Systematic review of sonographic measurements of the ulnar nerve at the elbow.

A systematic review was performed to identify studies reporting summary data (mean, standard deviation) of sonographic cross-sectional measurements of the ulnar nerve at the elbow. Comparisons of measurements were performed to determine whether statistical differences existed between groups of individuals symptomatic and asymptomatic of ulnar nerve entrapment at the elbow (UNE). Across the four studies meeting the selection criteria of the search, five sample groups were identified and compared: three asymptomatic of UNE and two symptomatic of UNE. There were significant differences between measurements of people with and without UNE (P < .0001-.041). Significant differences also existed between the two symptomatic populations (P < .0001-.0062) and between the three asymptomatic populations (P < .0001-.41). This systematic review demonstrates that significant differences exist between sonographic measurements of ulnar nerve dimension between people with and without UNE, confirming that these measurements are potential discriminators of UNE. The demonstration of significant differences between measurements of ulnar nerve size within sample populations with similar symptomatic status suggests that further studies are required to confirm the effect of ulnar nerve pathologies, measurement protocols, and anthropometric factors.