Electroencephalographic correlate of juvenile Huntington's disease.

The spectrum of clinical disease in juvenile Huntington's disease differs from that seen in adults. Younger patients often present with seizures, dystonia and rigidity. The mechanism and type of seizures, timing of onset and electrographic features have not been well characterized in either adults or children. We describe the electroencephalographic findings observed in a young child with Huntington's disease who presented with motor regression and seizures. Recordings demonstrated bilateral posterior quadrant epileptiform discharges and occipital intermittent rhythmic delta activity, generally considered a nonspecific abnormality. These findings have not been reported in adult or juvenile Huntington's disease. Its presence in proximity to bilateral posterior spikes suggests that occipital intermittent rhythmic delta activity is an epileptiform abnormality, on a continuum with the posterior spike-and-wave discharges. Intermittent rhythmic delta activity can occur secondary to either the subcortical gray-matter disease or the associated seizure disorder. Huntington's disease should be considered in the differential diagnosis of young children who present with seizures and developmental regression.