Distribution of partial seizures during the sleep-wake cycle - Differencesby seizure onset site

Objective: To evaluate the effects of sleep on partial seizures arising fro m various brain regions. Methods: The authors prospectively studied 133 pat ients with localization-related epilepsy undergoing video-EEG monitoring ov er a 2-year period. Seizure type, site of onset, sleep/wake state at onset, duration, and epilepsy syndrome diagnosis were recorded. Periorbital, chin EMG, and scalp/sphenoidal electrodes were used. A subset of 34 patients un derwent all-night polysomnography with scoring of sleep stages. Results: Th e authors analyzed 613 seizures in 133 patients. Forty-three percent (264 o f 613) of all partial seizures began during sleep. Sleep seizures began dur ing stages 1 (23%) and 2 (68%) but were rare in slow-wave sleep; no seizure s occurred during REM sleep. Temporal lobe complex partial seizures were mo re likely to secondarily generalize during sleep (31%) than during wakefuln ess (15%), but frontal lobe seizures were less likely to secondarily genera lize during sleep (10% versus 26%; p < 0.005). Conclusions: Partial-onset s eizures occur frequently during NREM sleep, especially stage 2 sleep. Front al lobe seizures are most likely to occur during sleep. Patients with tempo ral lobe seizures have intermediate sleep seizure rates, and patients with seizures arising from the occipital or parietal lobes have rare sleep-onset seizures. Sleep, particularly stage 2 sleep, promotes secondary generaliza tion of temporal and occipitoparietal, but not frontal, seizures. These fin dings suggest that the hypersynchrony of sleep facilitates both initiation and propagation of partial seizures, and that effects of sleep depend in pa rt on the location of the epileptic focus.