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- Fransson, Per-Anders, et al.
(författare)
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Postural Control Adaptation during Galvanic Vestibular and Vibratory Proprioceptive Stimulation
- 2003
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Ingår i: IEEE Transactions on Biomedical Engineering. - 1558-2531. ; 50:12, s. 1310-1319
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Tidskriftsartikel (refereegranskat)abstract
- he objective for this study was to investigate whether the adaptation of postural control was similar during galvanic vestibular stimulation and during vibratory proprioceptivestimulation of the calf muscles. Healthy subjects were tested during erect stance with eyes open or closed. An analysis method designed to consider the adaptive adjustments was used to evaluate the motion dynamics and the evoked changes of posture and stimulation response.Galvanic vestibular stimulation induced primarily lateral body movements and vibratory proprioceptive stimulation induced anteroposterior movements. The lateral body sway generated by the galvanic stimulation was proportionally smaller and contained more high-frequency movements (0.1 Hz) than the anteroposterior body sway induced by the vibratory stimulation. The adaptive adjustments of the body sway to the stimulation had similar time course and magnitude during galvanic and vibratory stimulation. The perturbations induced by stimulation were gradually reduced within the same time range (15–20 s) and both kinds of stimulation induced a body leaning whose direction was dependent on stimulus. The similarities in the adjustmentpatterns suggest that postural control operates in the same way independent of the receptor systems affected by the disturbance and irrespective of whether the motion responses were induced in a lateral or anteroposterior direction.
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- Johansson, Rolf, et al.
(författare)
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Discrimination between Patients with Acoustic Neuroma and with Peripheral Vestibular Lesion by Human Posture Dynamics
- 1994
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Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 1651-2251 .- 0001-6489. ; 114:3, s. 479-483
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Tidskriftsartikel (refereegranskat)abstract
- A group of normal subjects (n = 17) was compared with two groups of patients, either with vestibular neuritis (n = 18) or with acoustic neuroma (n = 35) by means of posturography when stance was perturbed with vibrators attached to the calf muscles. Dynamic control of human posture was quantified by means of system identification, and the characteristic parameters of swiftness, stiffness, and damping of a transfer function from vibration to force platform response were used for further comparison. Fisher linear discriminant analysis was used to distinguish sets of parameters characteristic of each disease. Hence it was possible to distinguish the vestibular neuritis group both from the normal group (p < 0.01), and from the patients with acoustic neuroma (p < 0.001). The normal group was characterized by a different postural performance, with higher swiftness and stability parameters (stiffness, damping) than those of the patient groups. These findings indicate that there are differences in the dynamic control of posture between the two patient categories, which may require the development of differentiated rehabilitation programs.
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- Johansson, Rolf, et al.
(författare)
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Discrimination of Patients with Acoustic Neuroma and Peripheral Vestibular Lesions with Human Posture Dynamics
- 1995
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Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 1651-2251 .- 0001-6489. ; 115:S520, s. 27-28
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Tidskriftsartikel (refereegranskat)abstract
- A group of normal subjects (n = 17) was compared with groups of patients with a diagnosis of vestibular neuritis (n = 18), and acoustic neuromas (n = 35). Fisher linear discriminant analysis was applied to distinguish clusters of parameters characteristic for each disease. Hence it was possible to distinguish the vestibular neuritis patients from the normal group with statistical significance (p < 0.01). Also the patients with an acoustic neuroma could be distinguished from the normal subjects with statistical significance (p < 0.05).
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- Johansson, Rolf, et al.
(författare)
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Multi-Stimulus Multi-Response Posturography
- 2001
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Ingår i: Mathematical Biosciences. - 0025-5564. ; 174:1, s. 41-59
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Tidskriftsartikel (refereegranskat)abstract
- In this study a method for the analysis of simultaneous multiple measurements of kinematics and stabilizing forces related to human postural dynamics is proposed. Each subject in a group of normal subjects (n=10) was tested with eyes-open and eyes-closed with simultaneous but uncorrelated vestibular and proprioceptive stimuli in order to investigate the contributions of individual sensory feedback loops. Statistical analysis was made by means of multi-input multi-output identification of a transfer function from stimuli to stabilizing forces of the feet and the resulting body position, the transfer function being compatible with a biomechanical model formulated as a stabilized segmented inverted pendulum subject to feedback of body sway and position. Each individual model estimated is effective in predicting a subject's response to new stimuli and in describing the interacting effects of stimuli on body kinetics. The proposed methodology responds to the current needs of data analysis of multi-stimulus multi-response experiments.
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- Karlberg, Mikael, et al.
(författare)
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Dizziness of Suspected Cervical Origin Distinguished by Posturographic Assessment of Human Postural Dynamics
- 1996
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Ingår i: Journal of Vestibular Research. - 1878-6464. ; 6:1, s. 37-47
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Tidskriftsartikel (refereegranskat)abstract
- Useful clinical tests are lacking for the controversial entity "cervical vertigo". In earlier studies patients assumed to suffer from cervical vertigo or dizziness manifested disturbed postural control as compared to healthy subjects, but were hard to distinguish from patients with other balance disorders. Using posturography in which stance was perturbed by a vibratory stimulus applied towards the calf muscles, we studied 16 consecutive patients with recent onset of neck pain and concomitant complaints of vertigo or dizziness, but normal findings at otoneurological examination and electronystagmography; 18 patients with recent vestibular neuritis; and 17 healthy subjects. We performed system identification of a model of the control of upright human stance, using the vibratory stimulus as input and the recorded body sway as output. According to values for the three normalized parameters of the transfer function of the model (i.e., swiftness, stiffness, and damping), cervical vertigo patients were distinguished both from healthy subjects (P < 0.001), and from vestibular neuritis patients (P < 0.001). It was also possible to distinguish the vestibular neuritis group from the group of healthy subjects (P < 0.01). The results show disturbed postural control in patients with cervical vertigo to differ from that in patients with recent vestibular neuritis, and indicate posturographic assessment of human posture dynamics to be a possible future tool for use in diagnosing cervical vertigo.
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- Karlberg, Mikael, et al.
(författare)
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Effects of Restrained Cervical Mobility on Voluntary Eye Movements and Postural Control
- 1991
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Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 1651-2251 .- 0001-6489. ; 111:3, s. 664-670
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Tidskriftsartikel (refereegranskat)abstract
- The effects of restrained cervical mobility on pursuit eye movements (PEMS), voluntary saccades and postural control, as measured by posturography, were studied in 11 healthy subjects whose cervical spine movement had been restrained for 5 days by means of a rigid neck-collar. At day 5 mean peak velocity of voluntary saccades at amplitudes of 40 degrees and 60 degrees was significantly reduced, as was mean peak gain of PEMs at a stimulus velocity of 50 degrees/s; the variance of body position in vibration-induced body sway was significantly increased, but there was no difference in variance of galvanically-induced body sway or in velocity of vibration-induced body sway. The results suggest that restriction of cervical movements per se affects voluntary eye movements, a conclusion also consistent with findings in patients with tension headache. Restriction of cervical movement only marginally affects postural control.
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