Dystonia
is characterized by painful, prolonged muscle contractions that cause
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. The severity varies from person to person.
Many people who have dystonia can maintain a relatively normal lifestyle. Others
may need full-time assistance. Dystonia is the third most common movement
disorder, affecting an estimated 500,000 adults and children in North America.
What causes dystonia?
What is the relationship between
Parkinson’s and dystonia?
What are the other types of
dystonia?
What treatments exist for dystonia?
What therapies are in development
for dystonia?
Where can I learn more about
dystonia?
What
causes dystonia?
Dystonia
likely results from dysfunction of a related brain region affected in
parkinsonism, the basal ganglia, although the ultimate cause is not
known. Further research is necessary to determine the various genetic,
environmental or other underlying mechanisms that may play a role in causing
dystonia.
Dystonia
is a prominent symptom for people with Parkinson’s who have a mutation in the
Parkin gene — one of a handful of Parkinson’s-implicated genes — though more
research is needed to understand why this is the case.
What
is the relationship between Parkinson’s and dystonia?
Dystonia
and Parkinson’s disease (or parkinsonism) are movement disorders that are
closely related. Parkinsonism is a term used to describe any clinical
presentation that manifests in the cardinal symptoms of Parkinson’s disease
(tremor, rigidity and slowness of movement).
Some
experts estimate that forty percent of people living with Parkinson's disease
experience dystonia as an early symptom or as a complication of
treatment. Some forms of dystonia (see below) are characterized by
parkinsonism, and other neurodegenerative disorders, such as Wilson's disease,
may have symptoms of both dystonia and parkinsonism.
What
are the other types of dystonia?
There
are two main categories 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.
Among forms of primary dystonia, the most common (and the most debilitating) is
generalized dystonia, which affects the legs or one leg and the trunk, plus
other regions, most commonly the arms.
Outside
the context of Parkinson’s disease, there are several other types of secondary
dystonia, in which other symptoms are also present. In this category are:
Myoclonus dystonia, characterized by
dystonia and myoclonus (rapid, lightning-like muscle movements), with onset in
childhood or adolescence.
Dopa-responsive dystonia, a genetic
disorder of childhood onset and may have features of parkinsonism or
exaggerated reflex responses.
Rapid-onset dystonia parkinsonism, a
rare inherited disorder characterized by sudden development of dystonia and
parkinsonism.
Paroxysmal dystonia, neurological
conditions characterized by discrete and sudden episodes of involuntary
movements.
Secondary
dystonia may also be triggered by trauma to the head or a specific area of the
body, drug use or exposure to rare toxins.
As
in Parkinson's disease, dystonia can be present in other neurological disorders
including:
Wilson's disease, a rare genetic
disorder in which copper accumulates in the organs.
Huntington's disease, a hereditary
progressive neurodegenerative disorder.
Spinocerebellar ataxias, a group of
progressive degenerative inherited conditions.
Methymalonic aciduria, an inherited
disorder of metabolism.
What
treatments exist for dystonia?
Dystonia
and Parkinson’s share common forms of treatment. Anticholinergic
medications (such as trihexyphenidyl or benztropin) and levodopa
may improve both conditions (though dystonia, like other Parkinson’s symptoms,
can return or worsen as levodopa wears off and loses efficacy with long-term
use). And deep brain stimulation (DBS) is a surgical treatment for both,
although the stimulation target in the brain may be different.
Other
medications such as muscle relaxants or antispastic agents may also treat
dystonia. In addition, physicians may prescribe botulinum toxin injections.
When a small amount of commercially prepared botulinum toxin is selectively
injected in overactive muscles, it causes a change in the muscle firing,
calming the abnormal movements for up to several months at a time.
Physical
therapy may be helpful as a supplement to other therapies. Many patients report
beneficial effects from complimentary therapies such as yoga, tai chi and
meditation, although rigorous studies evaluating their efficacy are lacking.
What
therapies are in development for dystonia?
For
dystonia with Parkinson’s disease, researchers are working on better levodopa
delivery. Optimizing the current standard of treatment to work more reliably
and last longer would help treat dystonia related to Parkinson’s and avoid the
medication wearing off and symptoms returning.
Read more
about Parkinson’s therapies in development, including those targeting better
levodopa delivery.
Where
can I learn more about dystonia?
For more information, and a
list of groups exclusively focused on dystonia (including pediatric dystonia),
visit the Dystonias
Information Page of the National Institute of Neurological
Disorders and Stroke (part of the National Institutes of Health).
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