Correlation between inter-ictal regional cerebral blood flow and sphenoidal electrodes--recorded inter-ictal spikes in mesial temporal lobe epilepsy

The objective of this study was to assess the reliability of the diagnosis of mesial temporal lobe epilepsy using EEG and sphenoidal electrodes. Inter-ictal 99 m Tc-HMPAO SPECT scans were registered in 21 patients with confirmed mesial temporal lobe epilepsy identified by scalp EEG and sphenoidal electrodes. Visual and quantitative SPECT analysis was performed blind to EEG data. An asymmetry index (AI) was measured from the ratio of two symmetrical regions of interest. A temporal lobe hypoperfusion was defined as an uptake reduced by 5% with respect to the contralateral region. Inter-ictal SPECT abnormalities were observed in 12 out of 21 patients (57%) from both visual and quantitative analysis (focal hypoperfusion in 11 cases, focal hyperperfusion in one case). In seven patients (33%) both visual and quantitative scintigraphy were normal. Abnormal AI was found in 11/15 patients with a high frequency of seizures and in 1/6 patients with a low frequency of seizures. The major data is that the probability to have an abnormal SPECT is statistically correlated to the frequency of the epileptic fits. The couple EEG recordings with sphenoidal electrodes and SPECT is sensitive and reliable in the diagnosis of mesial temporal lobe epilepsy.