Peripheral nervous system injury after high-dose single-fraction image-guided stereotactic radiosurgery for spine tumors

Abstract

OBJECTIVE The object of this study was to determine the percentage of high-dose (1800-2600 cGy) single-fraction stereotactic radiosurgery (SF-SRS) treatments to the spine that result in peripheral nervous system (PNS) injury. METHODS All patients treated with SF-SRS for primary or metastatic spine tumors between January 2004 and May 2013 and referred to the Rehabilitation Medicine Service for evaluation and treatment of neuromuscular, musculoskeletal, or functional impairments or pain were retrospectively identified. RESULTS Five hundred fifty-seven SF-SRS treatments in 447 patients resulted in 14 PNS injuries in 13 patients. All injures resulted from SF-SRS delivered to the cervical or lumbosacral spine at 2400 cGy. The overall percentage of SF-SRS treatments resulting in PNS injury was 2.5%, increasing to 4.5% when the thoracic spine was excluded from analysis. The median time to symptom onset following SF-SRS was 10 months (range 4-32 months). The plexus (cervical, brachial, and/or lumbosacral) was affected clinically and/or electrophysiologically in 12 (86%) of 14 cases, the nerve root in 2 (14%) of 14, and both in 6 (43%) of 14 cases. All patients experienced pain and most (93%) developed weakness. Peripheral nervous system injuries were CTCAE Grade 1 in 14% of cases, 2 in 64%, and 3 in 21%. No dose relationship between SF-SRS dose and PNS injury was detected. CONCLUSIONS Single-fraction SRS to the spine can result in PNS injury with major implications for function and quality of life.

Keywords: CTCAE = Common Terminology Criteria for Adverse Events; DRG = dorsal root ganglion; EGFR = epidermal growth factor; EMG = electromyography; GTV = gross tumor volume; PNS = peripheral nervous system; PTV = planning treatment volume; SF-SRS = single-fraction stereotactic radiosurgery; VEGF = vascular endothelial growth factor; complications; peripheral nerve; radiosurgery; spine.

FIG. 1

Percentage of PNS injuries in all patients treated with SF-SRS (18–26 Gy) by spinal level.

FIG. 2

Time to PNS injury (in years since SF-SRS) using competing risk methods—18 to 26 Gy (557 treatments).