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Editorial
. 2018 Sep;4(3):668-676.
doi: 10.21037/jss.2018.09.02.

En bloc resection in the spine: a procedure of surgical oncology

Stefano Boriani  1
Affiliations
Editorial

En bloc resection in the spine: a procedure of surgical oncology

Stefano Boriani. J Spine Surg. 2018 Sep.
No abstract available

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Conflict of interest statement

Conflicts of Interest: The author has no conflicts of interest to declare.

Figures

Figure 1
Figure 1
Type 1 WBB-based en bloc resection. Single anterior approach. For achieving a tumor-free margin the tumor must be only in sectors 8 to 5, layer A and B, but not layer C. In this case in fact, the osteotomy would violate the tumor mass: a posterior approach is necessary for a tumor free margin resection by including the posterior wall in the resection by entering the canal and releasing the dura. Three steps are to be considered: the first to provide under direct visual control an appropriate margin of the anterior tumor growing (I). The second step include performing an osteotomy between the tumor and the posterior wall (II). The third step is the tumor removal (III). WBB, Weinstein-Boriani-Biagini.
Figure 2
Figure 2
Type 2 WBB-based en bloc resection. (A) Type 2a WBB-based en bloc resection. Single posterior approach, en bloc resection of a tumor arising in the posterior arch. To achieve an appropriate margins sector 9 and 4 must be free from tumor. If the tumor grows in layer D, a margin violation will result intralesional during the dura release. This technique includes three steps: first to leave an appropriate margin over the posterior tumor mass (I). Second step to enter the canal by excision of sectors 9 and 4 (II). The third step is a transverse laminotomy above and below, the tumor release from the dura and the en bloc tumor removal (III). (B) Type 2b WBB-based en bloc resection. Single posterior approach. It allows to remove by en bloc resection a thoracic spine tumor growing in the vertebral body. Criteria suggested for a tumor free margins are that sector 9 or 4 be not involved by tumor. If the layer D is involved by the tumor, the margin can be violated intralesional during the release from the dura. If the tumor extends in layer A, the margin can be violated during the separation from the anterior structures. This is the most popular technique of en bloc resection of a spine tumor, as described by Roy-Camille et al. (6) and later by Tomita et al. (7). The digital blunt release of the anterior spine from the mediastinum should be performed before laminectomy to reduce the risk to damage the cord during the manual dissection. The aorta is safer released from the anterior spine wall if the segmental vessels are identified and the blunt dissection performed between the segmental vessels and the vertebra. Uninvolved posterior arch excision is then performed. At least 4 sectors should be removed, starting from sector 4 or from sector 9 (I). Section after ligation of the nerve root(s) involved by the tumor is necessary and dura must be fully released from the tumor. Discectomy or osteotomy is then performed above and below the tumor, and the tumor removal is completed (II). (C) Type 2c WBB-based en bloc resection. Single posterior approach to resect eccentrically growing tumors in the thoracic or lumbar spine with sagittal osteotomy. Criteria to achieve en bloc tumor free margin resection are the vertebral body not involved over sector 5 at left and over sector 8 at right and at least 3 posterior sectors not involved (4 to 1-2 or 12-11 to 9). This technique includes four steps: the first to provide a tumor free margin over the posterior growing tumor (I). The release should proceed laterally till the lateral side of the vertebral body. In the thoracic spine the pleura can be left on the tumor, in the lumbar spine the posterior part of the psoas must be dissected, but the segmental vessels must be found and ligated. The step II is the excision of the posterior arch not involved by the tumor to approach into the canal; the dura is released from the tumor (if the tumor grows in layer D, the margin can result intralesional) and the nerve root(s) involved by the tumor are sacrificed. In step III the dura is carefully displaced and osteotomy is performed from posterior to anterior in sector 8 or 5. Step IV is the tumor removal. WBB, Weinstein-Boriani-Biagini.
Figure 3
Figure 3
Type 3 WBB-based en bloc resection. (A) Type 3a WBB-based en bloc resection. This technique is specific for some cervical spine tumors and requires three approaches: first posterior, second anterior contralateral to the tumor side, third anterior on the tumor side. A single wide transverse anterior approach can be considered. The first step is a common posterior approach in prone position and is finalized to resect the posterior arch not involved by the tumor. At least 3 sectors are needed, from sector 4 or from sector 9 (I). If the tumor has a posterior extension in layer A, a margin must be provided by resecting inside the posterior muscles covering the tumor mass (II). The dura must be released from the nerve root(s) crossing the tumor sacrificed. The second and third steps are performed in supine position. In step II a sagittal grove is performed in the vertebral body not occupied by the tumor and the vertebral artery isolated and protected as the other is involved by the tumor and must be sacrificed. Step III: the upper and lower margins are defined by diskectomies or transversal grooves in vertebral bodies as planned, including ligation of the vertebral artery if necessary. The tumor is finally removed. (B) Type 3b WBB-based en bloc resection: when a thoracic or lumbar tumor is growing anteriorly (layer A) an anterior approach must be performed as first step to provide a wide/marginal margin under visual control. In case of tumors mostly occupying the vertebral body, the anterior approach can be the first step to release from mediastinum or retroperitoneal, eventually leaving involved structures as margin (I). A sheet of silastic or similar can be left as protection. Second stage, posterior approach: piecemeal excision of the posterior arch not involved by the tumor (II). At least 3–4 sectors are required, starting from sector 4 or from sector 9. Release of the dura from the tumor, section of the nerve root(s) involved by the tumor, then provide the appropriate margin over the tumor posteriorly growing by resecting inside the posterior muscles covering the tumor mass if it is expanding in layer A (III). Finally, the specimen is removed by rotating around the dural sac (IV). (C) Type 3c WBB-based en bloc resection. When a tumor is arising eccentrically and growing anteriorly (layer A) if and appropriate margin can be left, a sagittal or oblique osteotomy would be helpful in the thoracic spine to avoid approaching both pleural cavity and in the lumbar spine to make easier and less dangerous the final maneuvers of specimen removal. The steps are the same as in type 3b, but after step III, once fully released the dural sac, an appropriate back to front oblique osteotomy is performed through healthy bone. It will be necessary to take care to cut in the right direction at appropriate distance from tumor margin and be sure of the protection of the anterior and antero-lateral structured, particularly the vascular structures. Navigation assistance is particularly helpful during this procedure. (D) Huge radio-induced osteogenic sarcoma in a 27 years old man. The previous tumor was a Hemangioendothelioma submitted to intralesional excision and radiation 5 years before. En bloc resection by type 3c technique. Transverse cut of the specimen including the plate and screws previously implanted. The margins were wide all over the tumor except in proximity of the pedicle (sector 9) where the tumor was found in the epidural space (intralesional margin). WBB, Weinstein-Boriani-Biagini.
Figure 4
Figure 4
Type 4 WBB-based en bloc resection. This technique is proposed for eccentrically growing cervical tumors. Two anterior approaches are suggested: one on the non-affected side (III), to perform a longitudinal osteotomy in order to save the contra-lateral vertebral artery, the second for visual control over the anterior margin (IV) and the final specimen removal (V), once the vertebral artery has been cut above and below the tumor mass. The posterior approach is the first stage and includes: piecemeal excision of the posterior elements not affected by the tumor (I), release of the thecal sac, including sacrifice of the nerve root(s) crossing the tumor and release of the eventual soft tissue tumor expansion, leaving a safe tumor-free margin all around (II). WBB, Weinstein-Boriani-Biagini.
Figure 5
Figure 5
Type 5 WBB-based en bloc resection. This technique includes posterior approach first, and a second stage during which combined anterior and posterior approaches are performed with the patient on a side. In the author’s experience this technique allows a wide circumferential visual control of the margins, but is burdened by the higher complication rate. The first steps are performed in prone position: the posterior arch not involved by the tumor is removed piecemeal. At least 3 sectors must be removed for the canal approach, starting from sector 4 or from sector 9 (I). In case of tumor expanding posteriorly, invading layer A, dissection through the muscles covering the tumor mass will provide an appropriate margin (II). Then dura must be released from the tumor and the nerve root(s) crossing tumor will be sacrificed. The upper and lower margins of the resection are started by diskectomies or transversal grooves in vertebral bodies. The second stage is performed with the patient positioned on a side. The posterior approach is re-opened and the antero-lateral approach (thoracotomy, thoraco-abdominal, retroperitoneal) is performed. According to the tumor location (thoracic or lumbar) pleura or psoas are left over the tumor mass representing its margin (III). It is convenient to have the segmental arteries on the contralateral side embolized at the emergency from the aorta by spiral wires to make easier the release on the blind side. Once finalized the upper and lower diskectomies or osteotomies, by combined maneuvers the specimen is removed (IV). WBB, Weinstein-Boriani-Biagini.
Figure 6
Figure 6
Type 6 WBB-based en bloc resection. A double anterior approach is useful for a safe release the aorta/cava bifurcation, in combination with a posterior approach to perform en bloc resection of a tumor located at L5. Proposed technique: first step in lateral position: antero-lateral approach on the side opposite to the tumor, release the homolateral aorta/cava bifurcation and partial diskectomies or osteotomies to define upper and lower margin (I). Second step in prone position, same as type 5. The third step in lateral position. Re-opening of the posterior approach and contemporary retroperitoneal approach, release the homolateral aorta/cava bifurcation. Step IV: the psoas is transected to provide a margin over the tumor; step V: finalize diskectomies or osteotomies to complete the en bloc resection and remove the specimen by the anterior approach. WBB, Weinstein-Boriani-Biagini.
Figure 7
Figure 7
Type 7 WBB-based en bloc resection. It is indicated in thoracic and lumbar tumors which are growing anteriorly—even huge masses—in layer A without involvement of the canal (layer D) but with extension to layer C (in close proximity the posterior wall) and without involvement of sectors 4 and 9. This strategy allows to remove huge tumors without torsion around the spinal cord, but requires both pedicles free from tumor for an appropriate margin. It is mandatory to achieve by posterior a full release of posterior anatomical elements and spine-dura connection as in supine position no access will be possible. First steps in prone position: piecemeal excision of the posterior arch and both pedicles. Very careful full dura release. Diskectomies or transversal grooves in vertebral bodies are performed to define the upper and lower margins. Second stage in supine position. Step III is release of the anatomical structures from the tumor mass or even their sacrifice to provide appropriate margin under visual control. Arterial by-pass can be performed in case of aorta involvement. The specimen is finally removed by combined maneuvers after complete upper and lower diskectomies or osteotomies (IV). WBB, Weinstein-Boriani-Biagini.
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