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  • Eye movements  (3)
  • Achsenfehlstellung und Beinlängendifferenz  (1)
  • 1
    ISSN: 1432-1106
    Keywords: Vestibular system ; Optokinetic ; Otoliths ; Eye movements ; Motion perception
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Several studies in the past have demonstrated the existence of an Otolith-Ocular Reflex (OOR) in man, although much less sensitive than canal ocular reflex. The present paper 1 confirms these previous results. Nystagmic eye movements (L-nystagmus) appear in the seated subject during horizontal acceleration along the interaural axis in the dark for an acceleration level (1 m/s2) about ten times the perception threshold with a sensitivity of about 0.035 rad/m. When sinusoidal linear acceleration is combined with optokinetic stimulation, the recorded nystagmus slow phase velocity exhibits strong periodic modulation related to subject motion. This marked effect of linear acceleration on the optokinetic nystagmus (OKN) appears at a level (0.1 m/s2) close to the acceleration perception threshold and has a 4-fold higher sensitivity than L-nystagmus. Modulation of OKN can reach a peak-to-peak amplitude as great as 20 °/s; for a given optokinetic field size it increases with the velocity of the optokinetic stimulus, i.e. with the slow phase eye velocity. In parallel with changes in OKN slow phase velocity, linear acceleration induces a motion related decrease in the perceived velocity of the visual scene and modifications in selfmotion perception. The results are interpreted in terms of a mathematical model of visual-vestibular interaction. They show that sensory interaction processes can magnify the contribution given to the control of eye movements by the otolithic system and provide a way of exploring its function at low levels of acceleration.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 36 (1979), S. 509-522 
    ISSN: 1432-1106
    Keywords: Acoustic ; Vestibular ; Otoliths ; Eye movements ; Linear acceleration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to examine otolithic contribution to eye movements ten subjects were asked to track either a moving acoustic target or a stationary target during subect linear motion on a cart. The relative displacement between the subject and the target was the same in the two situations. Recordings of eye movements during subject lateral acceleration in the dark without any task, or with the task of tracking an imagined stationary target were made as a control. The frequencies ranged between 0.15 and 0.3 Hz and peak acceleration between 0.55 and 1.2 m/s2. No lateral eye movements (L-nystagmus) were recorded in the dark. Only saccadic eye movements were recorded during the tracking of a moving acoustic target. Slow eye movements interspersed by saccades were observed when the moving subject tracked an imagined or an acoustic stationary target. Contribution of the slow phase to tracking was more important in the presence of an acoustic target than in the presence of imagined target. The results are interpreted in terms of an otolithic contribution to the central reconstruction of the acoustic target velocity, or in terms of an adaptive control of the otolithic-ocular reflex gain. A conceptual model accounting for these interpretations is proposed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Der Orthopäde 29 (2000), S. 821-831 
    ISSN: 1433-0431
    Keywords: Schlüsselwörter Kongenitale Tibiapseudarthrose ; Ilizarov-Methode ; Simultane Korrektur von Pseudarthrose ; Achsenfehlstellung und Beinlängendifferenz ; Keywords Congenital pseudarthrosis of the tibia ; Circular frame technique ; Simultaneous correction of pseudarthrosis ; Length discrepancy and axial deformity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Congenital pseudarthrosis of the tibia (CPT) is one of the most challenging conditions in paediatric orthopaedics. The history of CPT treatment ischaracterised by repeatedly ineffective surgical interventions with the inevitable outcome of severe disability. Most procedures failed to account for the complexity of the problem. The past two decades have witnessed more experience having been gained with the Ilizarov technique. This method provides a comprehensive approach to all aspects of CPT problem, allowing the surgeon to simultaneously address the problems of union as well as those of deformity, length discrepancy joint function, ankle valgus and weight bearing. It appears that the goal to achieve stable fusion before the child begins school is attainable. In the pre-pseudoarthrotic stage, bracing should be preferred to surgery until the patient is in an older age group. This study reports on the results of 19 patients: 15 have finished treatment, and 14 of them with a stable fusion at follow-up. The results were highly encouraging in reaching the ultimate goal of avoiding amputation and achieving a well-functioning limb.
    Notes: Zusammenfassung Die kongenitale Tibiapseudarthrose gehört zu den schwierigsten Krankheitsbildern in der Kinderorthopädie. Anamenstisch findet sich bei diesen Patienten meist eine Vielzahl ineffektiver, operativer Eingriffe und letztendlich auch ein funktionell unbefriedigendes Ergebnis in Form einer den Patienten schwer behindernden Deformität. Bei den meisten dieser Behandlungsverfahren wird der Komplexität des Problems kongenitale Tibiapseudarthrose nicht entsprechend Beachtung geschenkt. In den letzten Jahren wurden deshalb Verfahren entwickelt, die eine erfolgreiche Behandlung ermöglichen. Es handelt sich dabei um den vaskularisierten Fibulatransfer und die Ilizarov-Technik. Letzterer muss unserer Meinung nach deshalb der Vorzug gegeben werden, da sie dem behandelnden Orthopäden die Möglichkeit gibt simultan sowohl Pseudarthrose, als auch Achsendeformität, Beinlängendifferenz, und Sprunggelenkvalgus zu behandeln. Weiter hat sich gezeigt, dass allzu frühe operative Eingriffe ungünstig sind und dass es sinnvoll ist, primär eine konsequente konservative Therapie durchzuführen, um im Alter von 3–6 Jahren operativ eine stabile Fusion der Pseudarthrose mit Korrektur der Begleitdeformität zu erreichen. Die vorliegende Arbeit berichtet über eigene Ergebnisse bei 19 Patienten, von denen bei 15 die Behandlung abgeschlossen wurde, wobei bei 14 Patienten eine stabile Fusion zum Zeitpunkt der Nachuntersuchung erzielt werden konnte. Die Ergebnisse waren sowohl klinisch als auch funktionell äußerst zufriedenstellend und lassen den Schluss zu, dass eine erfolgreiche Behandlung der Tibiapseudarthrose heute möglich ist und eine Amputation daher als obsolet angesehen werden muss.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 27 (1989), S. 617-622 
    ISSN: 1741-0444
    Keywords: Dynamics ; Eye movements ; Nonlinear gain ; Smooth pursuit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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