Types of Dystonia
The characteristics of dystonia are classified in two categories: Axis I and Axis II. Both Axis I and Axis II are used to describe every type of dystonia.
- Axis I characterizes dystonia types based on clinical features:
- Age of onset refers to the age when dystonia symptoms began:
- Infancy (birth to 2 years of age)
- Childhood (3 to 12 years of age)
- Adolescence (13 to 20 years of age)
- Early adulthood (21 to 40 years of age)
- Late adulthood (41 years of age and older)
- Body distribution describes the affected body regions and how close these areas are to each other. Subgroups include:
- Focal dystonia: Symptoms are in one body part or one muscle group
- Generalized dystonia: Affects most or all of the body, including the torso
- Hemidystonia: Affects the arm and leg on the same side of the body
- Multifocal dystonia: Affects two or more unconnected body regions
- Segmental dystonia: Involves two or more body regions next to each other
- Temporal patterns describe the changes in symptoms over time:
- Static (unchanging)
- Progressive (worsening)
- Symptoms that happen at specific moments (task-related symptoms, persistent symptoms, daytime-only symptoms or sudden, unexpected symptoms)
- Related clinical features describe whether dystonia occurs along with other neurological signs or symptoms:
- Isolated dystonia occurs without other signs
- Combined dystonia occurs with other signs
Axis II characterizes the cause of dystonia:
- Problems of the nervous system: Brain scans or other testing may show structural issues or injuries to the brain causing dystonia. Some medications used to treat psychiatric conditions (neuroleptics) can cause dystonia symptoms. These symptoms may be short-lived (acute dystonia) or more long-lasting (tardive dystonia).
- Genetics: Some dystonia types are passed down from parents to children through inherited gene mutations. Other types may result from changes to genes that happen over a person’s lifetime (acquired gene mutations).
- No known cause: Dystonia with no known cause is called idiopathic dystonia.