The NCV test is done to patients with suspected nerve injury and determines the speed of conduction of impulses along the course of the nerve affected. It is commonly done with EMG or electromyography to see it the problem lies in the nerve or muscular junction. Both tests are done to accurately diagnose a condition and therefore give the proper treatment.
Nerve conduction velocity testing is done when a patient feels signs associated with nerve damage such as tingling, burning, prickling, pins and needles, and numbness. The procedure is done through adhesive electrode patches attached to the area affected and an electrical impulse that is sent from one patch to the other. The speed of the nerve conduction is determined by measuring the amount of time it took for the impulse to reach the second adhesive patch. The conduction speed of the nerve that was measured is then compared to normal latency speeds, since healthy nerves tend to send signals much more quickly than damaged ones.
Damage to a nerve can occur at the nerve axon, or the part that sends impulses away from the body of the nerve, or the myelin sheath, which is the covering of the nerve that enhances delivery of impulses. The part of the nerve damaged will depend on the condition, such as injuries like carpal tunnel syndrome or a neuropathy that involves the damage of the myelin sheath. NCV testing allows physicians to determine what type of condition the patient has in order to administer proper care.
An EMG test done in conjunction with NCV testing can help in diagnosing conditions in the musculoskeletal level and see whether muscular damage has occurred. This is crucial in diagnosing neuromuscular conditions such as ALS (amyotrophic lateral sclerosis), MG (myasthenia gravis), or nerve root damage due to a herniated disc in the spine.