Dystonia is a neurological movement disorder characterized by involuntary muscle contractions that cause slow repetitive movements or abnormal postures that can affect different parts of the body. The muscle contractions can be intermittent and appear only during voluntary movements or stress, but they can also be seen while walking and ultimately even when the person is relaxed. Dystonia can be classified based on the body parts affected:

• Focal dystonia: affects only one part of the body, such as the neck (cervical dystonia), eyelids (blepharospasm), or hand (writers dystonia) .
• Segmental dystonia: affects two or more adjacent parts of the body.
• Generalized dystonia: affects all parts of the body.

The muscle spasms can range from mild to severe, and they may be painful and interfere with daily tasks. Dystonia often progresses through various stages, and the effects can worsen when the person is tired or stressed, or if they drink caffeine or alcohol. The exact cause of dystonia is not known, but researchers believe that it results from an abnormality in or damage to the basal ganglia or other brain regions that control movement. Some forms of dystonia are passed down in families, while others are acquired due to environmental or other damage to the brain, or from exposure to certain types of medications. There is no cure for dystonia, but medications and therapy can improve symptoms, and surgery is sometimes used to disable or regulate nerves or certain brain regions in people with severe dystonia.