Evaluation of postural stability using sensory organization test (original) (raw)
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Acta physiologica et pharmacologica Bulgarica, 2001
We investigated which sensor had dominant contribution to vestibulo-ocular reflex (VOR) and postural sway (PS) for the optimal body balance maintenance under conditions of visual or/and somatosensory input reduction. Healthy subjects were examined in upright stance on stable platform and foam rubber, under following conditions: in quiet stance with eyes open (EO) and closed (EC); during voluntary head movements in horizontal plane at frequency 0.2 - 0.3 Hz with EO (HO) and EC (HC). The results showed that PS increased smaller during HC than during HO on both supports stable and unstable, but particularly on the foam rubber. Mean gain of VOR induced by HO was 1.2 and this one evoked by HC was 0.9 on the two supports. Therefore, when in upright stance the vestibular input is stimulated, the reduction of either or both inputs visual and proprioceptive influences postural stability positively while VOR is affected negligibly. Hence, the vestibular contribution to both VOR and PS is domi...
Postural strategies associated with somatosensory and vestibular loss
Experimental Brain Research, 1990
This study examines the roles of somatosensory and vestibular information in the coordination of postural responses. The role of somatosensory information was examined by comparing postural responses of healthy control subjects prior to and following somatosensory loss due to hypoxic anesthesia of the feet and ankles. The role of vestibular information was evaluated by comparing the postural responses of control subjects and patients with bilateral vestibular loss. Postural responses were quantified by measuring 1) spatial and temporal characteristics of leg and trunk EMG activation; 2) ankle, knee, and hip joint kinematics, and 3) surface forces in response to anterior and posterior surface translations under different visual and surface conditions. Results showed that neither vestibular nor somatosensory loss resulted in delayed or disorganized postural responses. However, both types of sensory deficits altered the type of postural response selected under a given set of conditions. Somatosensory loss resulted in an increased hip strategy for postural correction, similar to the movement strategy used by control subjects while standing across a shortened surface. Vestibular loss resulted in a normal ankle strategy but lack of a hip strategy, even when required for the task of maintaining equilibrium on a shortened surface. Neither somatosensory nor vestibular loss resulted in difficulty in utilizing remaining sensory information for orientation during quiet stance. These results support the hypothesis that cutaneous and joint somatosensory information from the feet and ankles may play an important role in assuring that the form of postural movements are appropriate for the current biomechanical constraints of the surface and/or foot. The results also suggest that vestibular information is necessary in controlling equilibrium in a task requiring use of the hip strategy. Thus, both somatosensory and vestibular sensory information play important roles in the selection of postural movement strategies appropriate for their environmental contexts.
American Journal of Occupational Therapy, 1989
This paper reviews the research findings that support the presence of vestibulospinal reflexes in corrections for head and body instability. Studies of the importance of labyrinthine inputs to the central nervous system organization of eye, head, and body movements demonstrate that the vestibular nuclei are more than a simple relay station for labyrinthine activity. At all levels of the vestibular system beyond the primary vestibular afferents, parallel processing of labyrinthine signals occurs with input from other sensory systems. Thus, output of the vestibular nuclear complex (VNC) is not equivalent to the labyrinthine input. It is the VNC output that influences motor behavior. Various sensory inputs are available to the nervous system to detect and correct postural instability. Most notably, vestibular, visual, and proprioceptive signals contribute significantly to the stabilizing responses in humans. The intent of this paper is to review experimental results rather than to disc...
Visual-vestibular interactions in postural control during the execution of a dynamic task
Experimental Brain Research, 2002
The purpose of this experiment was to determine the interaction between visual and vestibular information during the transition from quiet standing to the completion of a forward step. Six subjects were asked to take one step forward at the sound of an audio tone, with their eyes open or closed, and terminate the step in a standing position. During stimulation trials, galvanic vestibular stimulation (GVS) was delivered 1500 ms before the auditory cue. GVS was delivered at an intensity three-fold that of each subject's quiet stance threshold with either stimulus right, left or no stimulation. Force data were collected from three forceplates for the calculation of centre of pressure (CoP), and kinematic data were used to calculate centre of mass (CoM) and body trajectories. In quiet stance all subjects responded to the GVS perturbation by demonstrating upper body segment roll and whole body sway towards the anode electrode. Unexpectedly, in the presence of vision during quiet stance, the upper body roll response was not attenuated, even though the CoP sway patterns were reduced when vision was available. During the initiation phase of the step, despite ongoing GVS stimulation, there were no significant effects seen in CoM, CoP or upper body roll responses. During step execution, however, both CoM displacement and upper body roll demonstrated significant effects and both responses were significantly reduced when subjects' eyes were open. Analysis of the medio-lateral CoP integrals also indicated a strong stimulation effect between conditions late in the execution phase, which were largely attenuated with vision. The results suggest that the importance of visual and vestibular information varies depending on the phase of the task. In addition, the different integration between visual and vestibular input during quiet standing suggests a dual role for vestibular information. We propose that vestibular information in quiet standing has a role in maintaining whole body postural stability, as well as playing an integral role in the alignment of the body segments in preparation for proper movement execution. Vision was demonstrated to differentially attenuate these responses based on the phase of the task. Thus, visual and vestibular information appear to be integrated differently across the different phases of a forward-stepping task.
Frontiers in Human Neuroscience
The visual system is a source of sensory information that perceives environmental stimuli and interacts with other sensory systems to generate visual and postural responses to maintain postural stability. Although the three sensory systems; the visual, vestibular, and somatosensory systems work concurrently to maintain postural control, the visual and vestibular system interaction is vital to differentiate self-motion from external motion to maintain postural stability. The visual system influences postural control playing a key role in perceiving information required for this differentiation. The visual system’s main afferent information consists of optic flow and retinal slip that lead to the generation of visual and postural responses. Visual fixations generated by the visual system interact with the afferent information and the vestibular system to maintain visual and postural stability. This review synthesizes the roles of the visual system and their interaction with the vestib...
Human Postural Responses to Sensory Stimulations. Measurements and Model
Measurement Science Review
In the paper we examined the influence of vestibular and leg proprioceptive inputs on the human upright posture. Vestibular input was changed by applying current 1 mA between places near to left and right ear. Proprioceptive input was modified by vibrating the calf muscle. Furthermore, the vestibular stimulus was combined with the muscle vibration using five different temporal relationships between the stimuli. Body postural responses were measured by force platform as a center of foot pressure (CoP) to the support surface. With the anode on the right side, vestibular CoP body response was towards the right side. Vibration of right tibialis anterior muscle induced CoP body shift forward and to the right. With combined stimulation, responses with complex trajectory resulted, which depended on the stimulus interval and reflected a superposition of the single vestibular and proprioceptive effects. The results show that the body vertical is under the continuous control of leg propriocep...
Gait & Posture, 2008
Maintaining erect human posture depends on graviceptive information. This can come from at least of three origins: vestibular, visual and somaesthetic. We hypothesize here that subject's use proprioception rather than visual or vestibular cues for their control of upright body posture and this even when subjects stand on a tilting body support surface. In order to find experimental evidence for this hypothesis, we exclude in our experiments visual cues (eyes close) and by keeping frequency and amplitude of the tilt stimulus so low that it would be below the detection threshold for vestibular semi-circular canal stimuli. The orientations of body segments were analysed during various phases of the perturbation cycle. Segmental stabilisations were defined in terms of both the global anchoring index calculated during the whole perturbation cycle and an appropriate sequential anchoring index calculated during various phases in the perturbation cycle. We show that subjects tend to align their bodies with the space vertical and do so better for their heads than for their upper bodies and lower bodies. A further finding is that stabilisation is related to the tilt stimulus in the form that it is minimal at the turning points of the tilt, where peak tilt velocity is minimal with the sinusoidal stimulus used.
Effect of vision, proprioception, and the position of the vestibular organ on postural sway
Acta Oto-laryngologica, 2010
Conclusion: When measured together, it seems that vision and proprioception as well as position of the vestibular organ affect postural sway, vision the most. Mediolateral (ML) sway does not seem to be influenced by the position of the vestibular organ. Objective: To investigate how postural sway was affected by provocation of vision, by the position of the vestibular organ, and by provocation of proprioception, when measured together. Methods: Postural sway was measured by using a force plate. Tests were performed with eyes open and eyes closed, with head in neutral position and rotated to the right and to the left and with head maximally extended, both standing on firm surface and on foam. Measures of ML speed (mm/s), anteriorposterior (AP) speed (mm/s), and sway area (SA) (mm 2 /s) were analyzed using a multilevel approach. Results: The multilevel analysis revealed how postural sway was significantly affected by closed eyes and standing on foam, and by the position of the vestibular organ. Closed eyes and standing on foam both significantly prolonged the dependent measurement, irrespective of whether it was ML, AP or SA. However, only AP and SA were significantly affected by vestibular position, i.e. maximal head movement to the right and extension of the head.
Proprioceptive control of posture: a review of new concepts
Gait & Posture, 1998
The assumption that proprioceptive inputs from the lower legs are used to trigger balance and gait movements is questioned in this review (an outgrowth of discussions initiated during the Neural Control of Movement Satellite meeting held in Cozumel, Mexico, April 1997). Recent findings presented here suggest that trunk or hip inputs may be more important in triggering human balance corrections and that proprioceptive input from the lower legs mainly helps with the final shaping and intermuscular coordination of postural and gait movements. Three major questions were considered. First, what role, if any, do lower-leg proprioceptive inputs play in the triggering of normal balance corrections? If this role is negligible, which alternative proprioceptive inputs then trigger balance corrections? Second, what is the effect of proprioceptive loss on the triggering of postural and gait movements? Third, how does proprioceptive loss affect the output of central pattern generators in providing the final shaping of postural movements? The authors conclude that postural and gait movements are centrally organized at two levels. The first level involves the generation of the basic directionally-specific response pattern based primarily on hip or trunk proprioceptive input and secondarily on vestibular inputs. This pattern specifies the spatial characteristics of muscle activation, that is which muscles are primarily activated, as well as intermuscular timing, or the sequence in which muscles are activated. The second level is involved in the shaping of centrally set activation patterns on the basis of multi-sensorial afferent input (including proprioceptive input from all body segments and vestibular sensors) in order that movements can adapt to different task conditions.