What is dystonia and what causes it?

Dystonia (or dystonic reaction) to a disorder of muscle tone, which generally appears as an overactivity of muscle, leading to twisting motions and abnormal body positions. The symptoms of a dystonic reaction can come on suddenly and be quite alarming. They include abnormal movements of the eyes, slurred speech, and twisting of the neck that can progress to a severe type of muscle spasm in which the head, neck, and back are locked in a muscle spasm. Some patients develop chronic dystonia, in which these symptoms persist for an extended period.

Dystonic reactions can be caused by medications, including prochlorperazine and metoclopramide used for nausea and vomiting and psychiatric drugs such as haloperidol. Other causes of dystonia include Parkinson’s disease, stroke, brain injury and birth injury. Dystonia can be inherited, but often no underlying problem is identified.