ALUMINA GEL INJECTIONS INTO THE TEMPORAL-LOBE OF RHESUS-MONKEYS CAUSECOMPLEX PARTIAL SEIZURES AND MORPHOLOGICAL-CHANGES FOUND IN HUMAN TEMPORAL-LOBE EPILEPSY

The goal of the present study was to determine whether alumina gel inj ections into temporal lobe structures cause complex partial seizures ( CPS) and pathological changes observed in human temporal lobe epilepsy . Rhesus monkeys with alumina gel injections in the amygdala, perirhin al and entorhinal cortices, or Ammon's horn and dentate gyrus all init ially displayed focal pathological electroencephalographic (EEG) slowi ng limited to the site of injection. After clinical seizures developed , they also displayed widespread pathological EEG slowing over both he mispheres, interictal and ictal epileptiform EEG abnormalities limited to the mesial-inferior temporal lobe on the side of injection, and di fferent degrees of spread to other ipsilateral and contralateral struc tures. Noninjected control and nonepileptic monkeys with injections in to the middle and inferior temporal gyri displayed no hippocampal neur onal loss or mossy fiber sprouting. When alumina gel was injected into the amygdala, CPS began within 3-6 weeks and degeneration of neurons and gliosis occurred in the perirhinal cortex or the hippocampus, with consequent sprouting of mossy fibers in the dentate gyrus. Dispersion of the granule cell layer was also observed. Other monkeys with alumi na gel in the perirhinal and entorhinal cortices developed CPS within 2-3 weeks after the injections and displayed mossy fiber sprouting onl y after 4 weeks after the injections. Alumina gel in Ammon's horn and the dentate gyrus also induced CPS, but mossy fiber sprouting was limi ted to sites immediately adjacent to the injection, probably because n one survived more than 4 weeks after the injections. This nonhuman pri mate model of CPS displayed similar anatomical, behavioral, and EEG fe atures as observed in human temporal lobe epilepsy and provides opport unities to analyze the chronological sequence of epileptogenesis and t o test potential therapies. J. Comp. Neurol. 401:266-290, 1998. (C) 19 98 Wiley-Liss, Inc.