EMG: continuous motor unit activity at rest

What it means

Continuous electromyographic activity of motor units at rest, i.e., without voluntary movement of the muscles.

The motor unit contains an anterior horn cell, its axon, and all of the muscle fibers that it innervates via the neuromuscular junction. Note that a healthy relaxed muscle does not show significant EMG activity at rest.

Rare diseases that can present with this1

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. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category