGICAL PATIENTS: ASSESSMENT OFTRANSFUSION REQUIREMENTSCJ Gerber, P deSouza, A Goringe, CAJWardrop, BA Simpson. Departments ofNeurosurgery and Haematology, UniversityHospital of Wales, Cardiff

In the critically ill patient, optimisation ofsystemic oxygen delivery (DO2) improvesoutcome. DO2 is influenced by both haemo-globin concentration ([Hb]) and blood vol-ume (BV, normal range 70-80 ml/kg). [Hb]is a ratio of, and so depends on, the plasmavolume (PV) and the total red cells in thecirculation-red cell volume (RCV, normalrange 20-35 ml/kg). Therefore, when PVand RCV fluctuate, [Hb] may not representaccurately the blood oxygen carrying capac-ity or blood volume (BV). Current bloodtransfusion practice may fail to optimiseDO2 in neurosurgical patients. 3RCV and [Hb] were estimated in a pilot

series of 40 patients (31 women, nine men)who had a major neurosurgical problem (forexample, head injury, subarachnoid haemor-rhage, intracranial tumour).

Generally, [Hb] correlated poorly withRCV and BV (r'2= 0-16, n = 40). In 17patients with normal [Hb], both RCV (19 1(4 7) ml/kg) and BV (54 3 (9 8) ml/kg) werelow.

Clinically unsuspected low BV is commonin neurosurgical patients. Reliance on [Hb]may result in suboptimal cerebral oxygena-tion in these patients. In such patients, RCVestimation gives a more accurate indicationof transfusion requirements. [Hb] does notgive a measure of RCV or BV.

THE PREDICTION OF DELAYED CEREBRALISCHAEMIA USING TRANSCRANIAL DOPPLERSONOGRAPHY AND MEASURING MEANCEREBRAL TRANSIT TIMEFC Wong, IR Piper, JD Miller, CStephenson, M Merrick. Department ofNeurosurgery, Leeds General Infirmary,Leeds and Department of ClinicalNeurosciences, Westem General Hospital,Edinburgh, UK

The value of combining transcranialDoppler (TCD) with the measurement ofmean cerebral transit time (MCTT) hasbeen investigated with the main aim of pre-dicting delayed cerebral ischaemia (DCI)more accurately.

Patients and method-Patients admittedwith a possible diagnosis of aneurysmal SAH

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were monitored. The mean flow velocities ofthe middle and anterior cerebral arteries(MCA and ACA) were measured. MCAmean flow velocities greater than 120 cm/s,or ACA/MCA velocity ratio greater than 1-2were considered abnormal. MCTT hadbeen measured using a technique developedin Edinburgh based on the first pass transitof technetium-99 through the cerebral circu-lation. MCTT greater than 7-7 seconds(95% confidence interval lies between 2-5 to7-7 seconds for normal MCTT) or inter-hemispheric asymmetry > 1 s in definedregions of interest were considered abnor-mal.

Results-Thirty two patients who had bothTCD and MCTT studies were suitable forfinal analysis. Using TCD results alone,TCD predicted 10 out of the 12 patientswho subsequently developed DCI, giving ita sensitivity of 83%. However, TCD resultswere normal in only four out of 20 patientswho did not develop DCI, giving it a speci-ficity of only 20%. Its positive and negativepredictive values were 38% and 67% respec-tively. When TCD results were combinedwith MCTT results, the sensitivity andspecificity of the combined tests were 67%and 70% respectively. Their positive andnegative predictive values were 57% and78% respectively.

Conclusions-The prediction of DCI usingTCD sonography alone was limited mainlyby a very poor specificity. When TCD wascombined with the measurement of MCTT,the sensitivity dropped from 83% to 67%but the specificity was greatly improved,from 20% to 70%. The positive and nega-tive predictive values were improved too.Therefore, the addition of MCTT to TCDstudies is potentially useful in the predictionof DCI.

REGIONAL AUDIT OF PATIENTS WITHTRANSIENT ISQHAEMIC ATTACKSJ Addison, P Tripathi, 0 Williams, JDPickard, PJ Kirkpatrick (on behalf of theEast Anglian TIA Audit Group). AcademicNeurosurgical Unit, Addenbrooke'sHospital, Cambridge, UK

Introduction-Questionnaires to determinethe variation in referral and treatment forpatients with TIAs, amaurosis fugax, andthose who have made a good recovery fromstroke, were distributed to all general practi-tioners (GPs), consultant physicians, andgeriatricians in East Anglia andBedfordshire. An internal study of patientsundergoing surgery between 1993 and 1994was also carried out to identify reasons fordelay in surgery.

Results-(A) Regional study: 1001 (59%)GP questionnaires were returned. Although984 (98%) start treatment with aspirin, only28% refer after the first TIA (a significantvariation between districts was found:18%-41%, P < 0 01). Most (62%) refer ifthe patient has further TIAs, and/or if thepatient had a carotid bruit (34%), and 34%consider such referrals as urgent. Of the 84consultant replies, 45% refer if the patienthad further TIAs and/or had a carotid bruit(20%), and 52% refer urgently. (B) Internalstudy: The median time to surgery (n = 56)after onset of symptoms was 124 days.Causes for delay included delay in GP refer-ral (median 90 days), delay in investigations(21 days), and subsequent delay in referralfor surgery (seven days).

Conclusion-Recent publication ofnational guidelines for the management of

carotid disease has not been followed byadequate implementation at GP or consul-tant physician level.

POSTERIOR TRANSARTICULAR SCREWFIXATION OF THE UNSTABLE ATLANTOAXIALJOINT: EXPERIENCES WITH 54 CASESATH Casey, A Madawi, R Veres, HACrockard. The National Hospital forNeurology and Neurosurgery, QueenSquare, London, UK

Objectives-In 1987 Jeanneret and Magerlfirst described this ingenious method for sta-bilising the atlantoaxial region. However,this technique is demanding and carries arisk of vertebral artery and spinal cordinjury. The question is does the increasedstability afforded by this technique justifythe potentially high risks involved?Design-We therefore decided to analyse

our own experience with this technique in acohort of 54 patients (1991-4) in particularexamining the operative complications.Radiological evaluation included dynamiccervical spine radiographs, and CT of theatlantoaxial region to assess stability andscrew location. If screw position or clinicalsymptoms were suggestive of vertebral arteryinjury the patient was further examined byangiography (n = 6).

Patients-The mean age of the patientsstudied was 52-5 (range 19-80). The indica-tions for surgery were classified into those ofrheumatoid arthritis (n = 35), psoriaticarthropathy (n = 1), trauma (n = 13), Chiarimalformation (n = 2), tumour (n = 1),infection (n = 1), and degenerative (n = 1).

Results-Stability of the atlantoaxialregion was achieved in 95% of cases. Injuryto the vertebral artery recognised at the timeof surgery occurred in three cases. In onecase this resulted in a Wallenberg's syn-drome. The other two patients were notneurologically compromised. A furtherpatient developed a delayed onset tetrapare-sis two weeks after surgery; vertebral angiog-raphy disclosed an occluded vertebral artery.Four patients (7 5%), all with rheumatoidarthritis, had fractured screws which wasrelated to screw malposition, with only uni-lateral screw purchase achieved. This instru-mentation failure occurred within threemonths of the procedure.

Conclusion-This technique has advan-tages over the existing methods of atlantoax-ial fixation, providing stability in 95%.However, enthusiasm for the demandingtechnique should be tempered by the risks ofvertebral artery injury and does not make ita procedure for the occasional operator.

QUANTIFICATION OF CEREBRALHAEMODYNAMIC RESPONSES AFTER INTERNALCAROTID ARTERY CLAMPING USING NEARINFRARED SPECTROSCOPYPJ Kirkpatrick, SA Love, MC O'Kane, DSimpson, P Smielewski, M Czosnyka.University Department of Neurosurgery,Addenbrookes Hospital, Cambridge, UK

Introduction-Near infrared spectroscopy(NIRS) and jugular venous oxygen (Sjo,)measurements have been used to charac-terise the cerebral haemodynamic eventsduring carotid endarterectomy.Methods-Forty one patients were moni-

tored with NIRS and transcranial Doppler(FV). In 21 Sjo2 estimations were made viaan ipsilateral jugular catheter. Mean vari-ables were calculated at specific stages ofsurgery and compared (paired t test). Two

patterns of changes in oxyhaemoglobin(HbO,) concentration were distinguished:Group 1 (n = 24) patients included thosewhere the fall in HbO2 was small (< 1,mol/l) or showed a rapid recovery ( >50%) towards baseline after internal carotid(IC) clamping. In group 2 (n = 17) HbO2signals showed little recovery (< 50%) or fellfurther.

Results-In group 1 an increased HbO2 (P- 0027) and total haemoglobin (P = 0 023)concentration was seen after clamp removalwhich was not seen in group 2. After ICrelease, the FV pulsatility index wasincreased above baseline values only ingroup 1 (P = 0 0082). Analysis of Sjo,changes showed a mean desaturation from67-8 to 65-5% after clamping, whichincreased to 69-8% after IC release. Thesedifferences were significant for right sidedcatheters only (P = 0.05 and P = 0-001respectively).

Conclusions-NIRS can distinguishchanges in cerebral haemodynamics whichare not seen with conventional monitoringfor carotid surgery.

POSTERIOR LUMBAR INTERBODY FUSION: ANEW TECHNIQUE IN THE MANAGEMENT OFLUMBAR DISC DISEASERW Gullan, AT King, GPF Selmon, CCPenney. Department of Neurosurgery,Brook General Hospital, London, UK

Posterior lumbar interbody fusion (PLIF)using the Brantigan carbon cage system is anew technique for the management ofdegenerative disc disease. Preliminary find-ings of a pilot study are presented using thissystem. Eleven patients (nine women, twomen) underwent a PLIF procedure for sin-gle level lumbar disc disease. The age rangewas 25-58 (mean 39 3) years. Follow upwas between 6 and 18 months (mean 10months, median 12 months), and over oneyear in eight patients. All patients had hadprevious disc surgery on the same level,twice in two cases. Three had gained norelief of symptoms from previous surgery. Ofthe remaining eight, recurrence of symptomsoccurred at between two months and 17years (median 20 months). All patients hadleg and back pain, with back pain being themajor complaint in five. Root tension signswere present in 10 patients. In sevenpatients radiology (MRI or CT myelogram)showed root compression. Leg pain wassymptomatically improved after surgery inall 11 patients. However, preliminary find-ings suggest that although this techniqueproduces radiological fusion, this does notnecessarily correlate with improvement inback pain.

CRANIOFACIAL ACCESS TO THE CLIVUSDA Lang, G Neil-Dwyer, BT Evans.Wessex Neurological Centre, andDepartment of Oral and Maxillo-facialSurgery, Southampton University Hospitals,Southampton, UK

Of 400 skull base operations using craniofa-cial access, 54 were done in patients har-bouring benign or low grade malignantpathology in the region of the clivus (54operations in 45 patients). There were 33women; age range 8-78 years. Most of thetumours were meningiomas (47%), chon-drosarcomas (11%), and chordomas (11%).A complete excision was achieved in 44%and a subtotal removal in 44%. The rest hada partial removal (9%) or biopsy alone (2%).

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Nine patients had postoperative radiother-apy. The mean follow up was 3-5 years

(range 6 months-7 years). Overall 33 had a

favourable outcome (73%), 5 (11%) were

severely disabled, and seven (16%) died.Whereas surgical expertise had been empha-sised in dealing with pathology in this regiona holistic approach is advocated, based on

the evidence obtained as to the care of thesepatients. The importance of preoperativepreparation/investigation, clear surgical aimsand objectives, and the role of biopsy are

emphasised. "Rules of access" have beendefined and key points underlined whendealing with the pathology, its vascularity,and effecting a safe reconstruction. It is con-sidered that a better outcome for patientsdepends on the recognition and acknowl-edgment of complications and the avoidanceof a narrow specialist view.

A TECHNIQUE TO PREVENT CSF LEAKAGEAFTER ACOUSTIC NEUROMA SURGERYNL Dorward, RD Illingworth, ADCheesman. Regional Neurosciences Centre,Charing Cross Hospital, London, UK

Objective-The evaluation of a new methodof meatal closure to prevent CSF rhinor-rhoea after retrosigmoid excision of acousticneuromas.

Design-Operations were performed by a

standard posterior fossa approach withdrilling of the internal auditory meatus(IAM) by an ENT surgeon. Before 1994 a

number of methods had been used to closeair cells in the IAM. Since January of 1994 a

small patch of superficial fascia, taken fromthe upper end of the retromastoid incisionand held with Histoacryl glue has been usedto close the IAM. Retrospective analysis ofthe incidence of CSF leakage before adopt-ing this method has been compared prospec-

tively with patients treated subsequently.Patients-Fifty consecutive patients

undergoing excision of acoustic neuroma ofall sizes from 1990 to 1995.

Results-Leakage occurred in nine of 23(39%) patients before the introduction ofthe new method. All of these required corti-cal mastoidectomy and fat implantation tostop the leak. After the introduction of thenew method one leak has occurred in 27(3-7%) cases and that settled after a lumbarpuncture (P < 0-01).

Conclusions-A graft of superficial fasciaheld with Histoacryl glue is an effectivemethod of closing air cells in the IAM andavoids the need to make a second incision toobtain fascia lata.

GASTROPROTECTION IN NEUROSURGERY: THEPRACTICE IN GREAT BRITAINTA Carroll, K Morris, D Rawluk. NationalNeurosurgical Unit, Beaumont Hospital,Dublin, Ireland

The indications for gastroprotection concur-

rent with corticosteroid use or as prophylaxisfor stress ulceration in the intensive care unitremain unclear. The aim was to determineto what extent gastroprotection is practised

in British neurosurgical units. Data were

obtained by questionnaire circulated first in1988 and then in 1994. A return of 76%and 74% respectively was obtained. Out of92 surgeons who replied in 1988, 49 rou-

tinely used a gastroprotective agent with cor-

ticosteroids and 47 with patients at risk of

stress ulceration-for example, severely headinjured. This compares with 63 out of 89surgeons using a gastroprotective agent withsteroid administration and 60 using prophy-laxis for stress ulceration in 1994. The gas-

troprotective agent of choice in 1988 was an

H2 antagonist (76) followed by antacids(36). In 1994, it was again an H2 antagonist(69) but sucralfate (15) was now the secondmost common agent used. The number ofreported peptic ulcer complications (perfo-ration or haemorrhage) among those sur-

geons who did not routinely use

gastroprotective agents was no higher thanthose who did. Our findings indicate exten-sive and increasing administration of gastro-protection agents within neurosurgery. Thepractice of H2 antagonist prescribing in theintensive care unit and the use of gastropro-tective agents with corticosteroids may notbe warranted.

WIDERANGING IMPROVEMENT AFTER

STEREOTACTIC PALLIDOTOMY (LEKSELL-LAITINEN OPERATION) FOR PARKINSON'SDISEASECHA Meyer. Midland Centre forNeurosurgery and Neurology, Birmingham,UK

Objective-To assess the effects of pos-

teroventral pallidotomy on symptoms ofParkinson's disease.

Design-Stereotactic pallidotomy was per-

formed unilaterally using the Hitchcockstereotactic system. Postoperative brainscanning confirmed the site of the thermole-sion. Patients took their established medica-tion both preoperatively and postoperatively.

Outcome measures-Patients were assessedduring off and on phases preoperatively andduring the week postoperatively by ratingscales (for clinical features and UPDRS) andby the time to complete standardised motortasks testing a wide range of voluntaryactions involving individual limbs or thetrunk and limbs.

Results-After stereoablation there were

statistically significant improvements (signtest) in dyskinesiae, rigidity, resting tremor,and action-postural tremor, improvementsin motor freezing, and restoration of auto-matic arm swinging. There was considerableimprovement (Wilcoxon tests) in bradykine-sia, especially during off phases, withimprovements-some striking-in a widerange of timed motor tasks testing hand andarm actions (unilateral and bilateral), repeti-tive foot movements, gait and, of particularinterest, various actions involving the trunk.

Conclusion-This operation has promisefor treating symptoms of Parkinson's dis-ease.

IMPORTANCE OF THE COCHRANECOLLABORATION TO NEUROSURGERYD Simpson, MC O'Kane, PJ Kirkpatrick.Academic Neurosurgical Unit, Adden-brooke's Hospital, Cambridge, UK

Evidence concerning the effectiveness of

health care is not readily available to clini-cians. Randomised controlled trials (RCTs)are most likely to provide accurate and reli-able information. Reports of originalresearch are numerous, hence most clini-cians rely on reviews as a means of copingwith the increasing volume of information.

The quality of many reviews varies because asystematic approach is not always followed.In particular the control of bias and randomerror is often overlooked. As a consequence,advice and recommendations on potentiallyeffective forms of care is often delayed.

In response, the NHS Research andDevelopment Programme established theUK Cochrane Centre in Oxford to facilitateand coordinate systematic review of treat-ments in health care. Their aim is to main-tain and disseminate evidence from RCTsthrough the Cochrane Database ofSystematic Reviews. Although considerablecontributions have been provided regardingimportant neurosurgical issues,' 2 severalareas in neurosurgery could still beriefit fromstandardised systematic review. TheCochrane Collaboration has identified 35such topics. The review group mechanismwithin the Collaboration provides neurosur-geons with the opportunity of delivering andmaintaining effective reviews in chosen areasof neurosurgery.

1 Anderson R, Meeker WC, Wirick BE, MootzRD, Kirk DH, Adams A. A meta-analysis ofclinical trials of spinal manipulation. JManipulative Physiol Ther 1992;15:181-94.

2 Brown EM. Antimicrobial prophylaxis in neu-rosurgery. J Antimicrob Chemother 1993;31:(suppl B) 49-63.

THE RELATION BETWEEN IDENTITYFUNCTIONING AND SEIZURE OUTCOME INPATIENTS WHO HAVE HAD SURGERY FORINTRACTABLE EPILEPSYDA McMackin, T Burke, JP Phillips, HStaunton. Richmond Institute,for Neurologyand Neurosurgery, Beaumont Hospital,Dublin, Ireland

Objective-Chronic seizures may impair nor-mal identity development and self evalua-tion. The objective of this study was toevaluate identity and self image after tempo-ral lobectomy for intractable temporal lobeepilepsy.Design-The methodology of identity

structure analysis (ISA) was employed,which facilitated the development of anepilepsy specific identity instrument. Twentyeight entities comprising significant othersand facets of self-image (ideal self) wererated on bipolar constructs representing 16areas of psychological vulnerability.

Subjects-The instrument was adminis-tered to 22 postoperative and eight preoper-ative temporal lobectomy patients.

Outcome measures-A two way analysis ofvariance was carried out to examine the rela-tion between seizure status and identityftunctioning.

Results-Both seizure free and palliativemedical outcome groups displayed signifi-cantly improved self evaluation although selfimage was more significantly enhanced inthe seizure free group. Those in the pallia-tive outcome group continped to perceivethemselves in a "sick role" by contrast withthe seizure free group. Those in the preoper-ative group displayed evideftce of a radicallydeclining self image.

Conclusion-These findings suggest thatpalliative medical outcome after temporallobectomy may serve to prophylacticallyarrest a declining self image while leavingmany of the psychological features ofchronic illness unchanged.

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LONG TERM FOLLOW UP OF PATIENTI S WITHEPILEPSY AFTER MODIFIED ANATOMICAILHEMISPHERECTOMYV Papanastassiou, Z Zaiwalla, SM Oxbury, JOxbury, CBT Adams. Department ofNeurological Surgery, The RadcliffeInfirmary, Woodstock Road, Oxford, UK

Anatomical hemispherectomy had beendescribed as the best procedure for epilepsycontrol, but was abandoned in the 1960sdue to the unacceptably high rate of longterm complications. In 1980, the operationwas modified in Oxford' and since thensome 45 patients have undergone this proce-dure for intractable, drug resistant, hemi-plegic epilepsy. Long term outcome data in23 of these patients, operated on between1981 and 1990, is presented. Their averageage at the time of surgery was 10-9 (range2-5 to 18-5) years. There were 13 boys and10 girls, with abnormality on the right in 12and on the left in 11. There was no mortal-ity. The pathological diagnosis includedperinatal brain injury (10), cortical dysplasia(four), Rasmussen's syndrome (three), post-encephalitis (three), Sturge-Weber (two),and infarction after embolus (one). Theaverage follow up period is 5-4 (range 1 to12) years, and 18 patients are now free ofepilepsy (78 3%), including 10 off medica-tion. Three patients have had a significant(> 75%) reduction in seizure frequency(13 0%), and two patients failed to improve(8-7%).

1 Adams CBT. Hemispherectomy-a modifica-tion. 7 Neurol Neurosurg Psychiatry 1983;46:617-9.

OUTCOME AFTER TIEMPORAL LOBE SURGERYFOR INTIRACTIABLE EPILEPSY IN THE

PAEDIATRIC AGE GROUPD Peterson, JH Cross, B Harding, BGNeville, WFJ Harkness. Great OrmondStreet Hospital for Sick Children, London,UK

Results are presented for temporal lobesurgery for medically refractory seizure con-trol in 20 patients with a mean age of 12-4years, performed between 1992 and 1994.Patients were assessed preoperatively inaccordance with an investigation protocolincluding neurological, neurosurgical, psy-chiatric, and psychometric opinions in addi-tion to MRI, EEG, and SPECT. Variousdiseases were encountered including dysem-bryoblastic neuroectodermal tumour(seven), hippocampal sclerosis (seven), andlow grade glioma (two) in addition totuberose sclerosis, cortical dysplasia,Rasmussen's encephalitis, and hamartoma(one each).Mean follow up of 21 (range 13-38)

months was achieved. All patients benefitedfrom surgery in terms of seizure control, 16patients became free of disabling seizures(Engel grade I). The remaining four patientsexperienced greater than 75% benefit inseizure control. All patients had improveddevelopmental and psychosocial scores.

In medically refractory epilepsy occurringin childhood, temporal lobe surgery mayprovide excellent seizure control withdemonstrated benefit in neurodevelop-mental outcome. These results comparefavourably with those seen in adult seriesand reinforce the strategy of early surgicalintervention.

RESULTS OF TEMPORAL LOBE RESECTIION FOREPILEPSY IN PATIENTS WITH A PREOPERATI IVEMRI DIAGNOSIS OF HIPPOCAMPAL SCLEROSISOR FOREIGN TISSUE LESIONBC Lopez, WFJ Harkness, J Duncan, DFish, S Shorvon, A Harding. The NationalHospital for Neurology and Neurosurgery,Queen Square, London, UK

The two year outcome after temporal loberesection for epilepsy is presented for 40patients operated on in the NationalHospital between October 1991 andOctober 1993.A preoperative diagnosis of low grade

neoplasia or hippocampal sclerosis wasmade by means of non-invasive tests includ-ing neuropsychometry, scalp electroen-cephalography, and MRI. The diagnosis wasconfirmed at operation in all cases.

In nine patients (22-5%) the diagnosiswas of dysembryoplastic neuroepithelialtumour (8-20%) or ganglioma (1-2-5%)with no side predominance. There were fivewomen (55%) and four men (45%), with anaverage age of 27 (range 23-38).Hippocampal sclerosis was diagnosed in 31patients (77-5%), 20 women (64-5%) with amean age of 28 years (range 20-46) and 11men (35-5%) with a mean age of 31 (range26-44). Right sided operations were pre-dominant in the women (12 right v eightleft), whereas in men left sided proceduresprevailed (seven left v four right).

All patients have been followed up for aperiod of at least 24 (mean 32; range 24-46)months. In the neoplasm group the overallseizure free rate was 66-7% (60% of womenand 75% of men). The outcome was slightlybetter in the hippocampal sclerosis group, inwhich 74% of patients were seizure free(75% of women and 72% of men). In thisgroup the outcome was better for left sidedlesions (80% left v 68-5% right seizurefree). Overall, 72-5% of patients haveremained seizure free, half of them withtheir medication reduced or stopped. Theresults were critically analysed using Engel'sclassification.

NEUROSURGICAL TREATMENT OFHYPOTHALAMIC HAMARTOMA CAUSINGGELASTIC EPILEPSYPK Doshi, CE Polkey, P Bullock. TheMaudsley Hospital, Denmark Hill, London,UK

Three patients, all boys, with gelasticseizures caused by hypothalamic hamar-toma, were treated by surgery. The meanage at the time of treatment was nine (range4-11) years. In one case the hamartoma waspedunculated and attached to the tubercinerium and in the other two they were ses-sile with a broad base and attached to thehypothalamus. A frontotemporal approachwas used. The pole and a part of anteriortemporal lobe were resected in one case toimprove the exposure. The hamartoma wascompletely excised in one patient and subto-tally excised in the other two.Postoperatively all three patients had a vary-ing degree of third nerve palsy. At the timeof follow up (mean 9; range 4-18 months)two patients had good seizure control (Engelgrade II) and one had some reduction in theseverity and frequency of seizures. It is con-sidered that the surgical excision of hypo-thalamic hamartoma causing gelasticepilepsy is possible and should be consid-ered in all medically intractable cases.

ENDOVASCUIAR OCCLUSION OF MIDDLECERFBRAL ARTERY: TREATMENT OFINTRACTABLE EPILEPSY BY MINIMAL. INVASIVE'I'ECHNOLOGYJP Phillips, J Toland, P Brennan, DAMcMackin, H Staunton. Department ofNeurology and Neurosurgery, BeaumontHospital, Dublin, Ireland

A 22 year old woman was referred forsurgery because of intractable epilepsy. Shepresented with cerebral palsy, mild mentalhandicap, and a mild right hemiparesis. Herseizure disorder began at age four.Throughout her childhood and adolescenceshe had frequent tonic clonic seizuresinvolving all four limbs with postictaldrowsiness occurring at least five times perweek. She also suffered partial seizuresoccurring on a daily basis. Telemetry con-firmed the presence of a left hemisphereepileptogenic source but without specificlocalisation. Brain MRI demonstrated ahemiatrophy involving the left cerebralhemisphere with a porencephalic cyst in thedistribution of the left middle cerebralartery. Cerebral angiography demonstratedimpaired circulation with revascularisationin the middle cerebral territory. Her visualfields were full.

She was ambulatory with retained func-tion in her right lower limb. She had a clawhand with reasonable proximal movement ofher right forelimb. Rather than carry out afunctional hemispherectomy with the disad-vantage of a homonymous hemianopia itwas elected to test the hypothesis that com-plete devascularisation of the revascularisedmiddle cerebral territory might reduce thevolume of epileptogenic cortex and reduceseizure frequency and severity.The right femoral artery was cannulated

and a detachable balloon catheter passeddistally without difficulty into the left inter-nal carotid artery. A 3 mm balloon wasplaced in position at the bifurcation of theleft internal carotid artery and expandedwith saline. Proprophrol anaesthesia wasutilised. Anaesthesia was reversed anda psychometric assessment performed.Neurological examination was unchanged.There was no speech or memory or cogni-tive deficit. The balloon position was con-firmed and detached from the deliverycatheter.

She underwent telemetry after theendovascular procedure. She had twoseizures in the first 10 days after operation.She had several minor partial seizures whichdid not develop. Telemetry showed occa-sional spike activity now localised to the leftfrontal region only. There was a 75% reduc-tion in seizure frequency in the postopera-tive three month follow up. Endovascularcoil obliteration of the residual frontal circu-lation is being considered.

COST-BENEFIT ANALYSIS IN EPILEPSYSURGERY

PO Byrne, AR Walsh. Department ofNeurosurgery, Queen Elizabeth Hospital,Birmingham, UK

Objective-To determine the cost of qualityadjusted life years (QALYs), after surgeryfor epilepsy.

Subjects-Twenty patients, age range 14to 55, mean 28-15 years, were operated onbetween June 1991 and September 1993,giving follow up of 12 to 40 months, average26-4 months. Nine patients were classifiedas Engel grade I, "seizure free", four

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patients as grade II, "almost seizure free",three patients as grade III, having a "worth-while improvement", and four patients asgrade IV, "no worthwhile improvement".

Results-For the purposes of this analysisEngel grade I was given a QALY value of0-8, grade II a QALY of 0-65, Grade III aQALY of 0 3, and Grade IV a QALY of 0.0.Using 1994/5 budget prices, a charge of£7957-40 per operation can be calculated,using total costs for the whole programmeand a flow chart of assessment of patientsfrom initial consultation all the way to resec-tional surgery. Estimated life expectancy to,say, 72 years gave an average of 43-85 yearsin this population; there were a total of10-7 QALYs derived from the treatmentof the population. The total cost,C7957 40, divided by the QALYs-namely,10-7 x 43-85, equalling 470-08 QALYs,gives the cost per QALY of C338-00. Thisfigure can be compared with league tables toassess other health care costs.' 2

1 Maynard A. Developing the health caremarket. The Economic Joumnal 1991;101:1277-86.

2 Pickard JD, Bailey S, Sanderson H, Rees M,Garfield JS. Steps towards cost-benefit analy-sis of regional neurosurgical care. BMJ71990;301:629-35.

ENDOSCOPICALLY ASSISTED VENTRICULAR

CATHETER INSERTION: COMPARISON WITHCONVENTIONAL BLIND TECHNIQUEGA Roberts, D Oluoch-Olunya, C Pidgeon.Beaumont Hospital, Dublin, Ireland

An endoscopically assisted technique forcatheter tip placement into the anterior hornof the lateral ventricle has been developed. Acohort of patients having had ventricularcatheters inserted with endoscopic assistancefor the purposes of ventriculoperitonealshunting, external ventricular drainage, andintraventricular intracranial pressure moni-toring were compared with an equivalentnumber of retrospective matched controlsand differences in terms of length of opera-tion, postoperative CT appearance, earlycomplications, and cost implications wereidentified.

FACTORS AFFECTING OUTCOME OFSTEREOTACTIC RADIOSURGERY (LINEARACCELERATOR) FOR CEREBRAL ARTERIOVENOUS MALFORMATIONSE Nenji, DA Yates, CHA Meyer. MidlandCentre for Neurosurgery and Neurology,Birmingham, UK

Design-During 1987-93, 63 patients hadcerebral vascular malformations (AVMs)treated by stereotactic radiosurgery using theHitchcock frame: localisation by orthogonalbiplanar stereoscopic paired angiograms,radiosurgical planning with CT giving sixnon-coplanar cranial slices, and treatmentby linear accelerator. Follow up was annu-ally by cerebral angiography. Changes inradiotherapy policy meant that reduceddoses of radiation were given to patientstreated in the midportion of the studyperiod.

Patients-Forty five patients with a singleAVM treated by single fraction radiosurgery,with follow up for two years or more. Lesiondiameters: large (over 2-5 cms) 20, medium12, small (1 cm or less) 13. Central dosebelow 2500 cGy in 23 patients; edge dose

below 1000 cGy in 17.Outcome measures-Obliteration or reduc-

tion ofAVMs on follow up angiograms.Results-Radiographic outcome (obliter-

ated, reduced, unchanged) at one year was10%, 43%, 47%; at two years 38%, 27%,35%-with no improvement thereafter.Outcome was significantly poorer (X2, Fisherexact probability test) if the AVMs werelarge, had a high flow rate, poor edgedemarcation, irregular shape, central dose3000 cGy or less, edge dose below 1500cGy, and if targeting failed to cover theAVM completely.

Conclusion-This technique can obliterateAVMs especially if lesions are small, spheri-cal, and totally encompassed by radiosurgerywith an edge dose of at least 1500 cGy.

AUDIT OF THE MEDOS PROGRAMMABLESHUNT: OUTCOME AT TWO YEARSA Kay for UK Medos Shunt Audit Group.Academic Neurosurgical Unit, Box 167,Addenbrooke's Hospital, Cambridge, UK

Objective-Evaluation of outcome two yearsafter insertion of a Medos programmablevalve for complex hydrocephalus.

Method-Multicentre audit study.Setting-Smethwick, Cambridge, Maudsley,

Southampton, Wakefield, Leeds, Sheffield,Royal London, St Bartholomews, Newcastle,Coventry, Belfast, Plymouth and Dublin.

Results-Of the 148 valves inserted in 139patients, 28 (18-9%) have been removed: 21(14%) due to infection; four (2 7%) due toshunt malfunction; two LP shunts due toprogramming difficulty; one due to ventricu-lar catheter disconnection. There were 13(8 8%) shunt revisions. Subdural collectionswere detected in 35 (23-6%) patients. Of the22 symptomatic collections, seven requiredevacuation and nine resolved at a higherprogram pressure. The mean adult Evansratio before shunting was 0 3 (n = 71) and0-21 (n = 25), 0-20 (n = 21) and 0-19 (n =12) at 6, 18, and 24 month follow uprespectively. The programming facilityproved useful in the control of headachepersisting after shunting. Outcome (Glasgowoutcome score) was good in 63 (52%),moderate in 31 (26%), severe in 17 (14%),PVS (0%), 19 (15%) died. Twenty seven(22%) patients had been discharged to thecare of their general practitioner at last fol-low up.

Conclusion-There is a learning curve forthe use of this valve but it facilitates themanagement of complex hydrocephalus.

EARLY EXPERIENCE WITH CHRONICELECTRICAL STIMULATION OF THETHALAMUS FOR THE CONTROL OF TREMORTRK Varma, A Forster, R Roberts.Departments of Neurosurgery, Neuro-physiology, and Neurology, Dundee RoyalInfirmary, Dundee, UK

Objective-To evaluate experience withchronic thalamic stimulation which has beenshown to be effective in the control oftremor refractory to medical treatment.'Design-A review of patients with tr mor

who underwent surgery for the placement ofthalamic stimulators.

Subjects-Five thalamic stimulators wereplaced in four patients (one bilateral) using atwo-stage stereotactic procedure with MRI

localisation and multimodel neurophysiolog-ical studies. All patients had chronic tremordue to Parkinson's disease or benign essen-tial tremor.

Outcome measures-Tremor control wasevaluated using tremor analysis, videorecordings, and the unified Parkinsonismrating scale or the essential tremor ratingscale. Complications and side effects werenoted.

Results-Three of the four patients hadabolition of the tremor during stimulationwith no side effects or complications. Onepatient had a microthalamotomy effect withsubsequent electrode migration.

Conclusions-Chronic electrical stimula-tion of the thalamus offers effective controlof drug refractory tremor and avoids thepotential hazards of thalamotomy.

1 Benabid AL, Pollak P, Gervason C. Long termsuppression of tremor by chronic stimulationof the ventral intermediate thalamic nucleus.Lancet 1991;337:403-6.

MEDIAL PALLIDOTOMY FOR DRUG INDUCEDDYSKINESIA AND RIGIDITY USING IMAGEFUSION AND STEREOPLANT Aziz, J Rowe, V Papanastassiou.Department of Neurological Surgery, TheRadcliffe Infirmary, Woodstock Road,Oxford, UK

Present day understanding of the neuralmechanisms underlying Parkinson's disease,would suggest that a precisely placed lesionin the medial pallidum should alleviate thesymptoms of rigidity, akinesia, drug induceddyskinesia, and possibly tremor.' Such alesion needs to be placed with extreme accu-racy, as encroachment on to the lateral pal-lidum will result in exacerbation rather thanrelief of symptomatology. In addition, exten-sion into the internal capsule or optic radia-tion would result in significant neurologicaldeficit. To place such lesions, surgeonswould normally extrapolate from the inter-commissural (AC-PC) line, 20 mm lateral,2-4 mm anterior, and 3-6 mm inferior tothe midcommissural point.2 Final localisa-tion would depend on intraoperative record-ing. We report the first ever use of theRadionics Stereoplan system with imagefusion to perform this procedure. The directcalculation of target coordinates usingStereoplan and MRI/CT image fusionresulted in greatly increased accuracy com-pared with the traditional method, con-firmed on postoperative MRI, with excellentclinical results and significant reduction inoperating time.

1 Aziz TZ, Peggs D, Agarwal E, Sambrook MA,Crossman AR. Subthalamic nucleotomy alle-viates parkinsonism in the l-methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP)-exposed primate. Br J Neurosurg 1992;6:575-82.

2 Laitinen LV, Bergenheim AT, Hariz MI.Leksell's posteroventral pallidotomy in thetreatment of Parkinson's disease. J Neurosurg1992;76:53-61.

USE OF IMAGE FUSION AND THE RADIONICSOPERATING ARM SYSTEM FOR IMAGE GUIDEDNEUROSURGERYV Papanastassiou, J Rowe, T Aziz. Depart-ment of Neurological Surgery, The RadcliffeInfirmary, Woodstock Road, Oxford, UK

The first ever use of image fusion and theRadionics Operating Arm System (OAS) for

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image guided neurosurgery (IGN) isreported. Both CT and MR images havebeen used separately for IGN and framebased stereotactic procedures.' The consen-sus of opinion is that, whereas MRI providesunsurpassed anatomical detail, it cannotmatch the three dimensional accuracy ofCT.2 The problem becomes particularlyimportant in functional neurosurgery andfor lesions that are deep seated and notdetectable with CT. This new techniqueallows MR images to be matched to the CTbone contour and thus retain the advantagesof both imaging modalities. Seven cases withdiverse pathologoanatomical characteristicshave highlighted the accuracy of the fusionprocess, the ease of use, and the operativebenefits of combining detail and accuracy.

1 Sandeman DR, Patel N, Chandler C, NelsonRJ, Coakham HB, Griffith HB. Advances inimage-directed neurosurgery: preliminaryexperience with the ISG Viewing Wandcompared with the Leksell G frame. Br 7Neurosurg 1994;8:529-44.

2 Sumanaweera TS, Adler JR, Napel S, GloverGH. Characterization of spatial distortion inmagnetic resonance imaging and its implica-tions for stereotactic surgery. Neurosurgery1 994;35:696-704.

ACCURACY OF CONTOUR MAP REGISTRATIONWITH THE ISG VIEWING WAND IN ROUTINECLINICAL PRACTICEC Bolger, P Byrne, PR Eldridge, MDMShaw. Walton Hospital, Rice Lane,Liverpool, UK

Objective-To investigate the "on the table"accuracy of the ISG viewing wand whenused as a routine tool in everyday neurosur-gical practice by all surgeons within thedepartment. Only one surgeon had formaltraining in the use of the wand.

Design-Patients were CT scanned (slicethickness 3 mm) with three fiducial markersin place before surgery. The patient was reg-istered to the wand with contour mapping,without reference to the fiducials, by theoperating surgeon. Accuracy of registrationwas checked independently by measuringthe difference between the true and wandpredicted fiducial position.

Subjects-To date 18 subjects (registra-tions) from six surgeons have been evalu-ated.

Outcome measures-Difference in true andwand predicted positions of three surfacefiducials.

Results-The mean (SD) differencebetween true fiducial position and wand pre-dicted fiducial position in this study was 3-4

(2) mm. There was a wide range of accuracyfrom 1 to 8-5 mm. Most of the variation wasassociated with one surgeon and if thesethree patients are excluded the mean differ-ence was 2-6 (1) mm.

Conclusions-These results support theuse of the ISG viewing wand as an aid togeneral neurosurgical practice, particularlyfor surgeons without an interest or trainingin formal stereotaxy. However, whereasaccuracy levels of 1 mm are obtainable, thewand should not universally be applied as areplacement for currently performed stereo-tactic procedures. Variation between sur-geons emphasises the need for accuracychecks before embarking on surgical inter-vention.

FRAME BASED IMAGE GUIDED STEREOTACTICPROCEDURES FOR MASS LESIONSMS Sankhe, TRK Varma. Department ofNeurosurgery, Dundee Royal Infirmary,Dundee, UK

Objective-To study the pathological yieldrate, histological diagnosis, and complica-tions of stereotactic surgery for mass lesions.

Design-Retrospective analysis of opera-tive details, histology, and complications of109 stereotactic procedures.Patients-One hundred and two patients

aged 4 to 77 years underwent stereotacticprocedures for mass lesions.

Outcome measures-Histological confirma-tion of diagnosis, identification of technicalproblems and evaluation of complications.

Results-There were 109 procedures in102 patients, with 76 (69-7%) biopsies and30 (27 5%) excisional procedures. Therewere six infratentorial lesions, and onepatient underwent an abscess drainage, can-nulation, and localisation. There were 101(92 6%) procedures done under CT guid-ance and eight (7 3%) under MRI guidance.A positive histological diagnosis wasobtained in all except four procedures, onlyone patient had neurological deteriorationafter the procedure, and one immunocom-promised patient died perioperatively due tofulminant meningitis.

Conclusions-The stereotactic proceduresfor mass lesions have a high reliability with alow morbidity.

1 Arbit E, Galicich JH. Importance of imageguided stereotactic biopsy to confirm diagno-sis in an oncological setting. Ann Surg Oncol1 994;1 :368-72.

2 Tasker RR. State of the art reviews.Neurosurgery 1987;2:165-91.

EVALUATION OF VISLAN, A NEW STEREO-VIDEO BASED SYSTEM FOR PREOPERATIVEPLANNING AND INTRAOPERATIVE GUIDANCEAJ Strong, ACF Colchester, RE Evans, JZhao, CJ Henri, DGT Thomas, P Roberts,N Maitland. Maudsley, Guy's, and NationalHospitals, London, UK and Roke ManorResearch Ltd, UK

Objectives-Current intraoperative imagebased guidance systems rely on mechanicalposition sensing and are not ideal for use inconjunction with the operating microscope.Alternative systems based on optical detec-tion of position are being developed by sev-eral groups: most systems use specialisedcameras to detect infrared LEDs.Methods-We have developed a more ver-

satile system where passive illumination isused with a pair of standard video cameraswith three functions. (1) The three dimen-sional shape of a part of a patient's face orscalp is reconstructed, and is used to providean initial registration with preoperativeimage data. (2) Markers which are attachedto the patient around the craniotomy, oralternatively to the Mayfield clamp, arelocalised by the system and used to updateregistration if patient movement occurs. (3)A hand held surgical pointer without con-necting cables is tracked in real time. Thecomplete VISual LANdmark systemincludes software for segmenting, registeringand displaying structures in preoperativeimages, as well as for merging these withintraoperative video images.

Results-After test shifts between two sur-faces of ± 5 mm and ± 100 the system wasable to reregister to 0 5 (SD 0 3) mm and0 3 (0 3) degrees. During stereo-videoreconstruction of a surface obtained frompatterned light, the SD of deviation of calcu-lated points from the flat plane was ± 0-15mm. The system has been evaluated in fourpatients undergoing surgery for glioma, andin one patient with an acoustic neuroma.Registration and verification in theatre mayrequire as little as 20 minutes. Surgical util-ity in respect of convenience, speed ofresponse and compatibility with the operat-ing microscope was very considerable.

Conclusions-Initial experience of this sys-tem is highly encouraging, although modifi-cations to the target capture routine arerequired to reduce its vulnerability to adverselighting conditions. In addition to use in the-atre, the preoperative facilities in the systemmay have significant potential as an aid toneurosurgical training and education.

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