Direct comparison of 3- and 8-channel ambulatory cassette EEG with intensive inpatient monitoring.

During the intensive monitoring of 30 patients by means of cable telemetry EEG, simultaneous 3- and 8-channel ambulatory EEG recordings were also obtained. Blinded interpretations of the cassette tapes were compared with those of the cable telemetry records. Both 3- and 8-channel ambulatory EEG reviews correctly identified 93% of the records as either normal or epileptiform. Lateralization of abnormalities was equally good with either cassette system, but more detailed characterization was achieved with 8-channel ambulatory EEG. Although 100% of seizures were detected on both systems, there were more false-positive errors when only three data channels were available. Better ability to differentiate renal abnormalities from artifacts was the most significant advantage of 8-channel over 3- to 4-channel ambulatory EEG.