Are there generalised spike waves and typical absences in benign rolandic epilepsy?

Generalised 3 Hz spike wave (SW) discharges with or without absences have been described in children with benign epilepsy with centrotemporal spikes (BECTS), leading to speculations about a continuum between childhood absence epilepsy (CAE) and BECTS. We thus decided to evaluate the prevalence of absence seizures (AS) and generalised 3 Hz SW in patients with BECTS. All patients with BECTS first referred since 1986 have been identified prospectively. Their medical and electroencephalograph (EEG) records were analysed retrospectively, in the search for AS and generalised SW discharges. Over a period of 11 years, we found typical rolandic spikes in 66 newly referred patients; 64 had seizures typical for the condition (18 female, 46 male), two were asymptomatic and were not further analysed. All had routine waking EEG recordings, and 49 children (76%) had at least one sleep EEG. AS or classical generalised 3 Hz SW were never recorded from history or EEG data, respectively. However, 17 patients had some diffuse SW discharges, lasting 1-5 s, which appeared as grossly symmetrical in only seven children, with a clearly asymmetrical aspect in the others. Among these seven patients, the discharges were only seen on awakening in one, both during waking and nREM sleep stage I or II in one and only during nREM sleep stage I or II in five. They were apparently subclinical in all. We thus found neither AS nor classical 3 Hz SW discharges among 64 consecutive patients with BECTS. Brief bursts of bilateral abnormalities occur in about 25% of the cases, mostly with sleepiness. Such findings do not substantiate the existence of a continuum between CAE and BECTS.