Lateral dorsal cutaneous branch of the sural nerve. Standardization in nerve conduction study

Lateral ankle or foot pain may have various etiologies including entrapment of or injury to the distal sural nerve or early peripheral neuropathy. Antidromic distal sural conduction studies have not been used in clinical neurophysiologic evaluation, however, for technical reasons. The purpose of this study was to determine if by modifying recording parameters and using electronic averaging adequate responses could be obtained to permit standardization of distal sural conduction. Standard surface recording electrodes with an inter-electrode separation of 37 mm were used. The distal sural nerve conduction of 40 healthy adult subjects (mean age = 33 +/- 9 yr, range = 23 to 52) was measured. The latency to the onset was 3.2 +/- 0.4 ms (range = 2.5 to 4.0 ms) and to the negative peak was 3.9 +/- 0.5 ms (range = 3.0 to 4.9 ms). The conduction velocity was 38 +/- 5 m/s (range = 30 to 48 m/s). The amplitude measured from baseline to negative peak was 5.8 +/- 2.1 microV (range = 3.0 to 11.0 microV). The results indicated that electrodiagnostic evaluation of the distal sural nerve could be readily achieved and that this might be useful in differential diagnosis.