Diagnostic Accuracy of Sensory Clinical Findings of the Hand Dorsum and of Neurography of the Dorsal Ulnar Cutaneous Nerve in Ulnar Neuropathy at the Elbow

Objective: The main objective is to investigate the diagnostic accuracy and the relation of touch sensation and subjective sensory symptoms in the medial aspect of the hand dorsum, and neurography of the dorsal ulnar cutaneous nerve (DUCN) in ulnar neuropathy at the elbow (UNE). Secondary objective is to report the electrophysiological occurrence of anatomical variant of sensory innervation of the medial aspect of the hand dorsum from superficial radial nerve (SRN). Design: Prospective, cohort study. Setting: Electromyography laboratory. Participants: Consecutive participants (N=282), those with UNE (n=81) and those without UNE (n=201), were enrolled. Interventions: Not applicable. Main Outcome Measures: Accuracy and agreement between sensory clinical findings of the medial hand dorsum and neurography of DUCN in UNE diagnosis. Results: DUCN neurographic and sensory findings had high specificity and relatively low sensitivity. Normal or abnormal sensory nerve action potential (SNAP) of DUCN matched with normal or abnormal touch sensation of the medial aspect of hand dorsum. Abnormal DUCN SNAP was related to the clinical severity of UNE and to the axonal damage of the ulnar nerve. Anatomical variant of the innervation of hand dorsum from SRN was demonstrated in 31 of 564 hands (6.2%) belonging to 26 of 282 participants (9.2%). If the variant was present, DUCN SNAP of the same side was more frequently absent or of low amplitude. Conclusions: The utility of DUCN neurography and sensory findings of the medial aspect of the dorsum of the hand is limited in the diagnosis of UNE. However, if DUCN SNAP is absent or low in amplitude, it is advisable to check the presence of the anatomical variant of the innervation of the medial aspect of the hand dorsum from SRN.