Early-onset absence epilepsy and paroxysmal dyskinesia

To report on the association of childhood absence epilepsy and paroxysmal dyskinesia (PD).

We describe six patients aged 6 to 27 years (mean, 14 years) who were identified in five centers participating in a European study group. Patients had been followed up clinically from the first symptoms and had been studied with video-EEG recordings of absence seizures, videotaping of dyskinetic attacks, and brain magnetic resonance imaging (MRI).

Four patients were sporadic, and two were siblings. Age at onset of absence seizures was unusually early (range, 3 months to 3 years 6 months; mean, 16 months), with four children having their first episodes within the first year of life, and the remaining two by age 3 years 6 months. Resistance to multiple appropriate drugs was seen in five children, in four of whom absences improved remarkably when ethosuximide was added. Absences remitted between age 8 and 13 years in the three patients in whom follow-up was long enough. Different types of PD were seen including paroxysmal kinesigenic dyskinesia (one patient), paroxysmal exercise-induced dystonia (three patients), and paroxysmal tonic upgaze (two siblings). In most patients, PD appeared at a later age than, co-occurred with, and outlasted absence seizures. Only in the two siblings with tonic upgaze, dyskinetic attacks had an earlier onset. PD improved with increasing age and did not usually produce severe disability.

There is a widening spectrum of epilepsy and PD syndromes, within which epilepsy has the characteristics of the common idiopathic syndromes, with some atypical features.