Introduction: The efficacy and safety of minimally invasive instrumented and non-instrumented procedures have benefited significantly from technological innovations. Many studies have demonstrated the efficacy of full-endoscopic decompression techniques in the lumbar spine. Regarding cervical pathology the surgical technique of endoscopic unilateral laminotomy for bilateral decompression (CE-ULBD) has resulted in improved neurological function, as evidenced by significant improvements in Nurick grade and mJOA scores. CE-ULBD carries certain complications that should be monitored for in the operative and postoperative period. Here we seek to better understand the role of intraoperative neurophysiological monitoring in CE-ULBD as well as risk factors associated with new postoperative neurological symptoms.
Methods: Retrospective analysis of cervical endoscopic unilateral approach for bilateral decompression (CE-ULBD) from two different University settings between 2016-2024 was performed. Patient charts were reviewed for demographic and operative data. The degree of central stenosis was recorded using the Kang Grading system. Neuromonitoring changes and the post-operative neurologic exam were also cataloged.
Results: Twenty-six patients 19 male and 7 female were included in the study with a total of 44 operative levels. The most common levels were C3-C4 (36%) and C4-C5 (22%). 16 patients (59%) of the had pre-operative weakness. Neuromonitoring changes occurred in 11 of the 26 procedures with three instances of sustained decrease on motor evoked potentials at the time of closing. Three (11.5%) of the twenty- six patients had new post-operative weakness. Out of these three patients two had existing pre-operative weakness. All of these three patients had Kang grade 3 central stenosis with chord signal change on pre-operative imaging.
Conclusion : Cervical Endoscopic approaches can achieve post-operative outcomes comparable to open procedures, with the added benefits of reduced hospital stay and faster recovery. This study suggests that patients with pre-operative weakness and a high degree of cervical central stenosis may be at an increased risk for post-operative neurological deficits. During endoscopic procedures, various factors such as fluid irrigation, mechanical manipulation of the thecal sac, and limited epidural space in severe cases may encroach the exposed spinal cord. Further studies are needed to better define the risk factors for neurological injury and post-operative weakness in this patient population.
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