Comprehensive Literature Review of EEG Findings in Focal Epilepsies: A Systematic Approach

An extensive literature review was done. Two independent researchers did a search on January 20th until May 30th, 2020. We used the following Pubmed and Medline descriptors alone and in different combinations for database searching: 'focal', 'partial', 'epilepsy', 'electroencephalographic findings', 'EEG'. Additional filters included 'review', 'original articles' and language limited to Spanish and English. All ages were included. Using the above criteria, a total of 1223 articles were collected. Although gathered by these keywords, 1063 articles did not report EEG descriptive findings in focal epilepsies and were then eliminated. Only 160 of them contained data related to EEG. Eleven manuscripts were written in a language different from English and Spanish and they were not considered in the present review. After a careful methodical revision of the remaining 149 papers’ methodology, only articles with more than 10 subjects, including a series of cases, previous reviews on different focal epileptic syndromes, ILAE task force positions regarding essential concepts and those papers that included in the method section an adequate description of electrode positions, montage, activation maneuvers, videorecording and/or electromyography electrodes were included in the present description. Only 69 articles fulfilled the above-mentioned criteria. Both researchers read the selected articles in full and analyzed them. Occasional divergence in selection was resolved by consensus.