Repetitive peripheral magnetic stimulation alleviates tactile extinction

Despite its frequency in right brain damaged patients crucial mechanisms of tactile extinction are still obscure and treatments are unavailable. Recent PET observations suggest a hypometabolism in the primary and secondary somatosensory cortex of the lesioned hemisphere in patients with tactile extinction. Functional and morphological investigations have shown that the sensorimotor cortex has a remarkable capability of reorganization when the sensory inflow is changed. Repetitive peripheral magnetic stimulation (RPMS) applied in patients suffering from central paresis alleviates sensorimotor as well as cognitive deficits by the induction of proprioceptive inflow, thereby activating plasticity in the CNS. Based on the observation of reduced metabolic activity in patients suffering from tactile extinction we applied RPMS to explore the effects of peripheral sensory stimulation on tactile extinction. Fourteen right-hemisphere lesioned patients with tactile extinction were randomly allocated to an experimental and a control group. The experimental group received one single RPMS treatment of the left forearm as well as a condition of attentional cueing known to improve visual extinction. The control group, with comparable tactile extinction scores, neither received RPMS nor verbal cueing, but was tested twice to evaluate possible learning or test repetition effects. In the experimental group RPMS led to a significant reduction of left-sided extinctions in the recognition of different tactual surfaces, but had no effect on ipsilesional errors. In contrast, attentional cueing had no significant effect on left-sided extinction errors but unexpectedly increased right-hand extinction errors slightly but significantly. The control group showed stable extinction scores of the left- and right-hand stimulus across two measurements, thus ruling out learning or test repetition effects. These results show that sensory inflow is an important modulatory factor in tactile extinction. Furthermore, multiple RPMS may prove a promising way for the rehabilitation of patients with this disorder.     

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A fronto-parietal network is mediating improvement of motor function related to repetitive peripheral magnetic stimulation: A PET-H2O15 study

Repetitive peripheral magnetic stimulation (RPMS) is a focused and painless stimulation method, in which muscle contractions are elicited by depolarization of the terminal motor branches. Clinical-experimental investigations on different disorders of sensorimotor integration in the last decade have shown that RPMS can be used for the rehabilitation of motor functions after stroke. It is supposed that this therapeutic effect is based on the RPMS-induced proprioceptive inflow to the CNS. To analyze the conditioning effects of RPMS on reorganization of the motor system on cortical level positron emission tomography (PET) is used. Regional cerebral blood flow (rCBF) has been measured using H(2)O(15)-PET in eight patients with arm paresis following focal cerebral ischemic infarction before and after treatment using RPMS on upper arm flexor muscles. Behavioral measures showed a significant improvement of kinematics of finger movements and a reduction of spasticity in the affected arm following RPMS treatment. The recovery was associated with significant increase of neural activation within the superior posterior parietal lobe and the premotor cortex (PM) areas. The increase of activation of the parieto-premotor network following RPMS treatment indicates a significant conditioning effect of RPMS on the cortical level. These results emphasize the positive therapeutic effect of RPMS and describe the physiological bases of its function on the central level.     

Gibt es Einflüsse der Witterung auf den Eintritt des Todes?

Ohne ZusammenfassungMit 18 Abbildungen im Text.     

Zur Frage der Innervation des Kehlkopfs durch Wurzelfasern des Accessorius

Zusammenfassung Eine klinische und anatomische Beobachtung nach einer Schiefhalsoperation, bei der es trotz Zerstörung aller Accessoriuswurzeln nicht zur Beeinträchtigung des Kehlkopfes gekommen war, wie dies bei der bisherigen anatomischen Ansicht zu fordern gewesen wäre, lenkte unsere Aufmerksamkeit auf die Feststellung der Innervationsbezirke des Accessoriuswurzelgebietes.Durchschneidungsversuche der Accessoriuswurzeln am Hund ergaben keine Einwirkung auf die Kehlkopfmuskelsteuerung.Das Schrifttum wurde eingehend darauf untersucht und es fanden sich zahlreiche frühere Feststellungen, die einen Zusammenhang der Kehlkopfinnervation mit dem gesamten Accessoriuswurzelgebiet ablehnen und somit im Widerspruch mit der bisherigen anatomischen Lehrmeinung stehen. Auf Grund der Beobachtung am Menschen und der experimentellen Ergebnisse am Hund lehnen wir die bisherige anatomische Anschauung ab und setzen an ihre Stelle die alteGrossmannsche Lehre, daß der Accessorius an der Kehlkopfinnervation nicht beteiligt ist.Mit 4 Abbildungen.Die Arbeit wurde auf Anregung von GeheimratE. Lexer, dem damaligen Direktor der Klinik, begonnen.     

Amyotrophic lateral sclerosis: macro-EMG and twitch forces of single motor units

Macro-EMG potentials (MEP)s and twitch contractions (spike-triggered-averaging) of single motor units (MUs) have been recorded in the first dorsal interosseus muscle (FDI) of 10 control subjects and 20 patients with amyotrophic lateral sclerosis (ALS). MUs over the full range of voluntary recruitment thresholds were studied. Patients with slightly affected FDIs (5) mainly showed MUs with enlarged MEPs and increased twitch forces. In contrast, the patients with more severely affected FDIs (15) revealed decreased twitch forces, especially in the MUs with higher thresholds. The corresponding MEPs could be enlarged as well as normal. It appears that MU sprouting and the resulting increase of twitch force can compensate for the loss of motoneuron in early stages of ALS. In more advanced stages, however, a decline of the force of the surviving MUs, especially of those with higher thresholds, seems to contribute to the progressive muscle weakness, in addition to the corticospinal degeneration and the reduction in the number of motoneurons.     

Discharge pattern of tonically activated motor units during unloading

In order to analyse the EMG pattern during unloading of brachial biceps muscle, the interference EMG and single motor unit activity were investigated. The measurements were done on seven healthy subjects with two types of unloading techniques: a) active unloading, when the subjects resisted against an external load (10, 20, 30 and 40 N) which is suddenly released, and b) passive unloading, performed by low inertia torque motors with independently adjustable background extension and suddenly applied flexion torques. Following active unloading the silent period duration, the amplitude of the rebound and its segmentation into consecutive bursts is changing with initial load, whereas the silent period latency remains constant. Following passive unloading the acceleration influences predominantly the amplitude of the rebound, without changing its latency and silent period duration. The initial voluntary activity influences both silent period duration and rebound parameters (latency, amplitude and duration).     

New trends in computer graphics and computer vision to assist functional neurosurgery

Computer vision (CV), a computerized method to analyze digital images (e.g., CT scans), and computer graphics (CG), a set of computer programs for displaying two, three- or four-dimensional data, are recent computer techniques which are appropriate to assist functional stereotactic surgery. CV and CG are useful for the evaluation of spatial relations between anatomical structures and the sites of spontaneous neuronal noise or of electrophysiological stimulation data gathered during stereotactic interventions for movement disorders. CV and CG can be employed for stereotactic operation planning, during the operation for target point evaluation and for further postoperative data analysis.     

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