What is Dystonia?

Aggregated from professional sources by Dr. Mark Zuccolo - Updated January 2024

Understanding Dystonia

The dystonias are a group of disorders defined by specific types of abnormal movements. The essential feature is over-activity of muscles needed for movement. This over-activity can be expressed as excessive force in the primary muscles used for a movement, overflow activation of additional muscles that are not required for a movement, or co-activation of muscles that antagonize the primary muscles. The clinical expression of dystonia is determined by the severity and distribution of muscles involved. In mild cases dystonic movements appear merely as exaggerations of specific actions. In moderate cases the movements are more clearly abnormal with a quality that is cramped, stiff or twisting. In more severe cases dystonic movements appear as persistent odd postures or fixed deformities.

Dystonic movements are often slow, but they sometimes may be rapid or jerky. Sometimes the movements may resemble tremor. They tend to be patterned or stereotyped in individual cases. Dystonic movements are typically patterned, twisting, and may be tremulous. Dystonia is often initiated or worsened by voluntary action and associated with overflow muscle activation.

Virtually any region of the body may be affected, alone or in various combinations. The dystonias may emerge at any age. Some remain relatively static, while others are progressive or intermittent. Dystonia may occur in isolation, or it may be combined with other clinical problems.

Types and Location

Generalized dystonia affects most or all of the body.

Focal dystonia is localized to a specific part of the body.

Multi-focal dystonia involves two or more unrelated body parts.

Segmental dystonia affects two or more adjacent parts of the body.

Hemidystonia involves the arm and leg on the same side of the body.

Cervical dystonia, also called spasmodic torticollis or simply torticollis, is the most common of the focal dystonias. In cervical dystonia, the muscles in the neck that control the position of the head are affected, causing the head to turn to one side or be pulled forward or backward. Sometimes the shoulder is pulled up. Cervical dystonia can occur at any age, although most individuals first experience symptoms in middle age. It often begins slowly and usually reaches a plateau over a few months or years. About 10 percent of those with torticollis may experience a spontaneous remission, but unfortunately the remission may not be lasting.

Blepharospasm, the second most common focal dystonia, is the involuntary, forcible contraction of the muscles controlling eye blinks. The first symptoms may be increased blinking, and usually both eyes are affected. Spasms may cause the eyelids to close completely, causing “functional blindness” even though the eyes are healthy and vision is normal.

Cranial-facial dystonia is a term used to describe dystonia that affects the muscles of the head, face, and neck (such as blepharospasm). The term Meige syndrome is sometimes applied to cranial-facial dystonia accompanied by blepharospasm. 

Oromandibular dystonia affects the muscles of the jaw, lips, and tongue. This dystonia may cause difficulties with opening and closing the jaw, and speech and swallowing can be affected.

Spasmodic dysphonia, also called laryngeal dystonia, involves the muscles that control the vocal cords, resulting in strained or breathy speech. It can be focal to the hands, in which case it manifests in the form of tremor, finger contractions, clamping or painful cramps.

Task-specific dystonias are focal dystonias that tend to occur only when undertaking a particular repetitive activity, such as playing golf, throwing a baseball pitch, or other sports. 

Writer's cramp affects the muscles of the hand and sometimes the forearm, and only occurs during handwriting. 

Musician’s dystonia is a term used to classify focal dystonias affecting musicians, specifically their ability to play an instrument or to perform. It can involve the hand in keyboard or string players, the mouth and lips in wind players, or the voice in singers.

DYT1 dystonia is a rare form of dominantly inherited generalized dystonia that can be caused by a mutation in the DYT1 gene. This form of dystonia typically begins in childhood, affects the limbs first, and progresses, often causing significant disability. Because the gene’s effects are so variable, some people who carry a mutation in the DYT1 gene may not develop dystonia.

Dopa-responsive dystonia (DRD), also known as Segawa’s disease, is another form of dystonia that can have a genetic cause. Individuals with DRD typically experience onset during childhood and have progressive difficulty with walking. Symptoms characteristically fluctuate and are worse late in the day and after exercise. Some forms of DRD are due to mutations in the DYT5 gene.  Patients with this disorder have dramatic improvements in symptoms after treatment with levodopa, a medication commonly used to treat Parkinson’s disease.

Genetic causes of dystonia include mutations in the following genes: DYT3, which causes dystonia associated with Parkinsonism; DYT5 (GTP cyclohydrolase 1), which is associated with dopa-responsive dystonia (Segawa disease); DYT6 (THAP1), associated with several clinical presentations of dystonia; DYT11, which causes dystonia associated with myoclonus (brief contractions of muscles); and DYT12, which causes rapid onset dystonia associated with parkinsonism.

The following sources were consulted for the creation of this website:
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