Neurophysiological study of the radial nerve variant in the innervation of the dorsomedial surface of the hand

Abstract

Introduction: Sensory innervation of the dorsomedial surface of the hand usually depends on the dorsal ulnar nerve (DUN). Innervation in this area by the superficial radial nerve (SRN) has been described as a normal variant.

Methods: We studied 358 patients using nerve conduction of the DUN and SRN with dorsomedial recording. Each hand was classified into usual innervation (only DUN response), mixed variant (response of both nerves), or complete variant (only SRN response).

Results: Mixed innervation was found in 14.2% of hands and complete innervation was found in 6.8% of hands, mostly unilaterally. No statistically significant differences were observed in age, sex, or clinical suspicion between usual and variant innervation. The potential amplitude after SRN stimulation was greater in the complete variant.

Discussion: It is important to know the characteristics of this variant in order to avoid diagnostic errors and to prevent iatrogenic lesions in surgery performed on the dorsum of the wrist. Muscle Nerve 58: 732-735, 2018.

Keywords: dorsal ulnar nerve; electroneurography; nerve conduction; radial nerve; sensory innervation; variant innervation.