Abstracts

RATIONALE: To characterize an under-recognized seizure type.
The individual electroclinical patterns[mdash]tonic seizures with generalized paroxysmal fast activity (GPFA, activity [gt]13 Hz), and absence seizures with generalized slow spike and wave activity (GSS&W, [lt]3 Hz)[mdash]have been extensively described in the literature. However, there has been only passing reference to the pattern of GPFA followed by GSS&W. In addition, these descriptions were formulated in the pre-EMU era, without benefit of video/clinical correlation.
METHODS: We retrospectively reviewed the data from 8 patients with seizures that demonstrated this stereotyped EEG and clinical pattern.
RESULTS: We identified eight patients (6 female; age 6-29 years old; age of seizure onset neonate to 10 years) who were evaluated at the Columbia Presbyterian Epilepsy Monitoring Units between 1993-2002. All eight carried an ILAE diagnosis of Symptomatic Generalized Epilepsy, with 6/8 manifesting multiple seizure types, 6/8 with mild mental retardation, and two with normal cognition. A total of 29 electroclinical seizures of this pattern were recorded. 26/29 seizures demonstrated GPFA (frequency between 14-30 Hz, lasting 2-8 seconds) followed by GSS&W (frequency range between 1-2 Hz, lasting 3-50 seconds). The predominant clinical correlate was bilateral tonic activity followed by a period of inattentiveness. In general, these seizures were differentiated from the patient[scquote]s typical tonic seizures by this protracted period of impaired attentiveness.
CONCLUSIONS: We describe a heretofore under-recognized and poorly characterized seizure type in patients with symptomatic generalized epilepsy, which we have termed [dsquote]tonic-absence[dsquote] seizures. Clinically and electrographically, this consists of a tonic seizure with GPFA followed by an absence seizure with GSS&W.