Epilepsia, 51(4):639–646, 2010 doi: 10.1111/j.1528-1167.2009.02421.x
FULL-LENGTH ORIGINAL RESEARCH
Cortical stimulation for language mapping in focal epilepsy: Correlations with tractography of the arcuate fasciculus *yBeate Diehl, yZhe Piao, zJean Tkach, yRobyn M. Busch, xEric LaPresto, #yImad Najm, yBill Bingaman, {John Duncan, and #Hans Lu¨ders *Department of Clinical Neurophysiology, The National Hospital for Neurology and Neurosurgery, London, United Kingdom; yEpilepsy Center, Cleveland Clinic, Cleveland, Ohio, U.S.A.; zDepartment of Radiology, University Hospitals, Cleveland, Ohio, U.S.A.; xBrain Tumor Institute, University of Cincinnati, Cincinnati, Ohio, U.S.A.; {Institute of Neurology, University College London, London, United Kingdom; and #Epilepsy Center, University Hospitals, Cleveland, Ohio, U.S.A.
SUMMARY Purpose: Diffusion tensor imaging (DTI) provides information about magnitude (diffusivity) and directionality (fractional anisotropy, FA) of water diffusion and allows visualization of major white matter tracts. The arcuate fasciculus (AF) connects anterior (Broca’s) and posterior (Wernicke’s) language areas. We hypothesized that essential language areas identified by direct cortical stimulation would colocalize with areas revealing subcortical connectivity via the AF. Methods: Fourteen patients with pharmacoresistant left hemispheric epilepsy and left hemisphere language dominance underwent invasive evaluations for localization of epileptogenicity and functional mapping. DTI and T1weighted volumetric magnetic resonance imaging (MRI) scans were coregistered, and subdural grid electrodes identified on postimplantation computed tomography (CT) scans were also coregistered to the MRI scans. The
Language function was classically thought to be mediated by two cortical regions in the left hemisphere: Broca’s area for speech production (Broca, 1861) and Wernicke’s area for speech comprehension (Wernicke, 1874). These areas are connected via the arcuate fasciculus (AF), a fiber pathway curving around the sylvian fissure that links the temporal and frontal language areas (Dejerine, 1895). The AF is considered to be a major component of the perisylvian language network (Catani & Mesulam, 2008). Accepted October 13, 2009; Early View publication December 7, 2009. Address correspondence to Dr. Beate Diehl, Department of Clinical Neurophysiology, National Hospital of Neurology and Neurosurgery, Box 141, Queen Square, WC1N 3BG, London, United Kingdom. E-Mail:
[email protected] Wiley Periodicals, Inc. ª 2009 International League Against Epilepsy
AF was reconstructed from a region lateral to the corona radiata on the FA map. Colocalization, defined as
