Perception of the Postural Vertical and Falls in Older People

Abstract

<b><i>Background:</i></b> Research on the relationship between vestibular function and falls in older people is sparse. The perception of the postural vertical (PPV) provides an indicator measure of vestibular (otolith) function in the absence of visual input and diminished somatosensory feedback. <b><i>Objective:</i></b> This study examined whether impaired PPV is associated with falls in this group. <b><i>Methods:</i></b> One hundred and ninety-five people aged 70 plus years stood blindfolded on a motorised platform that could be tilted in the roll plane and attempted to adjust it so that their bodies were aligned to the vertical. Somatosensory feedback was minimised as the base and vertical support surfaces on the tilting platform were covered in thick soft foam rubber. PPV error from true vertical and PPV variability (°) were calculated. Participants also underwent an assessment of distal tactile sensitivity and the physiological profile assessment (PPA); fallers were defined as those who had one or more falls during a prospective 12-month follow-up period. <b><i>Results:</i></b> Eighty-eight participants (45%) reported falling in the follow-up year. Increased PPV error and variability were correlated with increased lateral sway in a condition of absent visual input and reduced foot somatosensory feedback (eyes closed/foam; r range = 0.16–0.20, p < 0.05) and with composite PPA fall risk scores (r range = 0.22–0.26, p < 0.05). PPV variability was a significant and independent predictor of falls after adjusting for the composite PPA scores, age and gender [adjusted RR = 1.42 (1.01–1.98)]. <b><i>Conclusions:</i></b> Older people with increased PPV variability are at increased risk of falls. These findings indicate that assessment of PPV may augment fall risk assessments in older people.

The altered vestibular-evoked myogenic and whole-body postural responses in old men during standing

“…This larger medium latency response in the tibialis anterior was strongly correlated with a larger medium latency peak amplitude response in the AP force. Previous reports have speculated that increased central sensitivity of the vestibular input may overcompensate for the peripheral degeneration within the relevant structures for vestibular function (Jahn et al, 2003;Welgampola and Colebatch, 2002) or alternatively, the perception of vestibular information may be altered (Menant et al, 2012) in old men compared with the young. For example, increased anxiety (Brown et al, 2006) and attentional demands (Woollacott and Shumway-Cook, 2002) in older adults alter motor strategies during quiet standing compared with younger adults and may be tied to the heightened cortical processing in the old.…”

Contribution of Head Position, Standing Surface, and Vision to Postural Control in Community-Dwelling Older Adults

“…Including head position aligns with functional tasks that require extending the head when reaching for objects placed above eye level. Changes in head position have also been associated with fall risk and can be used to test the contribution of corresponding sensory receptors such as neck proprioceptors (Deshpande & Patla, 2005;Vuillerme, Pinsault, & Bouvier, 2008) and vestibular apparatus (Menant et al, 2012), the sensitivity of which declines with advancing age. Findings reveal that sway velocity was significantly greater with an HE than with an HN position for each of the visualsurface conditions, thereby supporting our hypothesis.…”

“…The vestibular system's contribution to postural sway has been tested by altering visual and proprioceptive information, and impaired vestibular function has been linked to risk of falls (Menant et al, 2012). However, Deshpande and Patla (2005) reported that reduced sensitivity of neck proprioceptors rather than reduced sensitivity of vestibular receptors altered path deviation during locomotion, which suggests that reduced sensitivity of proprioceptors may apply to changes in postural sway as well.…”

“…In contrast, the contribution of vestibular function to postural control and fall risk in older people has received little attention (Menant, St George, Fitzpatrick, & Lord, 2012), and the available evidence is controversial. Difficulties maintaining a vertical position of the head while seated on a tilt table and being moved side to side, hence utilizing information from vestibular receptors, did not distinguish fallers from nonfallers (Woolley, Czaja, & Drury, 1997).…”

“…This problem is a concern because 37% of people older than age 60 yr report moderate to severe vertigo (Neuhauser et al, 2005). Moreover, clinical assessment of vestibular function and its corresponding contribution to fall risks are rarely tested (Menant et al, 2012). Understanding how these factors affect postural sway may contribute to better assessment and intervention practices and outcomes and is especially important for occupational therapy practitioners when determining an objective method for assessing outcomes and directing interventions for ADLs related to balance, fall prevention, and postural control.…”