Abstracts

It is typically assumed that intractablility is evident soon after the onset of epilepsy. Retrospective histories from surgical patients, however, suggest that intractable seizures may not be evident for many years, particularly in partial epilepsy of childhood onset. In a community-based study of 613 children in Connecticut with newly diagnosed epilepsy (1993-97) prospectively followed a median of 9 years, the timing of the appearance of intractable epilepsy from date of initial diagnosis was determined. Two definitions for intractable epilepsy were used: 1) [quot]Strict:[quot] 2 AED failures, [underline][gt][/underline]1 seizure/month for 18 months; 2) [quot]Loose:[quot] 2 AED failures. Differences in the timing of the appearance of intractability were examined as a function of type of epilepsy syndrome. Eighty-two children met the strict criteria for intractability: 38/294 (13%) of those with cryptogenic or symptomatic partial epilepsy (C/S-PE), 35/67 (52%) of those with an epileptic encephalopathy (EE) and 9/241 (4%) of those with idiopathic or other forms of epilepsy (p[lt]0.0001). Eleven children followed[lt]18 months were not assigned an outcome. Twenty-five (30%) of the 82 intractable cases took [gt]3 years to meet the strict criteria for intractability. The primary interest was in comparing EE and C/S-PE groups. Five of 35 (14%) intractable cases in the EE group versus 17/38 (45%) in the C/S-PE group met criteria at [gt]3 years (p=0.005). Loose criteria for intractability (2 AED failures) were met by 135 children. Of these, 32 (24%) met criteria [gt]3 years after diagnosis: 1/46 in the EE group versus 25/69 in the C/S-PE group (p[lt]0.0001). In the C/S-PE group, 18/25 (72%) 25 who failed a second drug [gt]3 years after diagnosis had experienced a 1+ year remission before the second drug failure. Poor seizure outcome is generally evident from the outset in the epileptic encephalopathies such as West, Lennox-Gastaut syndrome. By contrast, the appearance of intractability may be delayed in cryptogenic/symptomatic partial epilepsy. Retrospective data¹ suggest that with a median follow-up of 9 years, roughly a third to half the intractable cases that might occur in the cryptogenic/symptomatic partial epilepsy group have yet to declare themselves. Only continued prospective study in the current cohort, however, will reveal the eventual true burden of intractability and its time course.
¹Berg AT, et al. How long does it take for partial epilepsy to become intractable? [italic]Neurology, 2003; 60:[/italic]186-190. (Supported by NIH RO1-NS31146.)