Franz Gerstenbrand

Karl Landsteiner Institut, Wien, Vienna, Austria

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Publications (8)22.98 Total impact

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    ABSTRACT: Although chronic sleepiness is common after head trauma, the cause remains unclear. Transcranial magnetic stimulation (TMS) represents a useful complementary approach in the study of sleep pathophysiology. We aimed to determine in this study whether post-traumatic sleep-wake disturbances (SWD) are associated with changes in excitability of the cerebral cortex. TMS was performed 3 months after mild to moderate traumatic brain injury (TBI) in 11 patients with subjective excessive daytime sleepiness (EDS; defined by the Epworth Sleepiness Scale ≥10), 12 patients with objective EDS (as defined by mean sleep latency <5 on multiple sleep latency tests), 11 patients with fatigue (defined by daytime tiredness without signs of subjective or objective EDS), 10 patients with post-traumatic hypersomnia "sensu strictu," and 14 control subjects. Measures of cortical excitability included central motor conduction time, resting motor threshold (RMT), short-latency intracortical inhibition (SICI), and intracortical facilitation to paired-TMS. RMT was higher and SICI was more pronounced in the patients with objective EDS than in the control subjects. In the other patients all TMS parameters did not differ significantly from the controls. Similarly to that reported in patients with narcolepsy, the cortical hypoexcitability may reflect the deficiency of the excitatory hypocretin/orexin-neurotransmitter system. These observations may provide new insights into the causes of chronic sleepiness in patients with TBI. A better understanding of the pathophysiology of post-traumatic SWD may also lead to better therapeutic strategies in these patients.
    Journal of neurotrauma 03/2011; 28(7):1165-71. · 4.25 Impact Factor
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    G. Bauer, S. Golaszewski, Franz Gerstenbrand
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    ABSTRACT: 1966 prägten Plum und Posner [1] den Terminus Locked-In-Syndrom (LiS). „Locked in“ bedeutet Eingesperrtsein. Das LiS bezeichnet topologisch ein ventrales Brückensyndrom, das klinisch durch eine komplette Lähmung bei erhaltenem Bewusstsein gekennzeichnet ist. Lediglich vertikale Blick- und Blinzelbewegungen sind willentlich möglich. Vom LiS im eigentlichen Sinne sind Zustände weitgehender Immobilität wie bei schwerem Guillain-Barré-Syndrom, bei fortgeschrittener Amyotropher Lateralsklerose, bei Morbus Parkinson, bei Multipler Sklerose, bei Alzheimerscher Demenz und bei anderen progredienten neurologischen Erkrankungen zu unterscheiden. Die diagnostische Abgrenzung dieser Zustände vom LiS ist aufgrund der Krankengeschichte unschwer möglich und in prognostischer Hinsicht wichtig, da LiS in einigen Fällen vollständig oder teilweise reversibel und meist nicht progredient ist. Totale Immobilität bei erhaltenem Bewusstsein stellt eine existentielle Extrem-situation dar und hat dementsprechend großes mediales Interesse erfahren. Dabei ist die Abgrenzung zu Reintegrationsstufen eines apallischen Syndroms (vegetativer Zustand) im Sinne eines so genannten minimal bewussten Zustandes [2] zumindest in der veröffentlichten Meinung nicht genügend beachtet worden.
    Psychopraxis 01/2010; 13(5):18-22.
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    ABSTRACT: The aim of the present was study to evaluate cortical and subcortical neural responses on vibrotactile stimulation of the food and to assess somatosensory evoked BOLD responses in dependence of vibration amplitude and stimulus waveform. Sixteen healthy male subjects received vibrotactile stimulation at the sole of the right foot. The vibration stimulus was delivered through a moving magnet actuator system (MMAS). In an event-related design, a series of vibration stimuli with a duration of 1 s and a variable interstimulus interval was presented. Four stimulation conditions were realized using a 2 (amplitudes 0.4 mm or 1.6 mm) x 2 (waveform sinusoidal or amplitude modulated) factorial design. Stimulating with 0.4 mm amplitude compared to 1.6 mm stimulus amplitude more strongly activated the pre- and postcentral gyrus bilaterally and the right inferior, medial and middle frontal gyrus. In the reverse comparison significant differences were observed within the left inferior parietal lobule, the left superior temporal gyrus, and the left temporal transverse gyrus. In the comparison of sinusoidal versus modulated waveform and vice versa no significant activation differences were obtained. The inter-subject variability was high but when all four stimulation conditions were jointly analyzed, a significant activation of S1 was obtained for every single subject. This study demonstrated that the BOLD response is modulated by the amplitude but not by the waveform of vibrotactile stimulation. Despite high inter-individual variability, the stimulation yielded reliable results for S1 on the single-subject level. Therefore, our results suggest that vibrotactile testing could evolve into a clinical tool in functional neuroimaging.
    NeuroImage 07/2008; 41(2):504-10. · 6.25 Impact Factor
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    ABSTRACT: To study cerebral responses evoked from mechanoreceptors in the human foot sole using a computer-controlled vibrotactile stimulation system. The stimulation system consisted of two stationary moving magnet actuators with indentors to gently contact and vibrate the foot sole during functional MRI (fMRI) experiments. To allow independent settings of contact force (0-20 N) and intensity of vibration (frequency range=20-100 Hz) the actuators were controlled by a digital servo loop. For fMRI experiments with complex stimulus protocols, both vibrating probes were further operated under supervisory control. The MR compatibility of this electromagnetic system was tested in a 1.5T scanner with an actively shielded magnet (Siemens Magnetom Sonata). Blood oxygenation level-dependent (BOLD) responses were detected in the contralateral left pre- and postcentral gyrus, bilaterally within the secondary somatosensory cortex, bilaterally within the supplementary motor cortex, and bilaterally within the anterior cingular gyrus. This stimulation device provides a new tool for identifying cerebral structures that convey sensory information from the foot region, which is of promising diagnostic value, particularly for assessing sensorimotor deficits resulting from brain lesions.
    Journal of Magnetic Resonance Imaging 12/2006; 24(5):1177-82. · 2.57 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the sensorimotor cortex response to plantar vibrotactile stimulation using a newly developed MRI compatible vibration device. Ten healthy subjects (20-45 years) were investigated. Vibrotactile stimulation of the sole of the foot with a frequency of 50 Hz and a displacement of 1 mm was performed during fMRI (echo-planar imaging sequence at 1.5 T) using an MRI compatible moving magnet actuator that is able to produce vibration frequencies between 0 and 100 Hz and displacement amplitudes between 0 and 4 mm. The fMRI measurement during vibrotactile stimulation of the right foot revealed brain activation contralaterally within the primary sensorimotor cortex, bilaterally within the secondary somatosensory cortex, bilaterally within the superior temporal, inferior parietal, and posterior insular region, bilaterally within the anterior and posterior cingular gyrus, bilaterally within the thalamus and caudate nucleus, contralaterally within the lentiform nucleus, and bilaterally within the anterior and posterior cerebellar lobe. The advantages of the new MRI compatible vibration device include effective transmission of the stimulus and controlled vibration amplitudes, frequencies, and intensities. The results indicate that plantar vibration can be a suitable paradigm to observe activation within the sensorimotor network in fMRI. Furthermore, the method may be used to determine the optimal responsiveness of the individual sensorimotor network.
    NeuroImage 03/2006; 29(3):923-9. · 6.25 Impact Factor
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    ABSTRACT: To investigate sensory and motor functions in microgravity, goal-oriented arm movements were performed by 9 cosmonauts in weightlessness. The ability to reproduce predefined motor patterns was examined pre-, in-, and post-flight under two different paradigms: In a first test, the cosmonaut had to reproduce passively learned movements with eyes closed, while in the second test, the cosmonaut learned the pattern with eyes open. The different learning paradigms effected the metric parameters of the memorized stimulus pattern while the influence of the different gravity levels resulted in significant offsets and torsions of the reproduced figures. In comparing the inflight condition with preflight, intact proprioceptive afference seemed to play an important role for reproducing movements from motor short-time memory correctly.
    Journal of gravitational physiology: a journal of the International Society for Gravitational Physiology 08/2004; 11(2):P115-7.
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    ABSTRACT: The human motor system responds to weightlessness by the slowing of movement. It has been suggested that deficits in visuo-motor co-ordination cause this effect. We studied the mechanisms of the slowing of movement in three long-term missions to the Russian space station Mir. In particular, the role of vision in the control of movement in microgravity has been studied in these experiments on seven cosmonauts, pre-, in-, and post-flight. The cosmonauts made arm movements to visual targets under the following conditions of visual control: no visual control, interrupted visual control, and undisturbed visual control. The results showed that the slowing of movement during weightlessness was manifested by decreases of peak velocity and peak acceleration, was not associated with a prolongation of the movement phase of deceleration, and was not affected by manipulation of the conditions of visual control. The slowing of movement tended to subside after the months of the flight and completely disappeared within days after the landing. Accuracy of the movements strictly depended on the constraints imposed on the vision and remained unaffected in-flight. The data presented demonstrate that the slowing of movement in microgravity is not directly related to deficits in sensori-motor co-ordination and is not associated with a reduction of the accuracy of movement. The strategy for motor control in microgravity seems to be directed towards the generation of smooth movements and the maintenance of their accuracy.
    Arbeitsphysiologie 11/2002; 87(6):576-83. · 2.66 Impact Factor
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    ABSTRACT: This contribution deals with the examination of the consequences of different head-to-trunk positions on arm movements under normal gravity and during prolonged space flight. One of the objectives of this study was to investigate the influence of weightlessness on the condition of the spatial analysis system. Aimed arm movements in the horizontal plane (pointings towards two visual targets) were recorded, first with eyes open, head straight (learning part), then with eyes closed, head straight and during yaw or roll position of the head (performance part). Measurements related to these different head-to-trunk-positions were taken in one short-term and nine long-term cosmonauts preflight, inflight, and postflight. Terrestrial control experiments were carried out with an extended experimental design in 14 healthy volunteers. The analysis of these experiments revealed that, with eyes closed and the head in yaw position, cosmonauts before flight and control subjects exhibit significant slants of the movement plane of the arm. Contrary to terrestrial measurements, in space experiments roll tilt of the head to the right is correlated with considerable counterclockwise slant of the movement plane. This slant of the movement plane of the arm was interpreted as tilt of the internal representation of the horizontal coordinate. The effect is larger with greater distortion induced by the changed head position and with larger muscular involvement to keep this position. This effect is also increased by the reduction of information (for example, in microgravity). The amount and the direction of the horizontal offset of the arm movements are shown to be dependent on the head-to-trunk position, too. Additionally, we have found changes in the amplitude and in the duration of the arm movement, in the vertical offset, and in the curvature of the movement paths, depending on the experimental conditions.
    Journal of Vestibular Research 01/1970; 8(5):341-54. · 1.00 Impact Factor

Publication Stats

55 Citations
22.98 Total Impact Points


  • 2010
    • Karl Landsteiner Institut
      Wien, Vienna, Austria
  • 1970–2010
    • Medizinische Universität Innsbruck
      • • Univ.-Klinik für Neuroradiologie
      • • Univ.-Klinik für Neurologie
      Innsbruck, Tyrol, Austria
  • 2002
    • University of Innsbruck
      Innsbruck, Tyrol, Austria