[Comparison of nerve conduction studies between conventional and lumbrical/interossei recording methods in diabetics]

Median nerve conduction studies were performed by conventional and lumbrical/interossei recording methods. The former is composed of recordings of compound muscle action potential from abductor pollicis brevis (APB) and sensory nerve action potential from second digit (D) after wrist stimulation. In the latter the recording electrode was placed lateral to the midpoint of the 3rd metacarpal bone, and recorded compound muscle action potential from the 2nd lumbrical (2 L) and sensory nerve action potential from the digital nerve (N) after wrist stimulation. Subjects were 57 healthy individuals and 97 patients with diabetes mellitus. Particularly in diabetic patients values of coefficient of correlation between each measurement were high enough; i.e., r = 0.91 between latencies to 2 L and APB, r = 0.55 between amplitudes of 2 L and APB, r = 0.86 between amplitudes of N and D. Corresponding measurements by conventional method and lumbrical/interossei method were identical in the values of coefficient of correlation between measurements. The characteristics of lumbrical/interossei method are to be able to record compound muscle action potentials and nerve action potential from the same electrode. In this study values obtained by lumbrical/interossei method showed identical correlation between measurements to the corresponding ones by conventional method. In conclusion recordings of APB and D by conventional method can be replaced with the recordings of 2 L and N by lumbrical/interossei method in the evaluation of diabetic neuropathies.