Use of Electromyography to Predict Likelihood of Recovery Following C5 Palsy after Posterior Cervical Spine Surgery.

Abstract Background : C5 palsy affects approximately 5-10% of patients undergoing cervical spine surgery. It has a significant negative impact on patient quality-of-life outcomes and healthcare costs. While >80% of patients improve, some are left with persistent, debilitating deficits. Our objective was to examine if electrodiagnostic testing could be used to successfully identify patients likely to experience complete, partial, and no recovery. Methods : Patients undergoing posterior cervical decompression and fusion at a single institution over a 10-year period were identified. Those experiencing post-operative C5 palsy were included. Outcomes examined included motor recovery of the affected deltoid as a function of time, and changes in electrodiagnostic testing as a function of time since injury. Electrodiagnostic testing included electromyography and was sub-analyzed by time of acquisition post-injury. Deltoid strength was graded on manual motor testing using the 5-point medical research council grading system. Results : Of 77 patients experiencing C5 palsy, 29 had post-operative electrodiagnostic testing. Patients experiencing complete recovery on average achieved functional (4/5) strength by 6-weeks post injury and 4+/5 strength by 6-months. Those experiencing partial recovery only achieved anti-gravity strength (3/5) by 6-weeks and low-function (4-/5) strength by 6-months. Electrodiagnostic testing performed 6-weeks to 6-months post-injury demonstrated that those experiencing complete recovery were more likely to have normal motor unit (MU) recruitment than those experiencing partial (p Conclusion : Electrodiagnostic testing may be a valuable means of differentiating between patients with C5 palsy likely to experience complete, partial, or no recovery. Testing between 6-weeks and 6-months post-onset may aid in identifying those least likely to have a complete recovery. No motor units at 4-6 months, or reduced units with strength that is not improving, portends a poor long term outcome. In this population, peripheral nerve transfers may be considered sooner.