Abstracts

Nonconvulsive status epilepticus (NCSE) is diagnosed when cognitive and/or behavioral impairments unaccompanied by significant motor behavior are the principal clinical manifestation of prolonged or repetitive electrographic seizures lasting [ge] 30-60 minutes. This major subtype of status epilepticus (comprising [sim]25% of the 60,000-150,000 cases of status/year) can last weeks, months or longer as early diagnosis is hampered by the subtle and often nonfocal nature of clinical deficits. Identification of patients predisposed to develop NCSE could facilitate earlier detection through closer clinical monitoring, improving quality of care and outcome. We reviewed records of adult patients previously identified between 1987 and 2002 as part of an ongoing study of cognitive deficits from recurrent frontally predominant subclinical seizures in Veterans with epilepsy. Severity of underlying subclinical epileptiform discharges (SEDs) was defined as % of time/EEG with SEDs (ictal + inter-ictal), permitting comparisons of records independent of EEG duration. Inclusion criteria included: recurrent SEDs on [ge] 1 EEG and [ge] 18 months of followup with serial EEGs. Patients with [ge] 1 EEG with [gt] 10% SEDs were rated [italic]High %SED[/italic] and the rest were rated [italic]Low %SED[/italic]. The cutoff of 10% was based on prior observations that suggested a minimum level of impairment with [lt]10% SEDs. Fishers exact test was used to compare proportions of patients receiving treatment for NCSE in the High and Low% SED groups. Statistical testing was conducted at the 0.05 level (two-sided). Nine of 11 male patients (82%) met inclusion criteria. Five were classified High % SED and four as Low % SED. Average age at onset or diagnosis of epilepsy did not significantly differ between the groups. The most common seizure types were (usually primary) generalized tonic-clonic seizures and absence-like events. Clinical seizures were infrequent in later years (average: 0-2/year). Comparing High% vs. Low %SED groups: Three patients (60%) in the High %SED group were treated for NCSE compared with 0/4 (0%) in of the Low % SED group (p = 0.17). No patient with a Low % SED was treated for NCSE. Although statistical significance was not obtained due to small sample sizes, power calculations indicated a sample size of only 12 patients/group would have shown statistical significance at 80% power and a 0.05 significance level (2-sided). Verifying that [gt]10% of time/EEG as SEDs predisposes patients to develop NCSE would provide a valuable objective marker to help clinicians identify patients who might benefit from more frequent cognitive testing.