THE ELECTROGRAPHIC DIFFERENTIATION OF TRIPHASIC WAVES WITH GENERALIZED NONCONVULSIVE STATUS EPILEPTICUS: NOT ALWAYS EASY
Abstract number :
2.150
Submission category :
Year :
2004
Submission ID :
4672
Source :
www.aesnet.org
Presentation date :
12/2/2004 12:00:00 AM
Published date :
Dec 1, 2004, 06:00 AM
Authors :
Charles Deacon, Jean-Martin Boulanger, Lécuyer Diane, and Black Robert
Triphasic waves (TWs) and generalised nonconvulsive status epilepticus (GNCSE) may share electrographic morphological features that create diagnostic ambiguity. The three phases of TWs are easily mistaken for the spike, trough and wave of epileptiform discharges. Both conditions are seen in patients with altered consciousness. The managment of the two conditions is quite different (treatement of the underlying metabolic encephalopathy for TWs and anticonvulsant drugs for GNCSE). A formal electrographic comparison of these two entities has not been performed. We compared retrospectively the EEGs of two groups of patients: TWs associated with proven metabolic encephalopathy and GNCSE confirmed clinically. All EEGs were done over a period of five years at the same institution. Several EEG morphological features were analysed. We reviewed 63 EEGs (54 patients) with TWs and 22 EEGs (10 patients) with GNCSE. Decreased consciousness was present in all patients. When compared to TWs, epileptiform discharges had a higher frequency (mean=2.6Hz vs 1.9Hz) (p[lt]0.01), showed more often extra-spikes components (60% vs 0%), (p[lt]0.01) and had less generalised background slowing (92.6% vs 20%) (p[lt]0.01). Lag of phase two was absent in all cases of GNCSE but present in 42.6% of patients with TWs (p[lt]0.01). Relative amplitude predominance of phase 2 within complexes (more than 50% of other phases) was present in 42.6% of patients with TWs versus none of the GNCSE patients (p[lt]0.01). Noxious or verbal stimulation frequently increased the amount of TWs (47.4%) while it had no effect on epileptiform patterns (p[lt]0.01). Electrode of highest voltage, distribution and duration of phase one were not helpful differentiating features in this study. This study confirms the usefulness of some electrographic features to correctly differentiate TWs from GNCSE. Low frequency ([lt] 2 Hz), relative amplitude predominance of phase two, lag of phase two, background slowing and increased amount of complexes with stimulation were all suggestive of TWs.