Abstracts

Rationale: Many epileptic patients suffer from comorbid sleep disorders and sleep fragmentation, characterized by decreased REM and increased disturbances. Although well recognized, the complex bidirectional relationship between seizures and sleep is not well understood. While the disruptive nature of nocturnal seizures on sleep is well-documented, it is unclear how diurnal seizures impact sleep quality and whether these changes persist in the nights following. In this study, we characterize the disruption of nocturnal sleep patterns after penicillin-induced diurnal neocortical seizures in a non-human primate (NHP) model.

Methods: The sleep patterns of two rhesus macaques were studied before and after induction of acute prefrontal seizures. Both subjects were permanently implanted with ECoG electrodes located over the motor cortex area and above the eye sockets. Recordings were performed via a telemetry system. Seizures were induced via PCN injection (2500u/ul) in the frontal cortex. Seizures lasted 4-6 hours after injection and stopped on their own, with no seizures occurring during the nights of recordings. For subjects 1 and 2 a total of 16 and 19 nights were recorded, respectively. Sleep (19:00-07:00) was scored in 30-second epochs based on video recording, accelerometer activity, EOG signal, and EEG spectral power. Sleep architecture and spectral activity were analyzed prior to seizure induction, the nights of seizures, and up to 4 nights after.

Results: On the nights of seizure induction, for both subjects, we observed a significant increase in movement (mean acceleration; p< 0.05), along with a decrease in sleep efficiency (% of time asleep; p< 0.05). These changes were no more different from baseline 2 nights after the seizure. We also observed a significant decrease in overall REM sleep duration compared to baseline that persisted up to 2 nights after seizure induction for both subjects (p < 0.05). No changes were noted in sleep stage transition index for either subject. Additionally, we did not find a significant correlation between the changes in nocturnal movement and sleep activity and the number of seizures induced by the PCN injection but a negative correlation between the delay since the last seizure and the amount of nocturnal movement and the wakefulness at night.