Electrophysiology-guided refinement of ulnar neuropathy at the wrist classification

Background: Ulnar neuropathy at the wrist (UNW) is traditionally classified based on clinical-anatomical findings. While useful, these classifications may not fully capture the complexity and variability of lesion sites. The aim of this work is to characterize the UNW from an electrodiagnostic (EDX) perspective. Methods: We reviewed a database of 180 UNW patients, integrating clinical data, EDX results, as well as causes and risk factors of UNW. Results: Thirty cases (16.7%) could not be classified using the existing five types of Wu's classification. Specifically, eight cases (4.4%) showed combined involvement of the sensory branch and the motor branch innervating only the hypothenar muscles (designated type 6), while 22 cases (12.2%) exhibited combined involvement of the sensory branch and the motor branch innervating the interosseous muscles (designated type 7). The clinical findings were consistent with the EDX data. Conclusion: Our findings indicate that current clinical-anatomical classification of UNW may fail to capture the full complexity and variability of lesion sites, which could be better captured using an electrophysiology-based approach. Significance: By integrating detailed clinical and electrophysiological assessments, we suggest that refining the classification system may explain unexpected sensory or motor deficits in the ulnar nerve distribution. We propose an expanded classification system comprising seven electrophysiological types, which may improve diagnostic accuracy and clinical interpretation.