Abstracts

Rationale: Mesial Temporal Sclerosis (MTS) has been well-recognized as a cause of intractable epilepsy in children and adults. The clinical significance of interictal discharges in MTS has not been well-established, especially in children. We present 5 children with intractable complex partial seizures and MTS on MRI, who subsequently underwent focal resection. We quantified the amount of interictal spikes and assessed the effect on the clinical course of MTS in children. Methods: The Institutional Review Board at Children's Hospital Boston approved the study. We retrospectively reviewed medical records of 5 children with intractable complex partial seizures and MTS on MRI, who subsequently underwent focal resection. Interictal spikes were quantified on prolonged video EEG telemetry with various awake and sleep states, obtained as a part of presurgical evaluation. Percentages of seconds occupied by interictal spikes and sharp waves were measured (“SWI: spike-wave index”), on randomly selected 100 second epochs and mean values were obtained. When multiple spike populations were detected, SWIs were measured on the predominant focus. SWIs were obtained during awake and non-REM sleep states independently, as frequency of discharges fluctuate between these states. SWIs were compared with factors such as age of seizure onset, onset of intractability (defined by failure of 3 antiepileptic drugs), and existence of co-morbid cognitive dysfunction. Results: Demographics of the 5 children (3 girls and 2 boys, ages 15-18) are outlined in table 1. SWI measurements are compared with other clinical variables in table 2. One had right MTS (1 girl), three had left MTS (2 girls and 1 boy), and one had bilateral MTS (left greater than right on MRI, and ictal EEG all originating from the left). All children underwent temporal resection between 12 and 18 years, including one who underwent a repeat temporal resection (right temporal resection in 1, left in 4). Age of seizure onset was 1.5-10 years, and onset of intractability was 7-14 years. Predominant spikes were seen in the temporal area ipsilateral to the MTS (the predominant left side in the bilateral case). SWIs were higher in non-REM sleep recordings in all children; SWI in the non-REM sleep recording ranged from 7-37%. The child with 7% SWI had later onset of seizures and later onset of intractability. Other children had SWI of 12.5-37% and onset of intractability before 10 years of age. Four children had memory problems. The two with highest SWI (23 and 37%) had co-morbid attention deficit disorder as well. Conclusions: The clinical significance of interictal discharges in MTS has not been established in children. Onset of seizure and intractability are earlier in children, compared to adults in MTS. In our cases, interictal discharges tend to be more frequent with younger seizure onset, younger onset of intractability, and with cognitive co-morbidity such as attention deficit disorder. Further studies are necessary to confirm this trend on effect of frequent interictal discharges in MTS, in children.