Correlation of ictal EEG and SPECT studies in patients of intractable epilepsy with normal MRI.

Identification of the epileptic focus is the most important requirement for a successful surgical outcome in intractable epilepsy. Patients with normal MRI on high-resolution imaging pose a significant challenge in this regard. We tried to identify the epileptic focus using interictal / ictal SPECT and ictal EEG patterns in 14 patients with normal MRI. Rhythmic ictal onset activity helped to identify a single focus in 10 patients (71.43%). Inter ictal SPECT detected a focus corresponding to ictal EEG in 6 out of 10 patients (60%) in whom the test was performed. Ictal SPECT done in 5 patients correctly identified the focus in all patients (100%). Our data indicate that it is possible to obtain localization in patients with normal MRI using a combination of ictal EEG patterns and an ictal SPECT study.