Sensitivity of Ictal Spect and Variables to affect this in the Presurgical Evaluation of Medically Intractable TLE Patients

ABSTRACT

BACKGROUND & OBJECTIVE: We did this study to evaluate the sensitivity of ictal SPECT in the presurgical evaluation of medically intractable TLE patients and 1,o know the variables to affect the results of ictal SPECT. METHODS: Ictal SPECT studies were performed in 49 medically intractable TLE patients and the results compared to the final anterior temporal lobectomy sites. Also, we have evaluated the effect of injection time of 99m7c-HMPAO and the presence of secondary generalization on the result of ictal SPECT. Results: In 43/49 (87.8%) patients, increased temporal perfusion of ictal SPECT was concordant to the estimated side of seizure origin. But in 6/49 (12.2%) patients, ictal SPECT studies were incorrect (2 patients - contralateral temporal increased perfusion, 1 patient - bilateral temporal increased perfusion, 1 patient ipsilateral but frontal increased perfusion, 2 patients - no significant perfusion change) Forty-two of forty-four (95.5%) patients in whom true ictal studies were done showed increased temporal perfusion in the final surgery sites. But only one of five patients with postictal injection correctly identified the site of focus. In all eight patients with secondary generalized convulsion and ictal injection, the ictal SPECT studies showed Increased temporal perfusion concordant to the final surgery site. Conclusions: Ictal SPECT studies were very sensitive and useful in the presurgical evaluation of medically intractable TLE patients especially when they were done during the ictal state. Whether generalization occurred or not did not seem to affect the ictal SPECT findings. And this study suggests that if ictal SPECT are used appropriately along with video-EEG monitoring, brain MRI, and other noninvasive studies, many patients can avoid invasive studies.