Figure 20.4. Initial DGI and discharge DGI scores are plotted for individual patients. The line is positioned at a DGI score of 19/24, which is considered at risk for falls. Scores falling above the line indicate patients who are at low risk for falls. (Adapted from Hall et al., 2004, with permission.)

because the VOR cannot effectively keep the eyes stationary in space (Herdman et al., 2001; Schubert et al., 2002; Herdman et al., 2003). In these circumstances, visual cues such as retinal target displacement, changes in image size or retinal disparity would not be as useful to maintain balance while walking (Paulus et al., 1989).

20.7 Summary

Vision, somatosensory and vestibular inputs each contribute unique information regarding body position and motion contributing to postural control. No single sensory system provides us with sufficient information to definitively determine body position and movement; therefore, the different sensory systems cannot fully substitute for each other when there is a loss of function.

The vestibular system can trigger appropriate balance responses to an external perturbation, but the primary role of vestibular inputs appears to be stabilization of the head in space. The functional outcomes of loss of vestibular function are decrements in postural stability under more challenging conditions and degradation of vision during head movements. Prospective, controlled studies provide evidence that the use of VR is beneficial in improving postural and gaze stability as well as decreasing subjective complaints for patients with vestibular hypofunction.

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