Cerebral SPECT in partial epilepsy

Effective surgical treatment of patients with medically intractable complex partial seizures depends on accurate preoperative localization of the seizure focus. 99mTc-HMPAO brain SPECT could assist us in localizing the epileptic foci showing focal hypoperfusion on interictal SPECT and hyperperfusion on ictal SPECT.

Methods: Video-EEG monitoring, MRI, as well as interictal and peri-ictal brain SPECT were performed on 37 patients with refractory epilepsy. Ictal brain SPECT was performed on 14 patients and in the remaining 23 patients a postictal SPECT was obtained. Video-EEG was used as the gold standard procedure for localizing the seizure focus and was compared to the interictal and peri-ictal brain SPECT results. Twenty-four patients suffered from temporal lobe epilepsy and 13 had extratemporal seizures.

Results: Interictal brain SPECT correctly localized the seizure focus in 43% of the patients (58.3% of the patients with temporal lobe seizures and 15.4% of the patients with extratemporal seizures). Ictal SPECT correctly identified the seizure focus in the 93% of cases (100% of the patients with temporal lobe seizures and 75% of the patients with extratemporal seizures). Finally, 52% of the patients were correctly identified with postictal SPECT (71.4% of the patients with temporal lobe seizures and 22.2% of the patients with extratemporal seizures).

Conclusions: Our findings suggest that interictal brain SPECT could assist in the localization of temporal lobe seizures. Tracer injection during seizure or immediately after it (peri-ictal SPECT) is the method of choice for SPECT imaging aimed at the non-invasive localization of seizure focus.