Acta Neurochir DOI 10.1007/s00701-014-2075-z
HOW I DO IT - SPINE
En bloc resection of primary malignant bone tumors of the cervical spine Tobias A. Mattei & Ehud Mendel
Received: 12 November 2013 / Accepted: 19 March 2014 # Springer-Verlag Wien 2014
Abstract Background Due to the poor response of primary malignant bone tumors to adjuvant therapies, surgical resection performed in an en bloc fashion with free margins remains the best option for long-term recurrence-free survival of patients harboring such lesions. Methods In this article the authors provide a stepwise review of the technical details involved in the performance of en bloc resections of tumoral lesions in the cervical spine. Conclusions Due to the anatomical peculiarities of the cervical spine related to the presence of functional nerve roots as well as the vertebral arteries, en bloc resections in this region remains a challenging surgical procedure.
year [4]. For malignant subtypes (such as chordomas, chondrossarcomas, and osteosarcomas), several studies have demonstrated that en bloc resection with free margins represents the best therapeutic alternative for long-term recurrencefree survival [7, 8]. In the sequence we discuss some indications and limitations of en bloc resections of spinal tumors in the cervical spine as well as important technical details of such a procedure.
Relevant surgical anatomy
Introduction
The en bloc resection of spinal tumors in the lower and mid-cervical spine is very challenging due to the presence of functional nerve roots and the vertebral arteries (Fig. 1). Additionally, the involvement of the upper cervical vertebrae leads to an additional degree of technical challenge, sometimes requiring transmandibular or transmaxillary approaches [6].
Primary bone tumors of the spine are rare entities, with an estimated incidence of 2.5–8.5 cases per 100,000 people per
Operative technique
Keywords Primary bone tumors . en bloc resection . Chordoma . Chondrosarcoma . Subaxial cervical spine . Spinal tumors
This paper has never been presented at a conference and has not been submitted for publication elsewhere. Clinical Trial Registration number: not applicable Electronic supplementary material The online version of this article (doi:10.1007/s00701-014-2075-z) contains supplementary material, which is available to authorized users. T. A. Mattei (*) Department of Neurosurgery, Brain & Spine Institute – InvisionHealth, 400 International Dr., Buffalo, OH 14221, USA e-mail:
[email protected] E. Mendel Department of Neurological Surgery - The Ohio State University Wexner Medical Center/The James Cancer Center, 410 W 10th Ave– N1037 Doan Hall, Columbus, OH 43210, USA
Instrumentation It is important to remember that, when considering an en bloc resection of a primary malignant bone tumor of the subaxial cervical spine, a robust fixation involving a 360° instrumentation must be planned (Fig. 2a and b) [8, 10]. Vertebral artery occlusion Due to the anatomical location within the transverse foramina, even when the vertebral arteries are not directly involved, it is frequently very challenging to achieve complete en bloc resection of a primary malignant bone tumor in the cervical
Acta Neurochir Fig. 1 Sagittal (a) and axial (b) MRi of the cervical spine (T2-sequence) demonstrating a tumoral lesion involving the C3, C4, and C5 vertebral bodies and extending anterolaterally to the left side with involvement of the left vertebral artery and infiltration of the left C3, C4, and C5 nerve roots. The CT-guided core needle biopsy revealed the diagnosis of a chondrosarcoma. Sagittal (c) and axial (d) CT-scan of the cervical spine in the same patient demonstrating a pathological compression fracture of the C4 vertebral body with destruction of the left side facets, pedicle, and lamina due to tumoral infiltration
spine while preserving both vertebral arteries. In such situations, a balloon-test occlusion is recommended in order to provide an appraisal of the feasibility of sacrificing one vertebral artery [5]. Because the vertebral artery is encased in the vertebral foramina and surrounded by an abundant venous plexus, endovascular occlusion of the vessel is strongly recommended before surgical ligation during the operation for tumor resection (Fig. 2c and d). Posterior approach Besides the posterior instrumentation, there are several surgical steps that, if necessary, are best executed during a posterior approach. They are: the posterior cuts in order to break the posterior bony ring (which should be performed without violating the tumor capsule), the exposition and ligation of the involved nerve roots, the ligation of the vertebral artery (whenever necessary), the initiation of the discectomies, and
the detachment of the spinal cord from the posterior longitudinal ligament with implantation of a silastic sheet in order to isolate the margins of the tumor located in the vertebral bodies from the neural elements (Fig. 3). Anterior approach One important difference between a standard anterior approach for degenerative spinal diseases and an anterior approach for en bloc resection of a spinal tumor is the extent of the exposure. For lesions involving the upper cervical spine, ligation of the external carotid artery (which can be performed without major consequences) may be necessary in order to provide a larger working channel for lateral mobilization of the carotid artery. After identification of the vertebral bodies, the bone incisions are performed with a bone chisel or a drill (Fig. 4). Afterwards, discectomies at the top and bottom levels of the lesion must be carried out until
Acta Neurochir
Fig. 2 a and b) Surgical exposure after a midline posterior approach to the cervico-thoracic spine. Before approaching the tumor, an occipito-T3 instrumentation with pedicle screws on the thoracic spine and lateral mass screws on the cervical spine was performed. On the left side, no lateral mass screws were placed on the C3, C4, C5 and C6 levels, anticipating the three-level (C3, C4, and C5) spondylectomy for en bloc resection of the tumor. Note the tumoral mass on the left side with involvement of the
left facets, laminae, and base of the spinous processes of C3, C4, and C5. After the cranio-cervicothoracic instrumentation and before tumor resection, the left vertebral artery was endovascularly occluded at the level of the C6 vertebral body (c) and distally at the level of C1 (d). e Navigationprotocol CT-scan (axial slice) performed before the second posterior surgical approach demonstrating the distal coils at the left vertebral artery during its course above the lateral mass of C1
identification of the silastic sheet that had been previously placed between the vertebral bodies and the spinal cord during the posterior approach. Then, the lateral dissection is performed until the lateral edge of the silastic sheet is identified. At this stage the tumor can be delivered en bloc (Video 1). Finally the anterior column is reconstructed. Our preference is to use a distractable cage and plating (Fig. 5).
the Weinstein-Boriani-Biagini system [1] reveals that such a procedure is feasbile [3, 7]. Nevertheless it must be highlighted that en bloc resections of spinal tumors may involve a high adverse morbidity profile even in tertiary oncological reference centers, with surgical complication rates ranging from 13 % to 56 % and mortality rates ranging from 0 to 7.7 % [2, 7].
How to avoid complications Indications and limitations According to recent systematic reviews, after a core needle biopsy confirming the presence of a primary malignant spinal tumor, en bloc resection is indicated (strong recommendation/moderate quality of evidence) if there are no signs of disseminated disease (lesions Enneking grades IA, IB, IIA or IIB), and if the staging according to
Despite the possible lower purchase strength of lateral mass screws (in comparison with pedicle screws) in the subaxial cervical spine, this is our preference in this type of procedure, as it has been demonstrated that the complication rates of cervical pedicle screws seem to be slightly higher [9]. Such a difference may be of special importance in the context of primary spinal malignancies, as a significant proportion of these tumors may require the sacrifice of
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Fig. 3 Intra-operative pictures of the second posterior surgical approach demonstrating tumoral infiltration of the left C5 nerve root as previously demonstrated by the MRi. a)The nerve root presented an enlarged and fibrotic aspect. b) The disection and surgical ligation of the left vertebral artery was performed during its course between the C5 and C6 transverse foramina. As the patient presented significant pre-operative deltoid weakness, a lengthy discussion with the family was conducted in order to explain the prognostic advantages of an en bloc resection of the tumor with free margins in face of the expected worsening of the motor deficits related to the ligation of the left C5 nerve root. c) Intra-operative picture
after ligation of the left C3 and C4 nerve roots (which, although sometimes leading to unilateral diaphragm weakness, usually can be performed without incurring additional motor deficits in the upper limb), as well as the C5 nerve root (which usually leads to deltoid paralysis). After execution of the discectomies at the upper (C2–C3) and bottom (C5–C6) levels of the lesion (d- intraoperative fluoroscopy), the authors implanted a silastic sheet between the spinal cord and the posterior longitudinal ligament, and which extended until the contralateral side, passing posterolaterally to the tumor
one vertebral artery in order to achieve complete en bloc resection. Additionally, when considering endovascular occlusion of the vertebral artery, it may be interesting to split the instrumentation and posterior dissection of the tumor into two separate stages, so that the placement of the lateral mass screws is performed while both vertebral arteries are still patent. One important technical detail during the posterior approach to such lesions is ensuring that, during the discectomies, the incision of the posterior longitudinal ligament is performed completely and as laterally as possible at the contralateral side. Otherwise it may be very hard to deliver the tumor in one piece during the anterior approach.
surgical manipulation, pre-operative tracheostomy and percutaneous gastrostomy (PEG) should be considered in such patients.
Information for patients It is important to make sure that patients bearing such lesions properly understand the magnitude of an en bloc resection of a primary malignant spinal lesion as well as the associated risks of each surgical stage.
Summary points –
Perioperative considerations Due to the necessity of multiple approaches and the possibility of upper airway and esophageal edema caused by the extensive
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After an MRi suggesting the presence of a primary malignant bone tumor of the spine, a core needle biopsy is the first step for confirming the histology of the lesion. Afterwards, the lesion should be staged according to the Weinstein-Boriani-Biagini system and the Enneking grade.
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Fig. 4 Intraoperative pictures of the last surgical stage (anterior approach to the cervical spine). A long longitudinal incision anterior to the border of the left sternocleidomastoid muscle was performed, followed by an extensive dissection of the tissue layers. After identification of the common, internal, and external carotid arteries, as well as the internal jugular vein and vagus nerve, a vessel loop was passed into each one of these structures so that they could be individually mobilized. In order to increase the surgical corridor at the upper portion of the field, the external carotid artery was ligated. a) After identification of the tumor protruding from the vertebral bodies and invading the longus colli muscles, the normal vertebral bone was identified at the contralateral (right) side, and a long longitudinal thread cut was performed in the C3, C4, and C5
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Surgical resection of primary malignant bone tumors performed in an en bloc fashion with free margins remains the best option for long-term recurrence-free survival in such patients. Incisional biopsy or intralesional resection significantly increases the risk of local recurrence of such lesions to nearly 100 %. The anatomic peculiarities of the cervical spine render en bloc resection of tumors in this region a technically challenging surgical procedure. As the associated morbidity of such a procedure is not negligible, it should only be performed by experienced multidisciplinary teams in tertiary care reference centers. When considering an en bloc resection of a primary malignant bone tumor of the subaxial cervical spine, a robust fixation involving a 360° instrumentation must be planned. Due to the anatomical location of the vertebral arteries within the transverse foramina, it is often
vertebral bodies using a drill. b) After completion of the discectomies at the upper (C2–C3) and bottom (C5–C6) levels of the tumor, as well as lateral dissection to the left side for identification of the silastic sheet placed during the posterior approach, the tumor and the lateral two-thirds of the C3, C4, and C5 vertebral bodies on the left side were delivered in one piece. c) The specimen was sent for immunohistochemical analysis in order to confirm the absence of violation of the tumor capsule. d) Intraoperative picture after the en bloc resection of the lesion, cage reconstruction, and plating. Note that because the C3, C4, and C5 nerve roots on the left side were ligated and the left vertebral artery was resected with the tumoral lesion, it was possible to visualize the left posterior rod during the anterior approach
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very challenging to achieve complete en bloc delivery of a spinal tumor while preserving these vessels bilaterally. When endovascular occlusion of the vertebral artery is necessary, it is recommended to split the instrumentation and posterior dissection of the tumor into two separate stages so that the placement of the lateral mass screws is performed while the two vertebral arteries are still patent. Although the number and type of surgical approaches will ultimately depend on the specific characteristics of each lesion [10], there are standard steps and technical details during each surgical stage that must be observed in order to enable successful performance of an en bloc resection of a cervical spinal tumor.
Conflicts of interest None.
Acta Neurochir Fig. 5 a) Sagittal post-operative MRi of the cervical spine (T1 post-contrast) at the left side (slice at the axial plane at the left inferior corner) demonstrating an empty space in the region previously occupied by tumor. b) Sagittal post-operative MRi (T2) at the midline demonstrating complete decompression of the spinal canal and re-alignment of the cervical spine. Post-operative CT-scan (c: sagittal and d: 3D-reconstruction) demonstrating the final construct involving a 360° fixation with reconstruction of the anterior and middle column with cage and a long posterior (occipito-T3) construct
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