R25: Abnormal involuntary movements

R25.1: Tremor, unspecified

A tremor is a rhythmic muscle twitch. The muscles usually only twitch faintly so that it is not noticeable. For various reasons, the muscles can twitch more than usual. The muscle twitching can affect the arms, hands, head and other parts of the body.

A noticeable tremor can occur with many different disorders, or as the side-effect of medication. However, the precise reason for the tremor may be unknown.