Indicators for Substantial Neurological Recovery Following Elective Anterior Cervical Discectomy and Fusion

Study Design: Retrospective cohort study. Objective: The purposes of this study were to determine the rate of improvement of significant preoperative weakness, identify risk factors for failure to improve, and characterize the motor recovery of individual motor groups. Summary of Background Data: While neck and arm pain reliably improve following anterior cervical discectomy and fusion (ACDF), the frequency and magnitude of motor recovery following ACDF remain unclear. Methods: We performed a retrospective review of patients undergoing 1-4-level ACDF at a single institution between September 2015 and June 2016. Patients were subdivided into 2 groups based upon the presence or absence of significant preoperative weakness, which was defined as a motor grade <4 in any single upper extremity muscle group. Clinical notes were reviewed to determine affected muscle groups, rates of motor recovery, and risk factors for failure to improve. Results: We identified 618 patients for inclusion. Significant preoperative upper extremity weakness was present in 27 patients (4.4%). Postoperatively, 19 of the affected patients (70.3%) experienced complete strength recovery, and 5 patients (18.5%) experienced an improvement in muscle strength to a motor grade ≥4. The rate of motor recovery postoperatively was 85.7% in the triceps, 83.3% in the finger flexors, 83.3% in the hand intrinsics, 50.0% in the biceps, and 25.0% in the deltoids. Risk factors for failure to experience significant motor improvement were the presence of myelomalacia (odds ratio: 28.9, P<0.01) and the performance of >2 levels of ACDF (odds ratio: 10.1, P<0.01). Conclusions: Patients with substantial preoperative upper extremity weakness can expect high rates of motor recovery following ACDF, though patients with deltoid weakness, myelomalacia, and >2 levels of ACDF are less likely to experience significant motor improvement.