Abstracts

Rationale: The goals of this study of children undergoing resective surgery for intractable epilepsy were to determine: (1) the proportion of children who achieved a remission of six months or longer in the first year after diagnosis of epilepsy (delayed intractability), and (2) factors associated with delayed intractability. Methods: All children (0-18 yrs) undergoing respective surgery for intractable epilepsy between January 2002 and May 2010 at Mayo Clinic Rochester were identified by review of the pediatric neurosurgical database. Demographic and epilepsy-related details were obtained through retrospective review of all outpatient and inpatient medical records. The course of epilepsy in the first year after diagnosis was subdivided into two groups: (1) delayed intractability, defined as remission of ?6 months in the first year and failure of no more than one AED in the first year for lack of efficacy, or (2) refractory from onset, defined as no remission of ?6 months or failure of two or more AEDs in the first year for lack of efficacy. Potential factors associated with delayed intractability including age at onset, febrile seizures, history of status epilepticus, cognitive delay, secondarily generalized seizures, abnormal MRI, abnormal EEG, temporal lobe onset, and pathology were evaluated by Chi square and paired t analyses. Results: Eighty-five children were identified (61% male, mean age at afebrile seizure onset 59 months, mean age at surgery 127 months). Nineteen (22%) achieved a remission of six months or longer within the first year before developing delayed intractability (mean duration of remission 35.3 months, SD 30, range 6-99). A history of febrile seizures was significantly more prevalent in the group with delayed intractability (p<0.008). There were also non-significant trends for a history of status epilepticus and normal EEG background to correlate with delayed intractability (p=0.05, and p=0.07, respectively). The remaining factors, including mesial temporal sclerosis or hippocampal gliosis, showed no significant correlation with delayed intractability. Conclusions: In this cohort of children undergoing resective surgery for intractable epilepsy, 22% achieved a six month or longer remission in the first year, with the mean duration of remission being approximately three years. These findings suggest that intractability in children with epilepsy may be difficult to predict within the first year.