This test measures the integrity of nerve tracts which conduct the electric impulses. It is used to assess the nature, severity and duration of the nerve lesion and in combination with EMG helps in predicting the chances of recovery after a nerve lesion.

The nerves of interest are stimulated with a very low voltage electric current which causes mild tingling over the area stimulated. The test takes 20 min to 1 hour depending upon the number of nerves to be tested. It is very useful, in cases of carpal tunnel syndrome, diabetic neuropathy, traumatic neuropathy, plexopathy, varius vitamin deficiencies.