Abstracts

Rationale: We analyzed the EEGs of unresponsive patients to determine the incidence of various EEG patterns, in particular of nonconvulsive status epilepticus (NCSE). Methods: We retrospectively reviewed EEGs of all unresponsive patients referred to our laboratory in a 4 month period. This group consisted of 93 patients ( mean age 52 years ;range 3 days to 99 years). Results: Two types of EEG patterns were observed. Twenty four(26%) had NCSE and 69(74%) had pattern indicating moderate to severe diffuse cerebral dysfunction (DCD). Among those with NCSE, six(25%) were less than 2 years old and 13(54%) were over 65 years. Fourteen patients (58%) had complex partial status epilepticus (CPSE) and ten(42%) had generalized nonconvulsive status epilepticus (GNCSE). In patients with CPSE, left hemispheric spike and wave discharges were predominant (71%). In the 69 patients with DCD, 16 had triphasic waves , three had suppression- burst (S-B) patterns and one had alpha coma pattern. The others had only background slowing. Conclusion: We found a bimodal age distribution of NCSE, occurring in the very young and very old. The left hemisphere appears more likely to generate seizures than the right hemisphere. NCSE is much more common among our unresponsive patients than are the patterns of suppression-burst or alpha coma.