SPINE Volume 19, Number 9, pp 1037-109]
`@1994. ]. E. Lippincou Company
`
`I Removal of a Protruded Thoracic Disc
`
`Using Microsurgical Endoscopy
`A New Technique
`
`Daniel Fiosenthal, MD.” Haul Rosenthal, MD,T and Anna de Simone, MDI:
`
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`A herniated disc in T64‘! was refnoved
`Eldon
`and tliespinei cord was deeompreseed; The patient
`recovefliiil Qbrlipletely and viies discharged at the ‘sev-
`'eritl1 postoperative day. He returned to work Jiweeks
`laten. .-
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`.
`.
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`Conclusions. The mierosurgical endoscopic tech-
`‘
`" niqtie-a|Iovrs.,'spIna| cord decompression with e-eub-
`fsrsfitial reduction in surgical trauma. It may shorten
`bed eonfinernent and allow early return to active life.
`Application of this technique in other areas is being
`studied, [Key words: disc herniation, dorsal spine, en-.
`dosoopic‘surg§t§r, spinal cord compression, ventral ap-
`proach _lo the spine] Spine t99l»':19:1001-_'1o_9I_
`
`Thoracic disc herniation is a rare cause of spinal cord
`compression that presents a variety of nonspecific
`symptoms leading to a wrong or delayed diagno-
`sis.‘"‘13"”"13‘23‘25*29 Until
`the early 1960s, numerous
`reports indicated that thoracic disc herniation had a
`subtle onset, required a complex therapy, and had a
`poor pr0gn0si5.3’”‘13 Arseni and Nash3 noted that the
`condition of about 50% of their patients deteriorated or
`remained unchanged after surgical decompression via a
`dorsal approach (laminectomy). In the following years,
`a variety of techniques, such as the c0stotransversecto—
`my“’”““ (and its modification,” the arthtopedicuieo
`tomyms) and the transthoracic8’22’24'25 approaches,
`were reported to be suitable for removing thoracic disc
`herniation without manipulating the spinal cord. How-
`ever, these techniques entail the use of thoracotomy or
`From the ‘Department of Neurosurgery, llniversiry Hospital, Franl<—
`Eurt am Maim'Germany, ‘(Department of Surgery, Nordwest Hospital,
`Frankfurt am M.aim'Germany, and 1Department of Neuroradiology,
`University Hospital. Frankfurt am Main, Germany.
`Accepted for publication October 27, 1993.
`
`wide bony resection of vertebral structures to reach the
`ventral part of the spine. Better imaging techniques
`(computed tomography and magnetic resonance imag-
`ing) and the development of new surgical procedures
`have substantially improved the prognosis of thoracic
`disc protrusion/T‘
`We report on a new microsurgical endoscopic tech‘
`nique (MET) that permits disc removal while substan-
`tially reducing the “approach-related” trauma.
`
`I Surgical Technique and Postmortem Studies
`
`Fresh, unautopsied cadavers were used for the study. After the
`body was placed in a left lateral decubitus position (Figure 1),
`the intervertebral space to be operated upon was located under
`endoscopic and fluoroscopic control. We prefer a dextrolateral
`approach because the aorta and the heart are displaced to the
`left paraverrebral area, improving spinal visualization and re-
`ducing the risk of complications. Four trocars (Ethicon, Ham-
`burg, (jermany) then are inserted in a triangular fashion along
`the middle axillary line, converging to the disc space (Figure
`1]. A rigid endoscope with :1 30° angle optic (Karl Storz,
`Tiittlingen, Germany) with a single chip camera attached to it
`(Kari Storz, Tijttlingen, Germany) were introduced through
`one of the trocars, leaving the other three as working channels
`(Figure 1).
`Surgery began by splitting the parietal pleura, starting at
`the medial part of the intervertebral space and extending up to
`the costovertebral process. The segmental arteries and the
`sympathetic nerve was mobilized out of the operation field and
`preserved. Part of the posterior aspect of the vertebral body
`and the proximal portion of the costovertebral process were
`drilled off, improving visualization of the spinal canal. Bone
`and disc removal were restricted to the posterior third of the
`intervertebral space and the costovertebral area so stability
`was not compromised. Removal of the disc and the posterior
`longitudinal ligament, using special forceps and rongeurs, then
`were performed. The instruments must be about 33 cm long to
`reach the spine comfortably. ll fusion is required, bone can be
`harvested from the ribs, iliac crest, or fibula; the positioning of
`the patient makes this possible. When surgery was finished,
`chest tubes were placed and set under watt-r—sealed suction.
`Between July and November 1992 and with the help of the
`Pathology Department of the University Hospital, Franl-zfurt
`am Main, we were able to standardize the approach. Twenty-
`etght thoracic discs were removed in six cadavers under con-
`ditions similar to those per training in the operating theater.
`The mean operative time for disc removal and inspection of
`
`1087
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`1038 Spine - Volume 19 ' Number 9 ' 1994
`
`Figure 1. Position on the operating table and distribution in the
`operating theater. The surgeons [SJ and nurse with the instru-
`ments U! are standing in front of the patient. The monitor WI} is
`placed at the back. The “working channels." ii, 2, 3: converge
`toward the spine. The channel for the optical system I4} is situated
`ventrally.
`
`the spinal canal was 2.17 hours. The last six discs and poste-
`rior ligaments were removed in a mean time of L38 hours.
`Clinical work was started after the technique was standard-
`ized, skills were developed, and the approach was performed
`safelv.
`
`extradiiral mass between T6—T7 (Figure 2, left). The preopv
`('l'3ll\-‘C diagnosis \=i'-as thoracic disc herniation. Siimatosen-sr>r_v—
`and motor—evoked potentials showed a slight increase in la-
`tencies on both sides.
`After analyzing the clinical and radiologic findings, we
`decided to remove this lesion using MET. Consent to use the
`new approach was obtained from the patient before surgery
`and after detailed information was provided.
`Using MET, a herniated, sequestrated thoracic disc was
`removed. The postoperative course was uneventful. The pa-
`tient was able to walk 24 hours after surgery. without body
`jacket. The chest drainages were removed on the second post-
`operative day (after 200 cc of serum was drained). The post-
`operative control MRI showed that the spinal canal was com—
`pletely decompressed and free of disc material
`(Figure 2.
`right).
`Upon discharge, he was still complaining about numbness
`in the genital region, although it had improved compared to
`the preoperative status}. No other deficits were observed. The
`wounds were closed and the sutures were removed on the sixth
`day. Somatosensory- and motor-evoked potentials still
`showed a slight increase in latency. He was discharged on the
`7th postoperative day.
`The first follow up examination took place 6 weeks after
`the p-.ltient's discharge. Clinical symptoms and soniatosen—
`sory-evolr.ed potentials had normalized. The patient had been
`working for 2 weeks without problems.
`
`I Discussion
`
`Case Report. Upon admission to the hospital, a 3il—}'ear—tild
`man was complaining of bilateral pain at the T7 level, gait
`disturbances, and numbness in the genital region that had
`begun 4 weeks earlier.
`Cerebrospinal fluid examination showed no abitormalitv,
`Plain x—rays of the dorsal region were iiornml. The MR] ex-
`amination revealed a clear, ventrally locatecl intraspinal and
`
`Pathaphysiologic Considerations
`The first surgical treatment of thoracic disc herniation
`was reported by Adsonl“ in 1922, who performed .1
`lantiriectomy and disc removal. The results obtained in
`subsequent years were disappointing and helped to doc-
`ument that the dorsal approach has an unpredictable
`
`Figure 2. Mi Preoperative MRI
`shows the herniated disc be-
`tween TB—T'i' and spinal cord
`compression larrowl. {BI Postop-
`erative MRI: The spinal cord is
`decompressed. The gap between
`TE—T? iarrtiwl shows where the
`intervertebral space was en-
`tered. The spinal cord is decom-
`pressed.
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`outcome and is exceedingly risky, probably because spi-
`nal cord retraction is required to reach the disc, which is
`situated anterior to the spin-ai cord.”
`Experimental and clinical reports demonstrated that
`compressive lesions situated ventrally in the thoracic
`spine frequently were followed by poor results when
`surgical treatment was attempted using the dorsal ap-
`proach.” A logical explanation for this is that the spi-
`nal canal is narrower at the thoracic level and manipu-
`lation leads to microcontusions that worsen the already
`compressed and ischemic, probably causing secondary
`damage. Deficits in blood supply through the segmental
`arteries also were discussed. Doppman and Girtonm
`found neurologic deterioration in all patients in whom
`ligature or thrombosis of a segmental artery occurred.
`On the other hand, Currierg described abundant collat-
`eral circulation around the neural foramina, routinely
`ligating the segmental vessels unilaterally, without ad-
`verse effects. A combination of microcontusions and
`
`alterations in microcirculation probably is the more ap-
`propriate explanation for this phenomenon.
`
`indications for MET
`
`Laminectomy has been practically abandoned and re-
`placed by ventral, ventrolateral, or dorsolateral ap-
`proaches, which have improved results because of the
`reduction in spinal cord manipulation.5‘3’”'l7'18‘22‘23'Z5
`Early surgical decompression is accepted as the treat-
`ment of choice,” and a wide variety of techniques has
`been described for this purpose.5‘5‘8'12‘2l‘23’25 All re-
`quire either bony removal of vertebral structures (caus-
`ing or worsening instability) or a thoracotomy to gain
`access to the ventral spinal canal and minimize cord
`manipulation.
`The posterolateral, lateral, and transpedicular tech-
`niques have been criticized because of postoperative
`instability in some cases,u'19 insufficient visibility over
`the midline,19‘2? and sectioning of muscle or ribs to
`improve visibility.”
`During the last 10 years, 16 patients with thoracic
`disc protrusions have been successfully treated at our
`department using the transthoracic approach. Although
`Arce and Dohrmannl reported that the best results are
`obtained with this technique, it has become unpopular
`for discectomy and is reserved only for special indica-
`tions, such as vertebral body resection and fusion.” The
`need for a second surgical team {thoracic surgeon),”
`insufficient exposure of the thoracic spine,19‘23 and re-
`spiratoty complications derived from thoracotomyzo are
`considered to be its main disadvantages by most au-
`th0rs_19,2o,27,2s
`Microsurgical endoscopy permits the same approach
`as the transrhoracic route, except for rhoracotomy.
`With appropriate instruments, any lesion situated ven-
`trally and compressing the cord probably can be re-
`moved with this technique.
`
`Removal of a Protruded Thoracic Disc ' Rosenthal et al
`
`1089
`
`Figure 3. Horizontal view at the T6 level. The patient is in the left
`lateral decubitus. 1, right lung lcellapsedl; 2, heart and pericar-
`dium; 3, esophagus; 4, aorta; 5, forceps and endoscope; 6, left
`lung; 7, surgeon.
`
`Preoperative considerations
`Patients who will undergo surgery using MET need to
`have their pulmonary function optimized. For patients
`with asthma or emphysema, pulmonary functional sta-
`tus should be improved befote surgery is considered.
`Marked respiratory deficit can be a contraindication for
`MET because unilateral ventilation may worsen hypox-
`emia.
`
`Advantages and Difficulties
`One problem to consider is that microsurgical endos-
`copy does not differ much from the hazards neurosur-
`geons are familiar with during microsurgical operations.
`Some abilities, however, need to be acquired. The sur-
`geon needs to look at the monitor in front of him or her
`with his or her head tilted up in a 90° angle while
`coordinating hand movements. Placing the surgeon and
`his or her assistant ventrally facilitates orientation and
`coordination. Nevertheless, we believe a period of prac-
`rice and adaptation is mandatory.
`The advantage of the left lateral decubitus position is
`that
`the spine can be reached while avoiding direct
`contact with the aorta, esophagus, and the pericardium,
`because these structures are displaced to the left para-
`vertebral area (Figure 3). Because of the intubation
`associated with using a Robertshaw—type tube (Malliric-
`krodt Laboratories, Athlone, Ireland) and intraopera-
`tive unilateral ventilation, the long on the surgical side is
`
`3
`
`

`
`1090 Spine ° Volume 19 ' Number 9 ' 1994
`
`without further lung retraction. Reducing trauma to the
`thoracic wall and to the lung parenchyma may prevent
`a variety of complications.7'20 This was confirmed in
`our patient by an insignificant intraoperative blood loss
`(100 ml), reduced consumption of analgesics in the post-
`operative period, and a considerable reduction in the
`amount of bed confinement after surgery.
`The lack of instruments suitable for MET may com-
`plicate surgery. We have used a variety of instruments
`that were designed for abdominal iaparoscopic surgery.
`Some prototypes and further applications for MET are
`now being developed at our department.
`MET ensures disc removal. It permits a wide expo-
`sure of the thoracic spine by changing only the insertion
`site of the trocars. A review of the literat11re1’2 showed
`that out of 258 patients, only 12 (4.6%) had a disc
`protrusion above T4, and 24 (9.3%) below T12, mak-
`ing MET suitable for over 80% of patients. Under ex-
`perimental conditions, we were able to reach the spine
`successfully from T4 to T11. Clinical experience will
`undoubtedly show us the real potential of this method.
`Herniated soft disc (medial or lateral) or calcified pro-
`trusions can be removed without compromising the spi-
`nal cord.
`
`In case fusion is needed, bone grafts can be brought
`into the thoracic cavity by dilating the holes made by the
`trocars. As a result of eariy mobilization, the incidence
`of thrombosis decreases as well. This is significant, es-
`pecially in elderly and high risk patients.
`Finally, by getting the same benefits as with other
`surgical procedures——early release and return to work
`(reducing hospitalization time up to 50"/o)—this tech-
`nique helps decrease therapy costs.
`
`I conclusions
`
`MET is a modification of the thoracic approach that
`allows complete disc removal with a substantial reduc-
`tion in surgical trauma (fewer wound and pulmonary
`complications). It shortens confinement to bed (reducing
`the risk of thrombosis) and reduces the postoperative
`period {early discharge). A training period is obligatory,
`although it should be learned easily by those familiar
`with microsurgical techniques.
`
`Acknowledgments
`
`We are grateful to Prof. K. Hiibner, Head and Chairman
`of the Department of Pathology from the University
`Hospital, Frankfurt am Main, and his coworkers for
`enabling us to perform postmortem studies. We also
`thank to Mrs. W Dutiné for her help in preparing this
`article.
`
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`4
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`

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`Removal of a Prorruded Thoracic Disc - Rosenthal et al
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`
`Address reprint requests to:
`
`Daniel Rosenthal, MD
`Kiinik for Neurochirurgie
`Klinikum der Johann Wolfgang Goethe Universitat
`Sch-leusenweg 2-I6
`60528 Frankfurt am Main
`Germany
`
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