Abstracts

Rationale: Adolescents may have an EEG study for indications other than high suspicion of seizure. In such instances, interictal epileptiform discharges (IEDs) may be an incidental benign finding that is mistakenly interpreted as suggestive of epilepsy. Knowing the pre-test probability of IEDs in healthy adolescents with no history of seizure would aid in determining the clinical significance of such discharges in EEG studies of adolescent patients with low suspicion for seizure or epilepsy. Methods: 11 and 12 year old 6th grade students (n=140) with no history of seizure, or neurologic or psychiatric disease were enrolled in a longitudinal physical activity intervention study. Each subject had two research EEGs, approximately 6 months apart, recorded with standard International 10-20 system electrodes. The 18 minute studies were recorded in the waking and occasionally drowsy states with equal intervals of eyes open and eyes closed. Results: Epileptiform discharges were present in 4 (2.9%) subjects: centrotemporal in 3 and generalized in 1. In three children the discharges were still present six months later. These 7 EEGs were otherwise normal, i.e. there was no pathologic slowing other than that associated with the actual IEDs. None of the children had developed seizures a minimum of one year after the second EEG. Conclusions: Our study indicates that about 3% of healthy 11 & 12 year old children with no history of seizure or neurologic disease have incidental Rolandic or generalized IEDs. These data are remarkably consistent with the findings of two landmark studies performed decades ago, both prior to the modern era of digital EEG. These also examined EEG findings in children screened to be free of neurologic or psychiatric disease or symptoms. Eeg-Olofsson et al. recorded 8-channel EEGs on 743 Scandinavian children aged 1 to 15 years. Definite IEDs were reported in 14 (1.9%), and equivocal "spike-like" activity in an additional 0.5%. In 9 of the 14 children with definite IEDs the discharges were central or centrotemporal, and of the 104 11 & 12 year old children, 3 (2.9%) had IEDs, all in the central region. Cavazutti et al. recorded EEGs (unspecified number of electrodes) in 3,726 Italian children aged 6 - 13 years. IEDs were reported in 3.5% of the entire group, as well as in 9 (2%) of the 442 11 and 12 year old children. Thus, in a young adolescent patient without a clinical history suggestive of epilepsy, the presence Rolandic or generalized epileptiform discharges in the absence of pathologic slowing is likely to be an incidental and benign finding that warrants neither further diagnostic studies nor an epilepsy diagnosis. Focal IEDs that are not Rolandic are extremely rare in healthy young adolescents, and if found incidentally should prompt an appropriate diagnostic evaluation. Funding: None