gms | German Medical Science

Objective: Pre-surgical assessment of language critical brain regions in patients suffering from tumors in those areas is crucial for pre-surgical planning to enhance postoperative health-related quality of life and prognosis. The sensitivity and specificity of the pre-surgical prediction of language laterality and determination of language critical areas depend to a high degree on the choice of language paradigms. This study explored the differences between a verb and a syntax generation paradigm in pre-surgical language mapping for patients with gliomas in the eloquent cortex.

Methods: To assess the difference between the two language paradigms, a total of 67 patients with brain tumors in language associated areas of the left hemisphere and 34 healthy subjects were included. Patients were further stratified according to tumor localization in a frontal (N=34) and a temporoparietal group (N=33). During the language fMRI paradigm subjects performed covertly a verb (VG) and a syntactic (SG) generation task. Data analysis was done by using SPM 12 including the Marsbar toolbox and the Automated Anatomical Labeling Atlas for region of interest (ROI) definition and analysis. Individual laterality indices (LI) for frontal, temporal and parietal ROIs were calculated using the Laterality toolbox included in SPM12 for each language.

Results: In healthy subjects, when compared to VG, SG led to more bilateral activation, more activation in left superior temporal gyrus (STG) and increased activation in the left inferior frontal gyrus. Patients with tumors in left frontal areas also showed more bilateral activation during SG than during VG as well as enhanced activation in the left temporal lobe, especially the left STG. In patients with temporoparietal tumors, SG led to an increased bilateral activation pattern in comparison to VG. Based on a parietal defined ROI, the medians of laterality indices of VG led to significantly higher LIs as compared to SG in healthy subjects and patients with frontal tumors. In the group of temporoparietal patients, the median LIs for VG were significantly higher than those for SG based on a frontal ROI.

Conclusion: The results suggest that VG determines language laterality better than a syntax generation task, while SG is more sensitivefor inducing language associated activation in the temporal lobe. The combination of both paradigms may achieve a complete mapping of language critical areas and valid identification of language laterality.