Medial and lateral antebrachial cutaneous nerves: standardization of technique, reliability and age effect on healthy subjects.

Techniques for performing antidromic conduction velocity studies on forearm sensory nerves were evaluated in 157 healthy subjects from 17 to 80 years of age. The lateral antebrachial cutaneous nerve (LABCN) and the medial antebrachial cutaneous nerve (MABCN) were studied in the same upper extremity at a distance of 14 cm. The mean values for LABCN were amplitude 18.9 microV, latency to peak 2.8 ms and conduction velocity (CV) 61.5 m/s; for MABCN, amplitude 11.4 microV, latency to peak 2.7 ms and CV 62.7 m/s; and for median nerve, CV 62.3 m/s. SNAPs were obtained in 98% of subjects for each forearm sensory nerve. Age-related changes in the MABCN and LABCN were small, but included a decreased number of high value SNAP amplitudes and CVs with advancing age, whereas values for the median nerve showed a slight overall decrease with age. Sex effects were negligible. It is concluded that: LABCN and MABCN conduction studies can be performed with equal and high reliability using standard techniques and the same constant distance; The amplitude of the LABCN tends to be larger than that of the MABCN (76% of subjects); In some subjects MABCN studies are technically more difficult to perform than LABCN studies; Forearm sensory nerve studies may be used in addition to median nerve sensory studies in the evaluation of peripheral neuropathy, brachial plexopathy and local neuropathic conditions.