What is NCS?
A Nerve Conduction Study(NCS) is a medical diagnostic test commonly used to evaluate the function, especially the ability of electrical conduction, of the motor and sensory nerves of the human body. These tests are performed by medical specialists such as specialists in clinical neurophysiology,physiatrists(physical medicine and rehabilitation [PMR] physicians), and neurologists. In the United States, neurologists receive training in performing needle electromyography and NCS is during a fellowship in clinical neurophysiology or neuromuscular medicine. PMR physicians receive this training during their residency and can get further training in a neuromuscular fellowship. Outside the US, clinical neurophysiologists learn needle EMG and NCS testing.
Nerve conduction velocity(NCV) is a common measurement made during this test. The term NCV often is used to mean the actual test, but this may be misleading, since velocity is only one measurement in the test suite.
Nerve conduction studies along with needle electromyography measure nerve and muscle function, and may be indicated when there is pain in the limbs, weakness from spinal nerve compression, or concern about some other neurologic injury or disorder. Spinal nerve injury does not cause neck, mid back pain or low back pain, and for this reason, evidence has not shown EMG or NCS to be helpful in diagnosing causes of axial lumbar pain, thoracic pain, or cervical spine pain.
Nerve conduction studies are used mainly for evaluation of paresthesias (numbness, tingling, burning) and/or weakness of the arms and legs. The type of study required is dependent in part by the symptoms presented. A physical exam and thorough history also help to direct the investigation. Some of the common disorders that can be diagnosed by nerve conduction studies are: