Dystonia
Overview
Dystonia (sometimes referred to in the plural, dystonias, because of the many different types) is a neurological disorder that causes repetitive, involuntary muscle contractions that can last from a few seconds to years. Various parts of the body can be affected, including the arms, legs, torso, neck, and eyelids.
The movements can cause twisting, abnormal positions, pain, and disability. There is no cure for dystonia and treatment options depend on location of the affected muscle and the severity of the condition. Dystonias usually do not impair the patient's cognitive ability (i.e., reasoning, judgment, memory) or intelligence.
Types
Types of dystonia are classified in three ways:
- Part of the body affected
- Generalized dystonia involves most or all of the body.
- Focal dystonia is found in one specific area of the body, such as a limb, eyelids, or neck.
- Segmental dystonia occurs in two or more adjacent parts of the body.
- Multifocal dystonia involves two parts of the body that are not adjacent.
- Hemidystonia affects an arm and leg on one side of the body.
Certain dystonias have more specific names. Cervical dystonia affects the neck muscles that position the head. Blepharospasm causes the eyelids to close without control, often resulting in functional blindness. Writer's cramp affects the hands, fingers, and forearm.
- Age that symptoms start to appear
- Early/childhood onset-before age 30
- Late/adult onset-after age 30
- Infantile-before age 2
- Childhood-between the ages of 2 and 12
- Juvenile-between the ages of 13 and 20
- Adult-after age 20
In patients who develop dystonia as children, the condition is more likely to progress to additional parts of the body.
- Primary or secondary
- Primary-develops on its own, apart from any illness
- Secondary-occurs with an illness, trauma, or from medications or toxins
Incidence and Prevalence
According to The Dystonia Medical Research Foundation, at least 300,000 people in North America have some form of dystonia, and it can affect people of any age or background. Some particular dystonias are more common to certain groups. For example, about twice as many women develop cervical dystonia as men. Approximately 50% of all dystonia cases are primary (i.e., unrelated to illness or injury).
Risk Factors and Causes
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
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.
Diagnosis
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.
Treatment
Treatment for dystonia may include medication, injections, and surgery. In some cases, patients are able to use "sensory tricks" (sometimes called geste antagoniste) to help alleviate symptoms or at least make them more manageable. By touching the affected area (or one close to it) in a particular way, the contractions subside.
For example, some patients place a hand on their chin, on the back of their head, or on the side of their face to help with neck muscle spasms. Others find that touching their eyebrows helps alleviate contractions in the eyelids. Orthopedic devices have been developed to perform some sensory tricks so that the patient does not have to perform them.
Medications can be used to affect neurotransmitters in the nervous system and control movement. Often, a combination of medicines is prescribed and patients are started on a low dosage. The medication can be gradually increased as needed, and may be discontinued slowly over time.
Types of medication that may be used to treat dystonia include the following:
- Anticholinergics (e.g., benztropine mesylate [Cogentine®], biperiden [Akineton®], diphenhydramine [Benadryl®], trihyxyphenidyl [Artane®])
- Benzodiazepines (e.g., diazepam [Valium®], clonazepam [Klonopin®])
- Baclofen (muscle relaxant and antispastic medication)
- Dopamine agonists (e.g., bromocriptine [Parlodel®], pergolide [Permax®])
These medications should not be discontinued abruptly. Side effects may include dizziness, drowsiness, fatigue, lack of coordination and balance (ataxia), nausea, and vomiting.
Injections can help focal (i.e., located in one area of the body) dystonias. The most common procedure uses botulinum toxin (e.g., BOTOX®, Myobloc®) to hinder the brain-body communication problems that cause dystonia. Botulinum toxin injections for dystonia must be repeated every three months.
Phenol/alcohol injections also may be used. These treatments, which are less expensive than botulinum toxin injections, usually last for six months. However, only certain types of nerves can be treated, and the procedure must be performed very carefully.
If medications and injections are unsuccessful, surgery may be considered. However, most types of dystonia are not treated surgically, and the results may be only temporary.
In deep brain stimulation (DBS), an electrode (lead) is inserted through a small incision in the skull and is implanted in the targeted area of the brain that control movement. An insulated wire (extension) is then passed under the skin in the head, neck, and shoulder, connecting the lead to the neurostimulator, which is surgically implanted in the chest or upper abdomen.
The stimulator emits an electrical pulse that is picked up by the electrode, calming the nerves that cause contractions and blocking nerve signals that trigger abnormal movement. However, the results are not consistent and deep brain stimulation is still being investigated and developed to make it more reliable.
Side effects of deep brain stimulation include the following:
- Bleeding at the implantation site
- Depression
- Impaired muscle tone
- Infection
- Loss of balance
- Slight paralysis (paresis)
- Slurred speech (dysarthia)
- Tingling (parethesia) in the head or the hands
For severe dystonias that affect the neck, certain nerves can be severed. Another surgical procedure (called ablative surgery) locates, targets, and destroys (ablates) the clearly defined area of the brain that produces chemical or electrical impulses that cause abnormal movements (i.e., the thalamus).
In this surgery, a heated probe or electrode is inserted into the targeted area. The patient remains awake during the procedure to determine if the problem has been eliminated. A local anesthetic is used to dull the outer part of the brain and skull. The brain is insensitive to pain, so the patient does not feel the actual procedure. In some cases, it may be difficult to estimate how much tissue to destroy and the amount of heat to use.
Ablative surgery for dystonia carries risks. The thalamus is very close to another part of the brain used for speech and if that area is disturbed, the patient may experience speech impediments following the procedure. Adverse effects of surgery often cannot be reversed and they may result in permanent disfigurement.
Follow Up
Dystonia symptoms can change over time, so patients should see their physician regularly to ensure effective treatment. Treatment with botulinum toxin or phenol/alcohol injections often must be continued indefinitely.
In many cases, patients benefit from ongoing rehabilitation therapy after treatment. Physical therapists can develop stretching and exercise plans that may improve strength, posture, flexibility, and range of motion. They can also help identify which types of movements worsen dystonia symptoms and which types can be substituted. Techniques like massage, ultrasound, biofeedback, and relaxation training are sometimes used. In some cases, orthopedic devices are helpful and therapists can help a patient work with them.
Speech therapists and language pathologists can help patients who have difficulty speaking, eating, and swallowing. Occupational and vocational therapists provide strategies to adapt to everyday living and working situations.
Because many patients with dystonia experience depression and anxiety, counseling and support groups can be beneficial. Relaxation is also important, since symptoms worsen during times of stress.
Prognosis
The outlook (prognosis) for patients with dystonia depends on the form and the severity, but many patients are able to lead normal lives by adjusting their activities. Dystonia is unpredictable and symptoms can fluctuate over time. Remission is possible, but rare.
Prevention
Primary dystonia does not appear to be preventable, but scientists are actively searching for ways to prevent the causes. For example, researchers are studying genes to learn more about inherited forms of dystonia.
Adopting healthy lifestyle habits (such as taking steps to prevent stroke and avoiding harmful drugs and toxins) may help prevent secondary forms of dystonias.