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Biomedical subjects

H J Freund

Publications and source records attributed to H J Freund.

188 records · Page 11Linked to original sources
PubMedDate not supplied

Multiple exercise-related mononeuropathy with abdominal colic.

Hereditary neuropathy with liability to pressure palsies (NLPP) is a rare disease characterized by recurrent sensory-motor deficits precipitated by exposure to minor pressure. This report describes a variant of this neuropathy in 5 siblings suffering from painful palsies after strenuous work with concurrent episodes of abdominal colic resembling that of acute intermittent porphyria. Electrophysiological studies of the index case showed the typical abnormalities of motor and sensory nerve conduction, including clinically non-affected nerves. Light and electron-microscopic examination showed the characteristic lesions of the NLPP with sausage-like swelling of the myelin sheaths. In addition, non-compacted, "loose" myelin lamellae were frequently observed in association with distended Schmidt-Lantermann incisures. Non-compacted myelin was a prominent finding in this type of demyelinating neuropathy. We suggest that an unknown metabolic factor may induce both demyelination of peripheral nerve fibers and functional disturbance in autonomic nerves leading to attacks of abdominal pain.

Abdomen↗
PubMedDate not supplied

Clinical aspects of premotor function.

Observations on patients with frontal lesions including the premotor cortex but not the primary motor cortex as shown by CT scans have shown a slight or moderate weakness of the contralateral shoulder or hip muscles which remained as a permanent deficit. The second deficit was an incoordination between movements requiring temporal adjustment between proximal muscle activities of both sides (limb-kinetic apraxia). From the clinical examination there was no evidence for deficient sensory guidance of movement. Visual control of hand and finger movements was normal as long as the arm could be supported during the tasks. In contrast, gross abnormalities of visually guided reaching (visuomotor ataxia) or somesthetic movement control (tactile apraxia) are seen after parieto-occipital lesions. On the basis of clinical observations it is therefore more likely that sensory-motor integration and transformation already takes place at the posterior lobes, where corresponding disturbances are pronounced but are absent after frontal lobe lesions.

Apraxias↗
PubMedDate not supplied

Learning "what" and "how" in a human motor task.

We studied the development of implicit and of verbally declared knowledge for normal human subjects who learned an unfamiliar motor task in one learning session. The exploratory nature of motor learning and a special period for optimizing skill were followed in real time. Subjects understood the goal for task success, but they had to learn a motor strategy of what pattern of serial movements to make and the tactics of how much to scale their amplitudes and timing. We compared the time course for acquiring tactical skill with that for acquiring knowledge of strategy and of tactics, and their necessary cues. Implicit and declarative knowledge were distinguished from one another by correlating subjects' verbal self-reports with movement kinematics and their results. Implicit generation of the correct strategy and of the tactics developed in an exploratory manner from the beginning of the learning session. Implicit strategy learning soon gave way to conscious efforts, but tactical learning remained implicit until its first unambiguous verbal declaration (with one exception). First strategy declarations were voiced before those for tactics, during trial-and-error learning that did not require task success, and referred to reversing the direction of hand movements (one exception). In contrast, first declarations of tactics almost always required actual or imminent success, referred to when direction was to be reversed, and it was achieved near the top of a sigmoid learning curve that rose to tactical skill (with one exception). During the sigmoid rise, movement amplitudes and timing were optimized in a distinct manner, although tactics usually adapted thereafter to movements of more moderate speed that could still be successful.

Adult↗
PubMedDate not supplied

Incidence of asymptomatic extracranial arterial disease.

Investigations of the incidence and the extent of the asymptomatic early stages of extracranial arterial disease (EAD) have been restricted for methodical reasons. Direct Continuous Wave-Doppler examination has given highly accurate results in the location and correct estimation of the degree of EAD both for the carotid (97%) and the vertebral arteries (90%), as shown from a detailed comparison with carotid (n = 604) and vertebral (n = 426) angiograms. Compared with this degree of reliability, the validity of normal auscultation for the diagnosis of EAD is shown to be poor: if bruits are taken as the only signs of associated EAD in patients with systemic atherosclerosis, only 27.6% in a group of 123 patients would have been correctly diagnosed. This parallels the number of false-positives (22.6%) in patients with normal results. The frequency and degree of EAD was studied by the use of direct Doppler examination in 2009 neurologically asymptomatic patients admitted either with severe vascular (n = 375) or coronary atherosclerosis (n = 262) or with high-risk factors (n = 1370). The frequency was significantly higher (32.8%) in patients with peripheral vascular disease than in those with coronary artery disease (6.8%) and in risk-factor patients (5.9%). The combination and degree of vessel involvement are presented in detail and their possible prognostic significance discussed.

Aged↗
PubMedDate not supplied

Variation of perisylvian and calcarine anatomic landmarks within stereotaxic proportional coordinates.

This investigation describes the variability in location of functionally important persylvian landmarks and of the calcarine sulcus within the Talairach stereotaxic grid, a system frequently used for cortical localization in functional images. Twenty healthy volunteers (40 hemispheres) had MR imaging under stereotaxic conditions. Outlines of the following structures were directly identified on sagittal 5-mm MR sections and marked on individual proportional grid overlays: inferior central sulcus, inferior precentral sulcus, inferior postcentral sulcus, anterior ascending ramus and posterior rami of the sylvian fissure, superior temporal sulcus, and calcarine sulcus. Maximal variation zones for these landmarks were defined by superimposition of the standardized individual data on a standard stereotaxic grid. The sulcal variation zones measured 1.5-2.0 cm. The findings indicate that macroanatomic individuality in the cerebral surface cannot be accounted for adequately by proportional coordinates, and that this method does not allow precise definition of anatomically based regions of interest for functional imaging. Instead, MR mapping of the individual sulcus pattern should be used to generate brain templates.

Adult↗
PubMedDate not supplied

Cerebral asymmetry: MR planimetry of the human planum temporale.

A method is described for the imaging and planimetric measurement of the planum temporale (PT) using computer reformations from three-dimensional fast low angle shot magnetic resonance (MR) data. The procedure allows the determination of size and left-right asymmetry of this area on the posterior supratemporal surface, which has been assumed by previous investigators to be a structural correlate of speech lateralization. To establish a consistent method for future studies, special effort was invested in the elaboration of reliable imaging criteria for the borders of the PT. The authors report MR planimetric measurements of the PT in 10 human cadaver brains performed independently and in a "blinded" fashion by two observers. A high degree of interobserver agreement was found, demonstrating the reliability of the MR criteria for PT delineation. The planimetric data correlated with those from subsequent anatomic measurements following section of the same specimens. The left-right ratios of PT size were almost the same with both methods (mean 1.9). Magnetic resonance planimetry of the PT is a noninvasive, reliable, and quantitative procedure to determine gross cerebral asymmetry in the posterior speech area.

Aged↗
PubMedDate not supplied

Cerebral cortical localization: application and validation of the proportional grid system in MR imaging.

The Talairach stereotactic proportional grid method for telencephalic localization was applied to magnetic resonance imaging of 30 brain hemispheres of healthy adult volunteers. Using sagittal images, outlines of the following characteristic principal sulci were identified on the brain surface to validate the method: callosal sulcus, parietooccipital sulcus, marginal sulcus, superomedial portion of central and postcentral sulcus, and posterior sylvian fissure. The maximal variation zones of sulcus location obtained by superimposition of the individual grid data on a standard proportional grid were similar to those originally reported by Talairach from pneumoencephalographic studies. However, the central sulcus, which was only studied postmortem by Talairach, was located 0.5-1 cm more posteriorly in the present study. Magnetic resonance also provided more detailed data on the considerable variation of the terminal parts of the sylvian fissure and on the well-known left-right asymmetries. The left sylvian fissure extended farther posteriorly in 11 of 15 brains. With the exception of this posterior perisylvian region, the proportional grid proved to be valid for indirect cerebral cortical localization in the regions studied.

Adult↗