Limitations of Local Brain Cooling on Generalized Motor Seizures from Unknown Foci in Awake Rats.

Local brain cooling of an epileptic focus at 15 degrees C reduces the number of spikes on an electrocorticogram (ECoG), terminates seizures, and maintains neurological functions. In this study, we attempted to suppress generalized motor seizures (GMSs) by cooling a unilateral sensorimotor area. GMSs were induced in rats by intraperitoneal injection of bicuculline methiodide, an antagonist of gamma-aminobutyric acid. While monitoring the ECoG and behavior, the right sensorimotor cortex was cooled for 10 min using an implanted device. The number of spikes recorded from the cooled cortex significantly decreased to 71.2% and 62.5% compared with the control group at temperatures of 15 and 5 degrees C (both P < 0.01), respectively. The number of spikes recorded from the contralateral mirror cortex reduced to 61.7% and 62.7% (both P < 0.05), respectively. The ECoG power also declined to 85% and 50% in the cooled cortex, and to 94% and 49% in the mirror cortex by the cooling at 15 and 5 degrees C, respectively. The spikes regained in the middle of the cooling period at 15 degrees C and in the late period at 5 degrees C. Seizure-free durations during the 10-min periods of cooling at 15 and 5 degrees C lasted for 4.1 +/- 2.2 and 5.9 +/- 1.1 min, respectively. Although temperature-dependent seizure alleviation was observed, the effect of local cortical cooling on GMSs was limited compared with the effect of local cooling of the epileptic focus on GSMs.