Prevalence of benign epileptiform variants
Balagopal Santoshkumar1, Jaron J R Chong, Warren T Blume
1Epilepsy Programme, London Health Sciences Centre, B10-108, 339 Windermere Rd, London, Ont., Canada N6A 5A5.
Summary
Benign epileptiform variants (BEVs) are uncommon EEG findings, identified in 3.4% of subjects. Accurate identification of these non-epileptic patterns is crucial to prevent misdiagnosis and unnecessary investigations for epilepsy.
Area of Science:
- Neurology
- Clinical Neurophysiology
Background:
- Electroencephalography (EEG) reveals numerous patterns that mimic epileptiform activity but are not associated with epilepsy.
- Benign epileptiform variants (BEVs) are a category of such non-epileptic EEG findings.
Purpose of the Study:
- To determine the prevalence of various benign epileptiform variants (BEVs) in a large cohort undergoing routine EEG.
- To assess the frequency of specific BEVs over a 35-year period.
Main Methods:
- Retrospective analysis of 35,249 outpatient EEG recordings from January 1, 1972, to December 31, 2007.
- Utilized standardized definitions from the International Federation of Societies for EEG and Clinical Neurophysiology (IFSECN) and established criteria for categorizing BEVs.
Main Results:
- BEVs were identified in 1183 out of 35,249 subjects, representing a prevalence of 3.4%.
- The prevalence of specific BEVs included: benign sporadic sleep spikes (1.85%), 6 Hz spike-and-waves (1.02%), 14 and 6 Hz positive spikes (0.52%), rhythmic temporal theta bursts of drowsiness (0.12%), subclinical rhythmic electrographic discharge of adults (0.07%), and wicket waves (0.03%).
Conclusions:
- The prevalence of these six BEVs in Canadian subjects was found to be relatively low compared to international reports.
- BEVs are infrequent incidental findings on EEG and do not predict epilepsy, underscoring the importance of accurate identification to avoid misdiagnosis and unnecessary patient management.
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