Postgraduate Medical Journal (1989) 65, 656- 659

Missed Diagnosis

Single central nervous system lesions can simulate multiplesclerosis

D.G. Grosset, D.M. Hadley and I. Bone

Institute ofNeurological Sciences, Department ofNeurology, Institute ofNeurological Sciences, Southern GeneralHospital, Glasgow G51 4TF, UK.

Summary: Three cases are reported in which an initial misdiagnosis ofmultiple sclerosis was made. Ineach of these a single central nervous system lesion with space occupying effect was present. These lesionscaused confusion because multiple closely running neurological tracts were affected, and there was relapseand remission in the neurological signs and symptoms produced. We conclude that such cases need carefulassessment to determine whether a single structural lesion could explain the presentation. Early imagingmay show remediable lesions or prevent unnecessary steroid therapy.

Introduction

Relapsing and remitting neurological symptoms andsigns should be carefully assessed to determine wheth-er an underlying single structural lesion could beresponsible. We report three cases in which delay indiagnosis was caused by an initial incorrect label ofmultiple sclerosis.

Case reports

Case I

A 17 year old girl had episodic dragging of the left legand dull aching limb pains over a period of 2 years.There had been transient left limb weakness 6 yearspreviously. Initial assessment found only bilateralankle clonus. Multiple sclerosis was presumed butfurther investigation not instituted. During the nexttwo months, progressive difficulty in walking followeddue to stiffness ofboth legs. There was a single episodeof paraesthesia of one hand. Precipitancy of micturi-tion developed. The limb pains had by now remitted.She was referred for neurological assessment. Thisshowed spastic paraparesis with dorsal column sen-sory loss in the legs and an area of hyperaesthesia inthe right tenth thoracic dermatome. Poor heel-shincoordination was elicited, due to proprioceptive loss

and weakness. Plain spinal X-rays showed con-siderable widening of the lower cervical and upperthoracic canal with retained bony cortication,indicating a chronic expanding lesion. Cervicalmyelography showed a large exophytic intramedullarytumour extending downwards from the level of thesixth cervical vertebra (Figure 1). The cerebrospinalfluid had a high IgG:albumin index at 0.94, referencerange 0.26-0.66, but was otherwise normal with nooligoclonal bands. At laminectomy, a huge intradurallipomatous swelling extended from the sixth cervicalto the third thoracic vertebra. It was only partiallyresectable as there was no plane of cleavage with thecord. Microscopically it was a lipoma. There was slowreturn to almost normal walking, but only partialproprioceptive recovery, at review 3 years later.

Case 2

A 25 year old man had transient diplopia followed bynumbness of the face and left palm. There were noabnormal physical signs. He deteriorated while onintramuscular ACTH therapy for presumed multiplesclerosis. Neurological referral was made. He haddeveloped a small right pupil, a right 6th nerve palsy,internuclear ophthalmoplegia, vertical nystagmus, mildright facial weakness, reduced perioral and left facialsensation, and slight dysarthria, with decreased sensa-tion to all modalities in the left arm and leg, and a leftextensor plantar. Computed tomography and

D The Fellowship of Postgraduate Medicine, 1989

Correspondence: D.G. Grosset, M.R.C.P.Accepted: 9 March 1989

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SINGLE CNS LESIONS CAN SIMULATE MS 657

Figure 1 Myelogram in Case 1, showing widened cer-vicothoracic canal with contrast outlining a chronicexpanding exophytic intradural lesion, at operationfound to be a lipoma.

magnetic resonance imaging showed a largehaematoma in the right pons, compressing and disp-lacing the 4th ventricle (Figure 2). There was nosubarachnoid blood. Bilateral vertebral angiographywas normal. Repeat computed tomography andmagnetic resonance scans at one month, and magneticresonance scans at three months, showed slow resolu-tion of the haematoma. Visual evoked responses werenormal. Cerebrospinal fluid was normal with nooligoclonal bands. The patient was managed conser-vatively during a total hospital admission of 60 days.Three months later there was no detectableneurological deficit.

Case 3

A 48 year old man developed slurred speech, emo-tional lability, and transient right leg weakness. Sixyears previously an episode ofabrupt unconsciousnessfollowed a hot bath. Five years previously he sufferedtwo tonic clonic seizures. Three years previously

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Figure 2 (a) Sagittal (SE 500/40) and (b) axial (IR2000/400/40) MRI in Case 2, showing a right pontinehaematoma.

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658 D.G. GROSSET et al.

during two weeks of unsteady walking, he had slurredspeech for 3 hours. In the previous 10 months therewas intermittent right sided ptosis with pupillarydilatation, choking with food, and slurred speech.Examination elicited hyperactive reflexes with apositive jaw jerk, and the optic discs had possibletemporal pallor. Cerebrospinal fluid examination forpresumed multiple sclerosis was normal. One monthlater he was referred for neurological assessment. Thereflex changes noted previously were confirmed. Adilated unreactive right pupil, a slight right ptosis, andright sided tongue wasting had now developed. Therewas dysarthria and dysphonia, and a mild right limbweakness. Magnetic resonance examination showed a3 cm diameter partially thrombosed aneurysm disp-lacing the pons posteriorly and the third ventriclesuperiorly, with compression of the aqueduct andconsequent hydrocephalus. Angiography showed theaneurysm to arise from the right internal carotid arterynear the posterior communicating artery (Figure 3).The aneurysm was clipped and excised.

Postoperatively a left hemiparesis due to a smallcapsular infarction (computer tomographyconfirmed) was attributed to temporary clipping oftheinternal carotid artery. At two years, severe left armweakness remained, but swallowing and speech hadimproved.

Discussion

An initial misdiagnosis of multiple sclerosis was madeelsewhere in these cases, and in each a single structuralspace-occupying lesion in the central nervous systemwas responsible: spinal lipoma, pontine haematoma,and intracranial carotid aneurysm respectively. Singlelesions can remit and relapse simulating multiplesclerosis.'"2 Slower expanding lesions (Cases 1 and 3)may produce longer symptom-free intervals (4 and 2years respectively) but in an acute presentation (Case2) remission of some symptoms may occur whileothers develop. The relapse-remit pattern also occursin brainstem gliomas3 and angiomas,4'5 spinalangiomas,6 foramen magnum lesions,7 cerebellartumours,2 meningiomas,8 cerebral lymphoma,9 andarachnoid cysts.'0Apparent dissemination, simulating demyelination,

is produced when a lesion disrupts multiple closelyrunning tracts. Spinal cord (Case 1), brainstem (Cases2 and 3), and cerebellar and optic tract involvement,are emphasized in this regard." Temporal optic discpallor (suspected initially in Case 2) should not berelied upon as sole evidence of eye involvement" andhence of dissemination; evoked response testing ishelpful in these circumstances.'2

Diagnostic criteria for multiple sclerosis'3 classifypatients into clinically and laboratory-supported

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Figure 3 (a) Sagittal (SE 700/32) MRI and (b) carotidangiogram in Case 3 with a right internal carotid arteryaneurysm impinging on and displacing the anterior pons.

definite, and probable, groups on the basis of attacksof neurological dysfunction, physical signs, andlaboratory investigations. Application ofsuch criteria,

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SINGLE CNS LESIONS CAN SIMULATE MS 659

mandatory in clinical research, also provides a usefulframework for individual case diagnosis.'4 None oftheillustrated cases fulfil the Poser criteria; the definitionofseparate symptoms and signs,"I which must never beexplicable by a single lesion, is of paramount impor-tance here. Criteria for multiple sclerosis can befulfilled when multiple sclerosis is not the correctdiagnosis, however.'3 Selection of patients requiringearly investigation can be helped by 'negative'criteria' casting doubt on the diagnosis, one or more ofabsence of eye signs, remissions, sensory findings, orbladder involvement. Normal visual evoked responsesand/or spinal fluid analysis (Case 3) will heightensuspicion of an alternative diagnosis,4 but the falsenegative rate for both investigations is high in earlymultiple sclerosis.'5 In Case 1, however, the firstepisode was 4 years prior to presentation, and inves-

tigative delay was due to clinical well-being. Treat-ment without investigation (Case 2) will confuse if analternative cause is steroid-responsive.9

In conclusion. a relapsing and remittingneurological illness in which clearly disseminatedinvolvement is not present may be due to a singlestructural space-occupying lesion. Early investigationin such circumstances can lead to identification ofremediable conditions.

Acknowledgements

We would like to thank our neurosurgical colleagues. TheMagnetic Resonance Imaging unit is funded by grants fromthe Medical Research Council and Scottish HospitalsEndowment Research Trust.

Referencess

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2. Matthews, W.B. Differential diagnosis. In: Matthews,W.B. (ed.) McAlpine's Multiple Sclerosis. ChurchillLivingstone, London, 1985, pp. 146-166.

3. Britt, R.H., Connor, S.W. & Enzmann, D.R. Occultarteriovenous malformation of the brainstem simulatingmultiple sclerosis. Neurology 1981, 31: 901-903.

4. Stahl, S.M., Johnson, K.P. & Malamud, N. The clinicaland pathological spectrum of brain-stem vascular mal-formations. Long-term course simulates multiplesclerosis. Arch Neurol 1980, 37: 25-29.

5. Sadeh, M., Shaked, I., Rappaport, Z.H. & Tadmor, R.Surgical extirpation of a venous angioma of the medullaoblongata simulating multiple sclerosis. Surg Neurol1982, 17: 334-335.

6. Aminoff, M.J. & Logue, V. Clinical features of spinalvascular malformations. Brain 1974, 97: 197-2 10.

7. Cohen, L. & Macrae, D. Tumours in the region of theforamen magnum. J Neurosurg 1962, 19: 462-469.

8. Bickerstaff, E.R., Small, J.M. & Guest, I.A. The relaps-ing course of certain meningiomas in relation to preg-nancy and menstruation. J Neurol Neurosurg Psychiatry1958, 21: 89-91.

9. Ruff, R.L., Petito, C.K. & Rawlinson, D.G. Primarycerebral lymphoma mimicking multiple sclerosis. ArchNeurol 1979, 36: 598

10. Lehman, R.A.W. & Fieger, H.G. Arachnoid cyst pro-ducing recurrent neurological disturbances. Surg Neurol1978, 10: 134-136.

11. Kurtze, J.F. Clinical manifestations ofmultiple sclerosis.In: Vinken, P.J. and Bruyn, G.W. (eds) Handbook ofClinical Neurology, volume 9. North Holland PublishingCompany, Amsterdam, New York, 1970, pp. 161-216.

12. McDonald, W.I. The role of evoked potentials in thediagnosis of multiple sclerosis. In: Bauer, H.J., Poser, S.,Ritter, G. (eds) Progress in Multiple Sclerosis Research.Springer-Verlag, New York, 1980, pp. 564-568.

13. Poser, C.M., Pary, D., Scheinberg, L. et al. Newdiagnostic criteria for multiple sclerosis: guidelines forresearch protocols. Ann Neurol 1983, 13: 227-231.

14. Ebers, G.C. Multiple sclerosis and other demyelinatingdisease. In: Asbury, A.K., McKhann, G.M., McDonald,W.I. (eds) Diseases of the Nervous System. Heinemann,London, 1986, pp. 1268- 1281. %

15. Matthews, W.B. Laboratory diagnosis. In: Matthews,W.B. (ed.) McAlpine's Multiple Sclerosis. ChurchillLivingstone, London, 1985, pp. 167-209.

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