Abstracts

Local cortical cooling for the elimination of epileptic discharges (EDs) has recently become a focus of research. However, the effect of focal cooling on seizures arising from the temporal lobe has yet to be thoroughly investigated. We devised an apparatus for the cooling of the hippocampus in order to examine the effect of focal cooling on experimental hippocampal seizures., We developed a cooling needle (measuring 1 mm diameter and 6mm length) made of copper which was attached to a thermoelectric (Peltier) chip. Next, experiments were performed on adult male Sprague-Dawley rats under halothane anesthesia. The cooling needle, a thermocouple and a needle electrode for the EEG recording were then inserted into the right hippocampus after performing a craniotomy. Kainic acid (KA) (1 mg/ml, 1 [micro]l) was injected into the left hippocampus to provoke epileptiform discharges (EDs). Thereafter, focal cooling was started and it was continued for 5 minutes after confirming the appearance of EDs in the right hippocampus which had been provoked by the KA in the contralateral hippocampus., The temperatures of the cooled site in the hippocampus were 9[deg]C in the center, while they were under 25[deg]C within 2.4 mm in radius from the cooling center in phantom experiments using the cooling device.The EDs began to significantly decrease in amplitude from 90 seconds after the start of cooling (p[lt]0.01). The mean amplitudes of the EDs were suppressed to 68.1 [plusmn]4.8% at the end of the cooling and then stayed low values during the subsequent period. The temperatures of the cooling site were maintained at 33.1[plusmn] 0.7[deg]C before cooling and then they decreased to 14.5 [plusmn] 1.3[deg]C finally., We confirmed that hippocampal cooling suppressed the EDs provoked by KA injection in the contralateral hippocampus. Our results therefore seem to suggest that hippocampal cooling may thus be a potentially useful minimally invasive therapy, which might thus be able to replace the need to perform a temporal lobectomy.,