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.
Alison M. Aries
Valerie M. Pomeroy
Julius Sim
Susan Read4 and 
Susan M. Hunter