Abstracts

Rationale: Benign focal epileptiform discharges (BFEDs) are the hallmark of benign focal epilepsy of childhood (BFEC). Although BFEC is one of the most frequent epilepsies in childhood, reports of epileptic seizures recorded on EEG with video are rare. The objective of our study was to calculate the frequency of recorded ictal events in patients with BFEDs and to describe the clinical and electrophysiological presentation of seizures in these patients. Methods: A retrospective chart review of all patients undergoing routine EEG with video during a ten year period was performed. All records were reviewed for recorded EEG seizures. Additionally, we performed a review of the literature for all patients with recorded EEG seizures and BFEDs. Results: From among 214 patients with BFEDs, we identified five patients (2 males) with recorded EEG seizures (2.3 %). Age ranged from 6 to 16 years (median 11). Seizures started at a median age of 6 years (Range 5-9). We identified one patient with BFEC, three patients with childhood absence epilepsy (CAE) and one patient presenting with both. One patient presented with the typical phenotype of BFEC and historically unilateral clonic seizures. Recorded semiology consisted of a right clonic seizure, with associated left centro-temporal EEG seizure pattern. Three children presented with the clinical phenotype of CAE and historically staring spells. Recorded seizures consisted of typical absence seizures with associated generalized spike and wave complexes. Interictally, brief bursts of 3 Hz spike and wave complexes in addition to BFEDs were noted. One patient presented with BFEC and CAE, historically presenting with unilateral nocturnal clonic seizures, generalized tonic clonic seizures and staring seizures. Recorded seizures consisted of typical absence seizures with associated 3 Hz spike and wave seizure pattern. Interictally, generalized spikes and BFEDs were seen. Our literature review identified 25 additional patients with BFEC and recorded seizures. The seizures presented as subclinical seizures or as unilateral facial clonic, unilateral body clonic, or generalized tonic-clonic seizures. EEG recordings revealed unilateral centro-temporal ictal patterns. Furthermore, 11 patients with CAE also had BFEDs. There are also reports of 25 patients who had CAE and BFEC concomitantly or at different intervals. Conclusions: BFEC seizures are rarely recorded during routine EEGs. We only found one patient (0.4%) with seizures on routine EEG and this may be related to their typical occurrence during the early morning part of the sleep cycle, which may differ from the brief nap during routine EEGs. BFEDC and 3 Hz spike and wave complexes may be related, possibly by genetic links. The generalized epilepsy is more likely to be the clinical phenotype if only one phenotype manifests as seen in four of our patients presenting with typical absence seizures. Further investigations are needed to determine whether the actual incidence of absence seizures in BFED patients is higher than in the general population.