Preoperative electrodiagnostic studies and postoperative outcomes for ulnar mononeuropathy at the elbow: A systematic review

Objective: To analyze the association between preoperative electrodiagnostic (EDX) studies and postoperative pain and functional outcomes following ulnar nerve decompression and/or transposition for ulnar neuropathy at the elbow (UNE).

Literature survey: Protocol was submitted and database search was conducted by an experienced librarian of all available studies in the English language from 1990 to June 8, 2022. Databases included Ovid MEDLINE(R) and Epub Ahead of Print, In-Process & Other Non-Indexed Citations and Daily, Ovid EMBASE, Ovid Cochrane Central Register of Controlled Trials, and Scopus.

Methodology: Inclusion criteria consisted of randomized controlled trials, prospective and retrospective longitudinal studies, and studies involving adults ≥18 years of age who underwent ulnar nerve decompression and/or transposition for UNE. Study quality and risk of bias were assessed using the National Heart, Lung, and Blood Institute (NHLBI) Study Quality of Assessment Tool. Certainty in evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. A meta-analysis was not performed.

Synthesis: A total of 289 studies were screened, and 8 retrospective cohort studies met inclusion criteria comprising 762 patients. A decreased or absent preoperative sensory nerve action potential amplitude (SNAP) showed significance with worse postoperative outcomes. The presence of preoperative conduction block showed significance in higher quality studies. There was limited evidence for slow preoperative motor conduction velocities or preoperative electromyography (EMG) abnormalities and postoperative outcomes. Overall quality assessment demonstrated that two studies had "good," four "fair," and two "poor" quality of evidence. Certainty in evidence was "low" due to risk of bias.

Conclusions: A decreased or absent preoperative ulnar SNAP may predict worse postoperative outcomes. Per higher quality studies, preoperative conduction block at the elbow may also predict worse postoperative outcomes. Careful interpretation is required with a full understanding of the limited evidence, risk of bias, and low certainty in evidence to support the use of preoperative EDX to predict postoperative outcomes in UNE.