Myoclonus-dystonia: classification, phenomenology, pathogenesis, and treatment

The present study will highlight recent advances in the field of myoclonus-dystonia with a focus on clinical aspects, pathogenesis, and treatment. We will also discuss genetics, classification issues, and diagnostic criteria.

Myoclonus-dystonia is a clinical syndrome corresponding to the phenotype linked to SGCE, the main causative gene. Childhood-onset myoclonus that predominates over dystonia with prominent upper body involvement, an absence of truncal dystonia, associated anxiety or compulsivity, and a positive family history are helpful diagnostic clues. Recent studies demonstrated that zonisamide is an interesting therapeutic option in myoclonus-dystonia, and that bilateral pallidal stimulation has major and lasting therapeutic effects. Accumulating evidence suggests that an alteration in cerebello-thalamic pathway function may play a prominent role and that this is possibly related to a GABAergic deficit reflecting Purkinje cell dysfunction. Impaired striatal plasticity and disturbed serotonin homeostasis may also be implicated. Newly available cellular and rodent models may further assist in investigating the pathogenesis of this disorder.

Comprehensive analysis of the phenotype and precise classification are important in patients with myoclonus and dystonia to identify homogeneous groups of patients. This is critical to guide tailored therapeutic strategies and promote effective research.