Sensory Stimulation of the Foot and Ankle Early Post-stroke: A Pilot and Feasibility Study

Since the outcome measure wasn't 100% recovery you used the tyranny of low expectations to get the survivors to  accept the outcomes. You'll have to ask your doctor to get the protocol for mobilization and tactile stimulation.

Sensory Stimulation of the Foot and Ankle Early Post-stroke: A Pilot and Feasibility Study

Alison M. Aries^1*, Valerie M. Pomeroy^2,3, Julius Sim¹, Susan Read⁴ and Susan M. Hunter¹

• ¹School of Allied Health Professions, Faculty of Medicine and Health Sciences, Keele University, Keele, United Kingdom
• ²Acquired Brain Injury Recovery Alliance (ABIRA), School of Health Sciences, University of East Anglia, Norwich, United Kingdom
• ³National Institute for Health Research (NIHR) Brain Injury MedTech Co-operative, Cambridge, United Kingdom
• ⁴School of Nursing and Midwifery, Faculty of Medicine and Health Sciences, Keele University, Keele, United Kingdom

Background: Somatosensory stimulation of the lower extremity could improve motor recovery and walking post-stroke. This pilot study investigated the feasibility of a subsequent randomized controlled trial (RCT) to determine whether task-specific gait training is more effective following either (a) intensive hands-on somatosensory stimulation or (b) wearing textured insoles.

Objectives: Determine recruitment and attrition rates, adherence to intervention, acceptability and viability of interventions and outcome measures, and estimate variance of outcome data to inform sample size for a subsequent RCT.

Methods: Design: randomized, single-blinded, mixed-methods pilot study.

Setting: In-patient rehabilitation ward and community.

Participants: n = 34, 18+years, 42–112 days following anterior or posterior circulation stroke, able to follow simple commands, able to walk independently pre-stroke, and providing informed consent.

Intervention: Twenty 30-min sessions of task-specific gait training (TSGT) (delivered over 6 weeks) in addition to either: (a) 30–60 min mobilization and tactile stimulation (MTS); or (b) unlimited textured insole (TI) wearing.

Outcomes: Ankle range of movement (electrogoniometer), touch-pressure sensory thresholds (Semmes Weinstein Monofilaments), motor impairment (Lower Extremity Motricity Index), walking ability and speed (Functional Ambulation Category, 5-m walk test, pressure insoles) and function (modified Rivermead Mobility Index), measured before randomization, post-intervention, and 1-month thereafter (follow-up). Adherence to allocated intervention and actual dose delivered (fidelity) were documented in case report forms and daily diaries. Focus groups further explored acceptability of interventions and study experience.

Analysis: Recruitment, attrition, and dose adherence rates were calculated as percentages of possible totals. Thematic analysis of daily diaries and focus group data was undertaken. Standard deviations of outcome measures were calculated and used to inform a sample size calculation.

Results: Recruitment, attrition, and adherence rates were 48.57, 5.88, and 96.88%, respectively. Focus groups, daily-diaries and case report forms indicated acceptability of interventions and outcome measures to participants. The 5-m walk was selected as primary outcome measure for a future trial [mean (SD) at end of intervention: 16.86 (11.24) MTS group and 21.56 (13.57) TI group]; sample size calculation indicated 60 participants are required per group.

Conclusion: Recruitment, attrition and adherence rates and acceptability of interventions and outcomes justify a subsequent powered RCT of MTS+TSGT compared with TI+TSGT.

Introduction

Every 2 s, someone in the world experiences a stroke; there are more than 1.2 million stroke survivors in the United Kingdom (UK) alone (1). Many stroke survivors—between 65% (2) and 85% (3)—experience somatosensory impairment. This impacts adversely on the ability to detect, discriminate, and recognise sensations from the body because somatosensory function includes tactile sensation, vibration, pressure, proprioception, temperature, and pain (4). Somatosensory impairment of the lower limb is experienced by between 45% (5) and 56% (6) of stroke survivors and makes performance of everyday tasks difficult (5, 7). Consequently, potential for achieving independent walking post-stroke is decreased (8).

Regaining the ability to walk is a priority for many stroke survivors. Identifying best treatments to address balance, gait, and mobility has been identified by the James Lind Alliance as one of the top 10 research priorities for stroke (9). Progress is promised by interventions aiming to reduce motor impairment and thus recovery of body functions toward their pre-stroke state by utilising the principles of activity-driven neuroplasticity (10). Interventions to facilitate activity-driven neuroplasticity are placed into a framework of priming, augmentation, and practise (11).

Priming interventions prepare the sensorimotor system for motor function, specifically when limited or no volitional control of movement exists. Priming can be achieved through the provision of somatosensory stimulation as a precursor to task-specific training (11). Therapists can deliver intensive proprioceptive and tactile stimulation through a hands-on intervention known as mobilization and tactile stimulation (MTS) (12). Research into MTS for the contralesional hand post-stroke found reduction of motor impairment and improved upper-limb function (13, 14). MTS is also applied to the foot (15, 16). It is hypothesised that greater somatosensory awareness and alignment of the foot, through intensive somatosensory stimulation using MTS, improves the ability to place and transfer weight over the foot, permitting adaptation to different floor surfaces. However, this has not yet been tested.

Augmenting interventions may also enhance somatosensation during task-specific activity. For example, standing on textured materials (17) and wearing textured insoles (TIs) in shoes to improve perceptual motor performance (18). TIs are designed to stimulate sensory receptors on the plantar surface of the foot: tactile (19), pressure (20), and vibration (21). Afferent information from the foot and ankle is, therefore, crucial for postural control and walking capacity (22). TIs that enhance sensory awareness of the foot during motor activity are also expected to improve contact of the foot with the supporting surface and thus interaction between the foot and the floor, which is important for functional activity (23). The use of TIs is a “hands-off,” low-cost augmentation strategy that has been shown to reduce mediolateral sway in healthy populations (24), and change spatiotemporal gait parameters in people with multiple sclerosis (25). However, TIs have not yet been investigated in a stroke population, stimulating the contralesional side.

Practice interventions use task-specific training, which is recommended when stroke survivors can repeat and practice movements or tasks (11). Task-specific training has been shown to improve motor function post-stroke (26–28). More specifically, task-specific gait training (TSGT) is an effective intervention after stroke (26, 29–31).

It is known that afferent input can influence motor control (32, 33). However, it is not known whether combining TSGT with somatosensory stimulation—either priming using MTS, or augmentation by wearing TIs—would increase the effect. The hypothesis is that MTS (priming intervention) immediately before TSGT has greater efficacy than TSGT combined with wearing TIs (augmentation intervention) in reducing sensorimotor impairment and improving functional ability of the more paretic lower limb after stroke. Before this hypothesis can be tested in an adequately powered randomized controlled trial (RCT) it was important to undertake a pilot study to determine the viability of a subsequent RCT (34, 35).

The objectives for this study were to:

1. Estimate recruitment rate for a subsequent RCT.

2. Estimate attrition rate for a subsequent RCT.

3. Estimate the adherence rate to the interventions and their acceptability to participants.

4. Investigate acceptability and feasibility (effective delivery and success of blinding) of a battery of outcome measures, to inform primary and secondary outcome measures for a future trial.

5. Undertake a sample size calculation for a subsequent RCT, using the estimated variance of the selected primary outcome measure.

6. Monitor the type and frequency of adverse events.