Predicting C5 palsy via the use of preoperative anatomic measurements

Abstract Background context C5 nerve root palsy (C5P) is a relatively rare complication after anterior and posterior cervical decompression surgery that leads to a variety of debilitating symptoms. The precise etiology remains obscure, and a clear understanding of preoperative risk factors for C5P development does not exist. Purpose To determine whether postoperative C5P can be predicted from preoperative anteroposterior diameter (APD), foraminal diameter (FD), and/or cord-lamina angle (CLA). Study design Retrospective review. Patient sample Consecutive patients who underwent either anterior or posterior decompression surgery at C4–C5 for cervical spondylotic myelopathy. Outcome measures Development of C5P. Methods Blinded reviewers retrospectively assessed magnetic resonance images for each included patient's C4–C5 interspace, including the midline APD, the left and right FDs, and the left and right CLA. Multivariable logistic regression was used to model the probability of palsy on the basis of one or more predictors. A jackknife validation was performed to internally validate the model and assess its generalizability. Results A total of 98 patients fit the inclusion criteria; 12% had developed symptoms of C5 palsy postoperatively. Using the three variables in a predictor-model, we found that the odds ratio of having palsy for APD, FD, and CLA was 0.3, 0.02, and 1.4, respectively. For every 1-mm increase in APD and FD, the odds of developing palsy decrease 69% (p