Dystonia is a group of complex neurological movement disorders. While the disorders vary in their symptoms, causes, progression, and treatment, dystonia is characterized by involuntary muscle contractions and spasms that result in abnormal postures and movements. Focal dystonias—which affect a single part of the body, such as the face, arms, or vocal chords—are the most common.
Description
Dystonia is not a single disease, but a group of disorders with a variety of symptoms. The most common characteristic of dystonia is twisting, repetitive, and sometimes painful movements that affect a specific part of the body, such as the arms, legs, trunk, neck, eyelids,
face, or vocal cords. Cervical dystonia, which affects the head and neck, is the most common adult form of dystonia, followed by blepharospasm (eyelids), spasmodic dysphonia (larynx), and limb dystonias (hands).
Researchers believe that dystonia is caused by a malfunction in the basal ganglia, the part of the brain involved in regulating voluntary and involuntary movement. A Berlin neurologist, Hermann Oppenheim, first coined the term "dystonia" in 1911 after observing muscle spasm and variation in muscle tone in several of his young patients. The term was widely accepted and used by neurologists; however, the definition has changed over time.
Today dystonia is classified in several ways, based on cause, location, and age at onset.
The most useful classification for physicians is location, or distribution of the dystonia. Focal dystonia involves a single body part while multifocal dystonia affects multiple body parts. In generalized dystonia, symptoms begin in an arm or a leg and advance, eventually affecting the rest of the body.
The patient's age at the onset of symptoms helps physicians identify the cause and determine the probability of disease progression. Dystonia that begins in childhood is often hereditary, begins in the leg or (less commonly) the arm, and may progress to other parts of the body. Dystonia that begins in adolescence (early onset dystonia) may be hereditary, often begins in the arm or neck, and is more likely to progress than the childhood form. Adult-onset dystonia typically begins as focal or multifocal and is sporadic in origin.
Genetic profile
The majority of primary dystonia cases are believed to be hereditary and occur as the result of a faulty gene. Most cases of early-onset primary dystonia are due to a mutation in the DYT-1 gene, which was first identified as a factor in the disorder in 1987.
Dystonia appears when an individual has one copy of the mutated gene and one copy of the normal gene; however, only 30–40% of individuals with the mutated genes develop symptoms.
Demographics
Dystonia affects more than 300,000 people in North America, affecting all races and ethnic groups. Early onset idiopathic torsion dystonia has a higher frequency among Ashkenazi Jews—Jews of Eastern European ancestry.
Dystonia is the third most common movement disorder, after Parkinson disease and tremor.
Signs and symptoms
Early symptoms of dystonia may include a deterioration in handwriting, foot cramps, tremor, voice or speech difficulties, and a tendency of one foot to pull up or drag while walking. Initially, the symptoms may be very mild and only noticeable after prolonged exertion, stress, or fatigue. Over a period of time, the symptoms may become more noticeable and widespread.
Symptoms may first occur in childhood (between the ages of 5 and 17 years) or early adulthood. In general, the
earlier the onset of symptoms, the greater the chance that the disease will progress with advancing age.
Diagnosis
There is no specific diagnostic test for dystonia and the diagnosis is often based on clinical signs and symptoms. Diagnosis may be difficult because the signs are similar to those of other disorders; the involuntary muscle contractions are often incorrectly attributed to stress, stiff neck, dry eyes, tics, or psychogenic or neurological disorders. According to Mount Sinai Medical Center, 90% of dystonia patients are initially misdiagnosed.
One thing that is helpful in differentiating dystonic movements from those caused by other disorders is the timing of the movements. Dystonic movements tend to increase during activity, nervousness, and emotional stress; and usually disappear during sleep.
Treatment and management
There is no cure for dystonia. However, symptoms such as spasms and pain can usually be managed with a combination of treatments.
No one treatment has proven universally effective. A physician's approach to treatment is typically three-tiered, encompassing oral medications, injections of therapeutic agents (e.g. botulinum toxin) directly into dystonic muscle, and surgery. Surgery, which involves cutting nerves and muscles or placing a lesion in the basal ganglia to reduce movement, is usually reserved for the most severe cases. Alternative medicine, such as physical therapy, speech therapy, and biofeedback, may also have a role in treatment management.
The cause and location of a patient's dystonia will play a factor in the treatment methods chosen by the physician. In secondary dystonia, treating the underlying cause may prove effective in improving or eliminating the associated symptoms. Patients with focal dystonia often respond best to targeted methods—such as injections of botulinum toxin or surgery—while patients with dystonia may first need to be treated with oral medications to alleviate the multiple symptoms.
Prognosis
Dystonia is not fatal; however, it is a chronic disorder and prognosis can be difficult to predict.
PERIODICALS
Adler, Charles H. "Strategies for Controlling Dystonia; Overview of Therapies That May Alleviate Symptoms." Postgraduate Medicine (October 2000). <http://www.postgradmed.com/issues/2000/10_00/adler.htm>.
Ozelius, Laurie J, Jeffrey W. Hewett, Curtis E. Page, Susan B. Bressman, Patricia L. Kramer, Christo Shalish, Deborah de Leon, Mitchell F. Brin, Deborah Raymond, David P. Corey, Stanley Fahn, Neil J. Risch, Alan J. Buckler, James F. Gusella, and Xandra O. Breakefield. "The Early-Onset Torsion Dystonia Gene (DYT1) Encodes an ATP-Binding Protein." Nature Genetics 17 (September 1997): 40.
ORGANIZATIONS
Bachmann-Strauss Dystonia & Parkinson Foundation, Inc. Mount Sinai Medical Center, One Gustave L. Levy Place, Box 1490, New York, NY 10029. (212) 241-5614. <http://www.dystonia-parkinsons.org>.
National Institute of Neurological Disorders and Stroke. 31 Center Drive, MSC 2540, Bldg. 31, Room 8806, Bethesda, MD 20814. (301) 496-5751 or (800) 352-9424. <http://www.ninds.nih.gov>.
National Organization for Rare Disorders (NORD). PO Box 8923, New Fairfield, CT 06812-8923. (203) 746-6518 or (800) 999-6673. Fax: (203) 746-6481. <http://www.rarediseases.org>.
WE MOVE (Worldwide Education and Awareness for Movement Disorders). Mount Sinai Medical Center, One Gustave L. Levy Place, Box 1490, New York, NY 10029. (800) 437-6682. <http://www.wemove.org>.
