- Email: [email protected]
Posterior Nerve–Sparing Multilevel Cervical Corpectomy and Reconstruction for Metastatic Cervical Spine Tumors: Case Report and Literature Review
Accepted Manuscript Posterior nerve-sparing multilevel cervical corpectomy and reconstruction for metastatic cervical spine tumors: case report and literature review Elias Shaaya, MD, Jared Fridley, MD, Sean M. Barber, MD, Sohail Syed, MD, Jimmy Xia, BSc, Michael Galgano, MD, Adetokunbo Oyelese, MD, PhD, Albert Telfeian, MD, PhD, Ziya Gokaslan, MD PII:
S1878-8750(18)32557-9
DOI:
https://doi.org/10.1016/j.wneu.2018.11.010
Reference:
WNEU 10694
To appear in:
World Neurosurgery
Received Date: 2 August 2018 Revised Date:
31 October 2018
Accepted Date: 2 November 2018
Please cite this article as: Shaaya E, Fridley J, Barber SM, Syed S, Xia J, Galgano M, Oyelese A, Telfeian A, Gokaslan Z, Posterior nerve-sparing multilevel cervical corpectomy and reconstruction for metastatic cervical spine tumors: case report and literature review, World Neurosurgery (2018), doi: https://doi.org/10.1016/j.wneu.2018.11.010. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Posterior nerve-sparing multilevel cervical corpectomy and reconstruction for metastatic cervical spine tumors: case report and literature review
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Elias Shaaya MD,1 Jared Fridley MD,1 Sean M. Barber MD,1 Sohail Syed MD,1 Jimmy Xia BSc,1 Michael Galgano MD,1 Adetokunbo Oyelese MD, PhD,1 Albert Telfeian MD, PhD,1 Ziya Gokaslan MD1
1
University, Providence, Rhode Island
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Department of Neurosurgery, Rhode Island Hospital, The Warren Alpert Medical School at Brown
Keywords: Posterior cervical corpectomy, spine metastasis, thyroid carcinoma, cervical spine reconstruction, spine tumor, polymethylmethacrylate
Declarations of Interest: None
Corresponding Author: Ziya L. Gokaslan, MD, FAANS, FACS Rhode Island Hospital
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Department of Neurosurgery Norman Prince Neurosciences Institute 593 Eddy Street - APC 6 Providence, RI 02903
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Tel: 401-793-9132
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Running Title: Posterior cervical corpectomy for metastasis
Email: [email protected]
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Email: [email protected]
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Abstract
Background
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Cervical spine metastases with circumferential spinal cord compression are often treated with combined anterior-posterior decompression and stabilization. In patients with large anterior neck masses, prior radiotherapy to the neck, or prior anterior neck surgery, however, anterior approaches may pose additional risk. In such cases, posterior-only approaches that allow for circumferential decompression and anterior column reconstruction may be beneficial. Case Description
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We present the case of a seventy-year-old male with follicular thyroid carcinoma metastatic to the cervical spine causing spinal cord compression. We utilized a posterior-only approach for a C6/7 partial corpectomy and posterior decompression and fusion from C2-T2. Our technique involved pre-operative embolization of the right vertebral artery to safely gain access to the ventral surface of the spinal cord and vertebral bodies. Anterior column support was provided by a chest tube/polymethylmethacrylate construct, allowing the implant to be placed within the anterior column from a posterior approach without nerve root sacrifice. The patient tolerated the procedure well. He had no post-operative neurologic deficits. Two months later he underwent a total thyroidectomy followed by stereotactic radiotherapy to the tumor bed (2700 cGy total, 3 fractions). At one-year follow-up he was active and without significant pain or focal neurologic deficits. Conclusions
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We propose a novel approach to ventral/circumferential cervical spine tumors that combines epidural decompression and cervical stabilization via a posterior-only approach. By using a chest tube/polymethylmethacrylate construct, anterior column support can be achieved through a posterior approach without nerve root sacrifice.
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Introduction The surgical management of spinal metastatic disease has evolved considerably over the last
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several decades. Modern surgical instrumentation and techniques - as well as advancements in spinal radiotherapy - have changed the treatment paradigm for affected patients.1 Indications for surgical
intervention include preservation or restoration of neurological function, reestablishment of mechanical stability, correction of deformity, or separation between tumor and spinal cord prior to radiotherapy.
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Radiotherapy functions as a mainstay for overall disease management but is also important as an adjuvant method of disease control following resection. The high rate of local control for metastatic disease with
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radiosurgery has led to the concept of separation surgery, with the goal being to create a circumferential tumor-free margin around the spinal cord, sparing the spinal cord from radiation toxicity incurred during radiosurgery to the remaining tumor.2
Surgical decompression of the spinal cord or nerve roots may be required based on the degree of
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compression and the presence of neurological symptoms or deficits. Patients with ‘high’ grade (Bilsky II, III) epidural spinal cord compression3 and/or radioresistant metastatic disease generally undergo surgical decompression, while those with minimal (Bilsky I) or no compression (Bilsky 0) will typically receive
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radiotherapy alone. Patients with primarily ventral cervical epidural spinal cord compression will typically undergo an anterior approach, such as an anterior cervical corpectomy with reconstruction,
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while patients with posterior-only disease typically undergo a posterior decompression with or without instrumentation. In patients with circumferential disease, a combination of anterior and posterior approaches is often used. A review of the literature by Fehlings et al. revealed that the most common approach for subaxial cervical spine metastatic disease is an anterior corpectomy followed by reconstruction, with a combined approached being reserved for multi-level and circumferential disease.4 Each surgical approach for tumor resection and stabilization within the cervical spine carries a unique risk profile based on the adjacent surgical anatomy. Minimizing the number of approaches needed
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to accomplish the surgical goals of decompression, stabilization, and or deformity correction may result in a decreased perioperative risk to the patient. In patients with prior anterior neck surgery, radiation, or the presence of tumor within anterior neck structures, anterior cervical spine approaches may confer an
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increased risk of morbidity. In this paper we present the case of a posterior multilevel transpedicular partial corpectomy and anterior column reconstruction for a patient with metastatic follicular thyroid carcinoma and review the available literature on the posterior cervical approach for circumferential
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metastatic disease.
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Case Presentation Presentation
A 70-year-old male with no significant past medical history presented to the emergency department with progressive weakness and decreased sensation in both arms and legs over the past 3
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months. He reported feeling particularly weak in his right hand and had been dropping objects more frequently. He denied any significant neck or back pain. On examination he was found to have 4-/5 weakness in bilateral triceps, grip strength, finger abduction and finger extension as well as decreased
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sensation in bilateral C7 and C8 dermatomes. Gait was within normal limits, and no hyperreflexia or
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pathological reflexes were evident on exam.
Diagnostic Workup
Magnetic resonance imaging (MRI) of the cervical spine revealed a 5cm x 6cm x 3cm mass
encompassing the right C7 vertebral body with epidural disease causing spinal cord displacement, and extension of the mass into the paraspinal tissues, posterior C7 bony elements via the right pedicle, and caudal C6 vertebral body (Figure 1, A and B). The mass abutted the right vertebral artery. Also noted
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was a right sided 3cm x 2cm x 4cm thyroid mass without an obvious direct connection to the cervical spine mass. Computed tomography (CT) of the cervical spine showed lytic destruction of the right C6 and C7 vertebral bodies (Figure 1, C and D).
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Due to suspicion for metastatic disease, a CT chest/abdomen/pelvis was performed, but was negative for additional lesions. MRI thoracic and lumbar spine revealed small lesions within the posterior elements of T4 and T7 without epidural disease. A CT guided biopsy of the right thyroid mass was
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performed, and pathology was consistent with a carcinoma of thyroid follicle origin (CK7, TTF-1,
thyroglobulin, and PAX-8 positive). After consultation with oncology and discussion with the patient, the
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decision was made to proceed with surgical decompression of the spinal cord and instrumented stabilization, followed by a total thyroidectomy and radiotherapy.
On diagnostic angiogram the tumor was noted to be hypervascular, with feeding vessels originating from muscular branches of the right vertebral artery and large branches from the thyrocervical and costocervical trunks (Figure 2, A and B). Particle embolization of these tumor-feeding vessels to
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reduce intraoperative blood loss - followed by coil embolization of the right vertebral artery - was
Surgical Technique
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successfully performed (Figure 2, C).
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The patient was positioned prone for a standard posterior cervical approach, the neck kept in
neutral position. Neuromonitoring (somatosensory and motor evoked potentials) was used for positioning and for the duration of the procedure. Spinal exposure was carried out from C2-T3. Tumor was encountered in the paraspinal tissues on the right at C6-7 during the initial dissection. Posterior T1-T3 pedicle screws, a right C2 pedicle screw and a left C2 translaminar screw were placed prior to proceeding with tumor resection. Lateral mass pilot holes were also drilled in the bilateral C3, C4, C5 lateral masses and the left C6 lateral mass. C5 and T1 laminectomies and left sided hemilaminectomies at C6 and C7
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were performed to expose the thecal sac. Tumor was noted to involve the right-sided laminae and facets at C6 and C7. Epidural tumor at C6 and C7 was dissected away from the thecal sac from left to right and resected. Paraspinal tumor was dissected away from surrounding musculature and resected piecemeal.
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The tumor was noted to be very vascular despite embolization. Foraminotomies were then performed on the right at C5/6 and C7/T1 to skeletonize the right C6 and C8 nerve roots laterally towards the vertebral artery and brachial plexus trunks. Tumor was adherent to the nerve roots and was carefully dissected
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away and resected. We encountered the embolized vertebral artery during tumor resection and removed a portion of it with the tumor. The right C6 and C7 lateral masses were resected and the right C6 and C7
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pedicles were drilled down into their respective vertebral bodies using a diamond bit. Partial right C6 and C7 corpectomies were then performed until relatively solid bone was encountered and the thecal sac was decompressed ventrally.
The C5/6 and C7/T1 discs were exenterated from the same posterolateral approach and the inferior C5 and superior T1 endplates were exposed. Circular defects were created in both endplates using
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a drill to accommodate a chest tube/polymethylmethacrylate (PMMA) construct. A 28-French chest tube was then cut to span from endplate to endplate, and the tube was bent and passed between the skeletonized nerve roots into the corpectomy defect. Once the chest tube was placed into the anterior
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column and fit into the endplate holes, it was filled with PMMA (Figure 3, Figure 4 A). Lateral mass screws were then placed in each of the previously drilled holes, and titanium rods were cut, bent, and
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secured to the screws from C2-T3 (Figure 4 B). The procedure lasted approximately 12 hours. Estimated blood loss was 800cc, and the patient required transfusion of two units of packed red blood cells during the procedure.
Post-operative course The patient tolerated the procedure well. He had no post-operative neurologic deficits and was discharged to home on post-operative day #9. Two months later he underwent a total thyroidectomy
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followed by spinal radiosurgery to the tumor bed (2700 cGy total, 3 fractions). At one-year follow up the patient was active, ambulating unassisted and without significant pain or focal neurologic deficits. Imaging at 1 year revealed stable minimal residual disease without tumor recurrence, hardware failure or
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evidence of pseudoarthrosis (Figure 5, A - D).
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Discussion
The cervical spine is reportedly involved in 8-20% of spinal osseous metastatic disease.4 Current
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management of cervical spine metastatic disease involves surgical decompression with or without stabilization and radiotherapy. Several large series have demonstrated improved survival in patients treated surgically with adjunctive radiotherapy compared to patients treated with radiotherapy alone. Patchell et al. conducted the only randomized trial addressing the subject, establishing the benefit of surgical intervention.5 Over a 10-year period, with an enrollment of a 123 patients, the results
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demonstrated improved ambulation rates in patients with epidural disease causing neurological deficit when treated with surgery and radiotherapy versus radiotherapy alone. In the current case, the patient presented with significant epidural disease with a neurological deficit and was thus felt to be a good
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candidate for surgical intervention. Furthermore, a preoperative biopsy was consistent with poorly differentiated thyroid cancer. Work done by Kuschchayeva et al. has shown that aggressive management
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of thyroid metastases leads to improved outcomes, and en bloc spondylectomy should be attempted when possible.6,7 This recommendation is echoed by the American Thyroid Association, which endorses complete surgical resection of isolated bony metastases.8 Given the clinical, radiographic and pathological findings in the current case, surgical intervention followed by radiation therapy was felt to be the most appropriate management. The goals of surgery were to perform a maximal safe resection, decompress the spinal cord and nerve roots, restore spinal stability and create enough epidural space for subsequent radiation therapy to be administered safely and successfully. Because the patient underwent anterior
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column osteotomies up to the level of C5/6, the authors felt that bony fixation up to and including C2 would lead to the most durable construct possible with minimal additional morbidity. Corpectomy in the cervical spine is traditionally performed via an anterior approach. When
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posterior decompression is also required, combined anterior and posterior surgeries are often utilized. Although partial corpectomies through a dorsal approach for metastatic disease and other pathologies of the thoracic spine and thoracolumbar junction have been well-described, the anatomical constraints of the
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cervical roots, vertebral arteries, and the cervical cord provide technical challenges to a posterior-only approach to the anterior column in the thoracic spine. As such, reports of posterior-only cervical partial
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corpectomies and reconstruction in the literature are lacking. In a systematic review of the literature, Fehlings et al. found that reports of posterior-only approaches to metastases in the subaxial cervical spine were rare and it was unclear if any substantial anterior reconstruction was attempted in those cases (12%).4 A large retrospective study at Sloan-Kettering detailed their experience with cervico-thoracic junction tumor resection and stabilization. Of their 90 patients, 44 had partial posterior vertebral body
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resection but required anterior reconstruction through a separate approach.9 Bydon et al. described the case of a patient with recurrent epithelioid sarcoma of the cervical spine with intradural extension treated with C1-4 en bloc spondylectomy from a single-staged posterior approach. As in our case, the authors
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sacrificed the ipsilateral vertebral artery in order to improve access and extent of resection, but instead of embolizing the vessel preoperatively, the authors clipped the diseased vessel intraoperatively for 30
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minutes while monitoring brainstem evoked potentials to ensure sufficient flow through the contralateral vertebral artery.10 The authors also sacrificed the right C1-4 nerve roots to achieve en bloc resection and allow for access to the anterior column, resulting in permanent right deltoid weakness. In our case, the use of the chest tube/PMMA construct allowed for anterior column reconstruction without the added morbidity associated with cervical nerve root sacrifice. Accessing the anterior column of the cervical spine through a posterior approach is challenging and several factors must be taken into consideration. Firstly, preoperative tumor embolization and/or
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vertebroplasty should be considered to help minimize intra-operative blood loss. Secondly, a sufficient corridor for resection and stabilization must be constructed while respecting the cervical cord and nerve roots. Angiography may be useful to assess the vertebral arteries and to determine if one may be
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sacrificed to improve surgical access. If the contralateral vertebral artery caliber is sufficient, preoperative embolization of the ipsilateral vertebral artery can be performed at the time of angiography. Sacrificing the vertebral artery affords the ability to access a further lateral corridor for reconstructing the anterior
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column. Even after vertebral artery sacrifice, however, the cervical nerve roots limit the size of the access corridor to the anterior column from a posterior approach. Rather than sacrifice roots, as other authors have done,10 a chest tube/PMMA construct was used in this case, as has been described previously for
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anterior column support in the cervicothoracic spine from an anterior approach.11,12 Because a chest tube is flexible, it can be bent and conformed to any given corridor and only elongated and solidified through PMMA injection after the tube is in place in the anterior column, making it an ideal construct for a posterior approach in the cervical spine. Expandable cages and other means of anterior support would be
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difficult to place from such an approach without nerve root sacrifice.
The approach described here allows for successful decompression of the spinal cord, extensive resection of anterior cervical masses, and anterior column reconstruction without requiring a combined
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anterior and posterior approach. While some sources argue for a combined anterior and posterior surgical approach to the cervical spine when a tumor involves more than one vertebral body,9,13 we show here that
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it is technically feasible and safe to achieve all goals of surgery from a posterior-only approach. Furthermore, a single posterior approach avoids the complications associated with anterior approaches (e.g. dysphagia, dysphonia, anterior neck hematomas) and the need for intraoperative repositioning. We suggest this this novel surgical technique be considered in patients with anterior cervical metastatic disease with circumferential spinal cord compression. This approach offers the ability to decompress the spinal cord and stabilize the cervical spine in a single stage with shorter anesthesia times, provided the patient has adequate blood flow in the contralateral vertebral artery.
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Conclusion
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Patients with spinal metastatic disease benefit from decreased mortality and increased quality of life when undergoing surgical resection in addition to radiotherapy, rather than radiotherapy alone.5 We propose a novel approach to anterior cervical spine tumors that combines epidural decompression and cervical stabilization from a posterior-only approach. By using a chest tube/PMMA construct, anterior
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column support can be achieved through a posterior approach without nerve root sacrifice. A singlestaged approach such as this decreases operative and anesthesia times while still achieving the goals of
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surgery (spinal cord decompression, restoration of stability) and resulting in favorable patient outcomes. References
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Laufer I, Rubin DG, Lis E, et al. The NOMS framework: approach to the treatment of spinal metastatic tumors. Oncologist. 2013;18(6):744-751. doi:10.1634/theoncologist.2012-0293 Laufer I, Iorgulescu JB, Chapman T, et al. Local disease control for spinal metastases following “separation surgery” and adjuvant hypofractionated or high-dose single-fraction stereotactic radiosurgery: outcome analysis in 186 patients. J Neurosurg Spine. 2013;18(3):207-214. doi:10.3171/2012.11.SPINE12111 Bilsky MH, Laufer I, Fourney DR, et al. Reliability analysis of the epidural spinal cord compression scale. J Neurosurg Spine. 2010;13(3):324-328. doi:10.3171/2010.3.SPINE09459 Fehlings MG, David KS, Vialle L, Vialle E, Setzer M, Vrionis FD. Decision Making in the Surgical Treatment of Cervical Spine Metastases. Spine (Phila Pa 1976). 2009;34(Supplement):S108-S117. doi:10.1097/BRS.0b013e3181bae1d2 Patchell RA, Tibbs PA, Regine WF, et al. Direct decompressive surgical resection in the treatment of spinal cord compression caused by metastatic cancer: a randomised trial. Lancet. 2005;366(9486):643-648. doi:10.1016/S0140-6736(05)66954-1 Kushchayeva YS, Kushchayev S V, Carroll NM, et al. Spinal metastases due to thyroid carcinoma: an analysis of 202 patients. Thyroid. 2014;24(10):1488-1500. doi:10.1089/thy.2013.0633 Kushchayev S, Kushchayeva Y, Theodore N, Preul MC, Clark OH. Percutaneous vertebroplasty for thyroid cancer metastases to the spine. Thyroid. 2010;20(5):555-560. doi:10.1089/thy.2009.0420 The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid. 2016;26(1):1-133. doi:10.1089/thy.2015.0020 Placantonakis DG, Laufer I, Wang JC, Beria JS, Boland P, Bilsky M. Posterior stabilization strategies following resection of cervicothoracic junction tumors: review of 90 consecutive cases. J Neurosurg Spine. 2008;9(2):111-119. doi:10.3171/SPI/2008/9/8/111 Bydon M, De la Garza-Ramos R, Suk I, et al. Single-Staged Multilevel Spondylectomy for En Bloc Resection of an Epithelioid Sarcoma With Intradural Extension in the Cervical Spine. Oper
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1.
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11. 12.
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13.
Neurosurg. 2015;11(4):E585-E593. doi:10.1227/NEU.0000000000000961 Errico TJ, Cooper PR. A new method of thoracic and lumbar body replacement for spinal tumors: Technical note. Neurosurgery. 1993;32(4):678-681. doi:10.1227/00006123-199304000-00030 Cooper PR, Errico TJ, Martin R, Crawford B, Dibartolo T. A systematic approach to spinal reconstruction after anterior decompression for neoplastic disease of the thoracic and lumbar spine. Neurosurgery. 1993;32(1):1-8. doi:10.1227/00006123-199301000-00001 Molina C, Rory Goodwin C, Abu-Bonsrah N, Elder BD, De la Garza Ramos R, Sciubba DM. Posterior approaches for symptomatic metastatic spinal cord compression. Neurosurg Focus. 2016;41(2):E11. doi:10.3171/2016.5.FOCUS16129
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Figure 1. Pre-operative MRI (top) and CT (bottom) images in a 67-year-old patient with a right anterior cervical spinal mass. Sagittal (A) and axial (B) T2-weighted MRI images demonstrate the isointense signal of the mass, which involves the vertebral bodies of C6 and C7. Epidural extension and spinal cord compression are seen. Sagittal (C) and axial (D) CT images demonstrate the bony destruction associated with the mass.
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Figure 2. Pre-operative angiographic images in a 67-year-old male with a right anterior cervical thyroid metastasis. Right subclavian injection, AP projection (A) demonstrates a hypervascular right anterior cervical tumor with supply from the thyrocervical and costocervical trunk. Pre-embolization right vertebral artery injection, AP projection (B) demonstrates vascular supply to the tumor from muscular branches of the right vertebral artery. AP radiograph (C) demonstrating coil embolization of the right vertebral artery.
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Figure 3. Intraoperative photo demonstrating injection of PMMA into a 28-french chest tube that has been deployed into the right C5 -T1corpectomy defect through a posterior approach. Because of the flexibility of the tube, it may be passed between the cervical nerve roots, obviating the need for nerve root sacrifice. The PMMA is being injected via a syringe placed between the right C6 and C7 nerve roots. Figure 4. An illustration depicting the surgical procedure. (A) After performing right C6 and C7 corpectomies, a chest tube is placed in the anterior column and filled with polymethylmethacrylate using a syringe. (B) Illustration depicting the final result.
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Figure 5. One-year postoperative images after multilevel cervical partial corpectomy through a singlestaged posterior approach. Sagittal T2-weighted MRI (A) demonstrating complete decompression of the spinal cord. Sagittal T1-weighted post-contrast MRI (B) demonstrating a small, stable focus of residual tumor (arrow). Lateral (C) and AP (D) x-rays show the hardware construct in stable position.
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Abbreviations
cGy, centigray MRI, magnetic resonance imaging
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CT, computed tomography CK7, cytokeratin 7 TTF-1, thyroid transcription factor 1 PAX-8, paired box gene 8
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PMMA, polymethylmethacrylate
S1878-8750(18)32557-9
DOI:
https://doi.org/10.1016/j.wneu.2018.11.010
Reference:
WNEU 10694
To appear in:
World Neurosurgery
Received Date: 2 August 2018 Revised Date:
31 October 2018
Accepted Date: 2 November 2018
Please cite this article as: Shaaya E, Fridley J, Barber SM, Syed S, Xia J, Galgano M, Oyelese A, Telfeian A, Gokaslan Z, Posterior nerve-sparing multilevel cervical corpectomy and reconstruction for metastatic cervical spine tumors: case report and literature review, World Neurosurgery (2018), doi: https://doi.org/10.1016/j.wneu.2018.11.010. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Posterior nerve-sparing multilevel cervical corpectomy and reconstruction for metastatic cervical spine tumors: case report and literature review
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Elias Shaaya MD,1 Jared Fridley MD,1 Sean M. Barber MD,1 Sohail Syed MD,1 Jimmy Xia BSc,1 Michael Galgano MD,1 Adetokunbo Oyelese MD, PhD,1 Albert Telfeian MD, PhD,1 Ziya Gokaslan MD1
1
University, Providence, Rhode Island
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Department of Neurosurgery, Rhode Island Hospital, The Warren Alpert Medical School at Brown
Keywords: Posterior cervical corpectomy, spine metastasis, thyroid carcinoma, cervical spine reconstruction, spine tumor, polymethylmethacrylate
Declarations of Interest: None
Corresponding Author: Ziya L. Gokaslan, MD, FAANS, FACS Rhode Island Hospital
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Department of Neurosurgery Norman Prince Neurosciences Institute 593 Eddy Street - APC 6 Providence, RI 02903
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Tel: 401-793-9132
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Running Title: Posterior cervical corpectomy for metastasis
Email: [email protected]
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Email: [email protected]
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Abstract
Background
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Cervical spine metastases with circumferential spinal cord compression are often treated with combined anterior-posterior decompression and stabilization. In patients with large anterior neck masses, prior radiotherapy to the neck, or prior anterior neck surgery, however, anterior approaches may pose additional risk. In such cases, posterior-only approaches that allow for circumferential decompression and anterior column reconstruction may be beneficial. Case Description
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We present the case of a seventy-year-old male with follicular thyroid carcinoma metastatic to the cervical spine causing spinal cord compression. We utilized a posterior-only approach for a C6/7 partial corpectomy and posterior decompression and fusion from C2-T2. Our technique involved pre-operative embolization of the right vertebral artery to safely gain access to the ventral surface of the spinal cord and vertebral bodies. Anterior column support was provided by a chest tube/polymethylmethacrylate construct, allowing the implant to be placed within the anterior column from a posterior approach without nerve root sacrifice. The patient tolerated the procedure well. He had no post-operative neurologic deficits. Two months later he underwent a total thyroidectomy followed by stereotactic radiotherapy to the tumor bed (2700 cGy total, 3 fractions). At one-year follow-up he was active and without significant pain or focal neurologic deficits. Conclusions
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We propose a novel approach to ventral/circumferential cervical spine tumors that combines epidural decompression and cervical stabilization via a posterior-only approach. By using a chest tube/polymethylmethacrylate construct, anterior column support can be achieved through a posterior approach without nerve root sacrifice.
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Introduction The surgical management of spinal metastatic disease has evolved considerably over the last
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several decades. Modern surgical instrumentation and techniques - as well as advancements in spinal radiotherapy - have changed the treatment paradigm for affected patients.1 Indications for surgical
intervention include preservation or restoration of neurological function, reestablishment of mechanical stability, correction of deformity, or separation between tumor and spinal cord prior to radiotherapy.
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Radiotherapy functions as a mainstay for overall disease management but is also important as an adjuvant method of disease control following resection. The high rate of local control for metastatic disease with
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radiosurgery has led to the concept of separation surgery, with the goal being to create a circumferential tumor-free margin around the spinal cord, sparing the spinal cord from radiation toxicity incurred during radiosurgery to the remaining tumor.2
Surgical decompression of the spinal cord or nerve roots may be required based on the degree of
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compression and the presence of neurological symptoms or deficits. Patients with ‘high’ grade (Bilsky II, III) epidural spinal cord compression3 and/or radioresistant metastatic disease generally undergo surgical decompression, while those with minimal (Bilsky I) or no compression (Bilsky 0) will typically receive
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radiotherapy alone. Patients with primarily ventral cervical epidural spinal cord compression will typically undergo an anterior approach, such as an anterior cervical corpectomy with reconstruction,
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while patients with posterior-only disease typically undergo a posterior decompression with or without instrumentation. In patients with circumferential disease, a combination of anterior and posterior approaches is often used. A review of the literature by Fehlings et al. revealed that the most common approach for subaxial cervical spine metastatic disease is an anterior corpectomy followed by reconstruction, with a combined approached being reserved for multi-level and circumferential disease.4 Each surgical approach for tumor resection and stabilization within the cervical spine carries a unique risk profile based on the adjacent surgical anatomy. Minimizing the number of approaches needed
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to accomplish the surgical goals of decompression, stabilization, and or deformity correction may result in a decreased perioperative risk to the patient. In patients with prior anterior neck surgery, radiation, or the presence of tumor within anterior neck structures, anterior cervical spine approaches may confer an
RI PT
increased risk of morbidity. In this paper we present the case of a posterior multilevel transpedicular partial corpectomy and anterior column reconstruction for a patient with metastatic follicular thyroid carcinoma and review the available literature on the posterior cervical approach for circumferential
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metastatic disease.
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Case Presentation Presentation
A 70-year-old male with no significant past medical history presented to the emergency department with progressive weakness and decreased sensation in both arms and legs over the past 3
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months. He reported feeling particularly weak in his right hand and had been dropping objects more frequently. He denied any significant neck or back pain. On examination he was found to have 4-/5 weakness in bilateral triceps, grip strength, finger abduction and finger extension as well as decreased
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sensation in bilateral C7 and C8 dermatomes. Gait was within normal limits, and no hyperreflexia or
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pathological reflexes were evident on exam.
Diagnostic Workup
Magnetic resonance imaging (MRI) of the cervical spine revealed a 5cm x 6cm x 3cm mass
encompassing the right C7 vertebral body with epidural disease causing spinal cord displacement, and extension of the mass into the paraspinal tissues, posterior C7 bony elements via the right pedicle, and caudal C6 vertebral body (Figure 1, A and B). The mass abutted the right vertebral artery. Also noted
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was a right sided 3cm x 2cm x 4cm thyroid mass without an obvious direct connection to the cervical spine mass. Computed tomography (CT) of the cervical spine showed lytic destruction of the right C6 and C7 vertebral bodies (Figure 1, C and D).
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Due to suspicion for metastatic disease, a CT chest/abdomen/pelvis was performed, but was negative for additional lesions. MRI thoracic and lumbar spine revealed small lesions within the posterior elements of T4 and T7 without epidural disease. A CT guided biopsy of the right thyroid mass was
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performed, and pathology was consistent with a carcinoma of thyroid follicle origin (CK7, TTF-1,
thyroglobulin, and PAX-8 positive). After consultation with oncology and discussion with the patient, the
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decision was made to proceed with surgical decompression of the spinal cord and instrumented stabilization, followed by a total thyroidectomy and radiotherapy.
On diagnostic angiogram the tumor was noted to be hypervascular, with feeding vessels originating from muscular branches of the right vertebral artery and large branches from the thyrocervical and costocervical trunks (Figure 2, A and B). Particle embolization of these tumor-feeding vessels to
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reduce intraoperative blood loss - followed by coil embolization of the right vertebral artery - was
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successfully performed (Figure 2, C).
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The patient was positioned prone for a standard posterior cervical approach, the neck kept in
neutral position. Neuromonitoring (somatosensory and motor evoked potentials) was used for positioning and for the duration of the procedure. Spinal exposure was carried out from C2-T3. Tumor was encountered in the paraspinal tissues on the right at C6-7 during the initial dissection. Posterior T1-T3 pedicle screws, a right C2 pedicle screw and a left C2 translaminar screw were placed prior to proceeding with tumor resection. Lateral mass pilot holes were also drilled in the bilateral C3, C4, C5 lateral masses and the left C6 lateral mass. C5 and T1 laminectomies and left sided hemilaminectomies at C6 and C7
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were performed to expose the thecal sac. Tumor was noted to involve the right-sided laminae and facets at C6 and C7. Epidural tumor at C6 and C7 was dissected away from the thecal sac from left to right and resected. Paraspinal tumor was dissected away from surrounding musculature and resected piecemeal.
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The tumor was noted to be very vascular despite embolization. Foraminotomies were then performed on the right at C5/6 and C7/T1 to skeletonize the right C6 and C8 nerve roots laterally towards the vertebral artery and brachial plexus trunks. Tumor was adherent to the nerve roots and was carefully dissected
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away and resected. We encountered the embolized vertebral artery during tumor resection and removed a portion of it with the tumor. The right C6 and C7 lateral masses were resected and the right C6 and C7
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pedicles were drilled down into their respective vertebral bodies using a diamond bit. Partial right C6 and C7 corpectomies were then performed until relatively solid bone was encountered and the thecal sac was decompressed ventrally.
The C5/6 and C7/T1 discs were exenterated from the same posterolateral approach and the inferior C5 and superior T1 endplates were exposed. Circular defects were created in both endplates using
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a drill to accommodate a chest tube/polymethylmethacrylate (PMMA) construct. A 28-French chest tube was then cut to span from endplate to endplate, and the tube was bent and passed between the skeletonized nerve roots into the corpectomy defect. Once the chest tube was placed into the anterior
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column and fit into the endplate holes, it was filled with PMMA (Figure 3, Figure 4 A). Lateral mass screws were then placed in each of the previously drilled holes, and titanium rods were cut, bent, and
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secured to the screws from C2-T3 (Figure 4 B). The procedure lasted approximately 12 hours. Estimated blood loss was 800cc, and the patient required transfusion of two units of packed red blood cells during the procedure.
Post-operative course The patient tolerated the procedure well. He had no post-operative neurologic deficits and was discharged to home on post-operative day #9. Two months later he underwent a total thyroidectomy
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followed by spinal radiosurgery to the tumor bed (2700 cGy total, 3 fractions). At one-year follow up the patient was active, ambulating unassisted and without significant pain or focal neurologic deficits. Imaging at 1 year revealed stable minimal residual disease without tumor recurrence, hardware failure or
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evidence of pseudoarthrosis (Figure 5, A - D).
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Discussion
The cervical spine is reportedly involved in 8-20% of spinal osseous metastatic disease.4 Current
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management of cervical spine metastatic disease involves surgical decompression with or without stabilization and radiotherapy. Several large series have demonstrated improved survival in patients treated surgically with adjunctive radiotherapy compared to patients treated with radiotherapy alone. Patchell et al. conducted the only randomized trial addressing the subject, establishing the benefit of surgical intervention.5 Over a 10-year period, with an enrollment of a 123 patients, the results
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demonstrated improved ambulation rates in patients with epidural disease causing neurological deficit when treated with surgery and radiotherapy versus radiotherapy alone. In the current case, the patient presented with significant epidural disease with a neurological deficit and was thus felt to be a good
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candidate for surgical intervention. Furthermore, a preoperative biopsy was consistent with poorly differentiated thyroid cancer. Work done by Kuschchayeva et al. has shown that aggressive management
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of thyroid metastases leads to improved outcomes, and en bloc spondylectomy should be attempted when possible.6,7 This recommendation is echoed by the American Thyroid Association, which endorses complete surgical resection of isolated bony metastases.8 Given the clinical, radiographic and pathological findings in the current case, surgical intervention followed by radiation therapy was felt to be the most appropriate management. The goals of surgery were to perform a maximal safe resection, decompress the spinal cord and nerve roots, restore spinal stability and create enough epidural space for subsequent radiation therapy to be administered safely and successfully. Because the patient underwent anterior
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column osteotomies up to the level of C5/6, the authors felt that bony fixation up to and including C2 would lead to the most durable construct possible with minimal additional morbidity. Corpectomy in the cervical spine is traditionally performed via an anterior approach. When
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posterior decompression is also required, combined anterior and posterior surgeries are often utilized. Although partial corpectomies through a dorsal approach for metastatic disease and other pathologies of the thoracic spine and thoracolumbar junction have been well-described, the anatomical constraints of the
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cervical roots, vertebral arteries, and the cervical cord provide technical challenges to a posterior-only approach to the anterior column in the thoracic spine. As such, reports of posterior-only cervical partial
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corpectomies and reconstruction in the literature are lacking. In a systematic review of the literature, Fehlings et al. found that reports of posterior-only approaches to metastases in the subaxial cervical spine were rare and it was unclear if any substantial anterior reconstruction was attempted in those cases (12%).4 A large retrospective study at Sloan-Kettering detailed their experience with cervico-thoracic junction tumor resection and stabilization. Of their 90 patients, 44 had partial posterior vertebral body
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resection but required anterior reconstruction through a separate approach.9 Bydon et al. described the case of a patient with recurrent epithelioid sarcoma of the cervical spine with intradural extension treated with C1-4 en bloc spondylectomy from a single-staged posterior approach. As in our case, the authors
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sacrificed the ipsilateral vertebral artery in order to improve access and extent of resection, but instead of embolizing the vessel preoperatively, the authors clipped the diseased vessel intraoperatively for 30
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minutes while monitoring brainstem evoked potentials to ensure sufficient flow through the contralateral vertebral artery.10 The authors also sacrificed the right C1-4 nerve roots to achieve en bloc resection and allow for access to the anterior column, resulting in permanent right deltoid weakness. In our case, the use of the chest tube/PMMA construct allowed for anterior column reconstruction without the added morbidity associated with cervical nerve root sacrifice. Accessing the anterior column of the cervical spine through a posterior approach is challenging and several factors must be taken into consideration. Firstly, preoperative tumor embolization and/or
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vertebroplasty should be considered to help minimize intra-operative blood loss. Secondly, a sufficient corridor for resection and stabilization must be constructed while respecting the cervical cord and nerve roots. Angiography may be useful to assess the vertebral arteries and to determine if one may be
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sacrificed to improve surgical access. If the contralateral vertebral artery caliber is sufficient, preoperative embolization of the ipsilateral vertebral artery can be performed at the time of angiography. Sacrificing the vertebral artery affords the ability to access a further lateral corridor for reconstructing the anterior
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column. Even after vertebral artery sacrifice, however, the cervical nerve roots limit the size of the access corridor to the anterior column from a posterior approach. Rather than sacrifice roots, as other authors have done,10 a chest tube/PMMA construct was used in this case, as has been described previously for
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anterior column support in the cervicothoracic spine from an anterior approach.11,12 Because a chest tube is flexible, it can be bent and conformed to any given corridor and only elongated and solidified through PMMA injection after the tube is in place in the anterior column, making it an ideal construct for a posterior approach in the cervical spine. Expandable cages and other means of anterior support would be
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difficult to place from such an approach without nerve root sacrifice.
The approach described here allows for successful decompression of the spinal cord, extensive resection of anterior cervical masses, and anterior column reconstruction without requiring a combined
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anterior and posterior approach. While some sources argue for a combined anterior and posterior surgical approach to the cervical spine when a tumor involves more than one vertebral body,9,13 we show here that
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it is technically feasible and safe to achieve all goals of surgery from a posterior-only approach. Furthermore, a single posterior approach avoids the complications associated with anterior approaches (e.g. dysphagia, dysphonia, anterior neck hematomas) and the need for intraoperative repositioning. We suggest this this novel surgical technique be considered in patients with anterior cervical metastatic disease with circumferential spinal cord compression. This approach offers the ability to decompress the spinal cord and stabilize the cervical spine in a single stage with shorter anesthesia times, provided the patient has adequate blood flow in the contralateral vertebral artery.
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Conclusion
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Patients with spinal metastatic disease benefit from decreased mortality and increased quality of life when undergoing surgical resection in addition to radiotherapy, rather than radiotherapy alone.5 We propose a novel approach to anterior cervical spine tumors that combines epidural decompression and cervical stabilization from a posterior-only approach. By using a chest tube/PMMA construct, anterior
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column support can be achieved through a posterior approach without nerve root sacrifice. A singlestaged approach such as this decreases operative and anesthesia times while still achieving the goals of
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surgery (spinal cord decompression, restoration of stability) and resulting in favorable patient outcomes. References
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Laufer I, Rubin DG, Lis E, et al. The NOMS framework: approach to the treatment of spinal metastatic tumors. Oncologist. 2013;18(6):744-751. doi:10.1634/theoncologist.2012-0293 Laufer I, Iorgulescu JB, Chapman T, et al. Local disease control for spinal metastases following “separation surgery” and adjuvant hypofractionated or high-dose single-fraction stereotactic radiosurgery: outcome analysis in 186 patients. J Neurosurg Spine. 2013;18(3):207-214. doi:10.3171/2012.11.SPINE12111 Bilsky MH, Laufer I, Fourney DR, et al. Reliability analysis of the epidural spinal cord compression scale. J Neurosurg Spine. 2010;13(3):324-328. doi:10.3171/2010.3.SPINE09459 Fehlings MG, David KS, Vialle L, Vialle E, Setzer M, Vrionis FD. Decision Making in the Surgical Treatment of Cervical Spine Metastases. Spine (Phila Pa 1976). 2009;34(Supplement):S108-S117. doi:10.1097/BRS.0b013e3181bae1d2 Patchell RA, Tibbs PA, Regine WF, et al. Direct decompressive surgical resection in the treatment of spinal cord compression caused by metastatic cancer: a randomised trial. Lancet. 2005;366(9486):643-648. doi:10.1016/S0140-6736(05)66954-1 Kushchayeva YS, Kushchayev S V, Carroll NM, et al. Spinal metastases due to thyroid carcinoma: an analysis of 202 patients. Thyroid. 2014;24(10):1488-1500. doi:10.1089/thy.2013.0633 Kushchayev S, Kushchayeva Y, Theodore N, Preul MC, Clark OH. Percutaneous vertebroplasty for thyroid cancer metastases to the spine. Thyroid. 2010;20(5):555-560. doi:10.1089/thy.2009.0420 The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid. 2016;26(1):1-133. doi:10.1089/thy.2015.0020 Placantonakis DG, Laufer I, Wang JC, Beria JS, Boland P, Bilsky M. Posterior stabilization strategies following resection of cervicothoracic junction tumors: review of 90 consecutive cases. J Neurosurg Spine. 2008;9(2):111-119. doi:10.3171/SPI/2008/9/8/111 Bydon M, De la Garza-Ramos R, Suk I, et al. Single-Staged Multilevel Spondylectomy for En Bloc Resection of an Epithelioid Sarcoma With Intradural Extension in the Cervical Spine. Oper
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Neurosurg. 2015;11(4):E585-E593. doi:10.1227/NEU.0000000000000961 Errico TJ, Cooper PR. A new method of thoracic and lumbar body replacement for spinal tumors: Technical note. Neurosurgery. 1993;32(4):678-681. doi:10.1227/00006123-199304000-00030 Cooper PR, Errico TJ, Martin R, Crawford B, Dibartolo T. A systematic approach to spinal reconstruction after anterior decompression for neoplastic disease of the thoracic and lumbar spine. Neurosurgery. 1993;32(1):1-8. doi:10.1227/00006123-199301000-00001 Molina C, Rory Goodwin C, Abu-Bonsrah N, Elder BD, De la Garza Ramos R, Sciubba DM. Posterior approaches for symptomatic metastatic spinal cord compression. Neurosurg Focus. 2016;41(2):E11. doi:10.3171/2016.5.FOCUS16129
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Figure 1. Pre-operative MRI (top) and CT (bottom) images in a 67-year-old patient with a right anterior cervical spinal mass. Sagittal (A) and axial (B) T2-weighted MRI images demonstrate the isointense signal of the mass, which involves the vertebral bodies of C6 and C7. Epidural extension and spinal cord compression are seen. Sagittal (C) and axial (D) CT images demonstrate the bony destruction associated with the mass.
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Figure 2. Pre-operative angiographic images in a 67-year-old male with a right anterior cervical thyroid metastasis. Right subclavian injection, AP projection (A) demonstrates a hypervascular right anterior cervical tumor with supply from the thyrocervical and costocervical trunk. Pre-embolization right vertebral artery injection, AP projection (B) demonstrates vascular supply to the tumor from muscular branches of the right vertebral artery. AP radiograph (C) demonstrating coil embolization of the right vertebral artery.
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Figure 3. Intraoperative photo demonstrating injection of PMMA into a 28-french chest tube that has been deployed into the right C5 -T1corpectomy defect through a posterior approach. Because of the flexibility of the tube, it may be passed between the cervical nerve roots, obviating the need for nerve root sacrifice. The PMMA is being injected via a syringe placed between the right C6 and C7 nerve roots. Figure 4. An illustration depicting the surgical procedure. (A) After performing right C6 and C7 corpectomies, a chest tube is placed in the anterior column and filled with polymethylmethacrylate using a syringe. (B) Illustration depicting the final result.
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Figure 5. One-year postoperative images after multilevel cervical partial corpectomy through a singlestaged posterior approach. Sagittal T2-weighted MRI (A) demonstrating complete decompression of the spinal cord. Sagittal T1-weighted post-contrast MRI (B) demonstrating a small, stable focus of residual tumor (arrow). Lateral (C) and AP (D) x-rays show the hardware construct in stable position.
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Abbreviations
cGy, centigray MRI, magnetic resonance imaging
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CT, computed tomography CK7, cytokeratin 7 TTF-1, thyroid transcription factor 1 PAX-8, paired box gene 8
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PMMA, polymethylmethacrylate