Dystonia: Age of Onset

The age at symptom onset of primary dystonia is an important indicator of whether the dystonia will potentially progress to involve other body regions. Generally, the younger the patient at symptom onset, the greater the likelihood that dystonia will gradually affect multiple areas of the body. In patients with early-onset primary dystonia, the dystonia usually starts in a leg or arm and progresses to affect other limbs and the trunk. In addition, early onset with initial involvement of a leg is also considered an important indicator suggesting eventual progression to generalized dystonia.

In contrast, the older the patient at symptom onset, the greater the likelihood that the dystonia will remain localized , potentially with limited involvement of adjacent regions. In patients with primary late-onset dystonia, the dystonia often begins in the upper body, such as the neck, head and/or neck, or an arm.

Dystonia may be classified based upon age of onset as follows:

• Childhood onset—0 to 12 years
• Adolescent onset—13 to 20 years
• Adult onset—older than 20 years

The broader term early onset generally refers to dystonia that develops before age 21; however, the late twenties have also been suggested to be early onset. "Late onset" indicates symptom onset later than age 20 or the late twenties.

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