Ontogeny of feline temporal lobe epilepsy in amygdala-kindled kittens: an update

Abstract

This report describes amygdala-kindled seizure development and the post-kindling course in 58 cats (29 males and 29 females), including 40 preadolescents between 2.5 and 6.5 months of age and 18 adults >1 year of age at the beginning of kindling. The results extend previous findings, as follows: (1) Youngest animals (<5.0 months, n=30) are far more likely than older kittens and adults to exhibit spontaneous epilepsy, indexed by seizures that occur >1 h after stimulus-evoked seizures. (2) The youngest animals also exhibit accelerated kindling rates and rapid post-kindling onset of multifocal spontaneous epilepsy with a catastrophic clinical course. The profile includes a variety of EEG and/or clinical seizure manifestations and a progressive increase in the number and density of convulsive seizure clusters. Behavioral sequelae accompany seizure clusters and can range from sensory or motor deficits (visual agnosia, sensory hypersensitivity, atonic episodes, restricted mobility) to social isolation and placidity. (3) Onset of spontaneous epilepsy with developmental deterioration is substantially enhanced by recurrent evoked seizures early in the post-kindling course. The post-kindling progression can be stopped or minimized by suspension of evoked seizure trials and/or by management of frequent spontaneous convulsions (>1 per hour) with anticonvulsants. (4) In older cats, many more evoked seizures are required to generate fewer spontaneous seizures with relatively innocuous behavioral disorders. The findings suggest a ‘critical period’ in kindled kittens for onset of spontaneous temporal lobe epilepsy with severe behavioral consequences and a favorable prognosis for the young following early detection and intervention.