Dystonia is a Movement Disorder
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Identifying the types of movements associated with PD is complicated. These movements may be dystonic, choreic, ballistic, or a combination. An individual may show one specific type of movement or a combination of movements.
Dystonic movements are typically patterned and repetitive, causing twisting movements and abnormal postures. Dystonia occurs when opposing muscles are contracting simultaneously. The activation of these muscles may “overflow” to other muscle groups unintentionally.
Ballistic movements are more severe limb movements that involve portions of the limb such as the shoulder and elbow, and hip and knee.
Choreic movements may be described as brief, rapid, involuntary movements that serve no purpose. When mild, choreic movements may resemble fidgeting.
Athetoid movements are slower and more continuous than chorea with a writhing quality. They especially involve the hands and may also affect the torso and other parts of the body.
When chorea and athetosis occur simultaneously, the term choreoathetosis has been used. Choreoathetosis may coexist with dystonia or occur independently.
Paroxysmal dyskinesias may be inherited or acquired by secondary causes.
Several genes have been associated with paroxysmal dyskinesias, including PRRT2, SLC2A1 and PNKD
Paroxysmal dyskinesias may be secondary to multiple sclerosis, cerebral palsy, metabolic disorders, physical trauma, cerebrovascular disease, and miscellaneous conditions including supranuclear palsy and AIDS.
Paroxysmal dyskinesias have also been associated with encephalitis and injury to the brain due to stroke and tumors. Drugs such as cocaine and dopamine blocking agents may also induce dyskinesias.
In some cases, paroxysmal dyskinesias may be a manifestation of a functional movement disorder. Only a qualified movement disorder specialist and/or psychiatrist (preferably a team of multiple specialists that includes both) should make such a diagnosis. Unfortunately, authentic cases of paroxysmal dyskinesias have often been inappropriately misdiagnosed as psychogenic.
A detailed patient history and (ideally) video documentation of the attacks are important tools toward diagnosing paroxysmal dyskinesias. The work-up for diagnosing paroxysmal dyskinesias may also include an electroencephalogram (a test to measure brain waves), brain imaging (such as MRI or CT scan), blood chemistries, and calcium tests.
The paroxysmal dyskinesias are currently classified into three types:
Paroxysmal Kinesigenic Dyskinesia (PKD) may be inherited, meaning that it is passed genetically from a parent or ancestor. Inherited PKD is an autosomal dominant disorder. (The term “autosomal dominant” indicates that only one parent need have the PKD gene in order for a child to inherit the disorder.) The age of onset in inherited cases of PKD is from five to fifteen years. PKD may also occur sporadically, meaning that symptoms manifest without a family history. The age of onset in sporadic cases is variable. In both cases the attacks, which may occur up to 100 times per day, are often precipitated by a startle, a sudden movement, a particular movement, or other factors. The attacks are usually short, lasting seconds or minutes. The symptoms may be preceded by an unusual sensation in the limbs and may be limited to one side of the body or a single limb. Most people with PKD have dystonia, and some have a combination of chorea and dystonia or ballism.
Paroxysmal Nonkinesigenic Dyskinesia (PNKD) is also inherited in an autosomal dominant fashion. The age of onset is usually between early childhood and early adulthood. The frequency of attacks is less than that of PKD, averaging between three per day to two per year. Fatigue, alcohol, caffeine, excitement, and other factors may trigger symptoms. The attacks generally last between a few seconds and four hours or longer. The attacks may begin in one limb and spread throughout the body, including the face. A person affected by PNKD may not be able to communicate during an attack but remains conscious and continues to breathe normally.
Paroxysmal Exertion-induced Dyskinesia (PED). Both inherited and sporadic cases of PED have been reported. The attacks are triggered by prolonged exercise and may last between five to thirty minutes. The attacks may occur once a day or twice a month.
A miscellaneous episodic dystonic condition is benign paroxysmal torticollis of infancy, which typically begins in the few months after birth. These attacks may occur once every two or three weeks and last from hours to days. Typically, the head and/or trunk tilt to one or the other side. These symptoms are often treated with specific physical therapy and disappear when the child is between one and five years old.
Treatment for paroxysmal dyskinesias must be tailored to the individual, and it may be necessary to try several options before symptoms are diminished or alleviated. Patience on the part of both physician and patient is important.
Oral medications are often a mainstay of treatment.
People with paroxysmal kinesigenic dyskinesia (PKD) generally respond well to anticonvulsant agents such as phenytoin, primidone, valporate, carbamazepine, phenobarbital, and diazepam. Other drugs that may be helpful include anticholinergics, levodopa, flunarizine, and tetrabenazine. Haloperidol has given inconsistent results.
Paroxysmal nonkinesigenic dyskinesia (PNKD) may respond to clonazepam, haloperidol, alternate day oxazepam, and anticholinergics. Anticonvulsants are ineffective in most cases. Trying to avoid triggering factors such as alcohol and caffeine is important.
There are a few cases of paroxysmal exertion-induced dyskinesia (PED) that improve with levodopa and acetazolamide, but drug treatment is ineffective for the most part. Avoidance of prolonged exercise may reduce frequency of attacks.
Paroxysmal dyskinesias associated with multiple sclerosis tends to respond well to anticonvulsants. Acetazolamide may be a helpful alternative or adjunct agent to anticonvulsants. PD due to head injury may improve with anticonvulsant medications or a combination of anticonvulsants and trihexyphenidyl. Underlying conditions need to be addressed in other cases of secondary PD.