Overview of Dystonia
Dystonia (sometimes referred to in the plural, dystonias, because of the many different types) is a neurological disorder that causes repetitive, involuntary muscle contractions that can last from a few seconds to years. Various parts of the body can be affected, including the arms, legs, torso, neck, and eyelids.
The movements can cause twisting, abnormal positions, pain, and disability. There is no cure for dystonia and treatment options depend on location of the affected muscle and the severity of the condition. Dystonias usually do not impair the patient's cognitive ability (i.e., reasoning, judgment, memory) or intelligence.
Types of dystonia are classified in three ways: Dystonias can be classified according to the part of the body affected
- Generalized dystonia involves most or all of the body.
- Focal dystonia is found in one specific area of the body, such as a limb, eyelids, or neck.
- Segmental dystonia occurs in two or more adjacent parts of the body.
- Multifocal dystonia involves two parts of the body that are not adjacent.
- Hemidystonia affects an arm and leg on one side of the body.
Certain dystonias have more specific names. Cervical dystonia affects the neck muscles that position the head. Blepharospasm causes the eyelids to close without control, often resulting in functional blindness. Writer's cramp affects the hands, fingers, and forearm.
Dystonia can be classified by the age that symptoms start to appear
- Early onset—before age 30
- Late/adult onset—after age 30
- Infantile—before age 2
- Childhood—between the ages of 2 and 12
- Juvenile—between the ages of 13 and 20
- Adult—after age 20
In patients who develop dystonia as children, the condition is more likely to progress to additional parts of the body.
Dystonias can be classified as primary or secondary
- Primary—develops on its own, apart from any illness
- Secondary—occurs with an illness, trauma, or from medications or toxins
Incidence and Prevalence of Dystonia
According to The Dystonia Medical Research Foundation, at least 300,000 people in North America have some form of dystonia, and it can affect people of any age or background. Some particular dystonias are more common to certain groups. For example, about twice as many women develop cervical dystonia as men. Approximately 50 percent of all dystonia cases are primary (i.e., unrelated to illness or injury).