Article
Correlation of hemispheric dominance of language examined by rTMS and postoperative course of language function in patients with left-sided perisylvian brain lesions
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Published: | June 2, 2015 |
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Objective: The resection of left-sided perisylvian brain lesions is accompanied by the potential hazard of postoperative language deficiency. Hence, the preoperative knowledge of the patient's language distribution would be advantageous for neurosurgeons. Meanwhile, repetitive navigated transcranial magnet stimulation (rTMS) plays an important role concerning the language mapping assessment of patients suffering from lesions within or adjacent to language-eloquent brain regions. In this study we compared the hemispheric dominance ratios (HDR) determined by rTMS language mapping to the patient's pre- and postoperative language function defined by conventional aphasia grading.
Method: We pooled language mapping data of 60 patients with left-sided perisylvian brain lesions scheduled for tumor resection at our two university hospitals. We calculated the error rates (ER = number of errors per number of stimulations) for both hemispheres and defined the HDRs as the quotient of the left- and right-sided ER (HDR > 1 = left dominant; HDR < 1 = right dominant). Preoperatively, five days, and three months after surgery, we evaluated the patient's language function by an aphasia grading adapted from the Aachener Aphasia Test. According to the aphasia grading, we defined different subgroups regarding the patient's course of language function, and correlated them to the preoperative HDR.
Results: We could find a significant difference concerning the HDRs of the patients assigned to the subgroups equal – improved – worse language function (p=0.0484). The means of patients with an equal (1.54 ± 0.9) or improved (1.20 ± 0.75) language function showed a statistically significantly higher HDR than patients within the subgroup "worse" (0.79 ± 0.29). Moreover, as determined by the means of the HDRs, the language dominance of the latter group was right-sided.
Conclusions: According to our results we assume that higher HDRs as determined by preoperative rTMS language mapping correlate with an increased potential for compensatory avenues in case of left-sided perisylvian resections.
Note: Thomas Picht and Sandro M. Krieg contributed equally.