Hypometabolism and interictal spikes during positron emission tomography scanning in temporal lobe epilepsy

To study the influence of interictal spikes on (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET), EEG monitoring was performed during PET scanning in 21 patients with temporal lobe epilepsy. Asymmetry indices were calculated in the polar, mesial, anterior-lateral, mid-lateral and posterior-lateral temporal region of interests of FDG-PET (PET-AI). 70.7% of spikes were recorded with their maximum at the anterior temporal region (F(7), F(8), FT(9), FT(10)), 29.3% at mid-temporal (T(7), T(8)), and none at posterior temporal region (P(7), P(8)). Regardless of the side of epileptic focus, right-left difference of the total spikes had a significant negative correlation with right/left PET-AIs of the anterior-lateral temporal region (Spearman's rho = -0.565, p = 0.009), polar (rho = -0.500, p = 0.021) and whole temporal region (rho = -0.480, p = 0.028). FDG-PET hypometabolism may reflect not only a permanent functional deficit but also a transient regional cerebral dysfunction related to the occurrence of interictal spikes.