Abstracts

Rationale: The mortality and morbidity of nonconvulsive status epilepticus (NCSE) is highly variable. Identifying the types of NCSE with a particularly poor or good prognosis will help clarify the pathophysiology and direct therapy in individual patients. We hypothesized that NCSE due to an acute medical problem (including neurological) has a high complication rate and NCSE occurring either during the course of epilepsy, following a single generalized tonic-clonic seizure (GTC), or of unknown cause (idiopathic) has a low complication rate. Methods: We identified cases of NCSE through review of EEG reports with confirmation through review of original EEGs. Patient and EEG characteristics, etiology, and acute and late complications were culled from the medical record. Fisher's exact or t-tests were used to determine whether age, gender, or general etiology of NCSE were associated with death during admission or any acute complication. Development of epilepsy and recurrence occurred in too few to perform statistics. Results: We identified 71 cases with mean age 51?28 years and 42% male. 12 died during hospitalization. Death occurred in 9/13 with NCSE due to acute medical problems, but in only 1/24 with NCSE due to epilepsy, 1/4 with NCSE following a single GTC, and in 2/18 with idiopathic NCSE. Death was more likely when NCSE was due to acute medical problems (p=.008) and less likely when due to epilepsy (p=.045). Acute complications occurred in 28 cases (39%) and were more likely to occur when NCSE was due to acute medical problems (p=.035) but not epilepsy, a single GTC, or idiopathic. No sex or age differences were found for death or acute complications. Of the 20 cases with follow-up available, epilepsy later developed in 4 and NCSE recurred in 7. Conclusion: The mortality and acute complication rate of NCSE is high when it is due to acute medical problems but low when occurring during the course of epilepsy, following a single GTC, or idiopathic. This suggests the pathophysiology of NCSE associated with acute medical problems is different from that due to epilepsy and could form the basis of a classification scheme. NCSE can be the first sign of epilepsy, or possibly cause it, and may recur.