ONTOGENY OF FELINE TEMPORAL-LOBE EPILEPSY .3. SPONTANEOUS SLEEP AND AROUSAL DISORDERS IN AMYGDALA-KINDLED KITTENS

We report the ontogeny and persistence of sleep and arousal disorders in amygdala-kindled kittens. We also identify procedural differences that may explain discrepancies in the literature on postkindling sleep disorders. The study population consisted of 12 preadolescent kittens kindled between 2.5 and 6.5 months of age, 8 of which were followed to adulthood (greater than or equal to 1 year), and 8 unkindled implanted control animals. Sleep and seizure patterns were monitored on 12-24-h polygraphic or split-screen video recordings of EEG and behavioral activity. Kindled kittens displayed spontaneous seizure and interictal sleep anomalies that persisted to adulthood, as follows. As compared with neurosurgical controls, kindled kittens exhibited slow-wave sleep (SWS) and REM sleep insomnia at least 1 year after kindling and 1-5 months after convulsions, regardless of postictal recording delay. Sleep and arousal defects in kindled kittens were similar to but more pronounced than those in kindled adult cats, possibly because kittens spontaneously became epileptic. Detection of postkindling SWS insomnia could be masked by brief scoring epochs (less than the preferred I-min epoch for cats); recurrent behavioral arousals after kindling frequently aborted 1-min SWS epochs but often did not interrupt 30-s SWS epochs (based on 1-min vs. 30-s minimum duration scoring criteria). Detection of postkindling REM sleep insomnia could be masked in kittens with alternating patterns of REM loss and REM rebound; all these kittens showed periodic bouts of REM onset from waking after kindling. Different data collection and analysis procedures influence detection of sleep and arousal disorders in amygdala-kindled cats when replication of findings is attempted. We conclude that these differences explain some controversies regarding the nature and prevalence of sleep disturbances in the kindling literature in temporal lobe epilepsy (TLE).