In vivo 3D visualization of normal pyramidal tracts in human subjects using diffusion weighted magnetic resonance imaging and a neuronavigation system.

We describe the potential of anisotropic diffusion weighted imaging to visualize the course of large cerebral fiber tracts. Five healthy volunteers were investigated at a field strength of 1.5 Tesla, employing a spin-echo diffusion weighted sequence with gradient sensitivity in six non-collinear directions to visualize the course of the pyramidal tracts. The pyramidal tracts were segmented and reconstructed for three-dimensional visualization. Reconstruction results together with a fusioned high resolution 3D T1 weighted image data set were available in a customized neuronavigation system. Origination in the primary motor cortex, convergence in the centrum semiovale, the posterior limb of the internal capsule, the cerebral peduncles, the splitting at the level of the pons, and the pyramidal decussation were identified in all subjects. Fiber tract maps might have the prospect of guiding neurosurgical interventions, especially when being linked to a neuronavigation system. Other potential applications include the demonstration of the anatomical substrate of functional connectivity in the human brain.

Collagen fibers in linea alba and rectus sheaths.

BACKGROUND: After the description of a general scheme of the architecture of collagen fibers in linea alba and rectus sheaths, variability and differences of fiber architectures were analyzed to describe their functional role. MATERIALS AND METHODS: Using confocal laser scanning microscopy the diameter of each layer of fibril bundles was measured in linea alba and rectus sheaths of 12 human cadavers, and each fibril bundle was classified according to its orientation (oblique I and II, transverse). RESULTS: The mean diameter of fibril bundles in the supraumbilical region of the linea alba was smaller than in the infraumbilical region, and in the supraumbilical region the thickness of the linea alba was smaller than in the infraumbilical region. Analyzing sex-dependent differences in the fiber architecture of the linea alba, a larger amount of transverse fibers relative to oblique fibers were found in females in infraumbilical regions. The thickness of the infraumbilical linea alba was smaller in females than in males, while its width was larger. CONCLUSIONS: There exist gender differences in the architecture of the linea alba. However, whether these morphological differences demonstrate the adaptability of this fiber architecture to biomechanical stress in raised intraabdominal pressure in pregnancy remains to be proven. The transverse fibers act as a counterpart to the intraabdominal pressure whereas the oblique fibers are involved mainly in movements of the trunk.

Supra- and infrasylvian conduction aphasia.

Fifteen cases of conduction aphasia which were tested with the Aachen Aphasia Test (AAT), are presented. The CT lesion data were transformed to a standard 3D-reference brain referring to the ACPC line. According to the lesion profiles a group of 6 patients had pure suprasylvian lesions, a group of 4 patients had pure infrasylvian lesions, and a group of 5 patients had lesions in both supra- and infrasylvian regions. Suprasylvian conduction aphasics are superior to infrasylvian conduction aphasics in the token test and in repetition tasks. Infrasylvian conduction aphasics use more stereotypes in spontaneous speech than suprasylvian conduction aphasics. Conduction aphasics with both lesion sites perform less well in tests of naming, writing, and comprehension than the pure types. Thus conduction aphasia is a heterogeneous syndrome anatomically and linguistically.

Fuzzy sets in human anatomy.

Artificial intelligence will have a great impact on the rather traditional field of anatomy. Techniques of artificial intelligence can advance anatomical research in a wide range of applications. Fuzzy logic is especially useful in facilitating the use of natural language in the mathematical description of structures or functions. Examples presented demonstrate the broad use of information technology in anatomical applications, including description and classification, knowledge representation, image processing, and three-dimensional anatomical atlases.

Spatial registration of digital brain atlases based on fuzzy set theory.

We present a semiautomatic method based on fuzzy set theory for adjusting a computerized brain atlas to magnetic resonance images (MRIs) of the human cerebral cortex. The atlas was registered to three-dimensional MRI data sets of 10 healthy volunteers. After a global matching using the external contour of the brain, several local procedures were performed regarding selected primary furrows and cytoarchitectonic areas. The final transformation matrix was calculated with respect to these anatomical structures and to their local matrices. Evaluation revealed an increase in accuracy as expressed by a reduction of the visible mismatch with respect to the registration of cortical and subcortical brain structures.

Morphological asymmetry in anterior limb of human internal capsule revealed by confocal laser and polarized light microscopy.

The fiber structure in the anterior limb of the internal capsule was investigated in a region where stereotactic lesions (anterior capsulotomy) result in successful treatment of obsessive-compulsive disorder (OCD). Eight human hemispheres were sectioned in comparable planes parallel to the ACPC plane. Microscopic slices were labeled with DiI and analyzed with confocal laser and polarized light microscopy. Three distinct systems of fibers were detected. Single fibers run from the caudate nucleus to the lentiform nucleus. The anterior thalamic peduncle connects the mediodorsal and partially the anterior thalamic nucleus with the frontal lobe. The frontopontine tract system connects the frontal lobe with the pons. This fiber tract occupies 38% of the anterior limb and is arranged in small bands. Right-left comparison of morphometric parameters of these bundles demonstrated that more and smaller bundles were located on the left-hand side than on the right-hand side. Tendencies for this configuration were noticeable in all brains investigated, with statistical significance in one brain. These morphological differences correlate with functional differences, as it was possible to demonstrate right hemispheric dysfunctions in cases of OCD. The benefit of anterior capsulotomy in OCD is generally seen in the interruption of fronto-basal ganglia-thalamic loops by disconnecting the anterior thalamic peduncle. In addition, the frontopontine fiber tract is disconnected in this stereotactic procedure.

Representation of cortical motor function as revealed by stereotactic transcranial magnetic stimulation.

Cortical motor representation of 12 muscles of the trunk and the upper and lower extremity was investigated in 18 healthy subjects using focal transcranial magnetic stimulation (TMS) in conjunction with a frameless stereotactic system (FSS). This combination allowed us to orientate stimulation sites to the individual central sulcus rather than to bony landmarks. Distinct but overlapping areas of muscle representation were identified and the 3-dimensional representation of those 12 muscles along the course of the central sulcus was obtained. With increasing stimulus intensity, the cortical output maps changed in that more muscles became excitable, motor evoked potential (MEP) amplitude and size of the responsive area increased and latency of the MEP decreased. These effects were more pronounced for proximal than for distal muscles, indicating a more widespread organization of corticospinal motor projection related to proximal muscles. The combination of TMS and FSS represents a method with which functional information can be directly related to underlying cortical anatomy. This correlation will be useful in the assessment of higher brain functions with TMS.

Unilateral laminotomy for bilateral decompression of lumbar spinal stenosis. Part I: Anatomical and surgical considerations.

A unilateral laminotomy for bilateral access to the lumbar spinal canal was investigated in human cadaver spine specimens to test its practicability in the treatment of spinal stenosis. Micro-surgical decompression was performed by partial resection of the ipsilateral facet, the medial portion of the laminar arch, the contralateral facet and by complete removal of the ligamentum flavum. Anatomical, radiological and morphometrical studies on 4 adult cadaver spine specimens have proved the feasibility of this unilateral approach. Complete bilateral flavectomy and partial bilateral facetectomy were the essential surgical steps for an adequate operative decompression.

A quantitative approach to spatial variation of human cerebral sulci.

The surfaces and the sulci of the lateral hemispheres of 30 postmortem brain specimens were three-dimensionally measured. The coordinates of all the structures registered constitute a digital brain model. The models were scaled linearly until they fitted a defined cuboid. Then all the models within the reference volume, each represented by a set of points, were considered together. The reference volume was divided into small cubic volume elements (voxels). Two parameters of the voxels were studied: the point density of each structure per voxel and the contribution index which designates how many of the hemispheres contribute points to a certain voxel. The latter parameter may serve as an index for the presence probability of a sulcus, which means the probability with which a sulcus will be contained in a defined volume element. The presence probability of a sulcus corresponds well with its first appearance in embryological development. Spatial variation in the early developing principal sulci is far less than in those which develop in later stages. As regards some defined regions of the brain, statements about the probable location of cortical areas in relation to the commissural system can be made.

Superimposition of an average three-dimensional pattern of brain structures on CT scans.

A method is described for the superimposition of an averaged telencephalic anatomical model and individual CT scans. The model is digitally available and derived from 3-D measurements of 30 post-mortem brains. It is averaged in size in relation to the midintercommissural point. The midintercommissural point in the individual brain is gained from reformed parasagittal projection images. The model is adjusted to the individual CT scan series by scaling and rotating according to the best fit and correspondence of the position of the central sulcus. The method needs no invasive neuroradiological techniques but is based on current computer algorithms.

A new method in computer-assisted imaging in neuroanatomy.

A procedure is described yielding computed images of postmortem brains with high topographic accuracy. Structures of the brain are traced and registered by means of a digitizer capable of measuring coordinates three-dimensionally. The information corresponding to one brain model is stored on a flexible disk with a capacity of 256 Kbytes. According to the output desired, the resulting brain images are either completely or partially displayed on the computer screen as stereo pairs. The brain models possess a local fidelity of about 1 mm. The images are useful in simultaneously studying superficial and central parts of the brain, spatial relationships of the various structures and the projection of deep structures onto the surface of the brain. A RAM of about 100 Kbytes is necessary for a program enabling the user to perform stereo projections, three-dimensional transformations and other image manipulations. The special features of anatomical computer imaging as compared to computed tomography (CT) and nuclear magnetic resonance imaging (NMR) are outlined. A combination of these different techniques seems to improve clinical diagnosis.

Neurolinguistic status and localization of lesion in aphasic patients with exclusively consonant-vowel recurring utterances.

Eight patients are presented whose speech production consisted exclusively of one and the same recurring consonant-vowel (CV) syllable, similar to Broca's first patient Leborgne ('Tan-tan'). Their neurolinguistic, aphasiological and localizational status was examined and compared with 32 patients with standard global aphasia and 15 with Broca's aphasia. Patients with exclusively CV speech production represent a variety of global aphasia, characterized by fluency of output and the preservation of some prosody. Localization of the CT lesion did not distinguish between the nonstandard fluent global aphasics described here and the well-known standard nonfluent global aphasics. The individual lesions in both subgroups show great variability in size and localization, which is not recognized in the usual cumulative representations of CT lesions.

[Latissimus arc of the upper arm]. / Studien über Latissimusbögen des Oberarmes.

We observed 2 different kinds of an arcus axillaris which might have caused neurovascular symptoms at the forearm and hand. According to our observations it seems that an arcus axillaris , which is an anomaly of the m. latissimus dorsi, occurs more often than is commonly reported in text-books of anatomy.

[Accessory tendons in the human carpal tunnel]. / Uber zusätzliche Sehnen im Karpaltunnel des Menschen.

Statistical analysis reveals that from 4 persons one possess supernumerary tendon on the right hand, one on the left hand, one on both hands and one has no one. If a supernumerary tendon is found, the probability of appearance of further accessory tendons is enhanced. The 3 fingers of the ulnar side of the hand appear as an uniform group, while the indicis seems to play a special role. A new variation of muscle which runs through the canalis carpi is described.

[A stereological study of the angioarchitecture of the cerebral cortex in rabbits]. / Stereologische Untersuchung der Gefässarchitektur der Grosshirnrinde des Kaninchens.

An attempt is made to describe the vascular architecture of the cortex employing a stereological method. Brains perfused with india ink were sectioned in frontal, sagittal and tangential levels. The course of the vessels was described as a spatial vector from the center to the penetration point of the globe or radius 1. In order to present a two-dimensional image, we projected the penetration point together with the longitudinal and horizontal meridians of the globe in an orthograde fashion into the level of the image. The frontal and sagittal sections were projected in an equatorial image, the tangential level was projected to an axis. Direct observations and stereological imaging demonstrated that, in lamina 4, there is a relatively constant hexagonal vascular net with branching angles of 60 degrees at an edge length of 50--60 microns.

[Local variation of brain structures related to C. T. reference line (author's transl)]. / Lagevariation von Hirnstrukturen im Bezugssystem der Computertomographie.

Median sagittal sections of the cranium of 18 males and 7 females aging from 42 to 74 years were investigated. The distance of brain structures from the skull varied about 11 to 22 mm if the orbitomeatal line is used as reference. A correlation coefficient below 0.5 is found between distances on the outside of the skull and on the median sagittal section as well in horizontal as in the vertical direction. The statistical deviation of the outline of the brain is less extended with an intracerebral reference line than with reference points on the outer surface of the skull. The localization of several telencephalic parts are correlated with the inclination angle of the brain stem. The long axis of the brain stem therefore appears to be the best reference line for localization of brain structures.

[Anomalies of the upper arm--tuberculosis cutis luposa of the hand]. / Anomalie am Oberarm--Tuberculosis cutis luposa an der Hand.

An anomaly of the right pectoralis major muscle is reported. Two muscle bundles are demarcated from the pars abdominalis. Some fibres of these bundles radiate into the distal part of the normal insertion on the humerus; most fibres, however, insert into an accessory tendon which attaches to the medial humeral epicondyle. The medial intermuscular septum is fixed to this tendon. The septum is traversed by filaments of the triceps muscle. Fibres of the triceps muscle also surround the ulnar nerve and the ulnar collateral blood vessels before they pass through the medial part of the septum. These findings are discussed under functional aspects. Catamnestically a tuberculosis cutis luposa exists on the right hand. A patho-causal connection between the anomaly and the tuberculosis of the skin cannot be excluded, because this may arise easier in an area of disturbed blood supply.