https://www.acns.org/UserFiles/file/ACNSStandardizedCriticalCareEEGTerminology_rev2021.pdf
Yamada, Thoru, and Elizabeth Meng. Practical Guide for Clinical Neurophysiologic Testing: EEG. Available from: Wolters Kluwer, (2nd Edition). Wolters Kluwer Health, 2017. Greenfield, John, L. et al. Reading EEGs: A Practical Approach. Available from: Wolters Kluwer, (2nd Edition). Wolters Kluwer Health, 2020.
GPDs are bisynchronous, high-amplitude discharges, reoccurring periodically or pseudo periodically for at least 50% of the EEG. Periodic discharges, either generalized (GPD*) or lateralized (PLED/LPD*) are common EEG patterns seen in CCEEG in an ICU setting and clinically most patients are clinically stuporous or comatose. GPD*s can take a variety of waveforms from rhythmic delta, triphasic waves to frank spike-wave discharges. The most common cause for this pattern is an anoxic brain injury.
GPDs can be associated with focal and generalized seizures as well as nonconvulsive status epilepticus (NCSE at approx 20%). GPDs associated with plus features (superimposed fast or rhythmic delta activity) or higher frequency (>1.5 Hz) are more strongly associated with seizures.
