This test has two components, EMG and Nerve Conduction. The purpose is to check if the muscles and nerves are healthy. A needle EMG electrode is used to test the muscles that will record the waves very similar to an electrocardiogram. The nerves are tested with an electrical stimulator to record how nerve conduct electricity. The abnormal waves and values will yield the specific diagnosis such as “pinched nerves”.
Electromyography (EMG) is performed using an instrument called an electromyograph, to produce a record called an electromyogram. An electromyograph detects the electrical potential generated by muscle cells when these cells are electrically or neurologically activated. The signals can be analyzed to detect medical abnormalities, activation level, recruitment order, or to analyze the biomechanics of movement.
Common indications for EMG are:
- Radiculopathy commonly known as “back/neck pinched nerve,” sciatica
- Neuropathy usually manifested by burning pain, numbness and/or tingling
- Brachial or lumbosacral plexus injury
- Muscle diseases such as myopathies like muscular dystrophy
- Motor neuron disease such as amyotrophic lateral sclerosis (ALS)
- Post-polio syndrome
- Myotonic muscular dystrophy
- Polymyositis / Dermatomyositis
Nerve Conduction Studies
A nerve conduction study (NCS) shows how well signals travel along large nerve fibers and can help find the cause of abnormal nerve function. To perform a study, a physician (or trained technologist working under physician supervision) applies small electric pulses to a nerve. The pulses cause the patient to feel a mild tingling sensation, and if the muscle is stimulated, it will move. The type of problem being evaluated determines how many nerves are tested.
Common indications for NCS are:
- Carpal tunnel syndrome
- Ulnar neuropathy such as cubital tunnel syndrome
- Tarsal tunnel syndrome
- Peripheral neuropathy
- Hereditary neuropathies like Charcot Marie Tooth
- Brachial/lumbosacral plexopathy
- Myasthenia Gravis
- Guillain Barre syndrome (AIDP)
- Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)
Preparation for test: When scheduling the appointment, notify if you are taking any anticoagulation therapy and if you have a cardiac pacemaker/defibrillator or spinal cord stimulator. On the day of the test, you can take your regular medications, no need to fast; and do not apply any body/hand lotion or cream.