The clinical utility of ambulatory cassette EEG.

We obtained ambulatory EEG monitoring (A/EEG) before intensive monitoring in 33 patients newly referred to an epilepsy center. The A/EEG yield of evidence to support a diagnosis of epilepsy was 83% of that of intensive monitoring and 2.5 times that of routine EEG. Accuracy of A/EEG analysis was confirmed by two blind reviews for each tape, with only three misreadings among 99 interpretations rendered. Among 25 patients with specifically diagnostic referrals, A/EEG served the purpose of admission as well as intensive monitoring in 60%. Episodes not accompanied by A/EEG change required behavioral observation for correct identification.