Movement-related potentials and magnetic fields: new evidence for SMA activation leading MI activation prior to voluntary movement.
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Electromagnetic Fields↗
Biomedical subjects
F Uhl
Publications and source records attributed to F Uhl.
Ultrasound treatment for treating the carpal tunnel syndrome: randomised "sham" controlled trial.
OBJECTIVE: To assess the efficacy of ultrasound treatment for mild to moderate idiopathic carpal tunnel syndrome. DESIGN: Randomised, double blind, "sham" controlled trial with assessments at baseline, after 2 weeks' and 7 weeks' treatment, and at a follow up assessment 6 months later (8 months after baseline evaluation). SETTING: Outpatient clinic of a university department of physical medicine and rehabilitation in Vienna. SUBJECTS: 45 patients with mild to moderate bilateral carpal tunnel syndrome as verified by electroneurography. INTERVENTION: 20 sessions of ultrasound (active) treatment (1 MHz, 1.0 W/cm2, pulsed mode 1:4, 15 minutes per session) applied to the area over the carpal tunnel of one wrist, and indistinguishable sham ultrasound treatment applied to the other. The first 10 treatments were performed daily (5 sessions/week); 10 further treatments were twice weekly for 5 weeks. MAIN OUTCOME MEASURES: Score of subjective symptom ratings assessed by visual analogue scale; electroneurographic measures (for example, motor distal latency and sensory antidromic nerve conduction velocity). RESULTS: Improvement was significantly more pronounced in actively treated than in sham treated wrists for both subjective symptoms (P < 0.001, paired t test) and electroneurographic variables (motor distal latency P < 0.001, paired t test; sensory antidromic nerve conduction velocity P < 0.001, paired t test). Effects were sustained at 6 months' follow up. CONCLUSION: Results suggest there are satisfying short to medium term effects due to ultrasound treatment in patients with mild to moderate idiopathic carpal tunnel syndrome. Findings need to be confirmed, and ultrasound treatment will have to be compared with standard conservative and invasive treatment options.
Carpal Tunnel Syndrome↗
Morphological dissociation between visual pathways and cortex: MRI of visually-deprived patients with congenital peripheral blindness.
MRI was used to study possible morphological changes in the visual system in 12 patients suffering from congenital blindness of peripheral (ocular) origin. While their optical pathways showed degeneration, hypoplasia or atrophy in 7 out of 12 cases, the occipital cortex appeared normal in all cases. This dissociation between afferent pathways and the cortex is contrary to the assumption that visually deprived cortex may undergo degeneration. The finding is congruent with evidence that the occipital cortex is used for other, nonvisual functions.
Adult↗
EMG fatigue patterns accompanying isometric fatiguing knee-extensions are different in mono- and bi-articular muscles.
OBJECTIVES AND METHODS: Isometric, fatiguing knee-extensions at 30%, 50% and 70% maximum voluntary contraction (MVC) were performed by 18 healthy human subjects. Surface electromyographic (SEMG) activity was recorded from the mono-articular vastus medialis (VM) and vastus lateralis (VL) muscles, and the bi-articular rectus femoris muscle (RF). To make the bi-articular muscle work under (1) constant and (2) similar working conditions as the two mono-articulars do, the hip was fixed in a flexed position. The root mean square (RMS) SEMG recorded during fatigue was standardized to the respective values of MVC. The mean coefficients of regression of the RMS and median frequency (MF) changes were then analyzed by multivariate analysis of variance. RESULTS: The load effect upon the muscle fatigue changes, as measured by increase in RMS EMG, differed between the bi-articular muscle and the two mono-articulars, in that the parameter dropped with maximum load for the bi-articular, whilst it remained stable or even increased for the mono-articulars. This might suggest that the mono- and bi-articular muscles have different roles in fatigue tasks where the bi-articulars function purely as mono-articulars. By contrast, such a clear dichotomy between the bi-articular RF and the two mono-articulars, VM and VL, was lacking for the fatigue parameter of MF. CONCLUSIONS: As these findings were confined to the changes in RMS EMG, different neuronal coding mechanisms for the mono- and bi-articular muscles in the central nervous system may be inferred.
Adult↗
Cortical DC potential shifts accompanying the central processing of visually presented analogue and digital time displays.
According to studies in brain-lesioned patients, the cortical substrate subserving the reading of digitally presented time displays seems to differ from that of reading analogue displays. While the right hemisphere has been assumed to be important for reading analogue displays, reading digital displays is attributed to the left hemisphere. This study attempts to localize the cortical substrate of reading analogue versus digital time displays in the intact human brain using scalp-recorded event-related slow negative DC potential shifts. In the arithmetic tasks, subjects had to judge whether or not the time conveyed by the last out of three tachistoscopically presented (analogue or digital) slides was the exact difference between the time conveyed by the first and the second slide. In the control condition, subjects only had to attend to (analogue or digital) time displays. With analogue slides, frontolateral recording sites revealed a right hemispheric preponderance of DC shifts measured in the interval between the second and third slide. Anterior temporal recording sites revealed a right hemispheric preponderance only when calculations were performed. By contrast, there was no hemispheric lateralization with digital slides. The arithmetic versus control manipulation modulated waveforms, but did not influence hemispheric laterality.
Adult↗
Dynamic changes of plasma lipids and lipoproteins in patients after transient ischemic attack or minor stroke.
PURPOSE: Only few data are available concerning variations of lipids and lipoproteins in the acute stage after ischemic cerebrovascular events. It was the aim of this study to investigate whether the lipid and lipoprotein levels obtained in the first few days after a transient ischemic attack (TIA) or a minor stroke (MS) actually reflect "correct' values or "changed' (ie, false low) values, as in patients after acute myocardial infarction. PATIENTS AND METHODS: Total cholesterol (TC), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), and triglyceride (TG) levels of 37 unselected patients with TIA or MS were determined within 12-48 hours (Group A) or within 49-168 hours (Group B) after the acute event. After a mean observation period of 15.3 months, all patients were re-examined; the results were compared with those of the baseline evaluation. RESULTS: At the time of the baseline evaluation, TC and LDL-C levels of Group B patients were significantly lower than Group A levels. At the end of the observation period, however, Group A and Group B patients did not differ with regard to all four parameters. In comparison with the baseline examination, the values of Group A patients had not changed. In Group B patients, however, TC, HDL-C, LDL-C, and TG levels had significantly increased. CONCLUSION: Our results strongly suggest that lipid and lipoprotein levels of patients with TIA or MS should be assessed within a maximum of 48 hours after the acute event. If the examination cannot be performed within that period, the determination of reliable values is possible only after several weeks or months.
Adult↗
Supplementary motor area in spatial coordination of bilateral movements: a new aspect to 'the SMA debate'?
To test whether the supplementary motor area's (SMA) role is confined to determining the 'temporal' but not the 'spatial' properties of a movement (H.H. Kornhuber et al., in: W.A. Hershberger (Ed.), Volitional Action, Elsevier, Amsterdam, 1989, pp. 107-168), movement-related scalp-recorded negative DC potential shifts were recorded in bilateral movements requiring complex spatial coordination. In such bilateral continuous rotation movements, the effect of the rotation sense (symmetrical vs. antisymmetrical), i.e. the direction in which an arm or a finger rotated in relation to the other, heavily affected DC shifts over the frontocentral midline. Antisymmetrical rotation of upper limb segments was associated with higher negative DC shifts than symmetrical rotation was. This was true for rotations in the sagittal plane, irrespective of whether the rotation involved predominantly proximal muscles (by a rotation predominantly in the shoulder) or only distal muscles (by a rotation in the metacarpo-phalangeal joint of the index finger). If these negative cortical DC-shifts over the frontocentral midline relate to activity of mesial frontocentral structures including the SMA, then the present results suggest that there is a role for these cerebral areas in spatial coordination of bilateral movements. Surprisingly, this was not the case for similar finger movements performed in the frontal plane. The results of the present study and particularly the considering of some fundamentals of theoretical physics and of Popper's philosophy of science, made us revise our assumption motivating the present study, that time and space would represent two orthogonal factors of a movement and that the contributions of a particular cerebral motor area (such as the SMA) to 'spatial parameters' versus 'temporal parameters' of a movement can thus be teased apart.
Adult↗
[Hyperhomocyst(e)inemia--an independent risk factor of stroke].
The total of free and protein-bound homocysteine including its derivatives is usually summarised as "homocyst(e)ine [H(e)]". Several congenital enzyme deficiencies may cause markedly elevated H(e) plasma levels, leading to the well-known clinical syndromes of homocystinuria. Recently, mild hyperhomocyst(e)inemia has been recognised as an independent risk factor for ischaemic cerebrovascular disease, coronary heart disease, and peripheral artery disease. H(e) levels are also related to the extent of atherosclerotic vessel wall alterations. The role of mild hyperhomocyst(e)inemia in venous thromboembolic disease, however, is not yet clear. A considerable proportion of patients with mild hyperhomocyst(e)inemia suffers from a deficiency of folate, vitamin B12, and/or vitamin B6. Supplementation of these agents--alone or combined with betain--leads to a decrease or even to a normalisation of elevated H(e) levels in the majority of such patients. Hitherto, no prospective randomised studies dealing with the clinical efficacy of such a--probably innocuous--supplementation have been performed. In the meantime, adequate alimentary intake of folate should be ensured.
Amino Acid Metabolism, Inborn Errors↗
[Subjective disability caused by physical and psychological complaints in long-term follow-up after transient ischemic attacks or "minor stroke"].
Fifty-nine patients with transient ischaemic attacks or minor strokes were re-evaluated after a mean observation period of 16 months. The aim of this study was to assess their somatic and/or psychic complaints semiquantitatively. Judging from the Beschwerdenliste and the Depressivitätsskala (von Zerssen) filled in by the patients, they exhibited hardly more complaints than healthy controls; their scores were considerably lower than those of patients suffering from other organic or psychiatric diseases. Patients who not only suffered from cerebrovascular disease but also from coronary heart disease showed significantly higher scores on both scales than patients with cerebrovascular disease without clinically manifest coronary heart disease. Patients under observation for more than 2 years exhibited considerably fewer psychic complaints than those under observation for shorter periods of time. The Beschwerdenliste and the Depressivitätsskala (von Zerssen) proved useful for assessing somatic and/or psychic complaints in patients after transient ischaemic attacks or minor strokes.
Activities of Daily Living↗
Slow potential shifts preceding human focal paroxysmal discharges, as represented by spikes of benign rolandic epilepsy of childhood.
We examined the slow potential shifts preceding interictal spikes in the scalp EEGs of the children with benign rolandic epilepsy of childhood (BREC). In contrast to our expectations and the observations reported by Stodieck and Wieser (1987), we were not able to detect focal negative slow shifts preceding interictal discharges. Possible reasons for this result are as follows. The cerebral event to which we triggered might have been too 'weak'. Another problem is that not every single spike generated in the deep reaches the surface. Thus, the moment, a spike occurs in the scalp-recordings does not necessarily represent the moment the brain changes from one state to another. The reference electrode might also play a role in obscuring any slow shift.
Adolescent↗
Unimanual motor learning impaired by frontomedial and insular lesions in man.
We correlated impaired unimanual motor learning with the lesion site in 53 patients with chronic lesions predominantly of the frontal lobe. The lesions were assessed using computed tomography (CT), then transferred to standard templates of nine slices parallel to the canthomeatal plane and digitized with a raster matrix of 3 mm by 3 mm width. The learning task was to track a moving target on a computer screen with a dot guided by the preferred hand, while the horizontal coupling between hand movement and screen was inverted. The mean tracking error was recorded over eight successive trials of 80s duration. If the mean error of the last three trials was not lower than that of the first three trials, impaired motor learning was assumed. We correlated performance and lesion with a contingency table analysis for each raster element. Impaired motor learning was associated with a lesion within the supplementary motor area and adjacent anterior cingulate, and within the anterior insular region. Our results indicate that these regions are critical for motor learning and functional plasticity in man. Our data support activation patterns obtained with positron emission tomography.
Adolescent↗
[Cocaine abuse--with special reference to cerebrovascular complications].
The role of drug abuse as a risk factor for cerebrovascular events has been underestimated, particularly in patients with juvenile stroke. The drug most often associated with acute cerebrovascular events is cocaine. After cocaine hydrochloride abuse intracerebral hemorrhages or subarachnoid hemorrhages--predominantly caused by ruptured aneurysms or arteriovenous malformations--are by far the most frequently observed cerebrovascular complications, whereas on abuse with the alkaloidal form ("crack") intracranial hemorrhages and ischemic strokes are encountered with equal frequency. In most cases, the time interval between drug abuse and the cerebrovascular event is less than 3 hours. Several pathophysiological mechanisms are discussed as serving as triggers for the cerebrovascular event, either alone or in combination. No specific antidote to cocaine is known. Nevertheless drug screening (urine analysis) should be performed immediately to allow optimal management of patients with drug-associated acute cerebrovascular events, especially in cases with juvenile stroke.
Cerebrovascular Disorders↗
Clinical and laboratory data in heterozygous factor V Leiden mutation positive versus negative patients with TIA and minor stroke.
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Adult↗
Tactile mental imagery in sighted persons and in patients suffering from peripheral blindness early in life.
Patterns of cortical activity as measured by scalp-recorded event-related slow negative DC potential shifts were recorded in 9 early blind and 23 sighted normals while they imagined the feel of textures with the fingertips of one hand. All sighted subjects reported to have concomitant visual imagery as well. Hence, it was not surprising to observe occipital negative shifts, previously described as a sign of occipital visual cortex involvement in visual mental imagery. Though having never had visual perception, the blind, too, had occipital negativities. Their absolute amplitudes were smaller than in the sighted, not only occipitally but also and more pronounced at other areas, particularly frontally where amplitudes were even positive. On the hypothesis that the smaller overall amplitudes in the blind could obscure topographical differences between groups, the relative distribution of negativity across the scalp was assessed, using normalized data. Such normalized parameters significantly differed between groups, indicating that the occipital potentials of the blind were relatively more negative as related to the other scalp areas, than were the occipital potentials of the sighted as related to the other scalp areas. This occipital finding might indicate a participation of the blind's visually deprived occipital cortex in tactile imagery. Second, parietal DC potentials were maximal over the hemisphere contralateral to the imaging hand, possibly indicating involvement of the contralateral parietal association cortex in tactile imagery. Reasons why this was true only for the sighted, are discussed.
Adolescent↗
Anterior frontal cortex and the effect of proactive interference in word pair learning--results of Brain-SPECT.
Technetium-99m-HMPAO-Brain-SPECT was performed twice in each of 12 right-handed students. The control condition was a standard word pair learning task. In the experimental condition, subjects had to overcome the detrimental effect that older memories exerted on the acquisition of new information (controlling proactive inhibition): they were presented with taxonomically similar words, which could easily be mixed up, and which reappeared in each list, but in different pairings. Results revealed an increase in right anterior frontal flow indices with the experimental condition. These results parallel the observed increase in negative event-related DC potential shifts. UHL et al. [J. cognit. Neurosci. 2, 373, 1990] recorded at frontopolar (Fp3, Fp4) scalp projections, although the extent of modulation was much higher for DC potentials (100%) than it was for SPECT (3%) thus suggesting different sensitivity.
Adult↗
Increased regional cerebral blood flow in inferior occipital cortex and cerebellum of early blind humans.
Cerebral flow indices were measured in 7 early blind and 13 sighted persons twice, during a task of passive and of active touch. In the blind, inferior occipital and cerebellar indices were higher. But they were not significantly modified by the kind of tactile task.
Adult↗
[Mefloquine and sulfadoxine/pyrimethamine overdose in malaria tropica].
A 39 year-old man with malaria due to Plasmodium falciparum received 3500 mg mefloquine over 3 days, in addition to 3250 mg chloroquine and 175/3500 mg sulfadoxine/pyrimethamine. He developed severe neuropsychiatric symptoms and had to be hospitalized. Treatment with diazepam, haloperidol and thioridazine achieved relief of the severe symptoms after 4 days. The patient was still suffering from discrete neuropsychiatric symptoms 8 months after treatment.
Adult↗
On the functionality of the visually deprived occipital cortex in early blind persons.
In early blind mammals, the deprived visual cortex undergoes anatomical and functional alterations. Its functional role was investigated in the early human blind by using patterns of cortical activation as measured by scalp-recorded event-related slow negative DC potential shifts. The blind showed higher occipital negativity than did sighted persons both during a tactile reading task and a non-reading tactile control task. Results point to a possible role for the blind's visual cortex in tactile processes.
Adult↗