They are commonly classified as periodic lateralized discharges (PLDs), bilateral independent PLDs or BIPLDs, generalized periodic discharges (GPDs) and triphasic waves. Periodic electroencephalographic (EEG) patterns are frequently recorded during ICU EEG monitoring in patients with Altered Mental Status (AMS) these controversial EEG patterns consist of discharges usually epileptiform in appearance, which occur at regular intervals, in critically ill patients. *Address all correspondence to: 10.5772/intechopen.95503 From the Edited Volume Department of Neurology, Shiraz University of Medical Sciences, Iran.Department of Neurology, Thomas Jefferson University, USA.Neurology and Neurophysiology Department, The Children’s Hospital Agia Sophia, Greece.Many authors consider these patterns as an unstable state on an ictal-interictal EEG continuum the aim of the present chapter is to gain knowledge of these EEG features, show their association with known neurologic pathologies/syndromes and finally how to manage them.

The role of most (not all) of these EEG patterns is controversial there is no consensus on which patterns are associated with ongoing seizure injury, which patterns need to be treated, and how aggressively they should be treated. They are known as lateralized periodic discharges (LPDs), bilateral independent periodic discharges (BIPDS), generalized periodic discharges (GPDs), continuous 2/s GPDs with triphasic morphology or triphasic waves (TWs) and Stimulus Induced Evolving Lateralized Rhytmic delta activity or Si-Evolving LRDA (previously SIRPIDS) other periodic, rhythmic patterns are Occasional frontally predominant brief 2/s GRDA (FIRDA previously), Lateralized rhythmic delta activity (LRDA) and Brief potentially ictal rhythmic discharges or B (I)RDs. Periodic electroencephalographic (EEG) patterns are frequently recorded during ICU EEG monitoring in patients with altered mental status these EEG features represent electrical discharges, ictal in appearance, occuring at regular intervals.

Pleds eeg