Generalized periodic discharges with triphasic morphology

Abstract

Generalized periodic discharges (GPDs) are electroencephalographic (EEG) waveforms that can be seen in a wide array of encephalopathies. By definition, they are repeated and generalized waveforms with relatively uniform morphology and duration, with a quantifiable interdischarge interval between consecutive waveforms, and recurrence of the waveform at nearly regular intervals (Fig. 1) [1]. There are different theories for their etiology and pathophysiology. Early work suggested that GPDs were due to widespread cortical destruction with relative sparing of white Generalized periodic discharges (GPDs) with triphasic morphology are an electroencephalographic (EEG) pattern traditionally associated with encephalopathy and coma, although they have been observed in a wide array of neurological disorders. The clinical significance of these waveforms and their relationship to seizures and prognosis has been debated, and differentiation between interictal patterns, patterns associated with seizures, and patterns representing nonconvulsive status epilepticus can at times be a challenge. The most established literature suggests that GPDs, including those with triphasic morphology, are associated with the development of electrographic seizures, but that in the absence of clinical information, distinguishing waveforms based on morphology alone may not be clinically useful. Recent work has advocated for a more proactive approach in evaluating GPDs with triphasic morphology. Further studies of nonsedating antiseizure drugs in patients with GPDs with triphasic morphology that incorporate continuous EEG monitoring will be useful in tailoring therapy to optimize long-term clinical outcomes and recovery.

EEG Abnormalities and Their Radiographic Correlates in a COVID-19 Inpatient Cohort

“…Recent literature supports their occurrence with multiple underlying etiologies-only modest interrater EEG reader agreement regarding triphasic classification, but increased risk of seizures similar to GPDs without triphasic morphology. 22 Focal IEDs, LPDs, or LRDA were observed in a quarter of patients in our study, indicating an elevated risk of focal onset seizures. A recent Critical Care EEG Monitoring Research Consortium study showed LRDA and LPDs, in particular, associated with seizures in 28% and 44% of EEG studies, respectively.…”

“…Unauthorized reproduction of this article is prohibited Associated etiologies typically involving diffuse cortical or thalamocortical dysfunction. 25 GPDs may increase the risk for associated electrographic seizures in at least 16% of patients. 26 Features such as motor manifestations, faster discharge rate, and response to ASMs may be associated with a higher risk of GPDs evolving to seizures or representing NCSE.…”

Encephalopathy Associated with Ifosfamide Use in the Treatment of Patient with Diffuse Large B Cell Lymphoma

“…The most common EEG findings in patients with IRE are background diffuse generalized slowing and periodic attenuation exhibited as a burst-suppression pattern with intermittent delta activity and Generalized Periodic Discharges (GPDs) with or without triphasic morphology waves; however, these findings have been observed in a variety of metabolic encephalopathy cases [34]. Occasionally, patterns consistent with NCSE, orofacial myoclonus, and epileptiform discharges, including spikes and sharp waves, have been reported, superimposed upon the pattern of background slowing.…”

The clinical neurophysiology of COVID-19-direct infection, long-term sequelae and para-immunization responses: A literature review

“…Furthermore, the frontal predominance of some reported EEG abnormalities may not always signify focal frontal pathology. Certain EEG features commonly associated with diffuse encephalopathic processes, such as generalized rhythmic delta activity (GRDA) and generalized periodic discharges (GPDs) with triphasic morphology, often have frontal predominance ( Hartshorn and Foreman, 2019 ).…”