Motor Evoke Potential (MEP)

Motor Evoke Potentials (MEP) assesses the brain pathways that help you move your muscles. Your doctor may have ordered this test because you have weakness or difficulty using a part of your body. It can help determine if there is an abnormality in the way your nervous system processes the brain signals that help you move.

The first part of the test begins like a nerve conduction study, which you may have had performed previously. One nerve is stimulated on both arms and legs to get some baseline data. This can cause some discomfort but is not painful. In the second part of the test, a circular wand containing a magnet is placed on top of the head. Specific motor pathways are then stimulated using a brief (less than 100 milliseconds) magnetic current, causing a quick and mild jerk of your limbs. As the magnet is activated, there is a loud clicking noise. This part does not cause pain, but does feel unusual.

Preparation:

No special preparation is needed.

It is advisable to wear loose fitting clothing.

The test takes 45 minutes.

The test has no side effects.