Stochastic Resonance Reduces Sway and Gait Variability in Individuals With Unilateral Transtibial Amputation: A Pilot Study

Abstract

Sub-threshold (imperceptible) vibration, applied to parts of the body, impacts how people move and perceive our world. Could this idea help someone who has lost part of their limb? Sub-threshold vibration was applied to the thigh of the affected limb of 20 people with unilateral transtibial amputation. Vibration conditions tested included two noise structures: pink and white. Center of pressure (COP) excursion (range and root-meansquare displacements) during quiet standing, and speed and spatial stride measures (mean and standard deviations of step length and width) during walking were assessed. Pink noise vibration decreased COP displacements in standing, and white noise vibration decreased sound limb step length standard deviation in walking. Sub-threshold vibration positively impacted aspects of both posture and gait; however, different noise structures had different effects. The current study represents foundational work in understanding the potential benefits of incorporating stochastic resonance as an intervention for individuals with amputation.

Vibration Sensitivity Is Associated With Functional Balance After Unilateral Transtibial Amputation

“…Specifically, Likens et al applied subthreshold vibration to the residual limb thigh among adults post-TTA (n=20), reducing postural sway and gait variability. 41 Although currently experimental, the use of vibratory technologies may provide augmented somatosensory feedback to overcome loss of the anatomic foot, and the environment inherent to the prosthesis-limb interface, to enhance functional balance post-TTA, particularly because vibratory thresholds appear to be preserved postamputation, in the absence of dysvascularity and pain.…”

Subthreshold Vibration Influences Standing Balance but Has Unclear Impact on Somatosensation in Persons With Transtibial Amputations

“…Impaired balance may lead to individuals avoiding certain activities, compounding some morbidities (Patla and Shumway-Cook, 1999). However, improving the somatosensation of the residual limb may improve standing balance (Quai et al, 2005;Likens et al, 2020).…”

“…For example, it has been suggested that the vestibular system uses SR to amplify sound to ward off hearing loss, presenting as tinnitus, or conductive hearing loss (Krauss et al, 2016). In the context of human movement, applying subthreshold vibration at or proximal to the site of interest has been associated with improvements in balance, proprioception, gait, and sensation (Gravelle et al, 2002;Liu et al, 2002;Khaodhiar et al, 2003;Priplata et al, 2006;Stephen et al, 2012;Enders et al, 2013;Kundu and Sarkar, 2015;Lakshminarayanan et al, 2015;Lipsitz et al, 2015;van der Groen and Wenderoth, 2016;Hathibelagal, 2018;Temple et al, 2018;Seo et al, 2019;Zandiyeh et al, 2019;Likens et al, 2020;Zwaferink et al, 2020). Notable areas of improvement in individuals with amputation include SR reducing COP sway, gait variability, and single leg stances measures (Lee et al, 2007;Likens et al, 2020).…”

“…In the context of human movement, applying subthreshold vibration at or proximal to the site of interest has been associated with improvements in balance, proprioception, gait, and sensation (Gravelle et al, 2002;Liu et al, 2002;Khaodhiar et al, 2003;Priplata et al, 2006;Stephen et al, 2012;Enders et al, 2013;Kundu and Sarkar, 2015;Lakshminarayanan et al, 2015;Lipsitz et al, 2015;van der Groen and Wenderoth, 2016;Hathibelagal, 2018;Temple et al, 2018;Seo et al, 2019;Zandiyeh et al, 2019;Likens et al, 2020;Zwaferink et al, 2020). Notable areas of improvement in individuals with amputation include SR reducing COP sway, gait variability, and single leg stances measures (Lee et al, 2007;Likens et al, 2020). Given previous promising results, SR may be beneficial to improve other measures of standing balance and somatosensation in individuals with amputations (Likens et al, 2020).…”

“…Notable areas of improvement in individuals with amputation include SR reducing COP sway, gait variability, and single leg stances measures (Lee et al, 2007;Likens et al, 2020). Given previous promising results, SR may be beneficial to improve other measures of standing balance and somatosensation in individuals with amputations (Likens et al, 2020).…”