Surgical management of chordomas of the cervical spine

Transcription

1 J Neurosurg Spine 6: , 2007 Surgical management of chordomas of the cervical spine IGNACIO J. BARRENECHEA, M.D., NOEL I. PERIN, M.D., F.R.C.S.(EDIN), AYMARA TRIANA, M.D., JONATHAN LESSER, M.D., PETER COSTANTINO, M.D., AND CHANDRANATH SEN, M.D. The Center for Cranial Base Surgery, Departments of Neurosurgery and Anesthesiology, St. Luke s Roosevelt Hospital Center, New York, New York Object. Chordomas of the cervical spine are rare tumors. Although en bloc resection has proven to be the ideal procedure in other areas, there is controversy regarding this approach in the cervical spine. The goal in this study was to determine whether piecemeal tumor resection was efficient in the management of chordomas that arise in this location. Methods. The authors retrospectively reviewed all 74 cases of chordoma treated by their group. Seven patients with isolated cervical chordomas who were treated between October 1992 and January 2006 were identified. There were four male and three female patients, whose ages ranged from 6 to 61 years (mean 34.4 years). Follow-up duration ranged from 7 to 169 months (median 23 months). All cases were managed using a retrocarotid approach with mobilization of the vertebral artery. When the tumor could not be completely resected via the initial anterior approach, a subsequent posterior resection was performed. Tumor resection was intralesional in all cases, and gross-total tumor resection was achieved in six cases. One patient required a second resection 4 months later. In all cases, a posterior stabilization procedure was performed. Five patients underwent anterior fusion (three with fibular allograft and two with iliac crest), whereas two underwent occipitocervical fusion. In two patients with dedifferentiated chordoma metastasis developed, and one of them died 7 months later. The other patient with metastasis died suddenly at home 26 months postsurgery, presumably from aspiration. At the time of this submission, there were no signs of recurrence in five patients. Conclusions. The authors believe that, in most cases, en bloc resection of cervical chordoma is not feasible. This is due to the tendency of chordomas to involve multiple compartments at the time of diagnosis. In the authors experience, intralesional radical resection remains an effective surgical approach to this disease entity. KEY WORDS chordoma vertebral artery cervical spine surgical approach C HORDOMAS are low-grade primary malignant tumors arising from notochordal remnants. They account for 1 to 4% of all malignant bone tumors and are found predominantly in the clivus and sacral spine. Only rarely is this tumor seen in the cervical spine, accounting for only 6% of all chordomas. 24 Cervical spine chordomas present significant surgical challenges because of the important anatomical structures present in this area. At the time of initial presentation, in most patients with cervical chordomas, tumor extension into the paravertebral and epidural compartments as well as the involvement of one or both VAs and the dura mater may already have occurred. Because of this, many authors believe that en bloc resection is rarely practicable, 10,11 unlike treatment of chordomas of the thoracic, lumbar, and sacral spine, for which en bloc resection should be the goal. 3 5,8,9,18 Abbreviations used in this paper: ASIA = American Spinal Injury Association; CT = computed tomography; MR = magnetic resonance; VA = vertebral artery; VB = vertebral body; WBB = Weinstein-Boriani-Biagini. 398 We present our experience in the management of this disease in seven patients with isolated cervical spine chordomas. On initial presentation, all patients in our series had evidence of tumor extension into paravertebral locations. All patients had undergone a gross-total intralesional resection; none of them had en bloc resection. Although radical tumor resection is the ideal treatment that we have attempted to perform in all the patients, a piecemeal resection to achieve the same goal was our surgical philosophy, as is the case in the treatment of skull base chordomas. In this paper, we discuss the rationale for our surgical approach to these lesions when they are found in the cervical spine, and address the challenge of cervical stabilization after tumor resection. Clinical Material and Methods Of the 74 patients in our Center for Cranial Base Surgery database at St. Luke s Roosevelt Hospital Center in whom a diagnosis of chordoma had been made, we identified seven who had chordomas in the cervical spine without J. Neurosurg: Spine / Volume 6 / May, 2007

2 Surgical management of chordomas of the cervical spine associated intracranial involvement. We then reviewed their medical charts for demographic data, presenting symptoms, perioperative complications, and survival. Between October 1992 and January 2006, seven patients with isolated cervical chordomas were treated by our group. All patients were available for follow up. There were four male and three female patients, whose ages ranged from 6 to 61 years (mean 34.4 years). Follow-up duration ranged from 7 to 169 months (median 23 months). Tumors included five classic and two dedifferentiated chordomas. All patients presented with neck pain or upperextremity symptoms. Upper-extremity symptoms ranged from hand tingling and numbness to overt weakness. One patient presented with difficulty swallowing (Table 1). Preoperatively, all patients had undergone contrastenhanced MR imaging to evaluate bone and soft-tissue involvement, tumor spread into adjacent areas, and the patency and location of the VA. Additionally, all patients had undergone CT scans and plain x-ray films to assess the degree of bone destruction and cervical spine stability. We used MR angiography to evaluate the patency and dominance of the VA. Careful note was made of the VA s ending as a posterior inferior cerebellar artery or as the anterior spinal artery with a unilateral origin (Type II). 17 Neurological deficits were assessed using the ASIA Impairment Scale. 22 Based on the preoperative images, we staged all tumors by using the oncological staging system devised by Enneking et al., 14 and after 1996 we used the WBB surgical staging system 6 (Fig. 1), adapted to the cervical spine. 1,7,21 All resections were performed initially via the retrocarotid, anterolateral approach to the region to establish control and mobilize the ipsilateral VA out of the way. Tumor resection was then performed using this route. 10,26 The standard anterior cervical approach (anterior to the carotid sheath) was also used in combination in all cases to achieve a radical resection of the tumor from the anterior part of the spine. Once gross-total resection of the anterior portion of the tumor had been achieved, an anterior stabilization was performed on the same day. If the tumor extended posterior to the pedicles, a posterior approach was taken either on the same or the next day to complete the tumor resection and perform a posterior stabilization. Immediate postoperative imaging was performed to confirm the extent of resection and stabilization. Anesthesia and Monitoring Preoperatively, all patients presenting for tumor resection in which cervical instability was present were placed in a firm collar. Endotracheal intubation was performed using either a fiberoptic technique or direct laryngoscopy with inline stabilization. Total intravenous anesthesia was induced and maintained using propofol and a short- or intermediate-acting narcotic agent. To facilitate physiological monitoring, patients did not receive nondepolarizing muscle relaxants during the operation. Baseline sensory and motor evoked potential recordings were obtained and were monitored continuously throughout the procedure. Surgical Approach The patient is placed supine on the operating table, with the head positioned in a soft doughnut and extended and rotated 30 to the contralateral side. In the earlier cases, a TABLE 1 Characteristics of seven patients with cervical chordomas* Staging Age Preop Postop Recur- Case (yrs), Presenting Pathological ASIA IS ASIA IS rence/ No. Sex Location Symptoms Features WBB Enneking Grade Treatment Grade Mets FU 1 46, M C3 4 lt shoulder & classic radial: 4 7 Ib E IL excision E no/no 169 mos hand pain concentric: 2 61, F C2 4 neck stiffness classic radial: 7 9 Ib E IL excision E no/no 163 mos & bilat hand concentric: numbness 3 36, M C1 2 neck pain dedifferentiated radial: 4 9 IIb E IL excision E yes/yes died at 26 & difficulty concentric: & PBRT mos swallowing & chemo 4 10, F C2 4 rt hand weak- classic radial: 6 9 Ib C IL excision D no/no 23 mos ness pro- concentric: & PBRT gressing to hemiparesis 5 6, F C2 5 neck pain dedifferentiated radial: 4 6 IIb E IL excision E no/yes died at 7 concentric: & PBRT mos A E & chemo 6 45, M C2 4 neck pain classic radial: 6 11 Ib E IL excision E no/no 12 mos concentric: & PBRT 7 35, M C2 4 neck pain & classic radial: 4 9 Ib E IL excision E no/no 11 mos bilat hand concentric: & PBRT numbness mean mos * ASIA IS = ASIA Impairment Scale; chemo = chemotherapy; FU = follow up; IL = intralesional; Mets = metastasis; PBRT = proton beam radiation therapy. J. Neurosurg: Spine / Volume 6 / May,

3 I. J. Barrenechea et al. FIG. 1. Schematic used for surgical staging of cervical tumors based on the WBB system. The transverse section is divided into 12 sectors (in clockwise order) and into six layers (five concentric areas and the VA canal). The six layers are identified as follows: A, expansion in the surrounding soft tissues; B, intraosseous; C, involvement of the canal wall; D, extrusion into the epidural space; E, involvement of the dura mater; and F, involvement of the VA canal. vertical incision was used, starting over the right mastoid process and extending anteriorly along the anterior border of the sternocleidomastoid muscle down to the necessary level. In recent cases a horizontal incision was used, with the cut being carried from the mastoid tip in a curvilinear fashion over the lateral neck, along a neck crease. The height of this incision is planned based on known anatomical landmarks (cricoid cartilage at C-6 and thyroid cartilage at C-4). A long incision is used to allow adequate craniocaudal exposure. We currently prefer horizontal incisions for the attack angle they provide, combined with superior cosmetic results (Fig. 2A). The dissection plane is carried to the platysma and along the anterior border of the sternocleidomastoid muscle, going between the internal jugular vein and the muscle. We then reach the transverse processes and try to identify them, depending on the levels to be treated; x-ray films are obtained to confirm the levels as needed. If a large paravertebral mass is present, the transverse processes above and below are identified by palpation. Importantly, the entire neurovascular bundle is individually dissected, including the vagus and hypoglossal nerves, as well as the sympathetic chain. Similarly, the accessory nerve is visualized (and adequately protected) as it turns around the lateral aspect of C-1 underneath the internal jugular vein. If there is a large retropharyngeal component of the tumor, it is carefully dissected away from the pharyngeal wall and removed. The longus colli and capitis muscles are usually involved and thus partially resected. The anterior scalenus muscle and phrenic nerve are identified and protected. Special care is taken to prevent injury to the pharyngeal wall and to leave no tumor behind. The operating microscope is brought in and the entire neurovascular bundle and pharynx are retracted anteriorly with a wide Layla retractor. During this part of the operation, the surgeon is seated and working from an anterolateral direction. The operating microscope is used for the entire anterolateral as well as the anterior approach and resection. The VA is exposed at the lowest transverse foramen, beyond the extent of the tumor. The muscles attaching to the transverse processes as well as the anterior part of the VBs are completely excised throughout the extent of the tumor. Prior to this maneuver, the sympathetic chain has been isolated and dissected away from the prevertebral tissues and held anteriorly with the entire carotid sheath. The VA surrounded by its venous plexus is identified in the transverse foramen, caudal to the lowest extent of the tumor. The venous plexus is then opened, coagulated and divided circumferentially, 400 J. Neurosurg: Spine / Volume 6 / May, 2007

4 Surgical management of chordomas of the cervical spine FIG. 2. Artist s renditions of the lateral retrocarotid approach used by the authors. A: Initial exposure of a C-3 chordoma (asterisk) through a horizontal incision. Note the lateral view of the neck structures provided by working behind the carotid sheath. B: The VA is freed from the C-3 and C-4 foramina and gently retracted laterally. C: The C-3 corpectomy and C2 3 and C3 4 discectomies are performed. The endplate of C-2 has also been drilled until healthy cancellous bone is seen. D: Fibular allograft is placed between C-2 and C-4 with anterior plate and screws at C-2 and C4. a. = artery; int. = internal; m. = muscle; n. = nerve; SCM = sternocleidomastoid muscle. and the adventitia is exposed. The venous plexus and periosteal sheath surrounding the artery are often invaded by tumor and are excised in a piecemeal manner. We have not observed tumor invasion of the arterial wall. With the use of rongeurs and meticulous dissection, the VA is freed from the foramen transversarium progressively at all the levels infiltrated by the tumor, to get past the cephalad extent of the lesion. Once the artery is freed up circumferentially, a vessel loop is passed and used for gentle traction to retract the artery out of the way so that an unimpeded access is provided to the anterior part of the spine (Fig. 2B). The tumor is resected in a piecemeal manner, carefully following all of its extensions in the pre- and paravertebal compartments. Special attention is necessary because it is easy to leave tumor remnants behind due to the nature of the lesion, which insinuates itself into every space that is available to it. The pharyngeal wall is freed of the tumor J. Neurosurg: Spine / Volume 6 / May, 2007 from this angle. This anterolateral approach allows excellent access all the way up to the level of C-1, without the impediment of the mandible. We then continue in a cephalad and caudad direction to remove the infiltrated VBs completely, all the way across to the opposite VA. In one case we simultaneously used a bilateral retrocarotid approach because of the involvement of both VAs by the tumor. When epidural or even intradural tumor is present, it is also removed in a piecemeal fashion. It is especially important to evaluate the dura mater carefully, because the tumor can invade the outer layer of the dura and extend in between the two layers or even intradurally. It is easy to miss tumor remnants in this area. Access to the portion of the tumor posterior to the pedicles is difficult via this approach, even if the nerve roots are divided at the high cervical level. This posterior portion of the tumor is left in place temporarily to be removed via a separate posterior 401

5 I. J. Barrenechea et al. approach. Any involved dura mater is also excised and a dural graft is sutured (we have used acellular dermis for dural grafts). After using the full extent of the retrocarotid approach, the dissection is carried anterior to the carotid sheath via a standard anterior cervical route. The combination of the anterior and anterolateral approach allows a thorough evaluation of all of the tumor in the anterior portion of the spine; that is, the epidural, paravertebral, and prevertebral extensions of the tumor. In cases of tumors extending to the body of C-2, care is taken to avoid overdrilling this body because this may impede the subsequent anterior fusion (Fig. 2C). Radical tumor resection is the goal and this is not compromised. However, a careful discussion and dialog is necessary between the surgeon performing the resection and the one who will do the stabilization. Posterior Tumor Resection When there is tumor extension posterior to the pedicles, it is removed at a separate stage via a posterior approach when the posterior stabilization is performed. Because the VA has already been dissected out via the anterolateral approach, resection of the posterior portion of the tumor is relatively straightforward. Hemilaminectomies are performed at the levels involved and the articular facets and remainder of the pedicles are removed with rongeurs. The nerve roots are fully exposed, accomplishing a thorough tumor resection from the epidural space. Tumor removal continues until the posterior dissection is fully in continuity with the anterior dissection space. The posterior stabilization is then performed as described in the next section. Stabilization and Fusion After completion of the anterior tumor resection, the bed to seat the bone graft has to be prepared. Bone removal is extended to the next endplate proximally and distally if feasible. Importantly, when the body of C-2 is infiltrated by tumor we try to preserve as much VB as possible to seat the graft proximally. We use either allograft fibular bone or tricortical iliac crest for anterior reconstruction, and we use morcellized autograft iliac crest bone for posterior onlay fusion. The fibular graft is packed with demineralized bone matrix (Grafton) and the cortical surface of the graft is placed against the anterior cortical surface of the VBs (Fig. 2D). This helps keep the hard cortical fibular allograft from telescoping into the proximal and distal vertebrae. A ledge is then created posterior to the graft in the endplates to prevent the graft from displacing posteriorly into the spinal cord. Anterior plating with screws fastened to the rostral and caudal vertebrae is used to hold the fibular graft in place. The procedure for posterior exposure and stabilization is based on the biomechanical features present after anterior stabilization and the presence of posterior tumor. The patient is turned to the prone position while supported in a firm cervical collar, maintaining the head and neck in a neutral position. The head is then fixed in a neutral position with the Mayfield three-pin head holder (Ohio Medical Instrument Co., Inc.). Lateral cervical spine x-ray films are obtained to establish a neutral head-to-neck position in patients undergoing occipitocervical stabilization to prevent postoperative swallowing difficulties. A midline incision is made depending on the spinal levels to be treated. The cervical spine is then exposed, extending the muscle dissection to the lateral aspect of the lateral masses to facilitate screw placement. Laminectomy and facetectomy are performed for tumor resection as indicated. Lateral mass screws are then placed at the levels to be stabilized. In cases requiring occipitocervical stabilization, a 5-mm CD rod or a 3.2-mm Vertex rod (Medtronic Sofamor Danek) is selected depending on the patient s age, body habitus, and biomechanical requirements. The rod is contoured using a rodbending device (Bend-Meister, Medtronic Sofamor Danek). Bone for fusion is harvested from the posterior iliac crest. Bone graft is laid lateral to the instrumentation after decortication. In cases of occipitocervical fusion, strips of corticocancellous bone are harvested and laid from the occiput between the contoured rod in the midline to the posterior arch of C-1 and the lamina and spinous process of C-2. Bone is also laid along the subaxial lateral masses. Results Based on the ASIA Impairment Scale, 22 six patients showed no signs of myelopathy (ASIA Grade E), and one had frank myelopathy (ASIA Grade C). No patient in this group had received radiotherapy preoperatively; however, one patient (Case 5) had received a course of chemotherapy (adriamycin, Cytoxan, and vincristine) before presenting to our institution. Two of the patients (Cases 4 and 6) had undergone a prior incomplete resection of the tumor at another institution. In all patients in this group the tumors were resected via an anterolateral retrocarotid approach combined with a standard anterior cervical approach for the anterior tumor, and a laminectomy for the posterior tumor. In the first two cases in this series we used a longitudinal neck incision, which we made along the anterior border of the sternocleidomastoid muscle. The other five resections (Cases 3 7) were performed through a horizontal neck incision. In four patients two vertebral levels were involved (C1 2 in one patient and C3 4 in three); in two patients there was involvement of three vertebral levels (C2 4); and in one there were four levels involved (C2 5). On initial presentation, all patients had extraosseous soft-tissue and epidural extension of tumor. One patient had intradural extension of tumor, which was noted at the time of surgery. Based on the WBB staging system, the tumors were classified both radially and concentrically. With respect to radial classification, there were three patients in whom six sectors were involved (sectors 4 9 in two cases and 6 11 in one); two patients in whom four areas were involved (sectors 4 7 in one case and 6 9 in the other); and two patients in whom three areas were involved (sectors 7 9 in one case and 4 6 in the other). With respect to concentric classification, there were six patients in whom areas A to D were involved, whereas in one patient areas A to E were compromised. Based on the oncological staging system devised by Enneking et al., 14 five cases were classified as Ib and two as IIb, the latter due to the dedifferentiated histological features (Table 1). An intralesional gross-total resection was achieved in six patients. In one patient (Case 3) residual tumor was revealed in the retropharyngeal space and at the C-1 anterior arch on postoperative MR imaging. Four months later, 402 J. Neurosurg: Spine / Volume 6 / May, 2007

6 Surgical management of chordomas of the cervical spine this patient underwent a second procedure through a midline mandibular split operation for resection of the residual tumor; 20 we were able to achieve gross-total resection at this time. Four patients underwent a combined anterior and posterior stabilization and fusion (Fig. 3). Two patients who had involvement of the upper cervical spine (Case 3, C1 2 and Case 4, C2 4) had occipitocervical stabilization with autograft iliac bone fusion (Table 2). In both of these cases the C-2 VB was infiltrated by the tumor to the extent that we were unable to place an anterior graft. We used a combination of lamina hooks and screws, avoiding cables to prevent telescoping of the rod and subsequent settling. Postoperative Course The duration of hospital stay following surgery ranged from 5 to 28 days (mean 13.2 days). Before discharge, a Gd-enhanced MR imaging study was obtained in all patients to evaluate the status of the tumor resection. A thinslice CT scan with sagittal reconstruction was also obtained to evaluate the instrumentation and alignment of the spine. All patients were instructed to wear a hard cervical collar (Philadelphia or Miami J collar) for 3 months. Follow-up assessment was by outpatient evaluation at 10 days, then monthly evaluations for 3 months, and semiannually to annually thereafter. A Gd-enhanced MR imaging study was obtained in each patient 3, 6, and 12 months postsurgery to evaluate early tumor recurrence. Assessment of spinal alignment and integrity of the instrumentation and fusion was typically undertaken with plain x-ray films. At approximately 3 to 4 months postoperatively, a CT scan with bone windows and sagittal reconstruction was performed to assess the status of the fusion. Successful fusion was defined as the presence of bone bridging across the fused levels seen either on plain x-ray films or CT scans. Once fusion was established, the patients started a program of isometric neck exercises and were gradually weaned off the collar over a period of 2 weeks. Distant metastasis developed in two patients. In one patient (Case 5), a lumbar metastasis developed 3 months after the surgery. This was the patient in whom intradural tumor was noted at the time of the initial surgery (area E; see Fig. 1). She died 7 months after the surgery due to disease progression. The other patient (Case 3) showed signs of tumor regrowth in the neck in addition to metastatic nod- FIG. 3. Case 6. Preoperative, intra-, and postoperative imaging studies. Preoperative T 2 -weighted sagittal (A) and axial (E) MR images demonstrate a hyperintense extradural lesion from the C-2 to C-4 levels. Note the signal changes in the body of C-3 (A). Postoperative T 1 -weighted sagittal (B) and axial (F) Gd-enhanced MR images show no areas of enhancement. Postoperative sagittal (C) and axial (G) CT scans with bone windows demonstrate the combined anterior posterior stabilization and fusion. Note how the fibular graft is placed against the anterior cortex to prevent telescoping of the graft. An x-ray film obtained intraoperatively (D) demonstrates the instrumentation in place. J. Neurosurg: Spine / Volume 6 / May,

7 I. J. Barrenechea et al. TABLE 2 Description of the fusion and stabilization techniques used in seven patients with cervical chordomas* No. of Upper/Lower Screws Age (yrs), Levels Case No. Sex Prev Fixation Infiltrated VBs Vertebrectomy Postop Fixation Fused Ant Pst Type of Graft 1 46, M none C3 4 C3 4 ant & pst 3 C-2/C-5 C-2/C-5 iliac crest (ant & pst) 2 61, F none C3 4 C3 4 ant & pst 3 C-2/C-5 C-2/C-5 iliac crest (ant & pst) 3 36, M none C1 2 C1 2 pst (OCF) 6 NA occ/c-6 iliac crest 4 10, F none C2 4 C2 4 pst (OCF) 5 NA occ/c-5 iliac crest 5 6, F none C2 5 C2 5 ant & pst 3 C-2/C-5 C-2/C-5 ant: fibular allograft; pst: iliac crest 6 45, M ant & pst C2 4 C2 4 ant (& prev pst) 2 C-2/C-4 C-2/C-4 ant: fibular allograft; pst: iliac crest 7 35, M none C2 4 C2 4 ant & pst 3 C-2/C-5 C-2/C-5 ant: fibular allograft; pst: iliac crest mean * Fusion was achieved in all cases. Abbreviations: ant = anterior; NA = not applicable; occ = occiput; OCF = occipitocervical fusion; prev = previous; pst = posterior. The C-2 VB was only marginally infiltrated, allowing us to place a screw higher up at the same level. ules in the thigh and pelvis 17 months after the initial surgery. He died suddenly at home 26 months after his initial operation. Adjuvant Treatments Five patients received postoperative combined photon and proton beam radiation therapy at a mean dose of 79 Co Gy equivalent. The two patients with metastatic disease also underwent chemotherapy. One patient received only imatinib mesylate and had stable disease until his sudden death, which was presumably caused by aspiration. The other patient received adriamycin, Cytoxan, vincristine, imatinib mesylate, and finally ifosfamide. Nevertheless, her tumor progressed rapidly and she died of the disease. Survival and Disease Status The median follow-up duration has been 23 months (range months). The shortest follow up was in the patient who died of metastatic disease. With the exception of the two patients who have died, the remainder are free of disease. They are being followed with annual MR imaging studies. Fusion has been documented in all cases. Postoperative Complications A cerebrospinal fluid leak developed in two patients (Cases 5 and 6) via the Hemovac drain in the immediate postoperative period. A lumbar drain was placed in both patients and the leak resolved within 2 days. In one patient (Case 7) a C-5 palsy developed, which affected ipsilateral shoulder abduction. The weakness was improving at the 3- month follow-up evaluation. In one patient (Case 3) who underwent a transoral mandibular split for resection of residual tumor, a dehiscence of the pharyngeal incision developed. Discussion Chordomas constitute 2 to 4% of all bone neoplasms and 1 to 4% of malignant bone tumors. After plasmacytomas, they are the most frequent primary malignant tumor in the spine. 8 The location of chordomas along the spinal canal is directly related to the location of the notochordal remnants, most frequently at either end of the spinal axis. Approximately 32% of chordomas are clival, 33% are spinal, 29% arise from the sacrococcygeal region, and 6% are extraaxial or ill defined. 23 Vertebral chordomas occur in the lumbar, cervical, and thoracic regions, in descending order of frequency. The cervical location represents approximately 6 to 7% of cases. 24 These are slow-growing, low-grade, malignant tumors, which are thought to arise from notochordal remnants. Chordomas are locally invasive and have a relentless tendency to recur. Metastases are noted in approximately 30% of cases. 13 These usually spread to contiguous anatomical structures, but they may be found in distant sites (skin, musculoskeletal system, brain, and other internal organs). Seeding of the tumor has also been reported, and the likely mechanism seems to be tumor cell contamination during the surgical procedures. Aggressive resection is the treatment of choice, although local recurrence is still a major problem in the treatment of these tumors. The treatment of chordomas in the cervical spine consists of radical excision and stabilization, followed by adjuvant treatments (radiation and sometimes chemotherapy). Proton beam radiation is the modality that has been used extensively for the treatment of chordomas. The Bragg peak effect is useful in delivering a high radiation dose while avoiding the spinal cord. This treatment method has been shown to achieve a 46% control rate at 5 years. 19 High doses of radiation are needed to provide effective control in chordomas. Other, more recent radiation modalities such as intensity-modulated radiotherapy and the 404 J. Neurosurg: Spine / Volume 6 / May, 2007

8 Surgical management of chordomas of the cervical spine CyberKnife have been introduced to deliver similarly high doses of radiation with the same type of sharp drop-off of the radiation, avoiding the surrounding areas as in the proton beam treatments, thus making it more acceptable to patients. Yamada et al. 27 reported on the use of intensitymodulated radiotherapy in a variety of spinal tumors. Over a median follow-up period of 15 months they reported a tumor control rate of 86% for primary spinal tumors. Such high-intensity radiation needs to be carefully planned because posterior pharyngeal breakdown can occur in a delayed manner and can be a significant morbidity. Few reports exist of treatment of these tumors with chemotherapy. 12,15 Fleming et al. 15 reported on two patients with dedifferentiated sacral chordomas in whom metastatic disease developed after sacral resection and radiation therapy. Both patients attained complete remissions, one due to a six-drug regimen and the other due to ifosfamide therapy. The authors concluded that a trial of aggressive chemotherapy is warranted in patients with metastatic dedifferentiated chordomas, although the optimum regimen is unclear. In a more recent report, Casali et al. 12 reported on six patients harboring advanced chordomas treated with imatinib mesylate (800 mg daily). The authors achieved encouraging results, with one of the patients showing signs of overt tumor liquefaction. Based on these results, a formal Phase II study is currently underway. In our series, two patients harboring metastatic dedifferentiated cervical chordomas received chemotherapy, and one of them showed no response. Authors of previous studies have reported on the surgical techniques for margin-free, en bloc tumor resection in the thoracic and lumbar spine. 3 5,8,9,18 The same authors have also advocated this approach in the cervical spine. This requires that the tumor be confined within the VB, with at least one pedicle being free of tumor. Removing large tumors in the cervical spine in an en bloc manner when the lesion extends well beyond the spine would be difficult if not impossible to accomplish without the patient facing a significant risk of morbidity. 25 The limitations encountered in resecting cervical spine chordomas result from the involvement of the VA, the dura mater, and the extraspinal tissues. Surgeons who advocate sacrificing a VA propose that a better en bloc oncological resection can be performed. In our opinion, however, there are limitations to this approach. Chordomas are well known to recur despite aggressive resections. If a VA is sacrificed and the tumor recurs on the other artery, the surgical options are severely limited at that point. Isolation and mobilization of the VA accomplishes the same goal as sacrificing the vessel, but with the advantage of preserving a vital structure. It removes the artery from the path of the surgery, thus allowing an unimpeded access. Even when the VA is sacrificed, en bloc resection is rarely possible because of the irregular extension of the tumor that invariably leads to violation of the lesion, which then has to be removed in a piecemeal manner after all. The method of managing the VA that was used by our group 26 and by Carpentier et al. 10 allowed us to remove the tumor around this vessel much more effectively than with other techniques involving artery occlusion because we can accurately define the cranial and caudal extent of the tumor by following the artery. Even in small intraosseous tumors, an en bloc resection does not guarantee a tumor-free zone. 16 At the time of initial diagnosis in this series of patients, the tumor had spread beyond the VB into the paravertebral areas and to the epidural space. One patient had involvement of both VAs, and another had obvious dural invasion requiring dural excision and grafting. Certainly, these cases would not be amenable to an en bloc resection. Although we performed a deliberate intralesional resection technique, we aggressively followed every tumor extension with the aid of the exquisite visualization and magnification of the operating microscope. Copious amounts of irrigation fluid were used throughout the operation to minimize the spillage of tumor cells. We were able to achieve a gross-total intralesional piecemeal removal of the tumor in six of the seven patients, as confirmed on postoperative images. Other authors have also advocated a similar approach for cervical spine tumors. 10,11 Surgical and oncological staging is not as well defined in primary bone tumors of the spine as it is in other, soft-tissue tumors. The WBB staging system was introduced to improve on and standardize surgical staging of primary malignant bone tumors. Using this system, the vertebra is divided in a clockwise manner into 12 radiating zones (numbered 1 12) and into six layers (five concentric areas and the VA canal, labeled A F), from the paravertebral extraosseous regions to the dura mater. This characterizes the axial extent of tumor. The longitudinal extent is assessed by noting the number of vertebral segments involved. There is no consensus for an accurate oncological definition of en bloc resection. Few data exist with regard to the surgical margins of spinal neoplasms and their relation to local control rates. It is generally accepted that it should be a margin-free resection without tumor breach. The extent of the free margin, however, varies according to the surgical team reporting it. Boriani et al. 5,7,8 recommend en bloc excision of all spinal chordomas when feasible, even if they are only marginal, because it provides superior local control compared with intralesional excision. A total en bloc spondylectomy involves the complete removal of one or more contiguous levels of the spinal column in two pieces (anterior and posterior to the thecal sac). The posterior arch is first removed by transecting the pedicles, and then an en bloc corpectomy is completed using a thread wire saw, taking care to protect the spinal cord and other soft tissues. This has been previously described for neoplasms of the thoracic and lumbar spine. 2,5,7,9 The procedure must be performed via a combined anteroposterior approach. Oncologically, en bloc resection appears to minimize the risk of tumor cell contamination of contiguous anatomical structures, 7 and it also minimizes the potential for neoplastic tissue related blood loss that is difficult to control. It is important to note that, based on the WBB surgical staging system, an en bloc excision of chordomas in the spine can only be attempted if the tumor is confined to zones 4 to 8 or 5 to 9. As pointed out by Boriani et al., 8 however, en bloc removal of a bone tumor is possible for a tumor arising in the scapula (scapulectomy) and tibia (above knee amputation), but it is absolutely impossible for a spine tumor. In this sense, even if the spinal cord is sectioned above and below, the epidural space represents a compartment extending from the skull to the coccyx. Chordomas remain a challenging disease to eradicate. Even when a radical tumor removal is achieved, it can never be confirmed that this is true at a microscopic level. In addition, there is the inherent biological behavior of a J. Neurosurg: Spine / Volume 6 / May,

9 I. J. Barrenechea et al. tumor that cannot be predicted on the basis of the histological findings and remains poorly understood. In our series, five patients have not shown tumor recurrence to date. Clearly the length of follow up in the present study is short, but the extent of tumor resection that could be achieved using these techniques, as well as the limited risk of morbidity encountered and the successful stabilization that was accomplished, has been encouraging. Conclusions Chordomas in the cervical spine are rare. In our series, the patients presented with nonspecific symptoms of neck pain with radicular and myelopathic findings. At presentation, the majority of patients had tumors beyond the VB. Intralesional, piecemeal radical tumor resection was performed via anterolateral, anterior, and posterior approaches in combination. Successful stabilization was also accomplished in all patients, both anteriorly and posteriorly. Combined proton and photon radiation therapy was given postoperatively in five patients. In two patients metastatic disease developed and they received chemotherapy (both of them died in a relatively short time). The risk of surgical morbidity was minimal and the five patients who are alive are able to lead a normal life. Reconstruction and stabilization of the spine were achieved with fibular allograft and plating anteriorly and laminectomy with stabilization and iliac bone graft posteriorly. It is our opinion that piecemeal removal of the tumor is a viable technique in the management of cervical spine chordomas when the goal is radical tumor removal. References 1. Abdu WA, Provencher M: Primary bone and metastatic tumors of the cervical spine. Spine 23: , Abe E, Sato K, Tazawa H, Murai H, Okada K, Shimada Y, et al: Total spondylectomy for primary tumor of the thoracolumbar spine. 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Response to aggressive chemotherapy in two cases. Cancer 72: , Fujita T, Kawahara N, Matsumoto T, Tomita K: Chordoma in the cervical spine managed with en bloc excision. Spine 24: , Govsa F, Aktan ZA, Arisoy Y, Varol T, Ozgur T: Origin of the anterior spinal artery. Surg Radiol Anat 18: , Hsu KY, Zucherman JF, Mortensen N, Johnston JO, Gartland J: Follow-up evaluation of resected lumbar vertebral chordoma over 11 years: a case report. Spine 25: , Igaki H, Tokuuye K, Okumura T, Sugahara S, Kagei K, Hata M, et al: Clinical results of proton beam therapy for skull base chordoma. Int J Radiat Oncol Biol Phys 60: , Janecka IP: Transoral-translabiomandibular approach to the craniovertebral junction, in Dickman CA, Spetzler RF, Sonntag VKH (eds): Surgery of the Craniovertebral Junction. New York: Thieme, 1998, pp Levine A, Boriani S: Benign tumors of the cervical spine, in Clark CR (ed): The Cervical Spine, ed 3. Philadelphia: Lippincott-Raven, 1998, pp Marino RJ, Barros T, Biering-Sorensen F, Burns SP, Donovan WH, Graves DE, et al: International standards for neurological classification of spinal cord injury. J Spinal Cord Med 26 (1 Suppl):S50 S56, McMaster ML, Goldstein AM, Bromley CM, Ishibe N, Parry DM: Chordoma: incidence and survival patterns in the United States, Cancer Causes Control 12:1 11, Noel G, Feuvret L, Calugaru V, Dhermain F, Mammar H, Haie- Meder C, et al: Chordomas of the base of the skull and upper cervical spine. One hundred patients irradiated by a 3D conformal technique combining photon and proton beams. Acta Oncol 44: , Rhines LD, Fourney DR, Siadati A, Suk I, Gokaslan ZL: En bloc resection of multilevel cervical chordoma with C-2 involvement. Case report and description of operative technique. J Neurosurg Spine 2: , Sen C, Eisenberg M, Casden AM, Sundaresan N, Catalano PJ: Management of the vertebral artery in excision of extradural tumors of the cervical spine. Neurosurgery 36: , Yamada Y, Lovelock DM, Yenice KM, Bilsky MH, Hunt MA, Zatcky J, et al: Multifractionated image guided and stereotactic intensity modulated radiotherapy of paraspinal tumors: a preliminary report. Int J Radiat Oncol Biol Phys 62:53 61, 2005 Manuscript submitted June 1, Accepted February 6, Address reprint requests to: Ignacio J. Barrenechea, M.D., Department of Neurosurgery, St. Luke s Roosevelt Hospital Center, th Avenue, Suite 5G-80, New York, New York ijbarren@hotmail.com. 406 J. Neurosurg: Spine / Volume 6 / May, 2007