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Surgical Approaches to Paraspinal Nerve Sheath Tumors

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Surgical Approaches to Paraspinal Nerve Sheath Tumors Neurosurg Focus 22 (6):E9, 2007 Surgical approaches to paraspinal nerve sheath tumors ALICE CHERQUI, M.D.,1 DANIEL H. KIM, M.D.2 SE-HOON KIM, M.D., PH.D.,2,3 HYUNG-KI PARK, M.D.,4 AND DAVID G. KLINE, M.D.1 1Department of Neurosurgery, Louisiana State University Health Sciences Center; 2Department of Neurosurgery, Ochsner Clinic Foundation, New Orleans, Louisiana; 3Department of Neurosurgery, Korea University Medical Center; and 4Department of Neurosurgery, Soonchunhyang University Hospital, Seoul, Korea Object. The goal of this study was to analyze the results of surgical treatment of paraspinal nerve sheath tumors (NSTs) and review the surgical approaches to paraspinal NSTs. Methods. A retrospective review of the cases of paraspinal NSTs treated surgically by two senior authors during the period between 1970 and 2006 was undertaken. Surgical approaches that allow minimal disruption of normal anatomy and are aimed at complete resection of paraspinal lesions and preservation of spinal stability are reviewed according to the spinal level. Results. Eighty-eight paraspinal NSTs were treated surgically during the period: 56 schwannomas, seven solitary neurofibromas, 21 neurofibromas associated with neurofibromatosis Type 1 (NF1), and four malignant peripheral NSTs. Schwannomas tended to occur in the cervical and thoracic areas. Neurofibromas were usually associated with NF1 and tended to occur in the cervical area. Pain (79 patients, 90%) and paresthesia (81 patients, 92%) were the predominant clinical presenting symptoms; others included weakness (28 patients) and myelopathy (12 patients). Total resection of the tumor was achieved in 50 patients (89.3%) with schwannomas and 22 patients (78.6%) with neurofibromas. There was a large reduction of pain in 70 (88.6%) of 79 patients who had preoperative pain, and weakness improved in 18 (64.3%) of 28. Postoperative transient weakness occurred in 12 (42.9% ) of these patients, but in 85% of this group, the symptom improved over a 12-month period. Myelopathy was reduced in eight (66.7%) of 12 patients. The average follow-up period was 18 months. Conclusions. Paraspinal NSTs present unique surgical challenges given their anatomical relation- ships to the spine, spinal cord, nerve roots, and major vasculature. The surgical technique should take into account the location of the lesion and its relationship to paraspinal anatomy, the extent of resec- tion, sparing of normal anatomy, and spinal instability. KEY WORDS • paraspinal nerve sheath tumor • retrospective review • surgical approach ARASPINAL NSTs are tumors with contiguous extra- Solitary neurofibromas are less frequent but do occur spo- and intraforaminal components that may extend radically. Malignant peripheral NSTs occur in 5% of P intraspinally. Their incidence varies with anatomi- patients with plexiform neurofibromas and NF1. cal location. Generally, approximately 10 to 15% of spinal Clinically, patients present with signs and symptoms NSTs have a characteristic dumbbell shape. Paraspinal related to the spinal level of involvement. Pain and pares- NSTs are found most often in the cervical spine, followed thesia are the prominent symptoms in 80 to 90% of pa- by the thoracic and lumbar spine. In the cervical area, tients, but radiculopathy and myelopathy can occur in up paraspinal NSTs account for approximately 10% of all to 25%, especially in patients with spinal cord compres- cervical NSTs. Paraspinal NSTs of the thoracic area gen- sion and eloquent nerve root involvement. Generally, erally account for 10% of posterior mediastinal lesions. Lumbosacral paraspinal NSTs are not as well reported but symptoms improve after surgical resection, although un- are found less frequently than cervical or thoracic lesions. due delay in treatment can lead to permanent disability. Schwannomas account for the majority of these lesions, except in NF1, in which neurofibromas predominate. Clinical Material and Methods A retrospective review of all cases of paraspinal NSTs treated surgically by two senior authors (D.H.K. and Abbreviations used in this paper: CT = computed tomography; MR = magnetic resonance; NF1 = neurofibromatosis Type 1; D.G.K.) during the period between 1970 and 2006 was NF2 = neurofibromatosis Type 2; NST = nerve sheath tumor; VA undertaken. Patients received preoperative and postopera- = vertebral artery; VB = vertebral body. tive neurological examinations. Diagnostic studies includ- Neurosurg. Focus / Volume 22 / June, 2007 1 Unauthenticated | Downloaded 09/25/21 07:16 AM UTC A. Cherqui et al. ed myelography and CT in the earlier years of the study period and MR imaging as it became widely used. Some patients also underwent preoperative electromyography. Patients diagnosed with NF1 and NF2 underwent full neu- roaxis evaluations. Intraoperative electrophysiological re- cordings were performed in most of the cases reviewed in this study. Surgical Considerations Regarding Paraspinal Nerve Sheath Tumors FIG. 1. A case of a cervical paraspinal NST in a 43-year-old woman. Preoperative axial T2-weighted MR image (left) and gross Approaches to Cervical and Upper Thoracic Tumors. The photograph of the tumor (right). The histopathological diagnosis level of the paraspinal lesion will determine the surgical was schwannoma. approach. Depending on the level, there are different ana- tomical considerations. Lesions of the cervical spine are best approached through a standard anterior cervical or appropriately padded to keep pressure off the orbits and midline posterior cervical approach and laminectomy maintain an open airway. (Fig. 1). Instrumented fusion may be required in the treat- The surgical exposure is carried down to the proximal ment of multilevel lesions. A posterior subscapular ap- plexus and upper thoracic nerve roots in a careful and proach can be added for lesions involving the lower deliberate fashion to preserve the normal anatomy. The brachial plexus or upper thoracic nerve roots, T-1 through muscles that connect the spine to the scapula are the tra- T-3. pezius, rhomboid, and levator scapulae. A curvilinear in- Posterior Approach. In a posterior approach, several fac- cision is centered between the thoracic spinous processes tors are important. The bony exposure must encompass and medial edge of the scapula. The spinal branch of the the tumor and may involve multilevel laminectomies and accessory nerve and the ascending branch of the trans- facetectomies. If needed, spinal stabilization with instru- verse cervical artery run near the medial vertebral border mentation is performed once the tumor has been resected. of the scapula. An occipitocervical fixation is performed for C-1 and C-2 The spinal portion of the trapezius is transected along disruption. Lateral mass fixation is used for the lower cer- the length of the incision. It is important to mark the edges vical spine. The VA should be freed. If the VA is embed- with suture for later accurate approximation. The levator ded in the lesion, the cephalad and caudal portion entering scapulae and rhomboids insert on the medial border of the and leaving the tumor mass is exposed for control. The scapula. The levator scapulae lies superiorly, the rhom- periosteal venous sheath can reveal significant venous boid minor medially, and the rhomboid major inferiorly to bleeding. The veins are best coagulated and stripped from the trapezius. These muscles are dissected in a segmental the artery. The VA can be transposed, provided there is fashion and clamped with a Kelly clamp midway between complete control of the artery and all of its branches have the scapula and spine. They are then sectioned in an infe- been secured and sectioned. If the VA is injured during rior to superior direction. The muscle edges are also dissection, it may be ligated if there is adequate collateral marked with suture. Dividing the musculature away from circulation, or direct repair may be undertaken. the scapula protects the deeper dorsal scapular nerve and Posterior Subscapular Approach. The posterior sub- ascending branch of the transverse cervical artery. The scapular approach to the plexus can be very useful alone clamps are removed, and the ends of the sutures are fas- or in combination with the posterior cervical approach for tened to the drapes. If the dissection approaches the neck, the treatment of proximal paraspinal lesions extending in- the thicker portion of the trapezius can be split in a medi- traforaminally and involving the lower brachial plexus al direction. In addition, some of the serratus posterior (C7–T1) or upper thoracic nerve roots, (T1–T3). Advan- muscle may also be divided. tages of the posterior subscapular approach include a large Once the rhomboids are divided, the posterior chest exposure and avoidance of an anterior approach to the wall can be seen. An avascular plane between the scapula lower thoracic spine, which is associated with significant and the shoulder plane and chest wall is created with blunt morbidity. The major disadvantage of the posterior sub- finger dissection. A chest retractor is placed to expose the scapular approach is that it is not routinely used by most area between the scapula mass and the thoracic spinous neurosurgeons. processes. The retractor is opened as the limb on the Care should be taken to position the patient. He or she padded Mayo stand is lowered or the operating table ele- should be placed in the prone position, with the operative vated. This allows maximal abduction and external rota- side placed close to the edge of the operating table. Rolls tion of the scapula and exposes the posterior aspects of the are placed under the anterolateral chest wall, transversely upper ribs. beneath both shoulders and the manubrium of the chest. The first rib is identified by palpation from the second The upper extremity on the operative side is partially ab- rib. The scalenus posterior is detached from the superior ducted and flexed forward at the shoulder. The arm is surface of the first rib. More medial segments of the sca- flexed at the elbow and secured to a padded Mayo stand, lene muscles are resected from their insertion to their ori- which is at a level lower than the operating table.
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