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). 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.