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Stabilometric assessment of context dependent balance recovery in persons with multiple sclerosis: a randomized controlled study
Journal of NeuroEngineering and Rehabilitation
Stabilometric assessment of context dependent balance recovery in persons with multiple sclerosis: a randomized controlled study
Davide Cattaneo
Johanna Jonsdottir
Alberto Regola
Roberta Carabalona
Background: Balance control relies on accurate perception of visual, somatosensory and vestibular cues. Sensory flow is impaired in Multiple Sclerosis (MS) and little is known about the ability of the sensory systems to adapt after neurological lesions reducing sensory impairment. The aims of the present study were to verify whether: 1. Balance rehabilitation administered in a challenging sensory conditions would improve stability in upright posture. 2. The improvement in a treated sensory condition would transfer to a non treated sensory condition.
Rehabilitation; Balance; Sensory strategies; Multiple sclerosis; Postural control
Background
Epidemiological studies have found that 25% of persons
with Multiple Sclerosis (PwMS) show evidence of
cerebellar and brainstem involvement already at disease onset
and that this figure increases to 68% after longstanding
illness [
1
]. Problems in these two neural systems, along
with lesions in sensory systems and other neural networks,
lead to frequent balance disorders, falls and fractures [
2
]
in this population. Adequate balance relies on accurate
perception of physical stimuli by visual,
somatosensory and vestibular systems, and the integration of their
inputs [
3-5
].
Therefore, difficulty in properly perceiving and
integrating those stimuli can lead to inadequate motor
responses [
6-8
]. Daley and Swank [
9
] assessed the postural
sway in 113 PwMS, categorized either as actively
ambulant but with moderate function impairment or as still
ambulant but severely impaired. In quiet standing with
eyes open condition 30% of the moderately impaired
persons and 69% of the severely impaired persons showed
abnormal body sway, whereas with eyes closed 40% of the
moderately impaired persons had problems in body sway
and all the severely impaired had abnormal body sway.
Similarly, Cattaneo et al. [
10
] assessed the body sway in a
sample of 53 PwMS and found that, with respect to
healthy subjects, half of the people with MS showed
abnormal increase of sway and velocity of sway in quiet
standing with eyes open. The alteration of a single sensory
input (e.g., eyes closed) led to an increase in the frequency
of abnormal performances for 80% of subjects, while
alteration of two sensory inputs (e.g., eyes closed on foam) led
to a sharp increase in abnormal performance for almost
all subjects and many of them fell during the test. Balance
rehabilitation is an important component of the retraining
program in people with MS [
11-13
]. Although the impact
of MS on balance has been studied, little is known about
the ability of the sensory systems to improve after
neurological lesions and consequently improve balance
functions and sensory integration [
13
]. Retraining of sensory
systems is an important issue in rehabilitation and can be
achieved with an approach that privileges execution of
tasks in which the intact sensory systems are inhibited
consequently forcing the use of the impaired sensory
input. An effective improvement in sensory motor
strategies would imply the transfer of skills learned in
the rehabilitation setting in other, less controlled
settings in which sensory information are conflicting and
continuously changing. This would allow the generalization
of the effect of rehabilitation observed during
treatment sessions to activities of daily life. Transfer has been
seen for a wide variety of motor skills in healthy persons
while results in persons with neurological disabilities are
controversial [
14-17
]. Further, little is known about
transfer of sensory-motor skills learned in a specific sensory
context to a different one in persons with neurological
disorders. Therefore it is important to understand whether
the effect of skill training in persons with MS done in
specific sensory conditions transfers to other sensory
conditions.
In the present paper we addressed the ability of
persons with multiple sclerosis to:
1. Reduce sensory impairments improving balance. We
aimed at expanding the results reported by Cattaneo
et al. [
18
] regarding effects of balance rehabilitation
on disability. Our hypothesis was that subjects
repeatedly exposed to a challenging sensory
condition would improve their stability with respect
to a control group;
2. Transfer acquired skills among sensory conditions.
We hypothesized that improvement would be
context-dependent, that is, differences between
groups would be detected just in sensory conditions
included in the treatment regime.
Methods
A randomized controlled study with blind assessment
was set up and approved by the local Fondazione Don
Gnocchi Ethics Committee. PwMS were considered
eligible for the study according to the following inclusion
criteria: clinically or (...truncated)