Nerve Conduction Study of the Distal Branches of the Superficial Radial Nerve

ABSTRACT

OBJECTIVE: To acquire normal values of nerve conduction study of the superficial radial sensory nerve (SRN) distal branches to the second web space (2 WEB) and second digit (2 DIG) and compare them with the results of the conventional method. METHOD: Forty-three healthy adult subjects (25 males, 18 females) were included. Nerve conduction study was performed in both hands. Superficial radial sensory responses were obtained with 2 recording montages 1) antidromic stimulation, recording electrode placed between the 2nd and 3rd metacarpals with stimulation 10 cm proximally on the lateral forearm (2 WEB); 2) orthodromic stimulation, stimulation at the second digit with recording 10 cm proximally at the snuff box (2 DIG). Each stimulation was performed twice, and onset latency, peak latency, and sensory nerve action potential (SNAP) amplitude (baseline-to- peak) were measured. Correlations between the values and body mass index (BMI), sex, and finger circumference were tested statistically. RESULTS: The age of the subjects was 36.0+/-10.4 years (range, 23~64 years), and the BMI was 22.6+/-2.8 kg/m2. The onset latency, peak latency and SNAP amplitude of the 2 WEB response were 1.7+/-0.1 ms, 2.2+/-0.2 ms, and 24.6+/- 8.2 micro V, respectively. The onset latency, peak latency and SNAP amplitude of the 2 DIG response were 1.6+/-0.2 ms, 2.2+/-0.2 ms, and 15.2+/-6.0 micro V, respectively. A statistically significant difference was observed between male and female subjects for both 2 WEB and 2 DIG responses. Weak correlations were found between the nerve conduction values and BMI, sex, and finger circumference. CONCLUSION: Sensory nerve action potentials can be successfully obtained from the distal branches of the superficial radial nerve.