Minimally Invasive Separation Surgery with Intraoperative Stereotactic Guidance: A Feasibility Study

BACKGROUND: The treatment of spinal metastasis consists of algorithms combining surgical and radiation modalities. Recently the concept of separation surgery followed by stereotactic radiosurgery was shown to be a safe and effective treatment to achieve local tumor control. OBJECTIVE: We examined a minimally invasive approach to separation surgery in a cadaveric study followed by a patient cohort with spinal metastasis using navigation to discuss our results and provide a technical note. METHODS: A cadaveric study using minimally invasive access systems examined the feasibility of spinal cord decompression. Subsequently, 17 patients with spinal metastasis underwent minimally invasive separation surgery and instrumentation using navigation. All patients were at least 3/5 and pre- and post-operative CT scans were used to evaluate the decompression. Endpoints included neurologic function, operative time, estimated blood loss, duration of hospital stay, and complications. RESULTS: The cadaveric study demonstrated adequate decompression of the spinal cord. For the operative cases, the post-operative imaging demonstrated excellent separation for safe stereotactic radiosurgery. The mean incision length was 4.9 cm. The average operative time was 6 hours and 48 minutes, the mean length of stay was 12.8 days and the mean surgical blood loss was 458 mL. The median Spine Instability Neoplastic Score score was 10 with a range of 6-16. All patients remained or improved their neurologic baseline with excellent pain control. One patient incurred a perioperative complication. CONCLUSIONS: Minimally invasive separation surgery for spinal metastasis allows for circumferential decompression of the spinal cord and safe post-operative stereotactic radiosurgery. In addition, we demonstrated the efficacy of intra-operative navigation in guiding the resection.