Ictal hyperperfusion of cerebellum and basal ganglia in temporal lobe epilepsy: SPECT subtraction with MRI coregistration

The ictal hyperperfusion (compared with the interictal state) of the cerebe llum and basal ganglia has not been investigated systematically in patients with temporal lobe epilepsy (TLE). Their ictal perfusion patterns were ana lyzed in relation to temporal and frontal hyperperfusion during TLE seizure s using SPECT subtraction. Methods: Thirty-three TLE patients had intericta l and ictal SPECT, video-electroencephalographic (EEG) monitoring, and volu metric MRI. SPECT subtraction with MRI coregistration was performed using c ommercial software. The presence of ictal hyperperfusion was determined in the ipsilateral and contralateral temporal lobe, frontal lobe, cerebellum a nd basal ganglia. Results: All patients showed ictal hyperperfusion in the temporal lobe of seizure origin. Vermian cerebellar hyperperfusion (CH) was observed in 26 patients (78.8%) and hemispheric CH was found in 25 (75.8%) . Compared with the side of the epileptogenic temporal lobe, there were 7 p atients with ipsilateral hemispheric CH (28.0%), 15 with contralateral hemi spheric CH (60.0%), and 3 with bilateral hemispheric CH (12.0%). CH was obs erved more frequently in patients with additional frontal hyperperfusion (1 4/15, 93.3%; 2 ipsilateral to the seizure focus, 10 contralateral, and 2 bi lateral) than in patients without frontal hyperperfusion (11/18, 61.1%). Am ong 18 patients with temporal hyperperfusion without frontal hyperperfusion , 11 patients showed hemispheric CH (5 ipsilateral to seizure focus, 5 cont ralateral, 1 bilateral). Hyperperfusion in the basal ganglia (BGH) was seen in 11 of the 15 patients with temporal and frontal hyperperfusion (73.3%) and in 11 of the 18 with only temporal hyperperfusion (61.1%). In 17 patien ts with unilateral BGH (13 ipsilateral to the seizure focus, 4 contralatera l), CH contralateral to the BGH was observed in 14 (82.5%), CH ipsilateral to the BGH was found in 2 (11.8%), and CH bilateral to the BGH was found in 1 (5.9%). Conclusion: During TLE seizures, hemispheric CH occurred not onl y in contralateral but also in ipsilateral or bilateral cerebellar hemisphe res to the side of seizure origin. Although temporal lobe origin seizures a ssociated with additional frontal hyperperfusion produced more frequent hem ispheric CH, seizures showing only temporal hyperperfusion without frontal hyperperfusion could produce BGH and CH. To determine the side of hemispher ic CH, the most important factor appears to be the side of BGH, not the sid e of seizure origin.