Abstracts

Rationale: The most commonly used classification of outcome for epilepsy surgery, the Modified Engel Scale, focuses largely on seizure frequency in determining whether or not surgery produced favorable results. It has been validated in adolescents and adults. The context of epilepsy surgery is different in the pediatric setting, however. Children differ from adults in the distributions of seizure types, onset, and localization. In addition, in catastrophic pediatric epilepsy, seizure freedom is only one goal of surgery. Often, improved quality of life of the patient and his or her family, as well as the hope of improved development, are unspoken goals of surgery. Because of the nature of certain catastrophic epilepsies of infancy (e.g, hemimegalencephaly) and plasticity of the infant brain, the risk-benefit ratio of operating in eloquent cortex is also different. The current use of the Engel system does not encompass these aspects of surgery and a more detailed approach to classification of surgical outcome is necessary. Methods: We propose a multiple axis approach to classification of outcome that includes outcome scores based on Seizure Freedom (1- Seizure free; 2 = Auras only; 3 = > 90 % reduction in seizure frequency; 4 = 50-90% reduction; 5= < 50% reduction; 6 = No change or increase); Neurological Outcome (a = improvement; b = no change; c= new non-disabling deficit or non-disabling increase in longstanding deficit; d = new disabling deficit) and Quality of Life ( = improved QOL; nc = no change; - = worse QOL). Institution of this classification scheme requires minimal changes in current pre- and post-surgical evaluations of patients that include seizure monitoring and seizure diaries, standard neurologic examination, and administration of age-specific quality of life measures. As part of our clinical practice, we routinely administer the Quality of Life in Children with Epilepsy Scale at pre- and post-surgical neuropsychological evaluation. Standardized measures of intellectual and neuropsychological functioning are used to assess cognitive and behavioral outcomes. Results: In 2008, we started using a Pediatric Epilepsy Surgery Outcome Scale (PESO) at one-year post-surgical follow-up evaluations. In comparison to their Engel ratings, patients ratings on this scale were more variable, as expected, given the greater number of dimensions, and provided more information. No significant delay in pre- or post- surgical assessments of our patients resulted from the inclusion of these measures in our clinics. Of the 6 patients where pre and 1-year post-operative QOL measures were available, no decline in QOL was seen, even in those who sustained a new (expected) neurological deficit (Neurological Outcome = d) or in those who were not seizure-free (Seizure Freedom <1). Conclusions: A multi-axial approach to the assessment of surgical outcome in children with epilepsy is needed to better characterize all important determinants of results of surgical management in infants and children with refractory epilepsy. Validation studies of the PESO are planned.