Early-onset isolated dystonia

Early-onset isolated dystonia is one of many forms of dystonia, which is a group of conditions characterized by involuntary tensing of the muscles (muscle contractions), twisting of specific body parts such as an arm or a leg, rhythmic shaking (tremors), and other uncontrolled movements. An isolated dystonia is one that occurs without other abnormal movements or other neurological symptoms, such as seizures, a loss of intellectual function, or developmental or intellectual delay. Early-onset isolated dystonia does not affect a person's intelligence.

The signs and symptoms of early-onset isolated dystonia tend to occur in mid-childhood or adolescence. Abnormal muscle spasms in an arm or a leg are usually the first sign. These unusual movements initially occur while a person is doing a specific action, such as writing or  walking. In some affected people, dystonia later spreads to other parts of the body and the movements may become persistent and present when at rest and not doing an activity. The abnormal movements persist throughout life, but they do not usually cause pain.

The signs and symptoms of early-onset isolated dystonia vary from person to person, even among affected members of the same family.  The mildest cases affect only a single part of the body, causing isolated problems such as abnormal posture and spasms of the hand while attempting to write (writer's cramp). Severe cases involve abnormal movements affecting many parts of the body.