Risk Factors and Causes of Dystonia
The basal ganglia are groups of cells that are located in the cerebral hemispheres of the brain and contribute to some aspects of voluntary movement. If these cells are compromised or do not communicate effectively with other areas of the body, dystonia can result.
People who are carriers of a gene mutation called DYT1 are at increased risk for some forms of dystonia. Researchers are not certain how this mutation leads to dystonia, but the connection is being studied closely.
Secondary dystonias can be caused by birth injuries, exposure to poisons, trauma, tumors, and stroke.
Signs and Symptoms of Dystonia
Symptoms of dystonia are usually mild at first. The patient may notice tremors or cramps during particular activities (e.g., walking, writing). Spasms in jaw muscles may interfere with the quality of speech. The head may begin moving involuntarily. Often the symptoms start in one area and gradually affect other parts of the body. Eventually, the contractions become more severe. They sometimes level off (plateau) after a few years.
Complications associated with dystonia are widespread because of the various types and range of body parts affected. Depending on the affected area, people who have dystonia can experience severe pain; functional blindness; slurred speech; difficulty eating, swallowing, breathing, and urinating; and limited mobility.
Anxiety, fatigue, and stress can worsen symptoms. Dystonia is a condition that is frequently misunderstood and some patients feel stigmatized and perceived as being cognitively deficient or incapable of managing their lives.
In some cases, awkward, uncomfortable postures become permanent. Dystonic storms, which are especially intense periods of muscle contractions, can also occur.
Dystonia usually is diagnosed by a neurologist, and the diagnosis is based on many factors. Other illnesses and disorders that have similar symptoms (e.g., Parkinson's disease, Huntington's disease, Wilson disease, Leigh disease, lipid storage disease) must be ruled out before the diagnosis is made.
Diagnosis involves taking a medical history and performing a physical examination. Reviewing the patient's medical history is important, since approximately 44% of patients have a family history of movement disorders.
During the physical exam, neurologists look for causes of secondary dystonia, such as stroke, head injury, or exposure to poison or drugs. The patient’s medication history also is considered, since some drugs (e.g., antihistamines, antiepilectics, caffeine, antidepressants, oral contraceptives, lithium, cocaine) can cause dystonia as a side effect.
Laboratory tests also can be used to help diagnose dystonia. Blood and urine tests can determine toxin or drug levels and liver function tests and analyses of cerebrospinal fluid can also be useful. If there is a family history of dystonia, genetic testing is conducted to look for the DYT1 gene mutation. Imaging tests (e.g., MRI scans, CT scans) can be used to detect a tumor or stroke, which may indicate secondary dystonia.