Surgery for Spinal Chordomas

Chordomas are rare neoplasms arising from remnants of the notochord, an embryonic precursor to the axial skeleton, and can occur anywhere along the spinal axis. ¹ They are relatively uncommon primary bone tumors, with an incidence rate of less than 0.1 per 100,000 per year. ² Approximately 250 affected people in the United States are diagnosed with chordoma each year. ²^,³^,⁴^,⁵ Chordomas account for approximately 1 to 4% of all primary malignant bone tumors, and they account for 4% of all bone tumors in the body. ⁴^,⁵^,⁶^,⁷ These tumors generally present in later-middle-aged adults and in the elderly, ⁸^,⁹ with a median age of presentation of approximately 60 years. ⁴^,¹⁰ The male-to-female ratio of patients found to have chordoma is 2:1. ³^,⁵^,¹¹^,¹²

Although chordomas can occur anywhere along the spinal axis, most tumors tend to occur on the rostral and caudal ends of the neural axis, at the spheno-occipital region of the skull base, and at the sacrococcygeal region, respectively. In fact, 35% of chordomas arise in the clivus and 50% in the sacrococcygeal region; 10% originate in the cervical vertebrae and 5% in the thoracolumbar vertebrae. ¹^,³^,⁴^,¹³^,¹⁴

Although these tumors are histologically benign and slow-growing, they exhibit a locally aggressive behavior and present significant management challenges. ³^,¹³^,¹⁵^,¹⁶ By the time that chordomas are found on radiographic imaging, they exhibit infiltrative growth that often occupies most of the vertebral body. ⁹ These tumors have a destructive behavior, slowly invading cancellous bone but rarely involving the intervertebral discs. ⁵^,⁹^,¹⁰ Chordomas have a slow disease course extending over a period of many years, with death resulting from complications associated with local extension of the tumor. ⁹ Furthermore, local recurrence occurs frequently when these tumors are not treated adequately with full en bloc resection preserving negative margins throughout. ¹⁶ Chordomas frequently recur locally and metastasize late, being found in the liver, lungs, other bone areas, soft tissues, brain, and even skin. ⁹^,¹⁷ Although the presence of metastasis actually does not significantly affect survival, the incidence of chordoma metastasis reported in the literature ranges from 5 to 43%. ³^,⁸^,¹⁸^,¹⁹ In autopsy studies, the rates of metastasis have been found to be as high as 65%. ⁹^,²⁰

Local tumor recurrence is the most important predictor of death in these patients and is often related to the extent of initial surgical resection. ¹³^,²¹^,²²^,²³ Local tumor recurrence has been found to be strongly associated with an increased risk of metastasis and tumor-related death. ¹³^,²² In fact, local recurrence has been highly linked to violation of tumor margins at the initial surgery, with a local recurrence rate of 64% in those patients in whom the tumor capsule was violated during surgery. ¹³^,²⁴ The time from surgery to local recurrence is approximately 2.27 years in patients undergoing radical resection, ²¹ compared with 8 months in those patients who receive subtotal resection. ¹³ The surgeon should bear in mind that subtotal resection or intralesional resection will lead to local recurrence, which is oftentimes more aggressive in behavior, much more difficult to approach surgically, and in the majority of patients only amenable to palliative therapy, resulting in death for the patient from disease. ⁵^,¹¹ Chordomas are fairly radioresistant to standard radiation treatment and do not respond to chemotherapy. Thus, treatment of chordomas entails total en bloc tumor resection, surgical excision combined with high-dose radiation, or palliative radiation. Wide en bloc surgical resection or radical extralesional surgery offers the possibility of total cure from the disease ( ▶ Fig. 22.1). ⁵^,¹¹^,²¹^,²⁵^,²⁶^,²⁷^,²⁸^,²⁹

Fig. 22.1 A 77-year-old man who presented with worsening sacral pain and was found to have a 4.2 × 5.9 × 8.7-cm lesion suggestive of chordoma arising from the sacrum and coccyx beginning at the level of S4. The figure shows T2-weighted sagittal (a) and axial (b) MR images of the lesion. The mass approximated the posterior margin of the rectum along its anterior margin. The patient denied any leg weakness of numbness. There were no changes in his bladder or bowel function. After undergoing a biopsy of the lesion that demonstrated chordoma, the patient was treated with a high sacrectomy with en bloc resection of the chordoma all through a posterior approach. Negative margins were obtained throughout. Given its caudal location in the sacrum, no instrumentation was required. The patient had no recurrence of tumor.

22.2 Indications and Contraindications

Considering that wide en bloc surgical resection offers the best prognosis for these invasive tumors, it is best that patients diagnosed with chordomas are treated in a timely manner before they develop metastasis and die from disease progression. ³⁰^,³¹^,³² At the time of being diagnosed with chordoma, patients should be offered a treatment plan consisting of surgical resection and possible adjuvant radiation. If the patient cannot handle the physiologic stresses of surgery or has very advanced disease, palliative radiation therapy should at least be offered.

The goal should be to achieve total excision and offer the patient the best chance of cure. However, the effectiveness of surgery is heavily influenced by the size and location of the tumor. ⁹^,¹² Chordomas in general are known to be locally aggressive tumors, destroying bone and invading into adjacent soft tissues. ¹⁴^,³³ The proximity to vascular, neural, and visceral structures imposes considerable challenges in the wide en bloc surgical resection of these tumors. ³⁰ A major criterion that negatively impacts whether a total en bloc resection of the tumor can be performed is tumor extension. ¹⁵ Chordomas may have a very insidious course and may not be detected until they have grown very large and begun to invade critical surrounding structures; in such cases en bloc resection may be much more complicated.

Extremely large tumor size may be a contraindication, especially if it has already begun to invade critical neighboring structures. All this must be carefully and realistically assessed to determine if total en bloc resection of the tumor is feasible. If only intralesional margins can be achieved in the tumor resection, the surgeon must carefully weigh the risk-benefit ratio for performing tumor resection before committing the patient to surgery. ¹⁵ In such patients, palliative radiation may be the best option, or the oncology team may consider a combination of debulking surgery with high-energy radiation (e.g., proton beam therapy), which has been used in recurrent tumors or tumors not suitable for en bloc resection.

When assessing a patient who comes with recurrence of chordoma, en bloc resection of such tumors is significantly more difficult, as tumor margins have been violated, making en bloc tumor resection with negative margins throughout no longer possible ( ▶ Fig. 22.2). Furthermore, the planes of dissection are less demarcated from scar tissue formation, thus greatly complicating surgery. ¹⁵ In these patients, the risks associated with such surgery often outweigh the benefits. In such situations of recurrence after initial resection, intralesional tumor resection combined with high-dose radiation may be the best treatment choice. ¹⁵

Fig. 22.2 A 42-year-old woman who had an initial high sacral amputation of sacral chordoma after presenting with sacral and buttock pain but neurologically intact. Although the surgery went well and it appeared that a full resection of the tumor had been achieved, the patient ultimately was found to have a recurrence of the tumor. Two years later, she came to our hospital for evaluation of how to treat the recurrent chordoma involving much of the sacrum as well as the right sciatic notch (a, b). She underwent en bloc resection with complex plastic surgery closure and then got subsequent radiation. Another 2 years later, she had another recurrence of the chordoma at the right sciatic notch. The tumor was resected and the patient received postoperative radiation therapy. At that point, she had already a total of five different surgical procedures for resection of recurrences of the chordoma (c). After a subsequent 4-year period, the patient returned with recurrence of the disease in the perirectal area in the perineal region (d, e). The patient was recommended to resect the tumor off the adjacent rectum. The tumor was resected off the rectum, taking part of the rectal wall along with the specimen. After tumor excision, general surgery repaired the defect in the rectal wall, followed by plastic surgery closure of the wound.

22.3 Preoperative Evaluation

A thorough preoperative evaluation is absolutely crucial. Diagnostic work-up traditionally had started with plain radiographs of the involved area of the spine. These radiographs would find a lesion with calcification, osteosclerosis, or bone erosion with a possible soft tissue component. ¹⁴ Computed tomography (CT) has since largely replaced plain radiographs as the initial diagnostic study assessing for these lesions. Chordomas frequently present on CT as radiolucencies with invasion of cancellous bone. These lesions can also demonstrate bone destruction or soft tissue invasion. ¹⁴^,¹⁵ Calcifications are also present in 30 to 70% of chordomas. ¹³^,³⁴ CT myelography can be occasionally used and may demonstrate epidural block or compression from tumor compression. ¹⁴ CT is also important preoperatively in planning the instrumentation necessary for reconstruction of the spine after en bloc tumor resection.

Magnetic resonance imaging (MRI) can detect chordomas that do not appear on plain radiographs or CT. ¹⁵ These lesions appear as isointense or hypointense on T1-weighted sequences and as hyperintense on T2-weighted sequences. ⁹^,¹³^,³⁴ The preoperative MRI needs to be carefully studied to identify whether the chordoma invades into surrounding visceral or vascular structures. This will have great bearing in regards to whether anterior, posterior, or combined approaches are utilized in the tumor resection.

Bone scans will demonstrate reduced uptake or normal distribution of radioisotopes, which is unlike most bone tumors. ¹³^,³⁵ Chordomas are relatively avascular lesions but can still be identified by angiography as a slight tumor stain. ³ Angiography is important in the evaluation of patients with cervical region chordomas in order to identify dominance between the vertebral arteries. If the cervical chordoma involves a vertebral artery, a balloon test occlusion may be performed to determine if the patient can tolerate sacrifice of the involved vertebral artery.

Although advances in diagnostic imaging modalities have allowed detection of smaller and more subtle tumors earlier in their progression, a biopsy is still usually necessary for diagnostic purposes. ¹³ Fine-needle aspiration biopsy is a minimally invasive technique that allows for accurate diagnosis of chordomas. ¹³ Ideally, the surgeon who will be performing the tumor resection should perform the biopsy or at least direct the choice of biopsy procedure. ¹³ It is critical that this phase of the patient’s care be performed correctly because poorly planned incisional biopsies or incomplete debulking surgeries increase the risk of local recurrence and metastasis. ¹³^,²² Ultimately, the chordoma will be resected with a wide margin including the route of the previous biopsy tract. In cases where the needle biopsy tract was not included in the tumor resection because its trajectory was unknown, long-term survival is still possible and has been documented. ⁵^,²⁹^,³⁶ However, this is not advisable because chordomas have a high tendency to recur after intralesional biopsy or biopsy contamination, which both risk seeding tumor cells along the wound or even intradurally. ¹⁵^,²²^,³⁷^,³⁸ Thus, as soon as a chordoma is suspected on diagnostic imaging, the patient should be referred to a tumor center to coordinate the biopsy, surgery, and postoperative adjuvant therapies.

Patients should be carefully counseled about potential postoperative deficits that may be incurred during the surgical resection. In order to ensure a total en bloc resection of the chordoma, sacrifice of neurologic structures may be inevitable. Thus, the trade-off for potential oncologic cure may be permanent neurologic deficit. It is imperative that the patient fully understand this before accepting and undergoing surgery. Sacrifice of a single nerve root may not necessarily produce a new or worsened neurologic deficit, especially in the presence of a preexisting deficit. However, combinations of nerve roots sacrificed may produce pronounced deficits. Starting at the rostral end of the spine, the C1 and C2 nerve roots can be sacrificed without significant morbidity. Sacrifice of C3, C4, or C5 may result in some diaphragm weakness, but sacrificed individually are unlikely to have a significant effect on diaphragm function. Sacrifice of C5, C6, C7, C8, or T1 results in weakness in the muscle groups of the upper extremities, whereas sacrifice of the T2–T12 nerve roots has inconsequential motor loss and may only result in a bandlike distribution of numbness in the thoracic and abdominal regions. Sacrifice of L1 or L2 nerve roots may potentially produce hip weakness postoperatively. However, many patients are able to compensate for this loss over time. Sacrifice of L3 or L4 will result in quadriceps weakness. The problem more commonly noted with L4 sacrifice is loss of proprioception at the knee joint, because without proprioception at the knee, the patient may find the knee weak and complain of buckling of the knee during ambulation. Foot drop results with sacrifice of the L5 nerve root. Although generally tolerated, sacrifice of S1 results in gastrocnemius weakness and difficulty standing on the toes. Sacrifice of bilateral S2 and S3 nerve roots results in bladder, bowel, and sexual dysfunction. ³⁹ Preservation of at least one S3 nerve root preserves bladder and bowel function in two thirds of patients. ³⁹^,⁴⁰ Similar trends have been found in regards to sexual function, where unilateral sacral resection still preserves overall sexual function, although there is numbness on the side of the sacrifice. ⁴¹ Especially when counseling patients diagnosed with sacral chordomas, it is important to educate the patient about the significant morbidity affecting bowel, bladder, and sexual function with surgery. ²⁵^,⁴¹^,⁴²^,⁴³ Lastly, the S4 and S5 nerve roots can be sacrificed without any major deficits.

22.4 Surgery

The main treatment options for spinal chordomas are surgical excision alone, surgical excision combined with radiation therapy, and isolated radiation therapy. ¹^,¹⁵^,²²^,⁴⁴^,⁴⁵ If at all possible, surgical en bloc resection should be attempted, as this provides the best long-term survival and disease-free intervals for the patient. ⁸^,⁹^,¹⁴^,³³^,⁴⁴^,⁴⁶ In fact, multiple studies have shown that negative margins throughout the en bloc tumor specimen is the most important predictor of local recurrence and survival associated with chordomas. ¹³^,²¹^,³⁰^,⁴²^,⁴⁷^,⁴⁸ Thus, the ideal goal of surgery is total en bloc resection of the tumor, decompression of neurologic structures, and stabilization and reconstruction of the spine. ⁵^,¹⁵

For newly diagnosed chordomas, total en bloc excision is the optimal treatment, even if marginal. In regards to nomenclature, resected lesions with a rim of normal tissue surrounding the tumor are considered wide excisions. Tumor resections with a pseudocapsule found at the margins are considered marginal resections. Resections with a violation of the capsule or neoplastic cells seen at the margin are defined as contaminated or intralesional. ³⁰ The treatment of choice is to obtain wide-margin resection and treat the patient with radiation therapy postoperatively. Intralesional or even marginal resections can result in local recurrence. ⁹^,¹⁶ Nevertheless, even if marginal resection is the best result that can be achieved, studies have noted that both wide and marginal en bloc sacral chordoma resections are associated with significant improvement in disease-free survival with acceptable perioperative morbidity. ³⁰

22.4.1 Overview of Surgical Technique

Before delving into the nuances for the various regions of the spine, we will provide a brief overview of the general surgical principles involved in en bloc chordoma resection. In general, most chordoma resections can be performed through a posterior approach, especially those of the thoracic or lower sacral region. Patients are positioned prone on a Jackson table. The incision is centered at the level of interest, ideally preserving the biopsy tract so that it can be removed en bloc with the tumor specimen. Subperiosteal dissection is carried out at the level of interest as well as the levels that will be instrumented. Exposure is carried out so that the tumor is circumferentially dissected, ideally preserving wide tissue margins that are all tumor-free. Standard spondylectomy techniques are oftentimes most appropriate with these tumor resections while in addition trying to leave a cuff of normal tissue on the chordoma if there is possible soft tissue involvement as well. Medial facetectomies with osteotome or Tomita saw disconnection of the pedicles flush to the vertebral bodies are performed. The intervertebral discs rostral and caudal to the vertebrectomy are removed. Nerve roots may be sacrificed if there is extensive tumor involvement or to provide a window to deliver the en bloc specimen. If nerve roots are sacrificed, double-suture ligation is used. After all the osteotomies have been performed, the specimen can be removed en bloc.

In some circumstances, en bloc chordoma resection cannot be fully performed via a posterior approach in a safe fashion. It is important to carefully study preoperative imaging to understand the extent of local tumor invasion. If the tumor invades or encompasses vital visceral or vascular structures, then an anterior approach may need to be incorporated into the surgical plan to prepare and/or deliver the en bloc tumor specimen. This way, the surgeon has better access and visualization of these vital structures during the dissection of the tumor. It should be noted that chordomas involving ventral vascular or visceral structures can still be prepared and delivered through a posterior-only approach if the surgeon is able to perform circumferential detachment of the tumor from the surrounding bone and soft tissue structures. ³⁰ However, visualization of the anterior structures and control if a complication were to occur are much more difficult. Furthermore, if the chordoma is in regions of the spine that are more likely to result in significant neurologic compromise with nerve root sacrifice (i.e., the brachial plexus or lumbosacral nerve roots), an anterior approach may be necessary to deliver the tumor without sacrificing more nerve roots than absolutely necessary. Lastly, an anterior approach may also be preferred if the chordoma is confined to the vertebral body only.

In the operative planning, spinal instrumented reconstruction should be considered for most segments of the spine because the en bloc surgical resection can result in significant spinal instability. ⁹ Anterior column restoration and three-dimensional balance are important if a vertebrectomy is being performed. ¹⁵ The one exception where instrumented stabilization may not be necessary is in the resection of distal sacral chordomas below the sacroiliac joint. Resection of chordomas distal to the S1 vertebral level oftentimes does not require reconstruction because more than 50% of the sacroiliac joint is still preserved, thus preserving the stability of the pelvic ring.

For simplicity, we will briefly review en bloc resections using spondylectomy techniques, starting in the thoracic spine and then discussing lumbar, sacral, and cervical resections.

22.4.2 Thoracic Spine Techniques

The unique advantage to resecting chordomas of the T2–T12 region is the ability to sacrifice thoracic nerve roots with minimal morbidity to the patient. This freedom to sacrifice nerve roots makes a posterior-only surgical plan more amenable. Patients are positioned prone on a Jackson table, and a standard midline incision with subperiosteal dissection is performed at the level of the tumor and two to three levels rostral and caudal for planned instrumentation. Laterally, the exposure should be carried out along the ribs at least 6 to 12 cm on each side. Cuts are made in the ribs 6 to 12 cm lateral to the costotransverse joint so that the cut portion of the rib can be removed and to allow the surgeon to dissect the lateral and anterior margins of the vertebral body affected by tumor. It is important to try avoiding violation of the pleura and to preserve the neurovascular bundles when dissecting the ribs. The ribs rostral and caudal to the index level may also be cut in a similar fashion and be used for bone graft later in the reconstruction if they are not involved with tumor.

In the dissection of the vertebral body, the surgeon will encounter segmental vessels draining in the inferior vena cava and arising from the aorta. These vessels should be dissected and traced to the neural foramen. Multiple segmental feeder vessels can also be ligated in the tumor exposure and delivery with minimal ischemic risk to the spinal cord. In fact, Kato et al found that in a canine model, interruption of bilateral segmental arteries at four or more consecutive levels, including the level of the artery of Adamkiewicz, was needed to risk producing ischemic spinal cord dysfunction. ⁴⁹ Although the canine spine model shares many similarities to the anastomotic vascular network of the human spine, such studies in the human spine are lacking. In our experience, we have sacrificed more than six segmentals bilaterally in a five-level spondylectomy without spinal cord ischemia. ⁵⁰

As the surgeon works down the lateral margins of the vertebral body and towards the ventral margin of the vertebral body, it is important to establish a clear plane separating the vertebral body from the aorta, inferior vena cava, azygous vein, and pleura. Once this plane is established, a Silastic sheet can be wrapped around the anterior aspect of the vertebral body to protect the vital structures anterior to the vertebral body.

The posterior vertebral elements that are not involved with tumor are removed in addition to the posterior elements of the levels rostral and caudal to the index level. Ideally, cuts are made across the pedicles flush with the vertebral body, and these cuts can be made with osteotomies or Tomita saws. Adequate removal of posterior elements is necessary to create a window that allows for the spinal cord to remain untouched as the en bloc specimen is removed in the vertebrectomy. After the posterior elements have been removed, the necessary nerve roots are ligated and transected proximal to the dorsal root ganglion. It is important that this be done proximal to the dorsal root ganglion to avoid postoperative neuropathic pain from these nerve roots. Within the spinal canal, the epidural plane is dissected and defined to create a free plane between the tumor-ridden vertebra and the spinal cord.

Tomita saws are assembled encircling the spinal column rostral and caudal to the index level. Prior to completing the final osteotomies with the Tomita saws, the surgeon must provide some stabilization for the spine because removal of the en bloc specimen will cause extreme destabilization of the spinal column and can be disastrous. For this reason, the spine should be instrumented two to three levels rostral and caudal to the index level and a rod should be placed and secured on the side opposite from which the tumor will be rotated out and removed. Once some instrumented stabilization has been created, the final osteotomies are performed and the en bloc tumor specimen is removed through the space created by removing the ribs.

Afterwards, the ventral defect can be reconstructed by a variety of means, including expandable cages, bone grafts, or other reconstructions, and the remaining rod on the posterior instrumentation is then placed and secured.

One situation in which a chordoma of the thoracic spine may require a combined anterior–posterior surgical strategy is if the tumor has invaded pleura. In such circumstances, an anterior approach is needed to adequately dissect the pleura and keep the portion of the pleura that has been invaded by tumor with the en bloc specimen so that negative margins may be obtained throughout. These anterior approaches can be performed via thoracotomy or thoracoscopy.

In instances where chordomas invade the dura, the surgeon must carefully weigh the risk-benefit ratio. Resection of such lesions without inclusion of the dura may be intralesional and puts the patients at high risk of local recurrence. ¹⁶ Wide resection of such lesions would include removal of the dura infiltrated by the chordoma in addition to the spondylectomy, although this puts the patient at higher risk of cerebrospinal fluid leak and potential intradural tumor seeding. ¹⁶ If dura-containing tumor is resected, a lyophilized bovine pericardium double wrapping or other dural substitute can be used to form a watertight cylindrical containment. ¹⁶ In most instances, there is no dural involvement, and in cases that there is epidural encroachment of chordoma, often there is still a margin that can be obtained without resecting dura. ¹⁰

22.4.3 Lumbar Spine Techniques

The lumbar spine is less forgiving in regards to sacrifice of nerve roots because of the lumbosacral plexus responsible for motor innervations to the legs as well as bowel, bladder, and sexual functions. In such circumstances, it may be best to do a combined anterior–posterior surgical approach to resect the tumor ( ▶ Fig. 22.3). For the posterior portion, the posterior spinal elements are removed in a similar fashion to the thoracic spine and the spine is instrumented to provide for some spinal stabilization. In the anterior portion, a ventral retroperitoneal/transperitoneal approach or lateral retroperitoneal approach can be used to resect the en bloc specimen away from the thecal sac. Some prefer to use a general surgeon or a vascular surgeon for the exposure and manipulation of the great vessels. Lesions above L5 can be approached with the lateral retroperitoneal approach, oftentimes from the side that the tumor originates. However, a midline approach can also be used in these lesions above L5, especially if there is no particular sided dominance of the tumor. For lesions at L5, a midline retroperitoneal or transperitoneal approach can be used.

Fig. 22.3 (a-e) A 31-year-old male who initially presented with back pain radiating down the left leg and was eventually found to have a lesion in the L2–L3 region. Initially it was thought to be a hemangioma, but CT-guided needle biopsy of the lesion showed that it was a chordoma. Prior to the biopsy, the patient had undergone kyphoplasty of the L2 vertebral body. The patient then presented to our hospital for evaluation and treatment. The patient had already received proton beam radiation therapy. He underwent a two-stage procedure for en bloc resection of the tumor. The first stage was approached posteriorly and the patient had a L1–L4 laminectomies, T11–L5 instrumented fusion, mobilization of the lumbar plexus, and placement of Tomita saws. The second stage was a left-sided retroperitoneal approach for an en bloc L2–L3 spondylectomy and lumbar reconstruction with distractible cage 2 days later (November 27, 2012). The patient did well postoperatively with full resection of the tumor. He had no evidence of residual disease several years later.

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