Cerebrovascular Reactivity (CVR) in mesial Temporal Lobe Epilepsy (mTLE)

Epilepsy surgery can achieve excellent outcomes with regards to seizure freedom in patients with intractable temporal lobe epilepsy. This is contingent upon accurate pre-operative localization of the epileptogenic zone. Cerebrovascular reactivity refers to the blood vesselsâ response to vasoactive stimuli. We hypothesized that cerebral vasculature in epileptogenic tissue have impaired reactivity that can be detected with CVR imaging. Methods: we acquired fMRI images in unilateral mesial TLE patients (n=13) who had undergone pre-surgical investigations for seizure localization, while changes in arterial carbon dioxide were induced. CVR datasets for 12 healthy volunteers who had undergone an identical study protocol were retrieved from a pre-existing database. Results: We report significantly increased CVR in the epileptogenic posterior and middle cingulate cortices compared to the contralateral hemisphere within the patient group. Conclusions: Our data suggest that CVR is altered in regions ipsilateral to the epileptogenic zone. Impaired CVR in the PCC has significant implications for the interpretation of fMRI studies in TLE patients.M.Sc