Abnormality of peripheral nerve conduction

What it means

An abnormality of the conduction of electrical impulses by peripheral (motor or sensory) nerves. This finding is elicited by a nerve conduction study (NCS).

A nerve conduction study (NCS) is commonly conducted together with electromyography in order to evaluate muscle disorders. For the NCS, dermal electrodes are placed at intervals over the nerve to be examined, and a low-intensity current is introduced to generate action potentials. The velocity of the action potential is related to the diameter of the nerve fiber and the presence of a myelin sheath. Diseases of the myelin sheath characteristically reduce the nerve conduction velocity (NCV). The amplitude of the response is also measured.

Rare diseases that can present with this15

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions, and Orphanet separately records 1 disease where this sign is specifically absent. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Abnormal peripheral nerve transmission · Sensory and motor nerve conduction abnormalities