Researchers from Helios Klinikum Wuppertal, Germany, analyzed the prevalence of epileptiform discharges in digitally recorded EEG (DEEG) of 382 healthy children (226 male, 156 female) ages 6-13 years, and compared the data to those of previously published paper analog recordings. The patients referred for EEG had suffered minor head trauma without impaired consciousness or amnesia; they had no focal neurological deficits. Recordings were a minimum of 20 min and included hyperventilation and photic stimulation. Epileptiform discharges were recorded in 25 (6.5%) children; 4 had generalized or bifrontal spikes, 12 had constant localized focal discharges, and 9 showed multifocal discharges. Epileptiform discharges were “rolandic” in 16 children (4.2%). Afebrile seizures, 1 or more, occurred in 3 (12%) of the 25 children with epileptiform discharges during a median follow-up period of 4.2 years (range 1.2-7.1 years).

Comparing prevalences of epileptiform EEG discharges in healthy children, those reported in 3 previous studies were lower than the present cohort (3.5%, 3.5%, and 5%) and significantly lower in one report (p<0.005). Subgroup analysis according to age and sex also showed differences, with a higher prevalence in a male subgroup and younger age group of 6-9-year old children in the present cohort. Comparison of prevalence data in selected previous reports of children with ADHD found no significant differences with the present data obtained from healthy children. The findings indicate the need for further research, using digitally recorded EEG, but the significance of the comparative data is limited by the small number of children examined. [1]

COMMENT. In this study using digital EEG, the prevalence of epileptiform discharges recorded in “healthy” children is 6.5%, and higher than that reported in three previous studies. The authors also claim that their findings in “healthy” children are not different from those reported in studies of the EEG in children with ADHD. Several questions limit the significance of the findings: 1) Should the children be accepted as “healthy”? They were referred for EEG because of minor head trauma, and the sequelae of mild traumatic brain injuries are controversial and sometimes serious [2, 3]; 2) A proportion of the patients with epileptiform EEG discharges developed afebrile seizures and some had seizure recurrences and epilepsy. These should have been excluded from the data; 3) Of 7 previous published reports of EEG epileptiform discharges in nonepileptic children with ADHD the authors selected only 2, both with the lowest prevalence of abnormalities; 5 previous reports with significantly higher prevalences were omitted from their discussion.

In a recent study of 612 children evaluated for symptoms of ADHD complicated by episodic altered awareness, the frequency of epileptiform abnormalities in the sleep-deprived EEG was 25.7% and similar to the mean frequency for 7 published studies [4]. Our findings and previous reports are not in agreement with the current German study conclusions. The weight of evidence favors an increased prevalence of epileptiform EEGs in non-epileptic children with ADHD.

When stimulant medication is prescribed in ADHD children with abnormal EEG, a conservative dose schedule may be advisable. In a study of children with ADHD complicated by EEG rolandic spikes, seizures occurred in 16.7% following methylphenidate compared with 0.6% in a group of ADHD children with normal EEGs [5]. The safety of high-dose stimulants in children with ADHD and epileptiform EEGs untreated with antiepileptic medication is unclear. An EEG may allow the physician and parent to make an informed decision regarding risks and benefits of high-dose stimulant versus nonstimulant selection and immediate-release MPH vs extended-release formulations.

OROS-MPH (Concerta) treatment of ADHD with epilepsy. A current report of a randomized control trial of OROS-methylphenidate, 18-54 mg daily for weekly periods, in 33 patients, 6-18 years of age, taking antiepileptic drugs, found an increased daily risk of seizures with increasing dose of OROS-MPH, an extended-release medication. Potential safety concerns require further study. [6]