Occipito-cervical instrumentation failure after radio-chemotherapy for axis solitary plasmacytoma: a case-based update.

INTRODUCTION: Axis solitary plasmacytoma is a rare cause of cranio-vertebral junction instability and atlanto-axial subluxation. Occipito-cervical instrumentation through lateral mass screws fixation is commonly used to obtain an internal stabilisation through a posterior approach in the management of axis tumours. Although radiotherapy and chemotherapy have been strongly advocated for treatment of spinal solitary plasmacytoma, their role in determining failure of instrumented fusion has not yet been emphasised. CASE REPORT: A 52-year-old man affected by an axis solitary plasmacytoma underwent occipito-cervical instrumentation through lateral mass screws fixation and subsequent radio-chemotherapy. Bone resorption and failure of instrumented fusion were observed at 6-month follow-up. New instrumented surgery by using Songer titanium sublaminar wires was then performed. Post-operatively, a Halo-Vest system was applied for 3-months and administration of oral bisphosphonates was started. The patient quickly regained walking ability. Computed tomography scan demonstrated the correct position of the sublaminar wires, as the initial bone fusion too. A 30-month follow-up computed tomography scan documented the maintenance of spinal stability and alignment due to successful fusion. DISCUSSION: Despite the effect of radio-chemotherapy on bony metabolism has been widely discussed, its role in influencing the failure of instrumented fusion has not yet been definitively analysed, especially when glucocorticoids are chosen as chemotherapic agent. Moreover, the most appropriate technique of instrumented fusion to be used after radio-chemotherapy is not established. Also the role of bisphosphonates in preventing the failure of instrumented surgery has not yet documented. All these aspects are discussed by the authors along with a literature review, taking a cue from the management of this case.