Retrospective study with long-term clinical follow-up of a cohort of patients with benign epileptiform variants on EEG.

INTRODUCTION Benign epileptiform variants (BEV) are uncommon epileptiform-like EEG graphoelements that do not meet diagnostic criteria for epileptiform or pathological discharges. The clinical significance of some subtypes remains uncertain.

Methods

We conducted a single-centre, retrospective, observational study of 57 408 EEG recordings from 32 349 patients who were followed up for more than one year. We determined the prevalence of each BEV and compared the presence of epilepsy at baseline and at the end of follow-up.

Results

BEV were identified in 192 patients (287 EEG recordings), yielding a prevalence of 0.58% in the total cohort and 1.26% among patients with otherwise normal EEG recordings (n = 15 172). Diagnosis of epilepsy was observed in 39% of patients with BEV at baseline and 35% of patients with BEV after a mean follow-up of 7.4 years. In subtype-based analyses, the 6-Hz spike-and-wave bursts subtype was significantly associated with a higher prevalence of epilepsy at baseline (OR: 12.3; 95% CI, 1.47-103.2; P =  .021), and the small sharp spikes variant was associated with a higher prevalence of focal epilepsy at the end of follow-up (OR: 3.05; 95% CI, 1.43-6.50; P =  .004), as compared to other BEV. In contrast, wicket spikes were associated with a lower presence of epilepsy (OR: 0.31; 95% CI, 0.13-0.72; P =  .007) than other BEV.

Conclusions

BEV are infrequent, heterogeneous EEG findings. Correct recognition, particularly of wicket spikes, may prevent overdiagnosis and unnecessary treatment. Overall, they lack pathological significance, although 6-Hz spike-and-wave bursts and small sharp spikes showed a stronger association with epilepsy and may be considered variants of uncertain significance warranting clinical follow-up.