Immediate Effects of Plantar Vibration on Fall Risk and Postural Stability in Stroke Patients: A Randomized Controlled Trial

Abstract

Background

Local vibration can improve balance problems of individuals with stroke when applied to the plantar region.

Aims

This study aimed to determine the immediate effect of local vibration applied to the plantar region on fall risk and postural stability in patients with stroke.

Study Design

Randomized controlled study.

Methods

30 patients (23 male,7 female) with stroke were randomized to either vibration (n = 15; 58.47 ± 8.23 years) or control (n = 15; 58.27 ± 9.50 years) groups. Before and after the intervention, the patients were evaluated using a Biodex Balance System. Local vibration was applied to the plantar region of two feet in the supine position using a vibration device for a total of 15 min to the individuals in the vibration group. While the patients in the placebo group were in the supine position, the device was brought into contact and no vibration was applied to the plantar region of two feet for 15 min.

Results

While significant improvements were observed in the postural stability and fall risk of the vibration group (p < 0.05), no significant change was observed in the placebo group (p > 0.05). Furthermore, significant improvements occurred in the SD values of the postural stability expressing postural oscillation in the vibration group (p < 0.05).

Conclusion

As a result of local vibration applied to the plantar region, immediate (within 5 min) significant improvements in postural stability and fall risk values were detected.

Introduction

Stroke is one of the common neurological problems and is the third leading cause of death in the world after cardiovascular diseases and cancer.^1,2 Motor, cognitive, sensory, and emotional problems occur in patients with stroke.³ As a result of these problems, one of the common problems observed in patients with stroke is fall. It is reported that 14–65% of stroke patients experience falls when they are at the hospital and that 73% of them experience falls within the first six months after discharge. Falls in the stroke population can cause four times higher bone fracture ratio and severe injuries in comparison with the general population. Therefore, improving balance and reducing fall risk are essential goals of post-stroke rehabilitation.⁴

Somatosensory problems occur in 45% of stroke individuals.⁵ The high incidence of somatosensory losses in individuals with stroke causes wrong perception of the body position and consequently, balance and postural control problems arise.⁶ Approximately 90% of patients with stroke experience motor control and balance problems.^7,8 As a result, sensory disorders directly cause post-stroke activity and social restrictions.⁹ The impairment of the lower extremity tactile sensation after stroke affects 30–56% of patients with stroke.^10,11 Wright et. al. suggested that the plantar region of the foot is a sensory " dynamometric map" for postural control, gait kinematics, adjustment of the foot position, and balance control.¹² This decreased plantar region sensation has a negative effect on gait, balance, and falls.¹³ In the literature, it has been stated in studies conducted on stroke individuals that local vibration reduces sensory loss, plays a role in ensuring somatosensory integration, especially with the increase in the sense of paretic side, weight transfer to the paretic side increases and provides symmetrical weight transfer.^14,15 Therefore, local vibration is one of the powerful methods to increase proprioceptive input, and increased proprioceptive input may induce functional recovery, such as muscle activation and postural control.^16,17

In the literature, it was observed that multiple frequency interventions were made in the studies examining the effect of local vibration on balance and that effective results were obtained. Novak et al. reported that as a result of a 70 Hz local vibration applied to the sole of the foot in patients with Parkinson's disease, gait velocity and step length increased, and improvement occurred in gait rhythm.¹⁸ See-Won Lee et al. reported that local vibration applied at 90 Hz frequency in stroke individuals had positive effects on postural control and gait.¹⁴ The study by Khalifeloo et al. reported that positive effects were obtained on balance as a result of a 100 Hz 5-min vibration intervention to the hemiplegic side of the sole of the foot in patients with stroke.¹⁵ In a systematic review conducted by Murillo et al., they detected that local vibration applied until a frequency of 80 Hz. increased the firing rate of group Ia-afferent fibres, and thus, that the proprioceptive inputs to the central nervous system increased.¹⁹

Recently, vibration interventions are among the current treatment approaches in stroke rehabilitation. In the literature, both whole-body vibration and local vibration are used in patients with stroke. However, it is observed that especially the use of whole-body vibration is more common and that there are many studies investigating especially its effect on balance.^16,20,21 The use of local vibration in patients with stroke focuses on its effects on gait, spasticity, hemineglect, muscle performance, and the upper extremity.^14,22, 23, 24 In the literature, the number of studies demonstrating the effect of local vibration on balance in patients with stroke are limited. Only one study demonstrating the immediate effect of local vibration applied to the plantar region on balance was found.¹⁵ In this respect, this study aimed to determine the immediate effect of local vibration applied to the plantar region on fall risk in patients with stroke. We hypothesized that after the local vibration stimulation applied to the plantar region, patients with stroke would show improvements postural stability and the risk of falling.