Charcot-Marie-Tooth disease (CMT), also known as hereditary motor and sensory neuropathy (HMSN), is one of the most commonly inherited neurological conditions characterized by damage to the peripheral nerves. These nerves connect the brain and spinal cord to the rest of the body and carry out functions such as controlling muscles and relaying sensory information from the limbs to the brain.

CMT is characterized by muscle weakness in the arms, legs, hands, and feet, but these symptoms alone are not enough for a doctor to confirm the diagnosis of CMT. Doctors may recommend various tests to diagnose CMT. These include genetic tests, nerve conduction studies, electromyography (EMG), and less frequently, nerve biopsy.

Genetic tests

Because CMT is a primarily hereditary disease, a doctor may conduct genetic tests to diagnose it. Genetic tests help doctors to detect genetic defects that are known to cause CMT. These tests are conducted by drawing a sample of blood and testing the genetic material from the blood cells for many common chromosomal defects known to cause CMT.

Nerve conduction studies

This is another type of test that doctors use to diagnose CMT. This test is usually performed by neurologists or physicians who specialize in treating conditions of the nervous system. In nerve conduction studies, a doctor places electrodes on the skin over peripheral motor or sensory nerves. These electrodes produce small electric shocks that stimulate the nerve. A delayed or a weak response in the stimulation may indicate type 1 CMT. A small response may be an indication of axon degeneration, or type 2 CMT.

Electromyography (EMG)

In EMG, a doctor inserts a needle electrode through the skin to measure the bioelectrical activity of muscles during contraction and relaxation. EMG helps doctors to determine the distribution and severity of peripheral nerve involvement by testing different muscles.

Nerve biopsy

A nerve biopsy is less common and mostly used when the results of all other diagnostic methods are negative or inconclusive. In a nerve biopsy, a neurologist creates a small incision in the skin and removes a small piece of peripheral nerve to examine under a microscope for signs of abnormal myelination and axon degeneration.

Note: Charcot-Marie-Tooth News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The opinions expressed in this column are not those of Charcot-Marie-Tooth News, or its parent company, BioNews Services, and are intended to spark discussion about issues pertaining to Charcot-Marie-Tooth disease.