Microsoft word - dystonias.docx

Dystonias
Generalized dystonia affects most or all of the body. Some patterns of dystonia are defined as specific syndromes: Cervical dystonia, also called spasmodic torticollis, or torticollis, is the most common of the focal dystonias. In torticollis, the muscles in the neck that control the position of the head are affected, causing the head to twist and turn to one side. In addition, the head may be pulled forward or backward. Torticollis can occur at any age, although most individuals first experience symptoms in middle age. It often begins slowly and usually reaches a plateau. About 10 to 20 percent of those with torticollis experience a spontaneous remission, but unfortunately the remission may not be lasting. Blepharospasm, the second most common focal dystonia, is the involuntary, forcible closure of the eyelids. The first symptoms may be uncontrollable blinking. Only one eye may be affected initially, but eventually both eyes are usually involved. The spasms may leave the eyelids completely closed causing functional blindness even though the eyes and vision are normal. Cranial dystonia is a term used to describe dystonia that affects the muscles of the head, face, and neck. Oromandibular dystonia affects the muscles of the jaw, lips, and tongue. The jaw may be pulled either open or shut, and speech and swallowing can be difficult. Spasmodic dysphonia involves the muscles of the throat that control speech. Also called spastic dysphonia or laryngeal dystonia, it causes strained and difficult speaking or breathy and effortful speech. Meige's syndrome is the combination of blepharospasm and oromandibular dystonia and sometimes spasmodic dysphonia. Spasmodic torticollis can be classified as a type of cranial dystonia. Writer's cramp is a dystonia that affects the muscles of the hand and sometimes the forearm, and only occurs during handwriting. Similar focal dystonias have also been called typist's cramp, pianist's cramp, and musician's cramp. Dopa-responsive dystonia (DRD), of which Segawa's dystonia is an important variant, is a condition successfully treated with drugs. Typically, DRD begins in childhood or adolescence with progressive difficulty in walking and, in some cases, spasticity. In Segawa's dystonia, the symptoms fluctuate during the day from relative mobility in the morning to increasingly worse disability in the afternoon and evening as well as after exercise.The diagnosis of DRD may be missed since it mimics many of the symptoms of cerebral palsy. What do scientists know about the dystonias? GABA (gamma-aminobutyric acid), an inhibitory substance that helps the brain maintain muscle control. Acquired dystonia, also called secondary dystonia, results from environmental or disease-related damage to the basal ganglia. Birth injury (particularly due to lack of oxygen), certain infections, reactions to certain drugs, heavy-metal or carbon monoxide poisoning, trauma, or stroke can cause dystonic symptoms. Dystonias can also be symptoms of other diseases, some of which may be hereditary. About half the cases of dystonia have no connection to disease or injury and are called primary or idiopathic dystonia. Of the primary dystonias, many cases appear to be inherited in a dominant manner; i.e., only one carrier parent need contribute the dystonia gene for the disease to occur, each child having a 50/50 chance of being a carrier. In dystonia, however, a carrier may or may not develop a dystonia and the symptoms may vary widely even among members of the same family. The product of one defective gene appears to be sufficient to cause the chemical imbalances that may lead to dystonia; but the possibility exists that another gene or genes and environmental factors may play a role. Some cases of primary dystonia may have different types of hereditary patterns. Knowing the pattern of inheritance can help families understand the risk of passing dystonia along to future generations. For other individuals, the symptoms emerge in late adolescence or early adulthood. In these cases, the dystonia often begins in upper body parts, with symptoms progressing slowly. A dystonia that begins in adulthood is more likely to remain as a focal or segmental dystonia. Dystonias often progress through various stages. Initially, dystonic movements are intermittent and appear only during voluntary movements or stress. Later, individuals may show dystonic postures and movements while walking and ultimately even while they are relaxed. Dystonic motions may lead to permanent physical deformities by causing tendons to shorten. In secondary dystonias due to injury or stroke, people often have abnormal movements of just one side of the body, which may begin at the time of the brain injury or sometime afterward. Symptoms generally plateau and do not usually spread to other parts of the body. physicians use a variety of therapies aimed at reducing or eliminating muscle spasms and pain. Medication. Several classes of drugs that may help correct imbalances in
neurotransmitters have been found useful. But response to drugs varies among patients
and even in the same person over time. The most effective therapy is often
individualized, with physicians prescribing several types of drugs at different doses to
treat symptoms and produce the fewest side effects.
Frequently, the first drug administered belongs to a group that reduces the level of the neurotransmitter acetylcholine. Drugs in this group include trihexyphenidyl, benztropine, and procyclidine HCL. Sometimes these medications can be sedating, especially at higher doses, and this can limit their usefulness. Drugs that regulate the neurotransmitter GABA may be used in combination with these drugs or alone in dystonias with mild symptoms. GABA-regulating drugs include the muscle relaxants diazepam, lorazepam, clonazepam, and baclofen. Other drugs act on dopamine, a neurotransmitter that helps the brain fine-tune muscle movement. Some drugs which increase dopamine effects include levodopa/carbidopa and bromocriptine. DRD has been remarkably responsive to small doses of this dopamine-boosting treatment. On the other hand, patients have occasionally benefited from drugs that decrease dopamine, such as reserpine or the investigational drug tetrabenazine. Once again, side effects can restrict the use of these medications. Anticonvulsants including carbamazepine, usually prescribed to control epilepsy, have occasionally helped individuals with dystonia. Botulinum toxin. Minute amounts of this familiar toxin can be injected into affected
muscles to provide temporary relief of focal dystonias. First used to treat blepharospasm,
such injections have gained wider acceptance among physicians for treating other focal
dystonias. The toxin stops muscle spasms by blocking release of the excitatory
neurotransmitter acetylcholine. The effect lasts for several months before the injections
have to be repeated.
Surgery and other treatments. Surgery may be recommended for some patients when
medication is unsuccessful or the side effects are too severe. In selected cases, advanced
generalized dystonias have been helped, at least temporarily, by surgical destruction of
parts of the thalamus, a structure deep in the brain that helps control movement. Speech
disturbance is a special risk accompanying this procedure, since the thalamus lies near
brain structures that help control speech. Surgically cutting or removing the nerves to the
affected muscles has helped some focal dystonias, including blepharospasm, spasmodic
dysphonia and torticollis. The benefits of these operations, however, can be short-lived.
They also carry the risk of disfigurement, can be unpredictable, and are irreversible.
Some patients with spasmodic dysphonia may benefit from treatment by a speech-language pathologist. Physical therapy, splinting, stress management, and biofeedback may also help individuals with certain forms of dystonia. Scientists at the NINDS laboratories have conducted detailed investigations of the pattern of muscle activity in persons with focal dystonias. One of the most important characteristics is the failure of reciprocal inhibition, a normal process in which muscles with opposite actions work without opposing each other. In dystonia, the tightening of muscles is associated with an abnormal pattern of muscles fighting each other. Other studies at the NINDS have probed the spinal reflex function and found abnormalities consistent with the defect in reciprocal inhibition. Other studies using EEG analysis and neuroimaging are probing brain activity and its relation to these observations. The search for the gene or genes responsible for some forms of dominantly inherited dystonias continues. In 1989 a team of researchers mapped a gene for early-onset torsion dystonia to chromosome 9; the gene was subsequently named DYT1. In 1997 the team sequenced the DYT1 gene and found that it codes for a previously unknown protein now called torsin A. The discovery of the DYT1 gene and the torsin A protein provides the opportunity for prenatal testing, allows doctors to make a specific diagnosis in some cases of dystonia, and permits the investigation of molecular and cellular mechanisms that lead to disease. The gene for Segawa's dystonia has been found. It codes for an enzyme important in the brain's manufacture of dopamine. Benign Essential Blepharospasm Research Foundation
Dystonia Medical Research Foundation
National Spasmodic Torticollis Association
Worldwide Education and Awareness for Movement Disorders (WE MOVE)
Bachmann-Strauss Dystonia & Parkinson Foundation
Spasmodic Torticollis Dystonia/ST Dystonia
This information was developed by the National Institute of Neurological Disorders and Stroke, National Institutes of Health. Office of Communications and Public Liaison, National Institute of Neurological Disorders and Stroke, National Institutes of Health. The Dystonias Fact Sheet. Available at: http://www.ninds.nih.gov/disorders/dystonias/detail_dystonias.htm. Last accessed July 26, 2011 Copyright MedLink Corporation 1993-2010 All Rights Reserved

Source: http://www.nelsonneurology.ca/documents/Dystonias.pdf