Association between Chronobiology of Seizures and Hemispheric Laterality in Patients Who Underwent Surgery for Refractory Epilepsy (P7.284)

OBJECTIVE: To characterize medically refractory nocturnal seizures by correlation with the location of the seizure focus; and nocturnal, diurnal or mixed pattern. BACKGROUND: Nocturnal seizures commonly occur in focal epilepsy. It is not known why certain patients have strictly nocturnal seizures, strictly diurnal seizures, or a mixture. This study evaluates the relationship between seizure focus (localization and laterality) and the circadian pattern of seizures. DESIGN/METHODS: The surgical database at Thomas Jefferson University was reviewed for patients with nocturnal or diurnal seizures (determined by history) with subsequent focal resections for intractable epilepsy between 1990 and 2011. Gender, type and laterality of surgery were noted and compared between those patients with nocturnal/mixed seizures and those with strictly diurnal seizures using Bonferroni corrected Chi-squared tests. RESULTS: 117 patients (age 34+12 years, 40.8% female) with nocturnal or mixed seizures (NS/MS) and 327 patients (age 34+11 years, 59.3% female) with strictly diurnal seizures (DS) were identified. Patients with NS/MS showed no bias towards gender (p > 0.05); however DS occurred more often in women (p < 0.05). For both groups, the majority of patients had one of 3 procedures: right anterior temporal lobectomy (RATL), left anterior temporal lobectomy (LATL), or right frontal resection (RF). For patients with NS/MS, there were 37% RATL, 17% LATL, 8% RF and 38% other. For those with DS, there were 36% RATL, 29.9% LATL, 5.8% RF and 29% other. Patients with NS/MS were significantly less likely to have LATL (p < 0.01); however there were no significant differences in the proportion of patients having other procedures. CONCLUSIONS: Nocturnal seizures may be more common in left temporal lobe epilepsy, and strictly diurnal seizures may be more common in women. Further studies are ongoing to determine if potential biases related to surgical selection might affect the results and to confirm these findings with correlation to surgical outcome. Study Supported by: Disclosure: Dr. Popescu has nothing to disclose. Dr. Misra has nothing to disclose. Dr. Nei has received research support from Medtronic Inc., Neuropace, GlaxoSmithKline Inc., UCB Pharma, Marinus, and Ortho-McNeil/Johnson & Johnson.