An Electromyography In-office EMG Test measures the electrical activity of a muscle. It detects any sign of blocking or slowing down of responses to nerve or muscle stimulation. This test provides information about the muscle itself and shows how well it receives stimulation from a nerve or how well it receives an electrical stimulation directly to the muscle. This test is used to evaluate muscle weakness, twitching, spasm or paralysis, and to find the causes of numbness, tingling and pain. It can differentiate between true weakness and reduced use because of pain or lack of motivation. This test can determine whether a muscle disorder begins within the muscle or perhaps at the neuromuscular junction or is caused by a nerve disorder. This test can detect sharp waves and fibrillations, jitter and fiber density in an abnormal muscle.
Electrical signals are generated in the brain and pass through the spinal cord and out into the peripheral nervous system. These signals are carried down the nerve to the Synaptic Cleft where a chemical release of Acetylcholine crosses the symaptic cleft to create an electrical discharge in the muscle. This electrical signal causes the muscle to contract.
Information about the impulse after nerve stimulation can be recorded, including latency (time to get from stimulus to recording), the distance traveled and the nerve conduction velocity (NCV). These measures are sensitive indicators of nerve damage and look specifically at the integrity of the myelination of the nerve. The amplitude of the muscle contraction can be determined providing information about the number of neurons that are functioning within the nerve.
Neurodiagnostic testing bypasses the brain by delivering a mild electrical stimulus to the patient. Our equipment is then used to measure several aspects of the body's response to that signal to determine whether it is functioning properly.
Location and degree of injury, clarity of pathology, prognosis and in some cases, specific diagnosis can be determined through electrodiagnostic testing.