Identification of Risk Factors for C5 Palsy After Anterior Cervical Spine Surgery Involving the C4/5 Level.

Abstract

Retrospective cohort study. To identify risk factors for postoperative C5 palsy in anterior cervical spine surgery involving the C4/5 segment, with a focus on the decompression procedure and postoperative changes in vertebral height and alignment. Postoperative C5 palsy is a known complication of cervical spine surgery, especially after posterior approaches. It can also occur after anterior surgery, but the causes remain unclear. Possible causes include spinal cord shift, nerve root traction, foraminal stenosis, and thermal injury. Limited research exists on risk factors for anterior procedures, particularly regarding decompression techniques and spinal changes, such as vertebral height and alignment. We retrospectively reviewed 957 cervical spine surgery cases from 2011 to 2023 at a single institution. Among these, 175 cases met the inclusion criteria for anterior surgery involving the C4/5 level for degenerative disease. Patients were divided into 2 groups based on whether they had postoperative C5 palsy, which was defined as new-onset deltoid muscle weakness within 2 weeks after surgery, without affecting the lower extremities. Clinical variables, surgical details, radiographic parameters, and preoperative intramedullary T2 high signal change at C3/4-C4/5 were compared. Multivariate logistic regression was used to identify independent risk factors. Of the 175 patients, 19 patients (10.9%) experienced C5 palsy. Corpectomy involving C4 or C5 was an independent risk factor (odds ratio, 4.86; P=0.023). Patients with C5 palsy had a greater decrease in vertebral height per level after surgery (-0.29 vs. +0.94 mm; P<0.001). No other variables remained significantly associated with C5 palsy in multivariate logistic regression. Corpectomy and segmental vertebral height reduction were associated with C5 palsy after anterior cervical spine surgery at the C4/5 level. These findings suggest that decompression strategies and postoperative structural changes should be carefully considered during surgical planning.