Functional MRI during verbal fluency test in patients with left hemisphere pathology: a part of surgery planning
Abstract
Functional magnetic resonance imaging (fMRI) was used for pre-surgical mapping of brain verbal processing in patients suffering from left hemisphere lesion. A file of patients contained 25 subjects divided into two groups according to the age: the group of young patients of 9-21 years and the group of older patients of 23-72 years.
A word generation with the verbal fluency test was used to stimulate brain verbal areas. Functional activations were qualitatively compared with standard functional maps measured on the group of healthy volunteers.
These standard maps showed 3 main clusters of active voxels in the left hemisphere (a group statistic was performed on both 10 right-hander subjects and separately 5 left-hander subjects). We found higher number of bilaterally activated clusters and also of complete inter-hemispherical shift in patients with left hemisphere lesion compared to normal population.
In group of young patients, there were 27 % of bilateral activations found in some of 3 standard functional locations and in 12 % even complete shift to the right hemisphere was observed. Some bilateral activation was found only in 17 % in the group of older subjects.
Our study confirms higher probability of bilateral verbal activation or even shift of activity from the left to the right hemisphere in young patients at least in some participating verbal area.