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Biomedical subjects

Marousa Pavlou

Publications and source records attributed to Marousa Pavlou.

4 recordsLinked to original sources

Simulator based rehabilitation in refractory dizziness.

UNLABELLED: Patients with chronic vestibular symptoms are common in neurological practice but the most effective treatment remains an open question. The purpose of our study was to conduct a controlled, between-group comparison of patients' responses to a customised exercise regime (Group C, for customised) versus treatment additionally incorporating simulator based desensitisation exposure (Group S, for simulator) integrating whole-body or visual environment rotators. Forty chronic peripheral vestibular patients who had previously undergone conventional vestibular rehabilitation without notable improvement were randomly assigned into Group C or S. Individuals attended therapy sessions twice weekly for eight weeks and were provided with a customised home programme. Response to treatment was assessed at four-week intervals with dynamic posturography, vestibular time constants, and questionnaires concerning symptoms, symptom-triggers and emotional status. At final assessment posturography and subjective scores had significantly improved for both groups, although Group S showed greater improvement. A statistically significant improvement for visual vertigo symptom scores was noted only for Group S (p < 0.01; total improvement 53.5 %). Anxiety and depression levels significantly decreased for both groups; improvements were significantly correlated particularly to improvements in visual vertigo (SCQ) (p < 0.01; r = 0.53 and r = 0.57, respectively). Significant differences were noted between groups (p = 0.02) for posturography scores. Vestibular time constants showed no notable change in either group. CONCLUSIONS: Both groups improved but exposure to simulator motion gave overall better results. These effects were also observed in psychological symptoms and partly relate to simulator effects on visual vertigo symptoms. Visual motion and visuo-vestibular conflict situations should be incorporated in the rehabilitation of patients with refractory dizziness.

Adult↗

The integration of multiple proprioceptive information: effect of ankle tendon vibration on postural responses to platform tilt.

Previous studies have looked at co-processing of multiple proprioceptive inputs but few have investigated the effect of separate dynamic and tonic predominantly proprioceptive disruptions applied concurrently at the same segment. The purpose of the present study was to investigate how simultaneous ankle tendon vibration, a tonic stimulus, with a dynamic toes-up (TU) or toes-down (TD) platform perturbation (1) affects postural stability and (2) influences the adaptation process. Sixteen normal subjects (ten male, six female, mean age 26 +/- 4.8 years) stood blindfolded on a moving platform with vibrators attached bilaterally over the Achilles tendons. Participants were tested in quiet stance (QS), and with five successive TU and TD tilts. All tests were conducted both with (QS+V, TU+V, TD+V) and without vibration. Centre of pressure (CoP) displacements and pitch angular trunk velocity were recorded. Results for QS+V showed a significant 1.02-cm backward CoP displacement (P<0.01) and a significant increase in trunk velocity (peak-to-peak amplitude, P<0.05; SD of trunk velocity, P<0.05). TU+V resulted in a non-significant increase of maximum backwards CoP displacement when compared to TU alone. In addition, no notable effect of vibration on other measures of CoP (pre-tilt position, SD and area of sway) and trunk velocity (peak-to-peak, SD and area of sway) indicates that TU+V does not introduce significantly greater instability compared to tilt alone. In the TD condition, vibration was found to be a stabilising influence, causing a significant shift of the mean pre-tilt position 0.85 cm backwards (P<0.01) and a substantial decrease in the area of forward CoP displacement (P<0.01). However, maximum forwards CoP displacement and trunk velocity measures were not significantly altered during TD+V. Furthermore, in neither TU nor TD was the time-course or pattern of adaptation disrupted by the additional application of vibration. In conclusion, although vibration significantly affects postural measures when applied in isolation, this finding does not hold when it is applied in combination with a more dynamic stimulus. Instead it seems that once postural stability has been disrupted the central nervous system can rapidly assess information from a weaker tonic input and utilise or suppress it appropriately, depending on its effect towards overall postural control. It can be concluded that postural responses to the concurrent application of different predominantly proprioceptive stimuli are dependent upon the type of stimulus and the ability of the central nervous system to rapidly assess and re-weigh available sensory inputs.

Adaptation, Physiological↗

Effect of semicircular canal stimulation on the perception of the visual vertical.

UNLABELLED: The subjective visual vertical (SVV) is usually considered a measure of otolith function. Herewith we investigate the influence of semicircular canal (SCC) stimulation on the SVV by rotating normal subjects in yaw about an earth-vertical axis, with velocity steps of +/- 90 degrees /s, for 60 s. SVV was assessed by setting an illuminated line to perceived earth vertical in darkness, during a per- and postrotary period. Four head positions were tested: upright, 30 degrees backward (chin up) or forward, and approximately 40 degrees forward from upright. During head upright/backward conditions, a significant SVV tilt (P < 0.01) in the direction opposite to rotation was found that reversed during postrotary responses. The rotationally induced SVV tilt had a time constant of decay of approximately 30 s. Rotation with the head 30 degrees forward did not affect SVV, whereas the 40 degrees forward tilt caused a direction reversal of SVV responses compared with head upright/backward. Spearman correlation values (Rho) between individual SCC efficiencies in different head positions and mean SVV tilts were 0.79 for posterior, 0.34 for anterior, and - 0.80 for horizontal SCCs. Three-dimensional video-oculography showed that SVV and torsional eye position measurements were highly correlated (0.83) and in the direction opposite to the slow phase torsional vestibuloocular reflex. IN CONCLUSION: 1) during yaw axis rotation without reorientation of the head with respect to gravity, the SVV is influenced by SCC stimulation; 2) this effect is mediated by the vertical SCCs, particularly the posterior SCCs; 3) rotationally induced SVV changes are due to torsional ocular tilt; 4) SVV and ocular tilts occur in the "anticompensatory," fast phase direction of the torsional nystagmus; and 5) clinically, abnormal SVV tilts cannot be considered a specific indication of otolith system dysfunction.

Acceleration↗