Objective and Methods:

In order to assess the reliability of ictal SPECT in the preoperative evaluation, 9 children aged from 3 months to 10 years and having partial epilepsy or infantile spasms, underwent ictal SPECT with video-EEG and interictal SPECT plus 3D-MRI two days later. ^(99m)Tc-ECD was injected at a mean 15 seconds after seizure onset. Ictal and interictal images were superimposed, normalized, and substraction images superimposed on MRI.

Results:

Seven partial seizures and 2 epileptic spasms (ES) were recorded on EEG. Hyperperfused foci concordant with EEG were found in only 2 cases by visual inspection of ictal SPECT but in 6 cases using ictal-to-interictal-substraction (2 temporal, 2 parietal, 2 central). Additional hyperperfused foci were found in 4 of them (2 central, 2 parieto-temporo-occipital). Two patients underwent electrocorticography using subdural strips. The hyperperfused foci corresponded to the onset and the propagation of seizures. Cortical hyperperfusion was not detectable in the 3 patients having seizures lasting less than 10 seconds; the 2 patients with ES exhibited hyperperfusion only in subcortical structures.

Conclusion:

Ictal SPECT is a useful technique for localizing seizure discharges and preparing deep investigations in surgical childhood epilepsies particularly when using ictal-to-interictal-substraction images.