Language Localization with Functional Magnetic Resonance Imaging for Neurosurgical Planning

The overall purpose of this study is to evaluate the effectiveness of functional MRI (fMRI) for determining language laterality/localization  and the functional integrity of mesial temporal lobe structures (primarily the hippocampus and related areas) in both healthy adults and persons with a variety of neurological conditions, primarily epilepsy.  The risk of post-surgical language deficits is related to the pre-surgical lateralization and localization of language and with a priori information about language localization we can potentially help avoid surgically acquired language deficits.  Similarly, in those individuals undergoing surgery for medial temporal lobe epilepsy, the risk of post-surgical changes in memory and learning is related to the functional integrity of both the hippocampal structure that will remain in tact, as well as the function of the hippocampus that is resected.  The current method for language lateralization and the assessment of mesial temporal lobe structures is the Wada test. This test is an invasive procedure in which sodium amytal (an anesthetic) is injected in to the left or right internal carotid artery in order to selectively anaesthetize each cerebral hemisphere.   Laterality is determined according to the performance of language tasks while a given hemisphere is anaesthetized.  Functional MRI is a promising noninvasive procedure that has shown good concordance with the Wada test in previous studies.  However, the correlations between fMRI data and the Wada test have not been perfect and further, the Wada does not provide localizing information (i.e. what areas within one hemisphere are critical for language).  One difficulty in evaluating the effectiveness of fMRI from previously published data is that very few studies use the exact same fMRI protocol.  This protocol is intended to evaluate a set of language and memory tasks as well as analyses procedures for the purpose of language and memory localization and lateralization.  The work will require scanning of normal subjects and selected patients.