MEDIAN MOTOR CONDUCTION STUDY

Median motor conduction study is performed by placing active electrode at abductor pollicis brevis (APB) muscle, reference electrode about 3 cm distal to active electrode and ground electrode b/w stimulator and active electrode. Median nerve is stimulated at wrist and elbow.

Usually, a distal latency in excess of 3.8-4.0 ms is taken as abnormal. Similarly, CMAP amplitude of less than 5 mv or conduction velocity of less than 50 m/s is taken as abnormal. However, these values may vary b/w various populations, machines etc, thus it is advisable to generate a normative data for each centre.



Reference:

1. Anatomy of Median Nerve
2. Routine Nerve Conduction Study
3. MNCS – Parameters
4. Recording Electrodes-For Motor Studies
5. Nerve Conduction Studies – Introduction
6. Recording Procedure-Nerve Stimulation