Development of postoperative C5 palsy is associated with wider posterior decompressions: an analysis of 41 patients

BACKGROUND CONTEXT: C5 palsy is a postoperative complication, characterized by deltoid weakness. The pathogenesis of C5 palsy after laminoforaminotomies in patients with degenerative spinal disease is poorly understood. We hypothesize that the spinal cord fallback is associated with postoperative C5 palsy. PURPOSE: We investigate radiographic parameters associated with the development of postoperative C5 palsy. STUDY DESIGN/SETTING: This is a retrospective single-institutional clinical study. PATIENT SAMPLE: The source population was all patients undergoing a C4-C5 posterior laminoforaminotomy plus instrumented fusion for the management of degenerative spinal disease at a single institution over a 7-year period. The study population was 41 patients who had both preoperative and postoperative imaging. OUTCOME MEASURE: The outcome measure was postoperative C5 palsy, defined as transient motor decline of the deltoid function. METHODS: Of those patients with both preoperative and postoperative radiographic studies, we measured cord position, Cobb angle, width of the C5 foramen, and width of the dura. RESULTS: Nine patients with C5 palsy and 32 patients without C5 palsy fit the inclusion criteria for this study. In comparison with the non-C5 palsy group, the C5 palsy group had a statistically greater widening of the C5 foramen (p<.001), dural expansion (p<.001), and posterior cord shift (p<.001). Change in lordosis did not differ (p=.985). Lordotic correction was not correlated with the posterior cord shift in linear regression analysis (p=.67) or C5 palsy in univariate analysis (p=.627). Conversely, widening of the C5 foramen was correlated with greater cord displacement (p=.002), and both of these factors statistically predicted C5 palsy after the multivariate regression analysis. CONCLUSION: Our findings suggest that wider decompressions at C4-C5 are correlated with greater fallback of the spinal cord, which statistically increases the risk of C5 palsy. (C) 2014 Elsevier Inc. All rights reserved.