Cerebral perfusion during word repetition in epileptic patients

OBJECTIVE: To localize the cortical regions for language in patients who are to have brain surgery. PATIENTS AND METHODS: We made a SPECT (Single Photon Emission using Computerized Tomography) study of cerebral perfusion in 14 patients with drug-resistant temporal epilepsy who were candidates for brain surgery. The patients were selected consecutively from those attending for surgical assessment. We selected the patients in whom two 99mTc-HMPAO studies could be done in the same week: one without sensory stimulation and one whilst listening and repeating a series of ordinary words in fairly frequent use. The two studies were assessed qualitatively (on a 16 colour image scale, with a background subtraction of 20% and standardized to the point of maximum uptake). Changes were considered to be significant when a greater intensity of two colours was localized and semiquantitative (with regular areas of interest, of 4 x 4 pixels, placed on the region in which the qualitative change was observed and referenced to cerebellar activity). RESULTS: We found increased perfusion in the temporo-parietal regions in 11 of the 14 patients. In most (9/14 cases) this was bilateral and in two cases on the left only. We observed a certain predominant pattern: a bilateral increase in temporal perfusion, involving the more anterior regions of the left hemisphere and also the middle and posterior regions of the right hemisphere. The maximum percentage increase in perfusion on semiquantitative assessment was 12%. CONCLUSION: Although the changes seen may correspond to activation in the cortical regions related to different cerebral functions, we consider that with the SPECT technique one may detect changes in perfusion of the regions of the brain which are involved in language processing.