treatment of thoracic disc herniation: evolution … · 11.09.2000 · will be given to the...

Few disorders have undergone more dramatic changesin neurosurgical management than thoracic disc hernia-tion and its evolving diagnosis and treatment. A relativelyunusual diagnosis for the neurosurgeon to make, this dis-order accounts for approximately five of every 1000 discherniations encountered in the clinical setting. The natur-al history can vary from a chronic pain disorder to suddencatastrophic neurological compromise.12,13 In 1911, thefirst surgical procedure for a herniated thoracic disc wasreported by Middleton and Teacher (as described in Ben-jamin1); it involved a patient with paraplegia who subse-quently died. This dismal outcome was unfortunately notuncommon for patients with this disorder as recognitionof the disease evolved.

The diagnosis of thoracic disc herniations had alwayspresented a challenge, especially when based solely onhistory and clinical findings. Imaging this region of thespine, which is contained within the surrounding chestcavity within a plethora of different tissue densities, is al-so difficult. Before the introduction of MR imaging, clin-icians were limited to the use of plain x-ray film and CTscanning. Plain films were useful when a calcified protru-sion was present; however, although thoracic discs dohave a higher tendency to become calcified than herniateddiscs in other vertebral locations, fewer than one half ofthese calcifications are evident on plain film studies.1 The

advent of myelography and CT myelography dramatical-ly improved the clinician's ability to recognize thoracicdisc disease radiographically. Overall, however, MR im-aging is still the first-line modality for imaging the tho-racic spine (Fig. 1). In the modern era of diagnostic MRimaging, the CT myelogram remains an indispensable ad-junct in both the diagnosis of herniated disc material andis equally important in determining exactly which verte-bral segment is involved. The risk of performing surgeryat the wrong spinal level is ever present and obliges thesurgeon to be vigilant and definitive in identifying the ap-propriate surgical level.2,35

As stated earlier, the treatment of herniated thoracicdiscs has undergone significant changes since the first sur-geries were attempted. Early cases were treated solely viaa dorsal approach and involved a significant risk of caus-ing irreversible paraplegia,12,13 with operative mortalitiesapproaching 10%.13 As surgeons began to explore alterna-tive techniques that allowed the lateral and ventral surfaceof the thecal sac to be exposed, the risk of neurologicalinjury was reduced dramatically. The last decade has seenthe application of minimally invasive methods to the treat-ment of thoracic disc herniation; these procedures havebrought about a significant change in the postoperativecare of these patients: critical care requirements and dis-charge times have been reduced dramatically.14,26,27,29,30,34

The purpose of this report is to review the evolution thathas taken place in the treatment of thoracic disc hernia-tion, with special attention to improvements in anatomicalapproaches and advances in technology. Special emphasiswill be given to the technique of thoracoscopic surgery fordisc herniation.

Neurosurg Focus 9 (4):E9, 2000

Treatment of thoracic disc herniation: evolution toward theminimally invasive thoracoscopic technique

TIMOTHY G. BURKE, M.D., AND ANTHONY J. CAPUTY, M.D.

Department of Neurosurgery, The George Washington University, Washington, DC

Thoracic disc herniation has always carried with it the potential for serious adverse neurological consequences ifnot treated appropriately. The authors review the historical evolution of treatment for thoracic disc herniation from theearly surgical series using dorsal approaches (which were known to involve a significant risk of paraplegia) to latersurgical series in which lateral and then ventral approaches to the disc were increasingly emphasized, with significantimprovement in patient outcome.

The evolution of minimally invasive thoracoscopic techniques is discussed, together with the results of several sur-gical series demonstrating significant reductions in morbidity compared with more traditional methods. The techniqueof thoracoscopic discectomy is presented in detail.

KEY WORDS • thoracic spine • herniated disc • thoracoscopic surgery • endoscopy •minimally invasive surgery

Neurosurg. Focus / Volume 9 / October, 2000 1

Abbreviations used in this paper: CT = computerized tomog-raphy; LECA = lateral extracavitary approach; LPEA = lateral para-scapular extrapleural approach; MR = magnetic resonance; VATS =video-assisted thoracoscopic surgery; 3D = three-dimensional.

HISTORY OF SURGERY FOR THORACIC DISCHERNIATION

Dorsal Approaches

Early treatment options for spinal cord compressionfrom disc herniation were limited to simple laminectomy.The first known case of a surgically treated disc herniationwas reported in 1922 by Adson (as described by Zeidman,et al.,37) who performed laminectomy and disc removal.

Mixter and Barr25 reported three cases of ruptured tho-racic disc herniations in 1934. Two of these patients devel-oped postoperative transverse myelopathy, and the otherwas only mildly improved after some time (see Zeidman,et al.,37 for historical review). The results of many otherearly dorsal approach procedures for herniated discs weretypical equally dismal.12,13 In a pivotal paper published in1952, Logue19 reported the results of surgery in a series of11 patients: three postoperative cases of paraplegia, twodeaths, and two cases of mild improvement after a tempo-rary increased motor weakness. In 1969, Perot and Mun-ro29 reviewed 91 cases from the literature on herniatedthoracic discs, all treated by dorsal approaches. Excep-tionally, Horwitz, et al.,14 reported good outcomes in fiveconsecutive cases of herniated thoracic discs treated usinga dorsal approach.

Many variations in surgical technique were applied inthese early cases. Some surgeons advocated simply per-forming a decompression without disc removal to avoidthe potentially harmful effects of spinal cord manipulationrequired to reach the ventrally located disc herniation. Theopposite extreme was to attempt to reach the disc materi-al via an intradural approach that involved sectioning thedentate ligaments with adjunctive rhizotomy.13,14 It wasbelieved that this approach permitted improved ventralvisualization. The significant rate of postoperative neuro-logical deficits after laminectomy for thoracic disc her-

niation was thought to be due to a combination of vascu-lar insufficiency and microcontusions secondary to spinalcord manipulation.37

Posterolateral Approaches

To avoid spinal cord manipulation, many surgeons be-gan to look for approaches that would allow a more directapproach to the disc space.

As with many of the surgical techniques that have beenapplied to the thoracic spine, the costotransversectomybears its roots in the treatment of Pott's disease. In 1894,Ménard24 first described the use of this technique to reachthe vertebral body via an expleural route. In 1958 Hulme15

used costotransversectomy to treat thoracic disc hernia-tion. The use of rib resection and removal of the transverseprocess in this approach provides a significantly moreventral window than that of laminectomy or later trans-pedicular techniques.

In 1978, Patterson and Arbit (as mentioned in Zeidman,et al.,37) described an approach involving removal of theentire pedicle and facet, which provided a more direct lineof exposure to the ventrally located disc space. This trans-pedicular approach evolved from recognition of the highmorbidity rates associated with treating thoracic discs byusing laminectomy, along with pulmonary and variousother complications found with the alternative lateral andventral surgical approaches to the thoracic spine. It shouldbe noted that the degree of anterolateral exposure afford-ed by the transpedicular approach, although much im-proved over that of simple laminectomy, is still limitedcompared with the more extensive lateral and ventral ex-posures. This exposure is particularly important whentreating a disc that is calcified or located in the midline. Inthe original series of Patterson and Arbit,28 all patients pre-sented with myelopathy and reportedly made uniformlygood recoveries.

A potential advantage to the transpedicular approachover costotransversectomy, transthoracic, and LECAs isthat it entails no damage to the radicular vessels. The pos-sible adverse effect of sectioning these vessels has longbeen a concern for many surgeons. It is well establishedthat the thoracic spinal cord is a watershed vascular zone.The artery of Adamkiewicz (arteria magna radicularis)usually arises on the left side at T8–L2.31 Based on thisanatomical fact, some surgeons have suggested obtainingan angiogram if the possibility exists for any division ofleft-sided thoracic radicular vessels.5,14,21 Mansour, et al.,22

reported an interesting case in which a patient sufferedfrom a Brown–Séquard syndrome from a left-sided later-al disc herniation at T9–10, with only radicular compres-sion. The site happened also to be the location of the arteryof Adamkiewicz in this patient, and thus the disc hernia-tion was presumed to be the cause of a vascular event.

Continuing efforts to improve the exposure of theventral surface of the spinal cord led to use of the LECAfor herniated thoracic discs. Capener4 first developed thistechnique for the treatment of tuberculous spondylitis;it was later applied to thoracolumbar fractures. This ap-proach provided the following advantages over othermethods for accessing the thoracic and thoracolumbarspine. 1) It afforded excellent ventral exposure of the cord.2) It was a completely extrapleural procedure. 3) It pro-

T. G. Burke, and A. J. Caputy

2 Neurosurg. Focus / Volume 9 / October, 2000

Fig. 1. Sagittal T2-weighted MR image of a herniated thoracicdisc with spinal cord compression at T-7. Note that the identity ofthe spinal level cannot be absolutely confirmed from this study; itis inferred by the marking. A myelogram is usually obtained toconfirm the level precisely.

vided surgeons with the ability to span both the thorax andabdomen without taking down the diaphragm. Maiman, etal.,21 used the LECA for thoracic disc herniation in 23cases, and none of their patients experienced new deficitspostoperatively. On the other hand, this approach has sig-nificant shortcomings. It requires exceptionally extensivesoft-tissue dissection and manipulation. More seriously,the paraspinous muscles are mobilized medially, thus de-nervating and devascularizing these structures. This maycontribute to poor wound healing and an increased risk forpostoperative kyphosis. With this approach it may stillbe very difficult to remove intradural disc fragments, al-though in their series, Maiman, et al., did not find this tobe the case.

The LPEA, developed by Fessler and colleagues9 pro-vides exposure of the upper thoracic spine comparable tothat provided by the LECA. The major additional risk en-tailed by this procedure compared with the LECA is thatof significant shoulder girdle problems, due to the fact thescapula is mobilized in a lateral direction.

Ventral Approaches

Use of a transpleural approach to the thoracic spine fordisc herniation dates to 1958, when Crafoord, et al.,6 re-ported the use of this technique in a patient with a herni-ated disc. In 1969, Perot and Munro29 reported the use ofthis technique for thoracic disc herniation in two patients.In that same year, Ransohoff and Spencer30 reported onthree patients with thoracic disc herniations treated with atransthoracic approach. Since the appearance of these twopivotal reports, there have been several series3,26,27 sup-porting the efficacy of this approach. Anatomically, it pro-vides unparalleled ventral exposure of the spinal cord,which not only creates a safe working channel adjacent tothe spinal cord but also provides the optimal angle forremoval of intradural discs and for dural repair. It also per-mits multiple levels to be addressed via the same approachif required. The obvious disadvantage to the transpleuralapproach is the risk of pulmonary morbidity. Risk ofinjury to major vascular vascular and visceral structuresis also present. The initial postoperative days are alsomarked by a considerable amount of pain secondary to thethoracotomy approach and presence of a chest tube. Itshould also be noted that this technique is limited to treat-ment of the T-5 disc space or below.

Thoracoscopic Approach

The advantages of a minimally invasive ventral ap-proach to the treatment of thoracic disc herniationsseemed obvious. Today, most spine surgeons would agreethat a ventral approach is most appropriate for anythingother than a far-lateral disc herniation.1,29,30,33 The mainobstacle to using the ventral approach was the associatedmorbidity of a thoracotomy. Patients were obliged tospend several days in the intensive care unit, undergo tho-racostomy drainage, and experience significant postoper-ative pain. Intercostal neuralgia, both temporary and per-manent, is also a potential drawback associated with thistechnique.

The dramatically improved optics and lighting of rigidglass endoscopes, developed by physicist Harold Hopkinsin 1970, nurtured the rapid growth of endoscopic surgical

techniques (see biographical articles by Gow10,11 and Jen-nings16). Thoracic surgeons recognized the potential ad-vantages of a minimally invasive technique for biopsy anddrainage procedures compared with the currently avail-able open technique, which involved significant risk ofmorbidity to the patient. In 1991 Lewis18 reported the useof VATS, which quickly proved to be a viable approach.Soon various centers were attempting increasingly com-plex procedures, including lung-lesion resections. Landre-neau, et al.,17 reported on 106 such cases in 1993, in whichhe compared VATS with thoracotomy. The patients whounderwent VATS suffered less pain and had improved pul-monary function and superior shoulder girdle functioncompared with thoracotomy patients. In the same year,Mack, et al.,20 published a report demonstrating the po-tential of VATS to provide a reliable route to the ventralsurface of the thoracic spine. In 1995 Caputy, et al.,5 dem-onstrated the successful use of VATS in performing a tho-racic discectomy in both a cadaver and porcine model. Inthat same paper a clinical case of a thoracoscopic discec-tomy was also reported. Although thoracoscopy was wellestablished in the field of thoracic surgery, the practicalityof its use in spine surgery remained in question. The rapiddevelopment and availability of special long instrumentshas facilitated the application of thoracoscopic spine tech-niques (Fig. 2).

Several large series have since been published demon-strating the efficacy of VATS and the reduced morbidityassociated with its use when compared with traditionalopen approaches.8,23,32,36 Note that although the benefit ofVATS is usually compared only with the alternative ofthoractomy, some data suggest that it is also a less mor-bid procedure than costotransversectomy. Rosenthal andDickman32 reported on a series of 55 patients who under-went thoracoscopic discectomy; they compared the rateof complications between thoracotomy patients and cos-totranversectomy patients with thoracic disc herniation.There were no instances of postoperative neurologicaldeterioration in either the thoracoscopy or thoracotomygroups, but of those patients undergoing costotransversec-tomy, 7% experienced neurological deficits after surgery.Intercostal neuralgia, both temporary and permanent, haslong been a significant problem associated with thoraco-tomy. The use of VATS has significantly reduced the inci-dence of this painful disorder, which frequently prevents

Neurosurg. Focus / Volume 9 / October, 2000

Surgical treatment of thoracic disc herniation

3

Fig. 2. Photograph of three types of endoscopic drills. Cuttingand rough-diamond burrs (bottom) are displayed. Long protectiveouter shafts minimize the risk of injury to other tissues.

patients from resuming their normal levels of activity. Inthe series reported by Rosenthal and Dickman, there wasa 16% rate of intercostal neuralgia in the VATS groupcompared with 50% in those patients who had a thoracot-omy. In all patients in the thoracoscopic groups with in-tercostal neuralgia, the condition was temporary and re-solved completely within 1 to 2 weeks. In those patientsundergoing a costotransversectomy there was a 20% rateof intercostal neuralgia.

A major criticism of minimally invasive surgery is theincrease in the total amount of time that usually is in-volved in such procedures. Although it is certainly truethat VATS takes longer than the transpedicular approach,this is not necessarily the case when compared with thealternative ventral approach, that is, the thoracotomy. Inour experience with the performance of VATS for thoracicdisc herniations, the mean operation time has been 260minutes (unpublished data). In their group of 55 patients,Rosenthal and Dickman32 reported a mean operation timeof 205 minutes. In thoracotomy patients the mean surgicaltime was 268 minutes, and those undergoing costotran-versectomy spent an average of 280 minutes in the oper-ating room. An additional concern regarding the currenttrend toward minimally invasive procedures is that theoverall effectiveness of the procedure is jeopardized. If thepatient is spared a painful and potentially morbidity-in-ducing thoracotomy only to undergo an endoscopic tech-nique that leaves the pathology unresolved, then treatmenthas certainly failed. Rosenthal and Dickman examined therate of retained disc fragments in those patients undergo-ing VATS, thoracotomy, and costotranversectomy, andfound that in the thoracotomy group there were no in-stances of retained fragments, whereas in the thoraco-scopy group 4% of patients retained incompletely re-moved fragments. Costotranversectomy yielded a retaineddisc fragment rate of 13%. In 1999, Dickman, et al.,8 re-ported on a group of 15 patients who had undergone sur-gery for herniated thoracic discs and were found to have

retained fragments. Eleven of these patients had previous-ly undergone a posterolateral approach, one had under-gone a thoracotomy, and three had undergone VATS. Thevast majority of these lesions were calcified. Thoraco-scopic techniques were used for reoperation in all but onepatient, who required a thoractomy.

From the above information, it appears that VATS pro-vides a very effective method of treating thoracic disc dis-ease, including reoperative situations.8 Although the datasuggest that thoracotomy may provide a slight decrease inthe rate of retained disc fragments, the significant differ-ence in postoperative morbidity between these two proce-dures seems to support the use of a thoracoscopic ap-proach.

Description of Endoscopic Technique

Patient Position and Operating Room Setup. The later-al decubitus position is used with the operative side up,unless the pathology is distinctly to the right; in that casethe left side of the thorax is preferred due to the locationof the inferior vena cava on the right. The patient is se-cured to the operating table with three-in tape; security istested by rolling the table from side to side before thepatient is prepared and draped. The spine surgeon and car-diothoracic assistant work on the ventral side of the pa-tient, while the second assistant is positioned at the dorsalside. Two video monitors are positioned, one on each sideof the patient's head (Figs. 3 and 4).

Localization of Operative Level. An x-ray film may beobtained after patient positioning is completed to assist inoptimal port placement. Alternatively, the ports may bepositioned followed by placement of a long bovie tip inthe estimated disc space by counting from the first rib,which lies adjacent to the subclavian artery and under-neath a pad of fat (Fig. 5). Proper placement of the opera-tive ports is particularly important to ensure that awkwardangles are not created for the surgical instruments. It isalso important to avoid placing ports too close together;



Fig. 3. Artist's illustration showing the proposed setup of theoperative suite for a thoracoscopic discectomy. The spine and car-diothoracic surgeons stand to the ventral side of the patient whilethe assistant is positioned on the dorsal side. Two video monitorsare always used. The patient is in the lateral decubitus position.

Fig. 4. Photograph showing the operative suite setup during acase of thoracoscopic discectomy. A 3D endoscopic system isshown in this paricular case. Note the liquid crystal display 3Dglasses.

this creates a frustrating situation in which the surgeon'sinstruments tend to make contact with the shaft of eitherthe endoscope or the suctioning device.32

Port Placement and Exploratory Thoracoscopy. Asmall skin incision is made toward the superior border ofthe caudal rib at the desired level to avoid damaging theneurovascular bundle of the cephalad rib. A Kelly clampis used to enter the pleural cavity, being careful not to in-jure the underlying lung. The first port is placed, and thishelps the surgeon visualize additional port placement. Fora standard discectomy, three ports are typically used. Theuse of soft rubber ports has recently become popular, inthe belief that they have less tendency to traumatize theintercostal nerve. It is not yet known whether the inci-dence of postoperative intercostal neuralgia has actuallybeen reduced by the use of these devices. At this point, thechest surgeon explores the thoracic cavity and takes downany pleural adhesions. The patient is then rolled ventrallyto allow the lung to fall away from the vertebral column.If this maneuver is not adequate to expose the vertebralstructures, the anesthesiologist may be asked to attemptfurther deflation of the ipsilateral lung. Lung retractionmay need to augmented by the use of a special fan retrac-tor, although we frequently find that the aforementionedtechniques suffice (Fig. 6).

Rib Resection. Once the operative level has been con-firmed with certainty, the pleura over the disc space andproximal rib is incised. The segmental vessels are typical-ly dissected and ligated with hemoclips, then cut with spe-cial endoscopically-guided cautery scissors. The pleura isthen mobilized from the rib head by an endoscopic Cobb

elevator. During our early experience with the procedure,the rib was typically removed in a 2- to 3-cm en bloc seg-ment and saved for potential grafting. The current tech-nique involves drilling the proximal 2 cm of the rib headwith a rough-cut diamond burr (Midas Rex, Fort Worth,TX) (Fig. 7 and Video Clip 1). The diamond bit serves tocontrol bone bleeding significantly, thereby improvingvisualization.

Click here to view Video Clip 1.

Pedicle Removal. The next step is to view a normal seg-ment of the thecal sac. This is accomplished by a combi-nation of drilling and application of Kerrison rongeurs.Bleeding from the epidural plexus is frequently encoun-tered at this point, but is easily controlled with bipolarcautery or Avitene (Davol, Kalamazoo, MI).

Creating a Working Trough. To prevent causing ana-tomical deformity or vascular compromise in the spinalcord, a pyramid-shaped space is created ventral to the spi-nal cord by removing a portion of both the cephalad andcaudal vertebral body with the drill (Fig. 8). Once thisspace is created, the disc material is pulled away from thethecal sac into this cavity (Video Clip 2). Throughout theprocedure the disc is pulled away from the spinal cord andthus no instruments are placed in the canal. The amount ofbone removed is dictated by the extent of the disc hernia-tion. One must always remove enough of the vertebralbody to be able to visualize normal dura on both sides ofthe disc herniation. For large calcified discs, somethingakin to a partial corpectomy is performed. Generous ver-tebral body resection is also performed when an intradu-ral fragment is found. Instability has not been a problemin this procedure, and a graft is usually not placed.



5

Fig. 5. Endoscopic intrathoracic view in a cadaver demonstrat-ing the rib-counting method to identify the operative level. The firstrib is typically hidden under the subclavian fat pad (SC). The sec-ond rib (2) is usually easily identified.

Fig. 6. Photograph of a thoracoscopic lung fan retractor, whichis used to facilitate exposure of the spinal column if lung deflationis not sufficient.

Fig. 7. Intraoperative photograph demonstrating the use of therough-cutting diamond burr to remove the rib head. The action ofthe diamond burr is to minimize bleeding while still providing acutting burr for more aggressive bone removal. Only the very endof the rotating shaft and burr are exposed from the protective sheath.

Video Clip 1. Thoracoscopic view of removal of the T-9 pedi-cle for a heavily calcified T8–9 herniated disc. The rib head hasalready been removed with the use of a drill. The use of the rough-cutting diamond bit can be seen to minimize the amount of bonebleeding encountered. A medium-sized hemoclip can be seen at thebottom of the screen on a previously divided segmental vessel. Thepulsations of the heart can also be seen.


Discectomy. After the vertebral body is fully resected,the disc material may be safely pulled away from the spi-nal cord into the working trough (Video Clip 3). The de-compressed canal must be palpated along the contralater-al pedicle with a long probe (Fig. 9 and Video Clip 4) tocheck for any residual intradural fragment; if found, thisshould be carefully removed while dissecting the discfrom the pia and arachnoid with a microdissector. The du-ra is then sealed with a tissue patch and fibrin glue. A lum-bar drain is placed postoperatively. It is also recommend-ed that the chest tube be placed on water seal, rather thansuctioned.32



Any remaining bleeding is then controlled by Gelfoamwith thrombin and Avitene. The pleural cavity is then irri-gated with a copious amount of antibiotic solution, whichis then suctioned out. A single chest tube is implanted; inmost cases this remains in place for 24 hours.

The Learning Curve

The procedure used to access and treat lesions of thethoracic spine with the aid of endoscopic guidance entailsthe use of techniques that may be foreign to most spinesurgeons. Becoming familiar with the hand–eye coordina-tion required to manipulate the endoscope takes manyhours before real agility is achieved. Becoming comfort-able with the use of extremely long instruments also re-quires practice.

The authors believe strongly that it is the duty of aca-demic programs to take the initiative in teaching both re-sidents in training and surgeons in the surrounding com-munity the new and evolving techniques, as well as toprovide an environment for continued development ofcompetency. At the George Washington University, forexample, the neurosurgical residency program has devel-oped structured training sessions in the endoscopic labo-ratory using live porcine models to train residents in tho-racosopic techniques before they attempt them in theclinical environment (Fig. 10). This has provided an inval-uable experience for the safe and effective teaching of ademanding surgical technique. The authors hope that oth-ers will emulate this model for the education of others inthe field.

CONCLUSIONS

The surgical treatment of few disorders has undergoneas dramatic an evolution as that of thoracic disc herni-ation. From an era in which surgery incurred significantmortality and dramatic morbidity rates, the field has pro-gressed to the point where effective procedures are viewedas routine, with significant improvements in patientoutcome.

Continued advances in technique, surgical instrumenta-tion, and endoscopic technology have suggested that thefuture may hold continued improvements for the treat-ment of this potentially devastating disorder. There arenow many published reports of minimally invasive en-doscopic surgery for the treatment of other disorders ofthe thoracic spine and neuraxis, such as tumors, as well asfor placement of instrumentation.7 While such advances



Fig. 8. Postoperative 3D CT scan demonstrating bone removalneeded to perform adequately a thoracic discectomy. The rib headhas been removed. It can also be seen that the cephalad portion ofthe caudal pedicle has been removed to expose the lateral aspect ofthe thecal sac. A significant cavity has been created in the vertebralbodies of the two adjacent levels. This cavity provides a workingtrough that allows the surgeon to pull disc material away from thespinal canal, thus avoiding compression of the spinal cord.

Fig. 9. Intraoperative photograph of a thoracoscopic proceduredemonstrating the exposed and decompressed thecal sac (whitearrow).

Video Clip 2. A partial corpectomy, or working trough, hasbeen previously created with the use of the drill. A portion of thecalcified disc material has been decompressed from the spinal can-al by pulling the disc away from the cord into the trough. An endo-scopically-guided pituitary rongeur is used to remove a remainingdisc fragment. The decompressed thecal sac is seen.

Video Clip 3. A thoracoscopic curette is seen being used to pullremaining calcified disc material into the working trough. The ex-posed lateral portion of the dura is clearly seen. This exposure isobtained by previous removal of the rib head and pedicle.

Video Clip 4. A straight probe is used to palpate across to thecontralateral pedicle along the ventral surface of the decompressedthecal sac. This is done to assure that no remaining portion of her-niated disc material is left behind. Again the motion of the heartcan be seen in the bottom portion of the screen.

should be viewed as welcome, their safety and efficacymust also be subjected to critical review before they canbe accepted into the spine surgeon's armamentarium.

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37. Zeidman SM, Rosner MK, Poffenbarger JG: Thoracic disc dis-ease, spondylosis, and stenosis, in Benzel EC, Stillerman CV(eds): The Thoracic Spine. St. Louis: Quality Medical, 1999,pp 297–303

Manuscript received August 17, 2000.Accepted in final form September 11, 2000.Address reprint requests to: Timothy G. Burke, M.D., Depart-

ment of Neurosurgery, The George Washington University, 2150Pennsylvania Avenue, NW, Suite 7-450, Washington, DC 20037.email: [email protected].



7

Fig. 10. Photograph of the porcine endoscopic surgical labora-tory at The George Washington University. This facility is dedi-cated to the education of surgeons in various endoscopic surgicaltechniques. It provides an invaluable resource for teaching thora-coscopic spine surgery in a safe and effective manner.

treatment of thoracic disc herniation: evolution … · 11.09.2000 · will be given to the...

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