Dystonia is a rare, progressive syndrome characterized by involuntary muscle contractions, which force certain parts of the body into abnormal, sometimes painful, movements or postures. Dystonia can affect any part of the body including the arms and legs, trunk, neck, eyelids, face, or vocal cords.
If dystonia causes any type of impairment, it is because involuntary muscle contractions interfere with normal function. Features such as cognition, strength, and the senses, including vision and hearing are normal. It is the third most common movement disorder after Parkinson’s Disease and Tremor, affecting more than 300,000 people in North America. Dystonia affects all races and ethnic groups.
Although there is currently no known cure for dystonia, we are gaining a better understanding of the disorder through research and are developing new approaches to treatments.
Types and Causes
Dystonia is often hereditary. Occasionally, symptoms of dystonia may be brought on by antipsychotic and antiemetic medications, which block dopamine receptors in the central nervous system.
Primary dystonia is believed to be due to abnormal functioning of the basal ganglia, deep brain structures involved with the control of movement. The basal ganglia assists in initiating and regulating movement. An imbalance of dopamine, a neurotransmitter in the basal ganglia, may underlie several different forms of dystonia, but more research is needed to improve our understanding of the brain mechanisms involved with dystonia.
Secondary forms of dystonia arise from and can be attributed to a number of factors, such as birth injury, trauma, toxins, or stroke. Secondary dystonia can also occur in association with other disorders such as Wilson’s disease. When dystonia is secondary to certain injuries or small strokes, lesions are often found in the putamen, one nucleus in the basal ganglia, as well as in certain nearby structures. Even though we can see no microscopic abnormalities of the brain in the great majority of cases of dystonia, including those with generalized dystonia, the evidence is so clear in the secondary dystonias that we believe the same part of the brain is also involved in primary dystonia.
At this time, the diagnosis of dystonia rests solely on the information from the affected individual and the physical and neurological examination. In order to correctly diagnose dystonia, doctors must be able to recognize the physical signs and be familiar with the symptoms. In certain instances, further tests may be ordered to be sure that there are not other problems associated with dystonia, but in many cases these tests will be normal.
When dystonia begins, often it may change significantly with different actions. For example, dystonia of the foot may occur when walking forward but disappear completely when walking backward or while sitting in a chair. In some people, dystonia involving the hand will only happen when writing and not with any other activity. The changeable nature of dystonia has led some physicians and even some dystonia-affected persons wondering if the cause of dystonia may be “all in their head.” This is not true. Dystonia is a neurologic condition that is not the result of a psychiatric problem. In order to diagnose dystonia, a doctor who is familiar with the disorder is necessary.
If dystonia is diagnosed it is important to remember that features such as cognition, strength, and the senses, including vision and hearing, are normal.
In primary dystonia, the MRI is normal. Blood tests are normal, and electrophysiology is, to a large degree, also normal. As far as secondary dystonia, it depends upon the underlying cause. A brain MRI often detects an abnormality that reveals the cause.
Dystonia is not fatal, but it is a chronic disorder and its prognosis is difficult to predict.
In very severe, generalized dystonia, affecting all body areas, there can be problems that may arise secondary to the dystonia which can cause medical illnesses. However, these instances are quite rare and usually treatable.
Recognizing symptoms and diagnosing dystonia
Unless dystonia is caused by medication, symptoms usually appear in childhood. Symptoms may include involuntary blinking, jaw-grinding, grimacing, and other abnormal movements.
Dystonia is primarily characterized by an involuntary sustained twisting or cramping posture. Tremor is not a primary symptom of dystonia. If someone began having a tremor, we would not necessarily expect dystonic postures as well. However, tremor can sometimes be seen as a secondary symptom. For instance, many patients with cervical dystonia will also have an associated head tremor and some patients with writer’s cramp will have an associated writing tremor of the hand. Dystonic tremors are quite variable in their presentation and on some occasions can look like essential tremor. They are, however, seldom seen in isolation and usually are associated with dystonic posturing. The tremors are also sometimes somewhat more irregular than what is seen with essential tremor. Essential tremor and dystonia tremor may look the same, and both can be genetic.
Symptoms of dystonia and parkinsonism can sometimes run together in the same patient because both of these movement disorders seem to arise from involvement of the basal ganglia in the brain. Both parkinsonism and dystonia can each be caused by a great many disorders, and some of these disorders actually have features of both parkinsonism and dystonia.
Treatment for dystonia is designed to help lessen the symptoms of spasms, pain, and disturbed postures and functions. Most therapies are symptomatic, attempting to cover up or release the dystonic spasms. No single strategy is appropriate for every case.
The goal of treatment is to allow the patient to lead a fuller, more productive life by reducing the effects of dystonia. Establishing a satisfactory regimen requires patience on the part of both the affected individual and the physician. The approach for treatment of dystonia is usually three-tiered: oral medications, botulinum toxin injections, and surgery. These therapies may be used in alone or in combination.
Complementary care, such as physical therapy and speech therapy, may also have a role in the treatment management depending on the form of dystonia. For many people, supportive therapy provides an important adjunct to medical treatments. Medications that block acetylcholine, a brain chemical involved in movement, and other therapies may help reduce symptoms.