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Electrodiagnostic (EDX) Medicine

Electrodiagnostic medicine is a medical subspecialty of neuromuscular medicine that aids in diagnosis, evaluation, and treatment of neuromuscular, musculoskeletal, and nervous system disorders. Electrodiagnostic physicians record and analyze results from the patient’s history and physical examination along with test results obtained from conductance of electrical impulses between muscles and nerves. Electrodiagnostic medicine helps in evaluating the causes of numbness, tingling, discomfort, weakness, fatigue, and muscles cramps.

Electrodiagnostic medicine employs different types of tests such as nerve conduction studies (NCSs) and electromyography (EMG) to study the functioning of nerves and muscles. EMG (electromyography) test is used to measure the electrical activity of the muscles whereas NCS (nerve conduction study) measures the intensity and the speed of the electrical signals traveling through the nerves.


During an EMG test, a tiny needle is inserted into a muscle in order to stimulate and measure the electrical activity of the muscle. A new sterile needle is used for every patient and is discarded after the completion of the test. You may feel a little pain when the needle is inserted. Muscles showing impaired function are selected for inserting the needle. Your doctor records and analyzes the electrical signals traveling through the needle to the EMG machine and utilizes this information for determining treatment of the disorder.

An NCS or nerve conduction study involves two electrodes placed on the patient’s skin over the affected area. Your doctor measures the conduction of the electrical signals in the nerves present between the electrodes by applying a small electrical shock to the nerve and recording how the nerve works. These shocks can cause a quick, mild, tingling feeling. The doctor may test several nerves by employing this test.

After the physical examination and going through your medical history, your doctor may recommend either of the above-mentioned tests. Patients should wash thoroughly to remove oil from the skin and should not use body lotion on the day of the test. The tests usually take 20-90 minutes to complete.

Patients can perform their normal activities such as eating, driving, and exercising after the tests. The tests do not have any lasting side effects.

Patients should inform their doctor before performing these tests if taking medications such as aspirin or blood thinners. Patient with pacemakers or suffering from disease conditions such as hemophilia or myasthenia gravis should also inform the doctor about their condition and should take medication as recommended by the doctor before the test.

Depending on the symptoms and condition of the patient, the doctor may recommend other tests such as neuromuscular ultrasound, muscle biopsy or genetic testing.

Electrodiagnostic testing determines the type, location, severity, and prognosis of a variety of disease conditions such as carpal tunnel syndrome, ulnar palsy, radiculopathy in cervical and lumbar regions, peripheral neuropathy, peripheral nerve or plexus injuries, myasthenia gravis, and many other neuromuscular disorders.

Electrodiagnostic medicine provides useful information in the evaluation of the motor and sensory neurons, the nerve roots, the brachial and lumbar plexi, the peripheral nerves, the neuromuscular junction, and the muscles.

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