Generalized periodic epileptiform discharges: Etiologies, relationship to status epilepticus, and prognosis

Generalized periodic epileptiform discharges (GPEDs) are generalized, synch ronous electrographic discharges. This study investigates etiologies, relat ionship to status epilepticus (SE), and the prognosis for patients with GPE Ds. 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 al ive or not at discharge. A comparison of histories and GPED characteristics among groups was undertaken using parametric and nonparametric t tests. Tw enty-five patients were enrolled: 7 (28%) had toxic-metabolic encephalopath y, 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 gr oup, GPED amplitude was higher (110 versus 80 mu V, P < 0.05), GPED duratio n was longer (0.5 versus 0.3 seconds, P < 0.05), and inter-GPED amplitude w as higher (34 versus 17 mu V, P < 0.05). Nine patients (36%) were alive at discharge; they were more likely to be younger (51 versus 68 years, P < 0.0 5), have a better mental status at the time of their EEG, and have a higher inter-GPED amplitude (33 versus 18 mu V, P < 0.05). A variety of condition s, including SE, can cause GPEDs. Intergroup differences in historic and GP ED features exist between those patients in SE and those not in SE and thos e with good and poor prognoses.