By Renée Grinnell

A neurological disorder of movement in which groups of muscles twist or contract involuntarily. Causes include drug side effects, trauma to the body, poisoning, or infection.

Example: A schizophrenic man experiences prolonged, painful spasms in his right arm soon after taking a dose of his neuroleptic medication.

    Last reviewed: By John M. Grohol, Psy.D. on 11 Oct 2008