[The motor response potential after distal and proximal stimulation: studies in healthy volunteers and in polyneuropathies (author's transl)].

Muscle responses evoked distally and proximally were recorded in median and in peroneal nerves from controls and patients with polyneuropathies of different origin. The following parameters were studied in the individual muscle response: 1. the amplitude of the potential, measured peak to peak, 2. the amplitude of the negative phase, 3. the total duration of the potential, 4. the duration of the negative phase, 5. the area covered by the negative phase. Results of the proximal measurements were divided by those of the distal records. Distal motor latencies and nerve conduction velocities were also determined. In controls a loss of amplitude of 10-15% and an equal reduction of the area covered by the negative phase was noted in proximally evoked responses and the duration of the negative phase was increased by 2-7% when compared with distal measurements. In some polyneuropathies these parameters showed significantly pathological changes, although distal motor latency, amplitude and nerve conduction velocity were still within the normal range. Comparison of distally and proximally evoked muscle potentials may thus lead to further information about the mode of conduction in altered motor nerves.