The most common slow repetitive stimulation studies are recorded from the  Median (APB), Ulnar (ADM), Spinal Accessory (Trapezius) and the Facial (Orbicularis Oculi) motor nerves.  However, myasthenia gravis repetitive stimulation studies can be performed on any motor point.

After performing the routine motor nerve conduction study distally, the following procedure should be used for slow repetitive stimulation:

1.    Select the repetitive stimulation program on the EMG machine

2.    Stimulate the nerve with a train of 5-6 stimulations at 2-3 stimulations per second (2-3 Hz).

3.    Exercise the recording muscle for 60 seconds, taking a small break at the 30-sec time.

4.    Stimulate the nerve with another train of stimulations.

5.    Every 60 seconds thereafter, record another train of stimulations, until you complete 3-4 trains.

6.    A decrement of more than 10% is a positive finding. A decrement of 5-10% is equivocal.