Identifizierung von eloquenten Kortexarealen der nicht-dominanten Hemisphäre mittels funktioneller transkranieller Dopplersonographie: Überprüfung einer mentalen Rotationsaufgabe und eines Memoryparadigmas

Rationale: Functional transcranial Doppler sonography (fTCD) during word generation is well established for language lateralization. In this study, we evaluated an fTCD-paradigm to reliably identify the non-dominant hemisphere. Methods: Twenty-nine right-handed healthy subjects (27.1 ± 7.6 years) performed the ‘cube perspective test’ (Stumpf & Fay, 1983), a spatial orientation task, while the cerebral blood flow velocity (CBFV) was simultaneously measured in both middle cerebral arteries (MCA). In addition, the established word generation paradigm for language lateralisation was performed. Subjects with atypical language representation were excluded. Data were analysed offline with the software Average®, which performed a heart-cycle integration and a baselinecorrection and calculated a lateralization index (LI) with its standard error of the mean increase in CBFV separately for both MCA. Results: Twenty-one of 29 subjects (72.4%) lateralized to the right hemisphere (χ²=5.828, p=0.016). The mean LI of the spatial orientation paradigm pointed to the right hemisphere (x¯ = -1.9 ± 3.2) and was different from the LI of word generation (x¯ = 3.9 ± 2.2; p<0.001). There was no correlation between the LI of spatial orientation and word generation (R=0.095, p=0.624). Age of the subjects did not correlate with the LI during spatial orientation (p>0.05) but negatively with the LI during word generation (R=-0.468, p=0.010). The maximum increase of CBFV was greater in the spatial orientation (14.0% ± 3.6%) than in the word generation paradigm (9.4% ± 4.0%; p<0.001). Conclusions: In more than two thirds of the subjects with left-sided language dominance, the spatial orientation paradigm was able to identify the non-dominant hemisphere. The results suggest both paradigms to be independent of each other. The spatial orientation paradigm, therefore, appears to be a non-verbal fTCD paradigm with possible clinical relevance.