What is Dystonia?
Dystonia causes involuntary repetitive twisting and sustained muscle contractions. These result in abnormal movements and postures. The symptoms usually begin in one body region, such as the neck, face, vocal cords, an arm or a leg, and then may spread to other parts of the body. When dystonia affects children, it often starts in a leg before spreading to other limbs and trunk. In adults, dystonia tends to remain localized to a body region and frequently affects first the upper body.
Dystonia usually occurs or worsens during voluntary movement. It may also happen with movement of other unaffected body regions or when the affected body part is at rest. Dystonia may lead to sustained fixed postures potentially causing permanent contractures. The symptoms of dystonia typically increase during stress, emotional upset or fatigue, and decrease during rest and sleep. Many people living with dystonia can temporarily suppress their symptoms by using “sensory tricks”. These are a unique feature of dystonia, consistent of touching the affected or an adjacent body part to decrease the pulling or posturing.
Please visit our FAQs page if you have questions regarding the symptoms of dystonia.
Dystonia may be an inherited condition caused by genetic mutations. It can also result from exposure to certain drugs, birth injuries, strokes, or as a symptom of other neurological disorders. For many patients, however, the cause remains unknown. There are two main categories of causes of dystonia: primary and secondary (or non-primary).
Primary dystonia is a condition in which dystonia is the only clinical feature. There is no evidence of cell death or a known cause. It is also known as idiopathic torsion dystonia. Primary dystonia is thought to have greater genetic contribution, even in the absence of a family history of dystonia. Several mutations have been identified in genes that are responsible for many cases of primary dystonia. The two most common and important genes associated with primary dystonia are DYT1 and DYT6. Most genetic forms of dystonia start with symptoms in childhood or adolescence. The DYT1 gene regulates the production of the torsinA protein. Mutations in this gene are associated with most cases of early-onset limb-onset primary dystonia and it is most common in individuals of North European Ashkenazi Jewish descent. The DYT6 gene was initially described in Mennonite families with generalized dystonia. This gene codes for the THAP1 protein. Mutations of this gene are associated with childhood and adult onset dystonia, usually affecting limbs and cervical and cranial muscles. Both DYT1 and DYT6 forms of dystonia tend to progress initially to involve multiple body regions. How mutations in these genes lead to dystonia is not yet well understood. Commercial tests are available to determine if these genes are affected in individuals. However, for the majority of people living with primary dystonia, the cause remains unknown.
- Myoclonus Dystonia, characterized by variable combinations of dystonia and myoclonus (marked, rapid, lightning-like muscle movements), with onset in childhood or adolescence. Myoclonus is often the most prominent feature, and tends to occur or worsen with voluntary movement. Its course is relatively benign with stabilization of symptoms after a few years. It is a hereditary condition and has been associated with mutations in the epsilon sarcoglycan gene (SCGE).
- Dopa-responsive Dystonia (DRD) is a genetic disorder of childhood onset. It affects girls more commonly than boys. Children affected by DRD had onset of dystonia affecting usually the legs initially and many may have features of parkinsonism or exaggerated reflex responses. The symptoms generally become more severe as the day progresses and are worse at night. Their symptoms dramatically and characteristically improve with low-dose levodopa, and amino acid that is a precursor of the neurotransmitter dopamine. It has been associated with mutations in the guanosine triphosphate (GTP) cyclohydrolase I (GHC1 or DYT5) gene.
- Rapid-onset Dystonia Parkinsonism (RDP) is a rare inherited disorder with onset in childhood or adulthood. It is characterized by sudden development over hours, days or weeks of a combination of dystonia and parkinsonism. The symptoms may in some cases develop after certain stressful events. Affected individuals may have abnormally low levels of homovanillic acid (HVA) in their spinal fluid. It has been linked to mutations in the ATP1A3 gene.
- Wilson’s Disease is a rare genetic disorder of copper metabolism, in which copper accumulates first in the liver, and eventually in other organs, including the brain. Its neurological manifestations may include dystonia, parkinsonism and tremor.
- Huntington’s Disease, also known as Huntington’s chorea is a hereditary progressive neurodegenerative disorder that results in behavioral and psychiatric abnormalities, cognitive decline and abnormal movements. While chorea is the most common involuntary movement in this condition (rapid irregular random jerky movements that may affect face, arm, legs or trunk), dystonia and parkinsonism may also be present.
- Spinocerebellar Ataxias are a group of progressive degenerative inherited conditions characterized by slowly progressive incoordination of hands, speech, eye movements and gait (called ataxia, from Greek “not ordered”). Onset may be at any age. Other symptoms may include frequently dystonia. Frequently, atrophy of the cerebellum occurs.
- Methymalonic Aciduria is an inherited disorder of metabolism. Neurological symptoms typically manifest during the first years of life and include generalize dystonia, difficulty swallowing and speaking and different degrees of paralysis.
- Parkinson’s disease caused by Parkin mutations. Among the several genes that are known to cause PD (accounting nonetheless for a small minority of patients), one of the most important is a gene called Parkin. This gene creates a protein that helps break down proteins inside brain cells, and when mutated, this function is impaired, leading to neuronal death. PD patients with Parkin mutations present very similarly to sporadic or non-genetic PD, but those patients tend to have a younger onset of disease (less than 40) and to have prominent foot, hand and neck dystonia as symptoms.
- Paroxysmal dystonia (also called paroxysmal dyskinesias) are neurological conditions characterized by discreet and sudden episodes of involuntary movements that may include dystonia or faster randomly irregular movements (chorea) and flailing movements of a limb (ballismus). The abnormal movements appear in a sudden and unpredictable manner with rapid return to normal function. They are classified based on precipitating factors into paroxysmal kinesigenic dyskinesia (PKD) and paroxysmal non-kinesigenic dyskinesia (PNKD). In PKD, the abnormal movements are provoked by sudden voluntary movement or startle. In PNKD, the attacks may occur spontaneously or be triggered by alcohol or caffeine. Genetic abnormalities have been recently linked to these conditions.
Age of onset
The age at onset is an important indicator of whether the dystonia is more likely to spread to other body regions. Early onset dystonia refers to dystonia that develops before age 21. The younger the patient at dystonia onset, the higher the likelihood that the dystonia may involve other areas. Late-onset dystonia begins after age 21. In patients with primary late-onset dystonia, the dystonia often begins in the upper body, such as the neck, head, neck, or an arm. Regions of the body Generalized Dystonia: is the most widespread form of dystonia; it affects the legs or one leg and the trunk, plus other regions, most commonly the arms. Focal Dystonia: involves only one region of the body, such as the neck, vocal cords or hand. Hemidystonia: affects one half of the body. Segmental Dystonia: affects two or more adjacent body regions, such as the neck and an arm. Multifocal Dystonia: affects two or more distant regions of the body, such as the upper face and the hand.
Focal dystonia is a form of dystonia that is limited to one area of the body.
Commonly described forms of focal dystonia include:
Blepharospasm: is characterized by intermittent or sustained eyelid closure. It is caused by involuntary contractions of the muscles around the eyes. It leads to excessive blinking and spasms of eye closure.
Oromandibular Dystonia: or Meige’s syndrome, affects the lower facial and jaw muscles causing involuntary opening, closing or deviation of the jaw. The tongue may be also involved.
Cervical Dystonia: also called spasmodic torticollis or ST, affects the neck muscles leading to abnormal movements of the neck and head. It is the most common form of focal dystonia.
Laryngeal Dystonia: or spasmodic dysphonia affects the vocal cords. There are two forms of laryngeal dystonia. Adductor dysphonia, which is the most common form, causes the voice to have a restricted, strangled or hoarse quality. Abductor dysphonia leads to a breathy, whispering voice.
Limb Dystonia: affects the legs, feet, arms or hands. Upper limb dystonia often appears only when performing a specific task, such as writing (Writer’s Cramp). Other task-specific or occupational dystonias include musician’s dystonia and “the yips” that affect golfers. Highly repetitive and extreme motor precision in music performance are tasks capable of inducing focal action limb dystonia. Muscian’s dystonia can occur in professional musicians using almost any kind of instrument but are more common in piano players.
Dystonia is usually diagnosed by a movement disorder neurologist. Proper diagnosis will be contingent on results from a thorough patient history, a careful family history, and complete physical and neurological examinations. Laboratory tests, imaging studies, and even genetic testing may be necessary to reach a diagnosis. Unfortunately, it is common for dystonia to be misdiagnosed or to remain undiagnosed when symptoms are mild. Many physicians are still unfamiliar with the disease. More education is needed to better inform the medical community about the symptoms associated with dystonia, and how to provide proper treatment.
Please visit our FAQs page is you have further questions about the diagnosis process for dystonia.
The treatment depends on the cause of the dystonia. Treating the underlying condition in cases of secondary dystonia may improve the symptoms. There are three approaches to the treatment of dystonia, depending on the region of the body affected and the severity of the symptoms: medications, botulinum toxin injections and surgery. Physical therapy may be helpful as a supplement to other therapies.
Botulinum toxin injections:
Botulinum toxin injections are the treatments of choice for most forms of focal dystonia. The toxin is produced by the bacterium that causes botulism. When a small amount of commercially prepared toxin is selectively injected in the overactive muscles, it causes a change in the muscle firing, calming the abnormal movements for up to several months at a time.
Segmental, multifocal and generalized dystonia are usually treated with oral medications. These include anticholinergic drugs (trihexyphenidyl or Artane®, benztropine or Cogentin®) and muscle relaxants or antispastic agents (diazepam or Valium®, clonazepam or Klonopin®, baclofen or Lioresal®). In addition, specific forms of dystonia can respond to particular medications. For example, dopa-responsive-dystonia is treated with levodopa (Sinemet®).
Patients with widespread or severe debilitating dystonia can benefit from surgery if they are unresponsive to other treatments. The most widely used current surgical approach is called deep brain stimulation, or DBS. In this surgery, thin electrodes are implanted into a part of the basal ganglia called the globus pallidus and are attached to a pacemaker-like device implanted in the chest wall. These electrodes deliver controlled electrical pulses that can have a marked improvement of dystonia symptoms, especially for patients with generalized primary dystonia. Please visit our FAQs page to find out more information about surgical treatments such as DBS.
Adjuvant therapy is an important component in the treatment of dystonia. Regular daily stretching exercises are a vital component to maintaining mobility, range of motion and flexibility. Physical therapy plays an important role in patients with cervical dystonia, usually as a supplement to other therapies such as botulinum toxin injections. Braces and other orthotics may be helpful for some patients by taking advantage of “sensory tricks” that involve touching a particular part of the body to relieve symptoms. Biofeedback techniques have been studied as adjuvant therapies in dystonia, although long-term benefits have not been shown. Many patients report beneficial effects and symptom relief from other complimentary therapies such as yoga, tai chi and meditation techniques, although rigorous studies evaluating their efficacy are lacking.
Although remarkable progress has been made in the study of dystonia in the last few years, there is not a known cure for it yet. Dystonia affects more people than Muscular Dystrophy, Huntington’s disease or Lou Gehrig’s disease combined, yet awareness of dystonia is limited. More research, treatments and education about its diagnosis are needed before a cure can be found.
Check out the current research being done for dystonia that is bringing us closer to a cure on our "Current Research Highlights & Stories" page.
Dystonia and Parkinson's Disease (PD) are movement disorders that are closely related. First, both conditions can occur together in certain diseases. People living with PD may experience dystonia as an early symptom or as a complication of treatment. Dopa-responsive dystonia and rapid-onset-dystonia-parkinsonism are hereditary forms of dystonia in which PD is often also present. Other neurodegenerative disorders, such as Wilson’s disease, may have both dystonia and PD, in conjunction to other clinical features. Second, dystonia and PD share common treatments. Anticholinergic medications and levodopa may ameliorate both conditions, and DBS is a surgical alternative for both, although the final brain target may vary. Lastly, PD and dystonia are thought to result from dysfunction of the basal ganglia and their output, although the ultimate cause of the disorders is not known. Further research is necessary to determine the various underlying genetic, environmental, or other underlying mechanisms that may play a role in causing these two related disorders.
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