One atlas - Three anatomies: Relationships of the Schaltenbrand and Wahrenmicroscopic data

The stereotaxic atlas of Schaltenbrand and Wahren is widely used for orient ation in functional neurosurgery of the human diencephalon. As the sagittal , frontal, and horizontal microscopic series were gathered from three diffe rent cerebral hemispheres, loci with the same ACPC (anterior commissure-pos terior commissure) coordinates are not exactly anatomically corresponding. We compared the 3-D position of 21 anatomical structures in the three serie s based on their digitally interpolated solid Volume representations. Regre ssion analysis of the centres of gravity revealed strong linear correlation s beween series (0.944 less than or equal to Pearson's r less than or equal to 0.976, alpha < 0.0001). Thus calculation of anatomically corresponding sites based on the regression equations seems justified. Volumetry revealed that the sagittally sectioned thalamus is approximate to 10% larger than t he frontally and 40% larger than the horizontally sectioned thalamus. So as to match it to the sagittal series, the frontal series has to be widened i n lateral direction by 19%, in anteroposterior and dorso-basal (vertical) d irection it has to be compressed by 5 and 9%, respectively. In contrast, th e distance of structures from the midline in the horizontal and sagittal se ries is very similar. The horizontal series is, however, 25% smaller than t he sagittal one in anteroposterior and 17% in vertical direction. On averag e, thalamic nuclei in the right hemisphere of brain LXXVIII (horizontal mic roscopic series) were located 2 mm more anterior as compared with the left side (sagittal series), which fact may be explained by difference in size a nd/or asymmetry. Spatial overlap between corresponding thalamic nuclei from the three series amounted to only 0-28% when superimposed in the ACPC refe rence space. Linear transformation towards an average red to significant in crease (0-37%, p < 0.001) of the overlap and ameliorated the quality of the fit of thalamic borders. Limited increase of the overlap is in part due to pronounced differences in the size of thalamic nuclei between the series.