EEG normal variants: A prospective study using the SCORE system

• Published in: Clinical neurophysiology practice 2022-01, Vol.7, p.183-200
• Main Authors: Wüstenhagen, Stephan, Terney, Daniella, Gardella, Elena, Meritam Larsen, Pirgit, Rømer, Connie, Aurlien, Harald, Beniczky, Sándor
• Format: Article
• Language: English
• Subjects: Benign epileptiform variants; EEG; Epilepsy; Normal variant; Research Paper
• ISSN: 2467-981X; 2467-981X
• DOI: 10.1016/j.cnp.2022.06.001

•We analyzed the number of normal variants in a SCORE database of 3050 EEG recordings.•The most common normal variant was sharp transients.•We present typical examples and detailed characterization of the normal variants. To determine the prevalence and characteristics of normal variants in EEG recordings in a large cohort, and provide readers with typical examples of all normal variants for educational purposes. Using the SCORE EEG system (Standardized Computer-Based Organized Reporting of EEG), we prospectively extracted EEG features in consecutive patients. In this dataset, we analyzed 3050 recordings from 2319 patients (mean age 38.5 years; range: 1–89 years). The distribution of the normal variants was as follows: sharp transients 19.21% (including wicket spikes), rhythmic temporal theta of drowsiness 6.03%, temporal slowing of the old 2.89%, slow fused transients 2.59%, 14-and 6-Hz bursts 1.83%, breach rhythm 1.25%, small sharp spikes 1.05%, 6-Hz spike and slow wave 0.69% and SREDA 0.03%. The most prevalent normal variants are the sharp transients, which must not be over-read as epileptiform discharges. EEG readers must be familiar with the normal variants to avoid misdiagnosis and misclassification of patients referred to clinical EEG recordings.