Paroxysmal kinesigenic dyskinesia

Neurological disorder characterized by sudden involuntary movements

Paroxysmal kinesigenic dyskinesia (PKD) is a rare neurological disorder characterized by sudden, involuntary movements triggered by sudden voluntary movements or changes in position. These episodes are typically brief, lasting seconds to minutes, and can include dystonia, chorea, or athetosis.

Presentation

PKD usually presents in childhood or adolescence, with the onset of symptoms typically occurring between the ages of 5 and 15. The disorder is characterized by episodes of abnormal movements that are triggered by sudden movements, such as standing up quickly or starting to walk. These episodes can vary in frequency, from several times a day to only a few times a month.

The movements in PKD are often unilateral, affecting one side of the body, but can also be bilateral. Common manifestations include twisting movements, muscle contractions, and abnormal postures. The episodes are usually brief, lasting less than a minute, and are not associated with loss of consciousness.

Genetics

Autosomal dominant inheritance pattern

PKD is often inherited in an autosomal dominant pattern, meaning that a single copy of the altered gene in each cell is sufficient to cause the disorder. The most commonly associated gene with PKD is the PRRT2 gene, which encodes the proline-rich transmembrane protein 2. Mutations in this gene are found in many individuals with familial PKD.

Diagnosis

The diagnosis of PKD is primarily clinical, based on the characteristic features of the episodes and their triggers. A detailed patient history and neurological examination are essential. Genetic testing can confirm the diagnosis in cases where a mutation in the PRRT2 gene is suspected.

Other conditions that can mimic PKD, such as epilepsy or other types of paroxysmal dyskinesias, should be ruled out. Electroencephalography (EEG) and magnetic resonance imaging (MRI) may be used to exclude other neurological disorders.

Management

The management of PKD involves both non-pharmacological and pharmacological approaches. Avoidance of known triggers can help reduce the frequency of episodes. In many cases, medications such as carbamazepine or phenytoin are effective in reducing the frequency and severity of the episodes.

Prognosis

The prognosis for individuals with PKD is generally good. Many individuals experience a reduction in the frequency and severity of episodes with age, and some may even experience complete remission. The disorder does not typically lead to any long-term neurological deficits.

Related pages

• Dystonia
• Chorea
• Athetosis
• Epilepsy