gms | German Medical Science

Objective: In case of surgery in the supramarginal gyrus attention has to be paid to avoid aphasia, because a language area and the arcuate fasciculus is located there. Adjacent areas are important for calculation and writing. With fMRI these areas can be localized.

Method: Preoperative functional imaging with fMRI was performed. For fMRI we used a 1.5T MR scanner with echo planar imaging (Sonata, Siemens Medical Solutions) and a block paradigm with 180 measurements in 6 blocks (rest alternating with activation, 25 slices, 3 mm thickness & resolution TR=2470, TE=60). During the activation intervals patients had to perform language tasks, writing tasks and arithmetical exercises presented visually. Correlation maps were calculated and merged with 3D-MR maps. DTI was used with 1.9 mm slices and 6 directions to reconstruct fibre connections of language areas. Repeated language- and calculation tests were conducted pre- and postoperatively to rate the recovery of neurological function. Intraoperative MRI was used and registered to the functional images to show the extent of resection, the brain shift and an update of the relation to functional structures.

Results: 51 patients with lesions in the lateral parietal lobe were examined with mapping of language-, calculation- and writing function areas. 41 of these underwent resective surgery and 5 only biopsy. We were able to localize language areas and calculation areas in all patients; As a consequence of lesions in the lateral parietal lobe the following deficiencies were observed: errors in sequence and selection of phonemes (errors in letters of words), disability of add or subtract numbers, distortions or disability in writing. Subsequently to the surgery, 19 patients experienced worsening or new such kind of deficiencies. These deficiencies resolved a few days after surgery in all cases except of one patient, whose mild phonem selection error persisted. In one patient language improved after surgery compared to the presurgical state.

Conclusions: It is advisable to conduct functional mapping including language tasks, writing tasks and arithmetical exercises to perform save surgery with maximized tumour removal.