Abstracts

Rationale: Periodic lateralized epileptiform discharges (PLEDs) are a common EEG finding in patients with acute necrotic structural disease such as stroke and herpes encephalitis. It is a persistent rhythmic pattern that can be confused with the rhythmic EEG pattern of nonconvulsive status epilepticus (NCSE). Therefore, we determined the frequency of PLEDs as the associated EEG abnormality in patients diagnosed with NCSE. Methods: All EEG reports at the University of Virginia from December 1994 to April 2004 were reviewed using full text searching techniques in order to identify a subset where the diagnosis of NCSE was being considered or was diagnosed. This subset of reports was reviewed manually by investigators in order to identify those EEG reports where the diagnosis of NCSE was made, and where the main EEG finding was that of PLEDs. Other EEG, clinical and demographic characteristics were collected. Results: A total of 18,741 EEG reports were found reviewed. PLEDS were present in 100 EEGs. The diagnosis of NCSE was reported in 76 (0.41%). Of these 76 reports, one report (1.3%) had PLEDs as the main EEG finding. This case was a 52 year old woman who developed altered mental status after having a right hemispheric stroke and subsequent generalized tonic clonic seizure. Right hemispheric PLEDs were seen on EEG. Administration of lorazepam caused resolution of the PLEDs and immediate resolution of her symptoms. Conclusions: PLEDS are a very rare ictal pattern in NCSE. Additional clinical information should be used to determine whether NCSE is suspected when PLEDS are identified. If NCSE is suspected, PLEDS should be treated as ongoing seizure activity.