Clinical and Electrophysiologic Features of Ulnar Neuropathy at the Wrist: Analysis of 150 Consecutive Cases

Purpose: To report clinical and electrodiagnostic (EDX) findings in ulnar neuropathy at the wrist (UNW). Methods: This is a monocentric study. We collected demographic and clinical data, history, symptom type, neurologic examination findings, EDX results, as well as causes and risk factors of UNW. Results: We enrolled 150 consecutive cases. Based on EDX findings, the most common UNW pattern involved the ulnar nerve at the entrance of Guyon canal, prior to its bifurcation into sensory and motor branches (44% of cases). We identified atypical topographic lesions involving the superficial sensory branch and motor fibers innervating the hypothenar (4.7% of cases) or the interossei muscles (12.8% of cases). The most frequent causes were compressive (20.7%) and traumatic (22%), mainly affecting males, blue-collar workers, and individuals aged ≤60 years. Ganglion was prevalent in females (66.7%). Cases of UNW with unknown etiology were significantly associated with age >60 years, the presence of muscle atrophy, and a history of carpal tunnel syndrome (CTS). Conclusions: Clinical and EDX characteristics of UNW depend on injury site at wrist or hand palm. It is not possible to determine the cause with certainty based solely on the type, although some causes tend to affect specific sites of nerve injury. The coexistence of Guyon canal syndrome and CTS is confirmed to be a fairly frequent finding. The awareness of the ulnar nerve anatomical variations should not lead to the exclusion of UNW if EDX abnormalities do not fall into any of the five classical types according to Wu's classification.