REDUCED DEGREE OF LANGUAGE DOMINANCE IN LEFT HEMISPHERE LOCALIZATION RELATED EPILEPSY ASSESSED BY A fMRI READING COMPREHENSION TASK
Abstract number :
1.247
Submission category :
Year :
2003
Submission ID :
1932
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
William D. Gaillard, Bonnie C. Sachs, Lyn M. Balsamo, Ben Xu, Madison M. Berl, Cecile B. Grandin, Phillip L. Pearl, Joan A. Conry, Steven L. Weinstein, Frank J. Ritter, Susumu Sato, William H. Theodore Neurology, Children[apos]s National Medical Center, W
fMRI provides a non-invasive means to assess the association of epilepsy and the re-organization of language networks. We investigated the extent of language dominance in patients with left hemisphere localization related epilepsy using a fMRI reading comprehension task.
We studied 30 patients (24 right handed, three left handed, three ambidextrous; 17 M, 13 F; aged 8.7-56 years (mean age 21.1 years; mean age seizure onset 9.6 years)), and 32 healthy volunteers (all right handed; 17 M, 15 F; aged 7.9-34.8 years (mean age 22.4 years)), using whole brain 1.5T fMRI (EPI BOLD) and a covert reading task -- naming to description-- employing a box car design. Data were analyzed with a region of interest analysis from t-maps. The number of activated voxels was determined in inferior frontal gyrus (IFG), mid-frontal gyrus (MFG), and Wernicke[rsquo]s area (WA), using a semi-automated program. An asymmetry index (AI) was calculated [(L-R)/(L+R)] for each region at t=4. fMRI language laterality was defined as |AI| [gt]0.20. Groups were compared using unpaired t-tests.
Seven of 30 patients had atypical (bilateral or right hemisphere dominant) language representation (23.0%). Regional AIs for patients were less than controls (IFG: 0.80 vs. 0.43; MFG: 0.94 vs. 0.34; WA: 0.84 vs. 0.47; all p[lt]0.005); Excluding atypical language patients (IFG: 0.13 MFG: -0.04; WA: -0.02), AIs for left hemisphere focus/left hemisphere dominant patients remained lower than for controls (IFG: 0.51 MFG: 0.45; WA: 0.59; all p[lt]0.02). Motion measures did not differ between groups.
Patients with left hemisphere localization related epilepsy have a greater likelihood of atypical language representation. Lower regional AIs in left dominant patients suggests increased recruitment of homologous right areas for language processing compared with healthy controls.
[Supported by: NINDS KO8-NS1663, NICHD P30HD40677, NINDS R01 NS44280, Clinical Epilepsy Section, NINDS,NIH]