Rarely are the face and legs affected. The dystonic symptoms of prolonged muscle spasms or abnormal posture may also be present. The age of onset is in the first or second decade of life, although some cases of adult-onset have been reported. Back to top Cause Myoclonic dystonia is often a familial disorder seen in successive generations. The mode of inheritance is autosomal dominant with a high, but incomplete penetrance and variable severity.
Research continues to map and identify the gene or genes responsible for the disorder.
Back to top Diagnosis Diagnosis of myoclonic dystonia is based on family history from the affected individual and the physical and neurological examination. Experts in the movement disorder field are aware of the different diagnoses, and debate continues as to whether all classifications may be an expression of a single genetic disorder. The course of the myoclonic dystonia is benign in the majority of cases. Most frequently, the disorder appears to be slowly progressive for a few years after onset, stabilizes, then fluctuates slightly over the years, or shows a mild, spontaneous improvement. If myolconic dystonia causes any type of impairment, it is because the symptoms are interfering with normal function.