DIAGNOSTIC CRITERIA

A diagnosis of CMT is initially based on a thorough physical examination in which the clinician observes CMT-type symptoms in the feet, legs, and hands. To confirm this initial diagnosis, more sophisticated tests are usually conducted.

One such test determines nerve conduction velocity (NCV), a measure of the speed at which nerve impulses travel along the nerves. Nerve impulses are slowed in type 1 CMT and may show other abnormalities in type 2 CMT.

Another important test, an electromyogram (EMG), records the electrical activity of muscle cells. Damage to nerves alters the characteristic pattern of electrical activity in the muscles that receive unput from those nerves.

These tests may cause some discomfort to the patient, but they're extremely valuable, because they allow nerve function to be directly observed.
 
Genetic testing is available for at least one form of CMT (the type caused by a defect on chromosome 17), but new developments in CMT genetic testing are ongoing.