Abstracts

Little is known of the relationship between the PCO2 level and the frequency of the interictal spikes in partial seizure disorders. The purpose of this study is to determine whether the change of end-tidal pCO[sub]2[/sub] (ETCO[sub]2[/sub]) level by hyperventilation evokes seizures or epileptiform discharges in temporal lobe epilepsy., Twenty-four patients of temporal lobe epilepsy were enrolled in this study. Hyperventilation was done for 5 min during EEG recording. We gathered data on ETCO[sub]2[/sub] levels during hyperventilation. The data included the baseline ETCO[sub]2[/sub] (B-ETCO[sub]2[/sub]), the ETCO[sub]2[/sub] after 5 min of hyperventilation (5min-ETCO[sub]2[/sub]), the mean value of the ETCO[sub]2[/sub] (M-ETCO[sub]2[/sub]), and the change in ETCO[sub]2[/sub] between the baseline and the level after 5 min of hyperventilation ([Delta]ETCO[sub]2[/sub]). We counted the numbers of interictal spikes and considered the cases with more than 120% increments of the number during hyperventilation as the cases with the increment of the number of spikes. We compared the four variables between the group of the patients with the increment to hyperventilation and the group of the other patients without the increment., Seizures were not induced by hyperventilation in all the cases. Thirteen of 24 patients were in the increment group. The M-ETCO[sub]2[/sub] was 33.0 [underline]+[/underline] 3.3 mmHg (mean [underline]+[/underline] SD) in the increment group and 29.4 [underline]+[/underline] 5.3 in the no-increment group (p=0.064). The [Delta]ETCO[sub]2 [/sub]was 13.0 [underline]+[/underline] 5.3 and 14.0 [underline]+[/underline] 5.3, respectively (p=0.622). The 5min-ETCO[sub]2[/sub] was 28.2 [underline]+[/underline] 4.8 and 24.8 [underline]+[/underline] 5.9, respectively (p=0.077)., In this study, the frequency of interictal spikes was increased in the cases of more than half of the patients with temporal lobe epilepsy. The increments may have not the association with the ETCO[sub]2[/sub] level or the change of that, but maybe with the individual susceptibility.,