Early-onset generalized dystonia, the most common hereditary form of dystonia, is characterized by the twisting of the limbs, specifically the foot/leg or hand/arm. The spasms may spread to involve twisting contractions of other parts of the body.
Blepharospasm is a focal dystonia characterized by increased blinking and involuntary closing of the eyes. People with blepharospasm have normal vision. Visual disturbance is due solely to the forced closure of the eyelids.
Cervical dystonia or spasmodic torticollis is the most common form of dystonia that results in involuntary turning of the neck to the side or pulling it back or forward.
A focal hand dystonia which affects the fingers, the hand, and the forearm, and occurs when the person attempts to write or perform fine hand functions.
Affects the muscles of the lower face causing them to pull or contract.
Affects the muscles that control the vocal cords, making it difficult to speak.
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Primary dystonia is believed to be caused by abnormal functioning of the basal ganglia which are deep brain structures involved with the control of movement. The basal ganglia assists in initiating and regulating movement. What goes wrong in the basal ganglia is still unknown. An imbalance of dopamine, a neurotransmitter in the basal ganglia, may underlie several different forms of dystonia, but much more research needs to be done for a better understanding of the brain mechanisms involved with dystonia.
Secondary forms of dystonia arise from and can be attributed to numerous causes, such as birth injury, trauma, toxins, or stroke. Secondary dystonia can be symptomatic and can also occur in association with other disorders such as Wilson's disease. When dystonia is secondary to certain injuries or small strokes, we often find lesions (areas of damage) 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 involved in all types. See 1 & 2 below.
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1. Dystonia is a disorder that has to do with the way we move. The control of our movements is very complicated and involves many areas in the brain. The area of the brain that is involved in dystonia is called the basal ganglia. The basal ganglia is a deep region of the brain that controls the speed of movement and prevents unwanted movements. If there is a small change in the way the basal ganglia works, it can cause movements to occur even if you don't want them to. This small change is not found by medical tests or pictures of the brain on an MRI scan. Even if this deep area of the brain is not working the right way and dystonia occurs, the areas of the brain that have to do with thinking and learning work normally. Once researchers understand what the problem is in this part of the brain, they will be able to come up with ways to allow persons with dystonia to control these unwanted movements.
2. Dystonia generally develops gradually. Occasionally the dystonia may occur suddenly, as in the acute dystonic reactions related to the administration of antipsychotic drugs. These attacks most commonly affect the head and neck muscles and are usually transient and readily treatable. Some clinical features may precede the full clinical presentation of dystonia. Eye irritation, excessive sensitivity to bright light, and increased blinking may precede blepharospasm. Subtle facial or jaw spasms, difficulty chewing, changes in the cadence or pitch of speech may suggest early face, jaw, or voice dystonia. Mild jerky head movements, stiff neck, or local neck discomfort may occur in early torticollis. Cramping or fatiguing of the hands during writing, other manual activities, or walking may suggest limb dystonia. Sometimes a local dystonia may seem to arise directly following injury to a local body region.
For information on how dystonia can affect the heart and other parts of the body, whether childhood diseases such as measles can cause dystonia, or whether various medications can cause dystonia, consult the DMRF Web Site.
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The probable cause of childhood-onset and generalized dystonia?
The absence of a clear family history of dystonia does not rule out a hereditary basis for childhood-onset generalized dystonia. Explanations for this phenomenon include mild undiagnosed dystonia in family members and certain types of inheritance (autosomal recessive, X-linked recessive, reduced penetrance of autosomal dominant genes). All these may result in "skipped generations" or indeed in a completely negative family history. It is possible that breakthroughs in genetics may soon allow the diagnosis of hereditary dystonia even in families without a clear family history.
Other conditions may cause childhood-onset generalized dystonia. Some of these conditions are hereditary as well. They are discussed separately from hereditary onset generalized dystonia because they also cause other signs of neurologic dysfunction such as seizures, mental retardation, weakness, coordination, and other difficulties.
These conditions are diagnosed with various tests such as brain scanning, blood, urine, and other tests. Lastly, childhood-onset generalized dystonia may result from a brain damage resulting from head trauma, lack of brain oxygen, stroke, or exposure to toxin. Your doctor will determine to what extent testing should be performed to try to explain the occurrence of dystonia in childhood.
Why dystonia sometimes manifests itself later in life?
See the DMRF Web Site for other possible causes for dystonia.
It is quite rare to see someone "born" with dystonia, manifesting symptoms at the time of birth. Childhood-onset dystonia associated with the inherited form of dystonia begins in early childhood after a period of normal physical development and often initially involves the leg and foot. In adult-onset dystonia, the onset is typically in the 40's following decades of normal physical function. The reason for the appearance of dystonia after initial normal development and function is not known. It is thought that in some people there are external factors which may trigger the dystonia, but specific triggers have not yet been identified.
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Dystonia has a variable nature, therefore making it difficult to predict the prognosis of the disorder. Currently, no medication or therapy can prevent progression from happening. The dystonia(both general and focal forms) will usually stabilize within five years of onset, but symptoms may fluctuate- for example, stressful situations may make symptoms temporarily worse. For questions concerning this situation consult the DMRF dystonia Web-Site.
How do doctors diagnose dystonia?
At this time, there is no test to confirm diagnosis of dystonia. Instead, 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, therefore, 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.
Treatments for dystonia include drug treatment, botulinum toxin(Botox) injections and several types of surgery.
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