Emanuel Wenger

The human corpus callosum and the controversy about a sexual dimorphism

The human corpus callosum was investigated with regard to sexual dimorphism by means of morphometry. At the macroscopical level, no part of the corpus callosum showed significant differences between the sexes. The concept that sex-related functional hemispherical discrepancies are correlated with the gross anatomy of the human corpus callosum was not confirmed.

Transcallosal approach to the third ventricle: normative morphometric data based on magnetic resonance imaging scans, with special reference to the fornix and forniceal insertion.

OBJECTIVE The ability to visualize median-sagittal brain structures by magnetic resonance imaging (MRI) improves the planning for surgical removal of lesions located in and around the third ventricle. The transcallosal approach is the most appropriate path to the anterior part of the third ventricle. The present study was undertaken to obtain normative morphometric data, derived from sagittal MRI scans, which are necessary for operation planning that takes into account the surgical microanatomy and landmarks encountered during this approach. METHODS The morphometric evaluation was performed on 72 median-sagittal MRI scans. The surface landmarks for the corridor were the two points, P5 and P7, located 5 and 7 cm anterior to the central sulcus, respectively. With these two points on the cortical surface as references, a variety of measurements were made to provide quantitative information about distances between brain structures encountered during the surgical approach. In addition, various parameters were determined to characterize the different shapes of the fornix and the different types of forniceal insertion. RESULTS The following measurements (means) were obtained: 1) the distance between P5/P7 and the cingulate sulcus was 25.76 mm (range, 17.113-42.73 mm) with reference to P5, and 25.41 mm (range, 12.91-36.29 mm) with reference to P7; 2) the distance between the cingulate sulcus and the corpus callosum was 12.91 mm (range, 7.19-22.60 mm) with reference to P5, and 12.92 mm (range, 6.75-23.37 mm) with reference to P7; 3) the height of the corpus callosum was 6.22 mm (range, 3.07-9.00 mm) with reference to P5, and 6.92 mm (range, 3.50-13.57 mm) with reference to P7; 4) the distance between the anterior commissure and the foramen of Monro was 6.78 mm (range, 1.86-14.57 mm), independent of P5 and P7; 5) the distance between the lower margin of the corpus callosum and the upper insertion point of the fornix was 12.44 mm (range, 2.71-26.13 mm) with reference to P5, and 13.34 mm (range, 3.74-27.58 mm) with reference to P7; 6) the distance between the lower margin of the corpus callosum and the lower insertion point of the fornix was 18.08 mm (range, 9.47-29.71 mm) with reference to P5, and 18.58 mm (range, 10.48-30.40 mm) with reference to P7; and 7) the distance between the lower margin of the corpus callosum and the anterior commissure was 23.46 mm (range, 11.98-32.70 mm) with reference to P5, and 22.89 mm (range, 11.05-33.04 mm) with reference to P7. Four different insertion types between the fornix and the corpus callosum were noted and classified. CONCLUSION Morphometric data concerning the surrounding structures of the third ventricle have received very little attention in the literature. This morphometric study permitted definition of the surgical corridor to the third ventricle by preserving important anatomic structures such as the motor strip, genu of the corpus callosum, forniceal commissure (hippocampal commissure), anterior commissure, and forniceal columns. The detailed morphometric data obtained on median-sagittal MRI scans of the brain structures involved in the transcallosal interforniceal and/or transcallosal transforaminal approach allow for exact planning of the surgical approach.

Subtemporal approach to the tentorial incisura: normative morphometric data based on magnetic resonance imaging scans.

OBJECTIVE: The tentorial notch can be contained within a transversal line made in front of the cerebral peduncles and another line through the posterior border of the quadrigeminal plate into the anterior, middle and posterior parts. Different approaches to the tentorial incisura have been established. The subtemporal approach represents one of those options. Since morphometrical analyses of this approach in this region have not yet been performed, the aim of the present study was to measure the surgical corridor along these borders. METHODS: Fifty-three magnetization prepared rapid acquisition gradient echo-sequences of individual brains without pathological lesions were analyzed. For this study, an axial section along the pontomesencephalic sulcus and two coronal sections along the above-described borders were measured using a program specially written by one of the coauthors to obtain various parameters. A triangle circumscribing the surgical corridor was delimited by exactly defined anatomic landmarks for the coronal section, and the depths of the temporal lobe at the incisural borders were measured for the axial section. RESULTS: Various data are given concerning the surgical corridor of a subtemporal approach to the tentorial incisura. The different shapes of this corridor to the incisural region were recorded. According to our measurements, four different types of the temporal lobe could be differentiated. CONCLUSION: Knowledge of these distances and various contours of the path is crucial to avoid brain damage during retraction or manipulation. The curvature of the floor of the middle cranial fossa is highly variable and thus determines the surgical path chosen.

The Reflection of Cognitive Tasks in EEG and MRI and a Method of Its Visualization

SummaryUp until recently, neurology was dominated by localisatory thinking. Language and other so-called“centers” were considered to be centers of command controlling the respective functions. Today, there is general agreement that, instead, for every brain function numerous brain regions must act together. For the exploration of these manifold topographic cooperations produced by cognitive tasks, coherence of long-term EEG periods proved to be a proficient parameter for the representation of functionally essential connections. Because of the unequivocal meaningfulness of absolute coherence values, instead, only the signs of significant differences between coherence values during cognitive tasks and periods of EEG at rest before and after the task were considered for all possible electrode pairings and charted on schematic maps of the brain. In addition, the signs of significant changes of amplitude were entered. This procedure was performed for each of 6 frequency bands and for the 19 electrodes of the 10/20 system, thus yielding 171 possible plus or minus values for coherence and 19 for amplitude, respectively. The positions of the electrodes were marked by an MRI contrast medium. After the EEG, MRI examination was performed. The MRI data were segmented and the cortex was mapped onto a plane using a method similar to cartography. The exact electrode positions are registered from a similarly obtained map of the scalp and the electrode position pattern is used as basis for the coherence graphs. A detailed map of the cortex based on the segmented MRI data with the electrode positions marked is provided as a reference enabling allocation of the electrodes to the cortical structures. The usefulness of this procedure is demonstrated with a single subject by means of different cognitive tasks including musical thinking.

Transforming Eulerian trails

Abstract In this paper a set of transformations (κ-transformations) between eulerian trails is investigated. It is known that two arbitrary eulerian trails can be transformed into each other by a sequence of κ-transformations. For compatible eulerian trails the set of κ-transformations is augmented by the set of κ-detachments and κ-absorptions. This augmented set is capable of transforming two arbitrary P -compatible eulerian trails ( P is an edge partition system) into each other. This result is applied to A -trails, alternating eulerian trails and digraphs.

Collagen dysplasia in idiopathic carpal tunnel syndrome.

Surgical biopsies of dissected transverse carpal ligaments of patients with idiopathic carpal tunnel syndrome were examined with an electron microscope revealing collagen fibrils with extremely varying diameters. Morphometric analysis was performed on electron micrographs exhibiting fibrils with a small diameter comparable to that in control tissue as well as fibrils with a far larger diameter than could be observed in control tissue. Morphometric parameters were evaluated in order to analyse the relation between the number of and the area covered by collagen fibrils in the electron micrographs. In control tissue the numerical density per image area was twice the numerical density in carpal tunnel syndrome. However, the area fraction of the electron micrographs occupied by collagen fibrils in carpal tunnel syndrome and controls were equal.

Morphometric Analysis of Collagen Fibrils in Idiopathic Carpal Tunnel Syndrome

Surgical biopsies of dissected transverse carpal ligaments of patients with idiopathic carpal tunnel syndrome were examined with an electron microscope revealing collagen fibrils with varying diameters. Morphometric analysis of transversely cut collagen fibrils was performed on photomicrographs exhibiting fibrils with a small diameter comparable to that in normal tissue as well as fibrils with a large diameter that could not be observed in normal tissue.

Surgery of the anterior part of the frontal lobe and of the central region: normative morphometric data based on magnetic resonance imaging

Modern magnetic resonance imaging (MRI) techniques have improved the planning of surgery to remove lesions in or around the frontal lobe. Since MRI-based morphometric analyses of the anterior part of the frontal lobe and the central region as part of it have not yet been performed, the present study was undertaken to obtain relative normative morphometric data. Median sagittal MRI scans from 53 magnetization prepared rapid acquisition gradient echo (MPRAGE) sequences of individual brains without pathological lesions were analyzed. The AC-PC line (anterior commissure-posterior commissure line) with vertical lines through the AC and PC were chosen as reference lines. Measurements of the anterior part of the frontal lobe included distances between different landmarks (frontal pole, tuberculum sellae, AC, outer point and inner surface of the genu of the corpus callosum, and the cortex at this level). For the measurements around the central region distances were obtained from the following landmarks: coronal suture, central sulcus, marginal sulcus, intersection point of the vertical line through the PC with the cortex, and PC. Knowledge of these distances will allow exact planning of surgical approaches to the anterior part of the frontal lobe, for example, the subfrontal or anterior interhemispheric approach and surgery around the central region.

Colorability of Planar Graphs with Isolated Nontriangular Faces

Abstract.By a hole graph we mean a 2-connected planar graph where no two nontriangular faces have a vertex in common. We give necessary and sufficient conditions for a hole graph to be 3-colorable.

Image Analysis for Dating of Old Manuscripts

This paper presents an application of digital image processing to historical sciences. A major tool for dating old undated documents are watermarks found in the paper. Hardcopies of the watermarks are scanned, preprocessed, improved and contrast enhanced by adaptive digital filtering methods for printing, storing in an image database, and extracting the watermark as a set of strokes from the image. For extraction, a semiautomatical procedure is suggested. The extraction result is a short sequence of cubic spline curves representing the watermark fully and allowing to select identical or similar watermarks from the existing database.