Clinical Predictors of C5 Spinal Nerve Viability in Pan-Brachial Plexus Injuries.

Abstract

In pan-brachial plexus injury patients, distinguishing between pre-ganglionic and post-ganglionic injuries is crucial to reconstructive planning. This study aimed to identify pre-operative factors that would accurately predict a reconstructible C5 spinal nerve. Pan-brachial plexus injury patients from a single institution between 2001 and 2018 were reviewed. Patient demographics, clinical examination, diagnostic imaging, and electrodiagnostic results were recorded. C5 viability was determined based on supraclavicular exploration and intraoperative electrophysiologic testing. Univariate analysis identified significant factors for regression analysis. Multivariable parsimonious model was created using stepwise high performance logistic regression. 311 patients (mean age 29.9 years; 46 females, 265 males; Injury Severity Score 17.2) were included. 134 (43%) had a viable C5 and 50 (12%) patients had a viable C6 nerve. Intact C5 spinal nerve on CT myelogram (OR 5.4), positive Tinel's test (OR 2.6), M ≥ 4 rhomboid (OR 1.3) or M ≥ 4 serratus anterior (OR 1.4), and rhomboid needle EMG (OR 1.8) were predictive of having a viable C5 spinal nerve. The multivariable parsimonious stepwise model (AUC 0.77) included four factors: positive Tinel's test, intact C5 spinal nerve on CT myelogram, hemi-diaphragmatic elevation, and mid-cervical paraspinal fibrillations. In this cohort of pan-brachial plexus patients with major polytrauma, there was a 43% incidence of viable C5 spinal nerve. A positive Tinel's test (OR 2.1) and intact C5 spinal nerve on CT myelogram (OR 4.9) predicted a viable C5 nerve. In contrast, hemi-diaphragmatic elevation (OR 3.1) and mid-cervical paraspinal fibrillations (OR 2.92) predicted root avulsion.