Section 6. Brain, Spinal Cord, and Nerve Disorders

Chapter 91. Movement Disorders

Topics: Introduction | Myoclonus | Tremor | Parkinson's Disease | Progressive Supranuclear Palsy | Shy-Drager Syndrome | Tics | Chorea and Athetosis | Huntington's Disease | Dystonia | Coordination Disorders

Dystonia

Dystonia is involuntary, slow, repetitive, sustained muscle contractions that may cause freezing in the middle of an action, as well as twisting or turning of the trunk, the entire body, or part of the body.

Causes

Overactivity in several areas of the brain--the basal ganglia, thalamus, cerebellum, and cerebral cortex--seems to cause dystonia. Causes of dystonia include a severe lack of oxygen to the brain that occurs at birth or later in life, Parkinson's disease, multiple sclerosis, toxicity due to accumulation of certain metals (such as copper in Wilson's disease), and stroke. Antipsychotic drugs can cause various types of dystonia, including involuntary shutting of the eyelids (blepharospasm), involuntary twisting of the neck (spasmodic torticollis), grimacing, and repetitive involuntary movements of the mouth and tongue (tardive dyskinesia). Chronic dystonia usually has a genetic cause.

Types and Symptoms of Dystonia

Idiopathic torsion dystonia refers to dystonia that has no known cause. Episodes begin between the ages of 6 and 12. Early symptoms can be mild or severe. Muscles contract slowly and abnormally, causing twisting and turning. The dystonia commonly starts in one foot or leg. It may remain limited to the trunk or a leg, but sometimes it affects the whole body, ultimately confining the child to a wheelchair. Another example of mild dystonia is persistent writer's cramp (however, not all writer's cramp is due to dystonia). When idiopathic torsion dystonia develops in adults, it usually begins in the face or arms and usually does not progress to other parts of the body.

Blepharospasm is a type of dystonia in which the eyelids are repeatedly and involuntarily forced shut. Occasionally, only one eye is affected at first, but ultimately, the other eye is also affected. It usually begins as excessive blinking, eye irritation, or extreme sensitivity to bright light. Many people with blepharospasm find ways to keep their eyes open, such as yawning, singing, or opening the mouth wide. These techniques become less effective as the disorder progresses. Blepharospasm can severely impair vision.

Spasmodic torticollis is dystonia involving the muscles of the neck.

Spasmodic dysphonia affects the muscles that control speech. People with this disorder usually have an essential tremor somewhere else as well. Spasms of the vocal cord muscles may block speech altogether or make speech sound strained, quavery, hoarse, whispery, jerky, creaky, staccato, or garbled and difficult to understand.

The yips are a type of dystonia experienced by some golfers who have muscle spasms. The muscles of the hands and wrists spontaneously contract, making putting nearly impossible. What is supposed to be a 3-foot putt can become a 15-foot putt when a golfer loses control because of the yips. Similarly, musicians who have bizarre spasms of the hands and arms that prevent them from performing may have dystonia.

Some dystonias are progressive; the movements may become more bizarre over time. Severe muscle contractions can force the neck and arms into odd, uncomfortable positions.

Treatment

Correcting or eliminating the cause of dystonia, if known, usually reduces the dystonia. For example, drugs used to treat Parkinson's disease may be effective for dystonia related to that disease. When dystonia is due to use of an antipsychotic drug, promptly taking diphenhydramine by injection or by mouth usually stops the episode quickly, and the antipsychotic is discontinued.

If the cause of dystonia is unknown, treatment is limited. Some people, especially children who have a hereditary form of dystonia (called dopa-responsive dystonia), improve dramatically when treated with levodopa. Benzodiazepines, a type of mild sedative, may be used. Baclofen, a muscle relaxant, may be given by mouth or by a pump implanted in the spinal canal. Anticholinergic drugs (see Section 2, Chapter 14), such as trihexyphenidyl and diphenhydramine, are sometimes helpful, but they also cause side effects, such as drowsiness, dry mouth, blurred vision, dizziness, constipation, difficulty urinating, and tremor, especially in older people. The antipsychotics clozapine and olanzapine may be useful.

Injections of botulin (a bacterial toxin used to paralyze muscles) into the overactive muscles have been the most successful treatment. These injections are particularly useful for blepharospasm, spasmodic torticollis, and spasmodic dysphonia.

If drug treatment is ineffective and symptoms are severe, surgery may be performed. Procedures include pallidotomy (surgical destruction of a tiny area in one basal ganglion) and implantation of electrodes to stimulate the same area of the brain.

Physical therapy helps some people, especially those who are treated with botulin.

Spasmodic Torticollis

Spasmodic torticollis (cervical dystonia) is a disorder characterized by painful intermittent or continuous contractions or spasms of the neck muscles, forcing the head to rotate or tilt forward, backward, or sideways.

Spasmodic torticollis, a form of dystonia, is diagnosed in 3 of 10,000 people in the United States and is about 1½ times more common among women than among men. The disorder can occur at any age but usually develops between the ages of 25 and 55.

Usually, the cause is unknown. Dysfunction within the basal ganglia (collections of nerve cells located at the base of the cerebrum, deep within the brain) may be the cause. Sometimes spasmodic torticollis is caused by injury to the neck muscles during pregnancy or during a difficult delivery. This type of spasmodic torticollis is called congenital torticollis. Imbalanced eye muscles and bone or muscle deformities of the upper spine can cause torticollis in children.

Symptoms and Diagnosis

Initially, symptoms may be mild, but they may become severe. They include involuntary turning of the head, muscle pains, and slight tremor of the neck muscles. Usually, only one side of the neck is affected. The direction in which the head tilts and rotates depends on which neck muscles are affected. Sharp, painful neck muscle spasms may start suddenly and occur intermittently or continuously. The spasms occur without warning but rarely during sleep. One third of people who have this disorder also have spasms in other areas, usually in the eyelids, face, jaw, or hand.

To diagnose the disorder in children and adults, doctors ask detailed questions about past injuries and other neck problems. During a physical examination of a newborn, doctors can detect neck muscle damage that may cause congenital torticollis.

Imaging procedures, such as x-rays, computed tomography (CT), and magnetic resonance imaging (MRI), are sometimes used to look for specific causes of neck muscle spasms, although such causes are not commonly identified.

Treatment and Prognosis

When a cause, such as bone or muscle deformities, is identified, torticollis can usually be treated successfully. However, when the cause is unknown, treatment is less likely to control the spasms. Sometimes the spasm can be temporarily relieved by physical and occupational therapy, which may include biofeedback, electrical stimulation, massage, cold packs, heat, and deep heat with ultrasonography.

Certain drugs help reduce muscle spasms and involuntary movements in about one third of adults with spasmodic torticollis. Usually, these drugs also help control pain due to the spasms. Commonly used are anticholinergic drugs (such as trihexyphenidyl and benztropine), which block specific nerve impulses, and benzodiazepines (particularly clonazepam), which are mild sedatives. Less frequently, muscle relaxants (such as baclofen) and antidepressants (such as amitriptyline) are used.

For people with significant pain and an abnormal posture, several injections of botulin (a bacterial toxin used to paralyze muscles), given in a low dose, is the best treatment. This toxin blocks muscle contractions. For most people, botulin injections reduce pain and spasms, so that the head can be held more normally. Improvement may last for a few months; then the treatment may be repeated as needed. Surgically removing the nerves to the dysfunctional neck muscles (called selective denervation) is sometimes successful and may be tried if other treatments do not provide relief. If emotional problems contribute to the spasms, psychiatric treatment may help.

For torticollis in newborns, intensive physical therapy to stretch the damaged muscle is begun within the first few months of life. If the physical therapy is unsuccessful or started too late, the muscle may have to be repaired surgically.

About 10 to 20% of people who have spasmodic torticollis--usually people younger than 40 with mild cases--recover without treatment within 5 years. However, in most adults, the disorder gradually worsens for 1 to 5 years, then stabilizes. Torticollis may persist for life, producing continued pain, restricted movement of the neck, and an abnormal posture.