PAROXYSMAL MICROAROUSALS IN AMYGDALA-KINDLED KITTENS - COULD THEY BE SUBCLINICAL SEIZURES

Amygdala-kindled kittens exhibit frequent epileptiform EEG transients, often in conjunction with phasic arousal events of sleep [k-complexes , pontogeniculooccipital (PGO) waves, and/or sleep spindles]. In this study, paroxysmal microarousals occurred throughout the sleep-wake cyc le after kindling, but were most frequent during seizure-prone states of slow-wave sleep (SWS) and the transition into rapid-eye-movement sl eep (REM). Their incidence correlated with interictal sleep fragmentat ion as well as onset of spontaneous convulsions. Results could reflect transsynaptic kindling effects on brainstem and forebrain arousal mec hanisms with which amygdala is reciprocally connected. Increased disch arge rates of neural generators for normal EEG and behavioral arousal could disrupt sleep at some times and recruit epileptic neurons in the kindled focus to precipitate seizures at others. Alternatively, epile ptiform EEG paroxysms were accompanied by subtle behavioral stereotype s (a head nod, limb elevation, eye twitch, lip smack, or a combination of these). Behavioral correlates were elements of partial kindled sei zures, suggesting that paroxysmal microarousals may be subclinical sei zures. Whether or not the microarousals are true seizures, our finding s may link ictal onset and interictal sleep disorders to a subclinical paroxysmal arousal disorder and suggest a common epileptic mechanism.