Abstract
The impact of previous surgery on the assessment of language dominance with preoperative fMRI remains inconclusive in patients with recurrent brain tumors. Samples in this retrospective study included 17 patients with prior brain surgery and 21 patients without prior surgery (38 patients total; mean age 43.2, SD = 11.9; 18 females; seven left-handed). All the patients were left language dominant, as determined clinically. The two samples were matched on 10 known confounds, including, for example, tumor laterality and location (all tumors affected Brodmann areas 44/45/47). We calculated fMRI language dominance with laterality indices using a whole-brain and region of interest approach (ROI; Broca’s and Wernicke’s area). Patients with prior surgery had decreased fMRI language dominance (p = 0.03) with more activity in the right hemisphere (p = 0.03) than patients without surgery. Patients with prior brain surgery did not display less language activity in the left hemisphere than patients without surgery. These results were replicated using an ROI approach in the affected Broca’s area. Further, we observed no differences between our samples in the unaffected Wernicke’s area. In sum, prior brain surgery affecting Broca’s area could be a confounding factor that needs to be considered when evaluating fMRI language dominance.
Highlights
We found that patients with prior surgery had lower language laterality values and more activity in the right hemisphere than patients with no prior surgery
This study examined the impact of previous brain surgery on functional magnetic resonance imaging (fMRI) language dominance, independent of known confounds
We compared two groups of patients with left hemisphere language dominance who were diagnosed with brain glioma s around the inferior frontal gyrus: patients who had undergone prior glioma resection and had recurrent brain gliomas and patients who had not yet had initial brain surgery
Summary
Several confounds have been shown to affect the estimates of language dominance in individuals with brain tumors around the language cortex of the language-dominant hemisphere, as shown by presurgical functional magnetic resonance imaging (fMRI). These confounds include, for example, tumor grade, tumor size, tumor location (i.e., anterior versus posterior language sites), age of tumor onset (e.g., pediatric versus adult), history of seizures, and presence of aphasia [1,2,3,4,5,6,7]. All of these variables need to be taken into consideration to correctly interpret the results of preoperative language fMRI [8,9]
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