Technique for studying conduction in the lateral cutaneous nerve of calf

We describe a novel technique for assessing conduction in the lateral cutaneous nerve of the calf (LCNC), a branch of the common peroneal nerve, based on a study of 32 healthy subjects. Both antidromic and orthodromic techniques were used in each of the 64 limbs to obtain a sensory nerve action potential (SNAP) of the LCNC over a distance of 12 cm. In 60 limbs (93.7%) a SNAP was obtainable with either the antidromic or orthodromic technique. In 21 limbs (32. 8%), the SNAP was obtained both antidromically and orthodromically. In 33 limbs (51.6%), the SNAP was obtained only antidromically, and in 6 (9.4%), only orthodromically. In four limbs, the response was unobtainable. Mean antidromic onset latency was 2.1 ms +/- SD 0.3, peak latency was 2.6 ms +/- SD 0.4, amplitude (without averaging) was 4.3 microV +/- SD 2.5, and conduction velocity was 60 m/s +/- SD 10. Mean orthodromic onset latency was 2.3 ms +/- SD 0.3, peak latency was 2.7 ms +/- SD 0.3, amplitude was 5.0 microV +/- SD 2.2, and conduction velocity was 52 m/s +/- SD 5. Utilization of this technique allows for more detailed localization of common peroneal nerve injury based on whether it is proximal or distal to the origin of the LCNC.