A new method for intraoperative localization of epilepsy focus by means of a gamma probe.

Objective: To evaluate the utility of a new multimodal image-guided intervention technique to detect epileptogenic areas with a gamma probe as compared with intraoperative electrocorticography. Materials and Methods: Two symptomatic patients with refractory epilepsy underwent magnetic resonance imaging, videoelectroencephalography, brain SPECT scan, neuropsychological evaluation and were submitted to gamma probe-assisted surgery. Results: In patient 1, maximum radioactive count was initially observed on the temporal gyrus at about 3.5 cm posteriorly to the tip of the left temporal lobe. After corticotomy, the gamma probe indicated maximum count at the head of the hippocampus, in agreement with the findings of intraoperative electrocorticography. In patient 2, maximum count was observed in the occipital region at the transition between the temporal and parietal lobes (right hemisphere). During the surgery, the area of epileptogenic activity mapped at electrocorticography was also delimited, demarcated, and compared with the gamma probe findings. After lesionectomy, new radioactive counts were performed both in the patients and on the surgical specimens (ex-vivo). Conclusion: The comparison between intraoperative electrocorticography and gamma probe-assisted surgery showed similarity of both methods. The advantages of gamma probe include: noninvasiveness, low cost and capacity to demonstrate decrease in the radioactive activity at the site of excision after lesionectomy. [ABSTRACT FROM AUTHOR]