Dyssynergia cerebellaris myoclonica refers to a collection of rare, degenerative, neurological disorders characterized by epilepsy, cognitive impairment, myoclonus, and progressive ataxia. It is also known as dyssynergia cerebellaris progressiva, dentatorubral degeneration, or Ramsay Hunt cerebellar syndrome.

Onset of the disorder generally occurs in early adulthood, but may also occur in children. It may be inherited in an autosomal recessive pattern or may occur in someone who has no history of the disorder in his or her family. It is not known how often dyssynergia cerebellaris myoclonica occurs.

Dyssynergia cerebellaris myoclonica is caused by the impairment of a regulatory mechanism between cerebellar and brainstem nuclei and has been associated with a wide range of diseases, including:

• Lafora body disease
• Dentatorubropallidoluysian atrophy
• Celiac disease

Symptoms, which worsen over time, include:

• Seizures
• Tremor
• Reduced muscle coordination

Tremor may begin in one extremity and later spread to involve the entire voluntary muscular system. Arms are usually more affected than legs. Some of the cases are due to mitochondrial abnormalities.

The progression of the disorder is usually 10 years or longer.

There is no cure, so treatment of dyssynergia cerebellaris myoclonica is symptomatic. Myoclonus and seizures may be treated with drugs like valproate.