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Total En Bloc Spondylectomy of C3: A New Surgical Technique and Literature Review.
Totální "en bloc" spondylektomie C3: nová chirurgická technika a přehled literatury.
PURPOSE OF THE STUDY Radical resection of a vertebra is reserved only for specific tumors that invade the surrounding tissues and recur when not removed completely. The vertebra may be removed using a piecemeal technique or en bloc, using only two (in thoracolumbar spine) or more osteotomies (in cervical spine). We present our technique of en bloc resection of subaxial cervical vertebra for Ewing's sarcoma of C3, with preservation of all nerve roots and both vertebral arteries. To our knowledge, this surgical technique has not been reported in the English literature. The aim of this study is to describe the new technique of radical resection of subaxial cervical vertebra. MATERIAL AND METHODS A transoral biopsy of tumor tissue anterior to C2-C3 was performed in 8-year old boy, revealing a diagnosis of Ewing's sarcoma. The patient was started on neoadjuvant chemotherapy. After 6 chemotherapy cycles with the VIDE regimen, the soft-tissue component completely regressed, with the only a residual deposit in C3 vertebral body. Based on further multidisciplinary meeting, an en bloc spondylectomy of C3 was recommended, preferably with preservation of nerve roots and vertebral arteries. In August 2014, prior to the planned surgery, we performed another thorough examination of the patient using plain films, CT and MRI. Neither angiography nor embolization was performed. DESCRIPTION OF SURGICAL TECHNIQUE The first stage of the operation consisted of resection of the posterior structures. We exposed the posterior elements of C2 to C4 by the mid-line incision. The C3 arch was without pathological changes. After partial resection of the C2 inferior and C4 superior articular processes we performed bilateral osteotomy in the region of the pedicle adjacent to the arch with a chisel and removed the whole of the C3 posterior arch. Subsequently we perforated the transverse foramina close to the pedicle, using fine Kerrison rongeurs. The lateral parts around vertebral arteries were left in situ. In the next step we used instrumentation with polyaxial screws to stabilize the C2-C4 section. After 19 days we performed the second stage surgery from an anterior approach with the removal of the anterior and lateral parts of the vertebra. We made a transverse incision anterior to the sternocleidomastoid between the internal carotid artery and the trachea on the right side at the level of C3 to expose the spine. We resected C2-C3 and C3-C4 intervertebral discs and then performed osteotomy with fine Kerrison rongeurs on both sides, again, close to the vertebral body. Subsequently, the vertebral body was released and extracted en bloc. In the next step, both vertebral arteries were mobilized and shifted medially and the lateral portions of the transverse processes were released and removed en bloc. The empty space was filled with solid allograft and the C2-C4 levels were bridged by the cervical plate in 2+1+2 configuration. RESULTS There were no complications during both surgeries. The follow-up CT examination 4 months after the operation revealed a clear bone fusion of C2-C4, both anteriorly between vertebral bodies and posteriorly between the arches. Clinically the patient has reached 8 month follow up and had no complaints, both he and his parents were satisfied. Physiotherapy is proceeding according to plan. The patient remains under supervision at our centre. DISCUSSION Total en bloc resection of a subaxial cervical vertebra with preservation of neural and vascular structures has been described in the English literature only once. In 2007 was published a total en bloc resection of C5 for chordoma, preserving the above mentioned structures. Authors removed the lamina en bloc after bilateral osteotomy. Transverse foramina were perforated by the Gigli saw and removed in piecemeal fashion, including the posterior tubercle. In the next step, they removed the vertebral body and the anterior tubercle from the anterior approach. However, their treatment differs from the technique described here and does not correspond fully to the principle of en bloc resection. Our surgical technique is based on a similar principle of performing several osteotomies without the use of high speed burr, while preserving all neural and vascular structures. The difference can be particularly seen in the approach to remove lateral parts of the transverse foramen, which are surrounding the vertebral arteries. We consider it as ideal to split the cervical vertebra by smooth cuts into four parts and remove them en bloc. CONCLUSION Total en bloc spondylectomy of a subaxial cervical vertebra with preservation of vertebral arteries and nerve roots is a radical surgery that should be used to treat only the most serious conditions. The risk of neurological deficit is outweighed by the benefits of oncological radicality. This new surgical technique has not yet been described and it is clear, that a larger cohort of patients is necessary to assess and potentially modify this technique so that it can be used more frequently in the future. Key words: en bloc spondylectomy, total spondylectomy, cervical spine, vertebrectomy.
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