Correlation between provoked ictal SPECT and depth recordings in adult drug-resistant epilepsy patients

To correlate ictal hyperperfusion single-photon emission computed tomography (SPECT) area during provoked seizures to the epileptogenic zone (EZ), as defined by depth recordings in adult drug-resistant patients.

We included in the study eight drug-resistant epilepsy patients, subjected to both noninvasive and invasive (stereo-electroencephalography, SEEG) presurgical evaluation in the Epilepsy Surgery Center of the Catholic University in Rome, from 2001 to 2003. All patients were subjected to interictal and provoked ictal SPECT scans during scalp video-EEG monitoring. The ictal hyperperfusion area assessed by visual image analysis and, when possible, by statistical parametric mapping (SPM), was compared with the EZ, as assessed by SEEG, to define whether they colocalized.

For each provoked seizure, we obtained a SPECT hyperperfusion area. In five patients, the SPECT hyperperfusion area was included in the EZ as assessed by SEEG. The effectiveness of provoked SPECT was confirmed by comparison with SEEG data, SPM analysis (four patients), and spontaneous ictal SPECT (two patients). Our data were obtained in adult drug-resistant epilepsy patients whose EZ was either located in or extended to extratemporal regions in all but two patients.

Provoked ictal SPECT confirmed its efficacy and accuracy in the presurgical evaluation because of the colocalization to the EZ. Although the low number of patients precluded any statistical correlation with the surgical outcome, it is worth pointing out that the five patients in whom the hyperperfusion area was included in the EZ showed very satisfactory results.