Cervical intramedullary schwannoma: complete ...

British Journal of Neurosurgery 2000; 14(4): 345± 372

CASE REPORTS

Cervical intramedullary schwannoma: complete excision using the KTP laser B. I. OGUNGBO1 , R. D. STRACHAN1 & N. BRADEY2

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Departments of 1 Neurosurgery and 2 Neuroradiology, Middlesbrough General Hospital, Middlesbrough, UK

Abstract Intramedullary cervical spinal cord schwannomas are rare tumours and complete excision is often an elusive goal. The use of the KTP laser to accomplish complete excision has not been reported previously. Postoperatively, our patient had no additional de® cit and after 1 year has made a good recovery. This case further highlights the difficulty in interpretation of intraoperative biopsy specimens. Key words: Cervical, intramedullar y spinal cord, laser, schwannoma.

Introduction Reports of subtotal excision of intramedullary schwannomas of the cervical spinal cord indicate that complete excision is the desired goal, but seldom achieved.The various techniques advocated to achieve this include ultrasound localization, ultrasonic aspiration and planned two-staged operations.1± 4 The application of the laser in neurosurgery is established5 and we have frequently employed the potassium titanyl phosphate (KTP) laser in excision of acoustic neuromas and other intracranial benign tumours. Although the use of the laser for the removal of cervical cord tumours has been reported, this is the ® rst report of its effective use in the complete excision of a cervical intramedullary schwannoma. Case report A 24-year-old Caucasian male was originally seen by a rheumatologist complaining of clawing of the fingers of the right hand, associated weakness of hand grip over a period of 2± 3 years, and more recent gait disturbance and incoordination affecting the right side of his body. A neurological referral was made and clinical examination con® rmed muscle wasting in the right upper limb with clawing of the hand. He had evidence of a spastic tetraparesis worse on the right side. He also had a partial Brown± SeÂquard lesion with altered joint position and vibration sense on the contralateral side. MRI of the brain was normal. MRI

of the cervical spine revealed an enhancing lesion within the spinal cord extending from C4 to C7 (Figs 1 and 2). There were multiple cystic areas above the tumour extending as high as the brain stem and below the tumour as far as T2. These appearances were therefore radiologically strongly suggestive of an intramedullary astrocytoma or ependymoma. Surgical exploration through a C4 to C7 laminectomy was performed. Opening the dura revealed considerable expansion of the cord with an odd looking exophytic tumour growing from within the cord and compressing it at its lower pole, but intrinsically buried within the cord at its superior pole. There was a considerable vascular network over the cord and tumour in the midline, making a midline myelotomy more difficult. The posterior spinal roots at the level of the tumour appeared to be intimately involved with it. There appeared to be no clear demarcation between the cord and the tumour at its superior aspect. Surprisingly, frozen section was reported as a probable astrocytoma and therefore a subtotal excision was carried out leaving a substantial amount of the intramedullary component behind to avoid increasing the neurological de® cit. Owing to the ® rm ® brous nature of the tumour, the use of the ultrasonic aspirator was relatively ineffective. The patient made a good postoperative recovery with noticeable improvement in his neurological symptoms. The subsequent more de® nitive histopathological

Correspondence: Mr R. Strachan, Department of Neurosurgery, Middlesbrough General Hospital, Ayresome Green Lane, Middlesbrough TS5 5AZ, UK. Received for publication 5 October 1998. Accepted 1 June 1999. ISSN 0268± 8697 print/ISSN 1360± 046X online/00/040345± 28 ½ The Neurosurgical Foundation

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FIG. 3. Tumour showing pallisading of spindle cells in an Antoni type A area to form Verocay body (haematoxylin and eosin, 3 100).

FIG. 1. Preoperative gadolinium-enhanced MRI of the cervical spine, showing enhancing lesion from C4 to C7, and associated tumour syrinx.

vaporising and debulking the tumour (higher power, contact and non-contact), offering controlled haemostasis throughout (non-contact) and ® nally shrinking the vascular tumour capsule with remarkable precision (lower power, non-contact). This last effect allowed microsurgical dissection of the tumour capsule away from the cord with reduced cord trauma or manipulation. Bipolar electrocautery was still required for larger vessels, usually greater than 1± 2 mm. Another advantage of the laser was the ® ne ® breoptic delivery system offering improved manipulation, access, and vision compared with the weight and size of the ultrasonic aspirator. The patient made an uneventful recovery, and after 18 months follow-up he is fully mobile. There has been a substantial improvement in his gait, which nevertheless still remains spastic. He has only a mild residual weakness on his right side largely affecting his hand. His bladder and sexual function are normal. He has completed his college degree and is currently in employment. Follow-up MRI has con® rmed complete tumour excision (Fig. 4). Discussion

FIG. 2. Preoperative axial gadolinium-enhanced MRI suggesting almost complete cross-sectional involvement of the cord.

diagnosis clearly con® rmed a schwannoma (Fig. 3). It was therefore agreed that we should reoperate to achieve a total excision if possible. Three weeks later, using the KTP laser for the ® rst time in this situation, the tumour was removed completely. The midline myelotomy was extended to the superior pole of the tumour, with sacri® ce of some bridging midline vessels. The considerable vascularity of the tumour made capsular dissection from the cord particularly difficult, especially anteriorly where the cord was wafer thin. In this respect, the KTP laser proved to be far superior to the ultrasonic aspirator. It was able to perform a number of different functions, ® rstly

Intramedullary schwannomas of the cervical spinal cord are probably not as rare as recent reviews indicate.6,7 Ebersold in Minnesota believes there is under-reporting and that the true incidence must be more than the 38 cases reported in contemporary literature. 8 Schwannomas appear more common in males with a male to female ratio of 2:1.9 In a review of all reported cases of intramedullary schwanommas, cervical cord tumours account for 63% of the total. The clinical syndrome highlighted by Lesoin et al. includes motor de® ciency, reduced sensation and the loss of genitourinary function.10 Surprisingly, our patient also demonstrated a unique adaptation to the motor de® cit by putting up with clawing of the right hand for 2 years before presentation. Intramedullary cervical cord tumours such as astrocytomas, ependymomas, meningiomas and metastatic tumours are commonly reported, with complete excision of these tumours often achieved. Such tumours


Cervical intramedullary schwannoma

FIG. 4. Postoperative gadolinium-enhanced MRI showing complete excision of the tumour. (The patient had an asymptomatic pseudomeningocoele, but in view of its size, a secondary repair was considered. However, it subsequently rapidly diminished in size, and has since resolved.)

are amenable to excision with the use of microsurgical techniques, although surgery carries risks of quadriplegia and respiratory dysfunction. However, in recent reviews, we can ® nd only 12 reported cases of complete excision of an intramedullary schwannoma. Where such tumours are completely removed, excision has been facilitated by various techniques including intraoperative ultrasound for diagnosis and tumour localization,1,2 and planned two-stage operations.4 The use of ultrasonic aspiration is also documented.3 Although laser surgery in more common spinal cord tumours is now widely practised,9,11,12 this is the ® rst report of the effectiveness of the laser, in this case the KTP laser, in the complete excision of a cervical intramedullary schwannoma. Hermann et al. reported the use of the CO2 laser in excision of spinal tumours, and reported the subtotal excision of a C2± T1 neuro® broma.11 Devaux & Roux reported that the resection of spinal cord neurinomas may bene® t from the use of lasers.5 They considered lasers as accurate and haemostatic non-contact instruments which reduce surgical trauma to eloquent areas. The depth of the burn is important in limiting surgical morbidity, and in this respect the KTP laser appears superior to the CO2 laser. The CO2 laser is

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the most highly absorbed of all types of laser with the most intense heating effects. It is therefore a powerful cutting and vaporising tool, but its coagulative properties are less precise.1 3 The KTP laser offers greater haemostasis both histologically and clinically,14 and has the added advantage of delivery to the tissues by a precise light-weight ® breoptic system. Our laser is a combined Yag/KTP laser (Laserscope). There is little to choose between the two types of laser Ð neodynium: Yag or KTP Ð although the latter uses crystals of KTP at its output to change the colour of light from Nd:Yag (wavelength = 1060 nm, near infrared) to that of KTP (wavelength = 532 nm, green light). This gives the KTP laser a higher speci® city for haemoglobin, offering more precise coagulation properties, coagulating to a depth of 0.5± 2 mm. Nd:Yag lasers are more powerful causing a burn depth of 2± 6 mm. Sapphire probes can reduce the spread of thermal damage normally associated with Nd:Yag lasers, but limit their use to a contact-mode only, or as a cutting knife.1 3 The KTP laser has been employed in our unit for the excision of acoustic neuromas and intracranial meningiomas without any additional risks to the patients. With respect to operating within the spinal cord, where tumour bulk is less and relationships to critical neural structures more evident, the lower power, smaller thermal burn and greater ¯ exibility of the KTP laser offers some obvious advantages. In our case, the laser greatly facilitated haemostasis. At the superior pole of the tumour, where it blended closely into the spinal cord, substantial controlled vaporisation of the interior of the tumour combined with standard neurosurgical techniques improved the safety and ease of the dissection. Our patient underwent a two-stage operation, because the initial pathology reported the tumour as an astrocytoma and preoperative counselling had assumed the tumour to be malignant making a full excision less likely. Furthermore, at the time of the ® rst operation, no clear demarcation was seen between cord and tumour at its superior pole, suggesting tumour invasion. However, with the bene® t of the revised pathology result, the midline myelotomy was more con® dently extended at the time of the second operation, revealing the encapsulated nature of the tumour. Imaging of spinal cord tumours is performed with MRI, CT myelography and plain radiography. MRI offers the least invasive technique with the greatest soft tissue discrimination. Meningiomas and neurinomas are the most frequent intradural extramedullary tumours and can generally be readily distinguished from each other. 1 5 ,1 6 Histological prediction based on imaging is usually dependent only on the anatomical compartment of the tumour (i.e. intra/extramedullary, intra/extradural).Within the intramedullary compartment, where astrocytomas and ependymomas predominate, most tumours have a similar appearance.17 Androulidakis et al. reported


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on the ® nding of central low-intensity dot on T1 postgadolinium views as being a speci® c feature in schwannoma/neuro® broma.1 8 However, they only described three cases and, although this sign is helpful if present, it is by no means speci® c. Our case did not have this feature, and looked like a typical astrocytoma. The preoperative diagnosis of malignancy was supported by MRI, which showed cystic areas in the cord as high as the medulla which were thought to represent tumour cysts (Fig. 1).With hindsight, these cystic areas were representative of syrinx formation, although this is often observed with ependymomas. Our case demonstrates that `typical’ features may be misleading. A high level of clinical suspicion is always needed to avoid making injudicious decisions intraoperatively based only on the imaging and frozen section pathology. Unlike Epstein,2 we unfortunately did not have access to intraoperative ultrasonography. This would have facilitated identi® cation of the upper limit of the tumour. Ultrasonographic detail using 7.5 MHz differentiates the topical relationship between tumour and spinal cord, and intratumoral cysts are more common in schwannomas. Histopathology ultimately con® rmed typical features of a schwannoma, with characteristic separation into cellular (Antoni A) and less cellular (Antoni B) areas on low power examination. Numerous Verocay bodies were also present. The tumour cells were spindled-shaped staining for S-100 by immunochemistry. Many blood vessels were evident in the tumour showing hyalinization of their walls, which supported the vascular nature of the tumour apparent at surgery (Fig. 3). Radakrishnan et al. highlight the difficulty in differentiating these tumours from ® brillary astrocytomas and the usefulness of glial fibrillary acidic protein (GFAP) and S-100 in making the diagnosis.19 The information offered by the surgeon to the pathologist, including clinical impressions and radiological diagnosis, may not always help the pathologist in frozen section diagnosis.The interpretation of specimens in less than 10 min without employing adequate staining techniques does rely heavily on the experience of the pathologist and the clinical information available. Duong et al. commented on this problem.2 0 The armamentarium of the neurosurgeon now includes the laser, in addition to the ultrasonic aspirator and bipolar coagulation, to supplement microsurgical operations in the management of lesions in the brain and spinal cord.Where possible, the goal of treatment for intramedullary tumours of the spinal cord should be complete excision. The KTP laser offers tremendous advantages over the ultrasonic aspirator particularly with benign tumours where their compact nature often makes the ultrasonic aspirator less effective. Two-stage operations and the use of intraoperative ultrasound for tumour localisation should be considered to improve surgical outcome and clinical success.

Acknowledgments We are indebted to David Scoones, Consultant Neuropathologist, who performed the histology in this case, and whose helpful comments and provision of Fig. 3 would justify his inclusion as fourth author. References 1 Matsuzaki H,TokuhashiY,Wakabayashi K,Toriyama S. Clinical value of intraoperative ultrasonography for spinal tumours. Spine 1992;17:1392± 9. 2 Epstein FJ, Farmer JP, Schneider SJ. Intraoperative ultrasonography: an important surgical adjunct for intramedullary tumours. J Neurosurg 1991;74:729± 33. 3 Jacquet G, Czorny A, Godard J, Stermle R, Wendling D. Intramedullary neurinoma Apropos of a case: review of the literature. Neurochirurgie 1992;38:315± 21. 4 Kalangu KK, Couto MT. Radical resection of intramedullary spinal cord tumours without cavitron ultrasonic aspirator or CO2 laser. A `2’ stage technique. Surg Neurol 1996;46:310± 14. 5 Devaux BC, Roux FX. Experimental and clinical standards, and evolution of lasers in neurosurgery (Review). Acta Neurochir (Wien) 1996;138:1135± 47. 6 Melancia JL, Pimenyel JC, Conceicao I, Antunes JL. Intramedullary neuroma of the spinal cord: case report. Neurosurgery 1996;39:594± 8. 7 Nicolletti GF, Passanisi M, Castana L, Albanese V. Intramedullary spinal neurinoma: case report and review of 46 cases. J Neurol Sci 1994;38:187± 91. 8 Ebersold M. Comments. Neurosurgery 1996;39:598. 9 Herregodts P, Vloeberghs M, Schmedding E, Goossens A, Stadnik T, Haens JD. Solitary dorsal intramedullary schwannoma: case report. J Neurosurg 1991;74:816± 20. 10 Lesoin F, Delandsheer E, Krivosic I, et al. Solitary intramedullary schwannomas. Surg Neurol 1983;19:51± 6. 11 Hermann HD, Neuss M, Winckler D. Intramedullary spinal cord tumours resected with CO2 laser microsurgical technique. Recent experience in 15 patients. Neurosurgery 1988;22:518± 22. 12 Stranjalis G, Torrens MJ. Successful removal of intramedullary spinal cord metastasis: a case report. Br J Neurosurg 1993;7:193± 5. 13 Absten GT, Joffe SN. Lasers in Medicine and Surgery Ð An Introductor y Guide, 3rd edn. London: Chapman and Hall, 1993. 14 Megello S, Camache FW. The histopathological effects of CO2 versus KTP laser on the brain and spinal cord: a canine model. Neurosurgery 1993;32:100± 4. 15 Fuki M, Furukawa T, Hasuo K, et al. MRI of intradural extramedullary spinal neurinomas and meningiomas. Clin Imaging 1993;17:46± 52. 16 Osborn AG. Tumours, cysts and tumour-like lesions of the spine and spinal cord. In: Osborn AG, editor Diagnostic Neuroradiology. Philadelphia: Mosby, 1993:876± 918. 17 Sevick R. Cervical spine tumours. Neuroimag Clin N Am 1995;5:385± 400. 18 Androulidakis J, Gouliamos AD, Kalovidouris AE, Kontogiannis DS, Papavasiliou CG, Vlahos LJ. Spinal neurilemmomas and neuro® bromas: central dot sign in postgadolinium MRI. J Comput Assist Tomogr 1993;17:446± 8. 19 Radakrishnan VV, Saraswathy A, Radakrishnan NS, Rout D. Diagnostic utility of immunohistochemical techniques in intramedullary schwann-cell tumours. Ind J Pathol Microbiol 1993;36:87± 91. 20 Duong H, Tampieri D, Melancon D, Salazar A, Robert F, Alwatban J. Intramedullary schwannoma. J Can Ass Radiol 1995;46:179± 82.