DYT 11 Myoclonus-Dystonia Syndrome (MDS) with generalized epileptic discharges

We report on an 11 year old boy with a mutation in the Epsilon-Sarcoglycan (SGCE) gene associated with familial DYT 11 myoclonus-dystonia syndrome (MDS). At the age of 2 years he initially presented with a movement disorder by gait disturbance with inward rotation of both legs. Adiotionally the patient suffered from multifocal myoclonus affecting both arms, the upper part of the body and the head with a frequency of 100 a day over a period of 10 seconds remaining difficulties with eating and writing from the age of 6 years. In the absence of myoclonus or long repetitive jerks continous EEG videomonitoring showed epileptic activity: generalized (maximum electrode F4 and F3, 55%), left frontal (maximum electrode F3, 30%), right frontal (maximum electrode F4, 12,5%) and right parietal (maximum electrode P8, 2,5%). Meanwhile, epileptic EEG-activity during myoclonus was not seen.

Up to date Myoclonus in DYT 11 MDS seems to be generated at subcortical level, and possibly involves basal ganglia and brainstem circuits. EEG discharges were likely to be exclusion criteria for the diagnosis of DYT 11 MDS. However, in this patient epileptic discharges have to be regarded as a matter of coincidence.