Generalized Periodic Epileptiform Discharges: Etiologies, Relationship to Status Epilepticus, and Prognosis

Abstract

Generalized periodic epileptiform discharges (GPEDs) are generalized, synchronous electrographic discharges. This study investigates etiologies, relationship to status epilepticus (SE), and the prognosis for patients with GPEDs. All EEGs with GPEDs performed at Duke University Medical Center between January 1994 and October 1995 were identified. Clinical histories and EEGs were reviewed. They were divided into groups depending on the etiology of the GPEDs, whether the patients were in SE or not, and whether they were alive or not at discharge. A comparison of histories and GPED characteristics among groups was undertaken using parametric and nonparametric t tests. Twenty-five patients were enrolled: 7 (28%) had toxic-metabolic encephalopathy, 10 (40%) had anoxia and toxic-metabolic encephalopathy, and 8 (32%) had a primary neurologic process. Eight patients (32%) were in SE. In the SE group, GPED amplitude was higher (110 versus 80 microV, P < 0.05), GPED duration was longer (0.5 versus 0.3 seconds, P < 0.05), and inter-GPED amplitude was higher (34 versus 17 microV, P < 0.05). Nine patients (36%) were alive at discharge; they were more likely to be younger (51 versus 68 years, P < 0.05), have a better mental status at the time of their EEG, and have a higher inter-GPED amplitude (33 versus 18 microV, P < 0.05). A variety of conditions, including SE, can cause GPEDs. Intergroup differences in historic and GPED features exist between those patients in SE and those not in SE and those with good and poor prognoses.

The Utility of EEG, SSEP, and Other Neurophysiologic Tools to Guide Neurocritical Care

“…Nonconvulsive status, however, may masquerade as a triphasic encephalopathy (e.g., in association with cephalosporin overdose in the setting of renal dysfunction) [73]. Husain et al [74] sought to discriminate which GPED patterns were most likely to be associated with status epilepticus; GPEDs with high amplitude and longer duration, and those which preserved inter-GPED amplitude were more commonly associated with status epilepticus; however, no cut-point had sufficient receiver-operator characteristics to permit discrimination. …”

Generalized periodic discharges in the critically ill

“…Prior investigations of GPDs consist of 2 small, unmatched case series 8,9 and subgroup populations in 2 additional case series. 10,11 In the last decade, increased awareness of nonconvulsive seizures and improved technology have led to increasing use of prolonged continuous digital EEG monitoring (cEEG) in the hospital setting, particularly in the intensive care unit (ICU).…”

Long-Term Monitoring: An Overview

“…In such cases, it is not easy to differentiate NCSE from metabolic encephalopathy, particularly when TWs run at a frequency exceeding 1 per second. Hence there exist the terms triphasic-like waves and nonepileptic true TWs [63]. Indeed, in NCSE, TWS and generalized spike-wave discharges look similar.…”

“…They GPEDs [ Figure 12] occur in anoxic-ischemic coma, Creutzfeld-Jacob disease, metabolic encephalopathies, CNS infections such as SSPE , H S V , a n d i n f i n a l s t a g e s o f s t a t u s epilepticus. GPEDs may represent NCSE [63] or an epileptic encephalopathy [64-65]. Fig.…”