For disorders affecting nerves and muscles, electrodiagnostic studies can help establish diagnoses, identify other problems, and define the severity of the problem. Electromyography (EMG) and other electrodiagnostic tests read the electrical signals that travel from the brain to motor nerves to muscles. An injury or disease can interrupt these electrical signals, causing problems such as carpal tunnel syndrome, sciatica or nerve entrapment.
Patients who experience weakness, atrophy, fatigue, cramps, muscle movements, stiffness, pain, paresthesias (tingling skin sensations), and numbness may be asked to undergo an electrodiagnostic test.
Indications for electrodiagnostic testing include:
- Entrapment neuropathies including:
- Carpal tunnel syndrome
- Cubital tunnel syndrome
- Radial nerve palsy
- Peroneal nerve palsy
- Tarsal tunnel syndrome
- Radiculopathy in the cervical and lumbar regions
- Brachial and lumbosacral plexopathy
- Peripheral nerve injuries
- Pain, numbness or weakness of upper or lower extremities
- Diseases of the neuromuscular junction like myasthenia gravis
- Motor neuron disease
- Autonomic neuropathy
What to Expect
Our active electrodiagnostic service studies 2,500 patients a year. Nerve conduction studies and needle electromyography are the most common tests. Nerve conduction studies involve electrodes that are taped to the skin near the affected nerve, which is then stimulated with a slight electrical current. The electrodes measure how fast the electrical signal travels. Healthy nerves can conduct signals at more than 100 miles an hour. Damaged nerves conduct signals much slower than that.
The Washington University neurologists who perform electrodiagnostic studies are all board certified and have extensive experience in electrodiagnosis and in neuromuscular diseases. They are available for consultation on nerve and muscle disorders, and can offer an opinion as to whether electrodiagnosis would be useful.
For a referral to a Washington University neurologist or neurosurgeon at Barnes-Jewish Hospital, call