Biomedical Engineering Reference
In-Depth Information
useful tool to detect the no visual data. Comparing the results of the present work
there is evidence that the exclusive use of the BBS is test is ineffective in small
postural disorders.
1
Introduction
Multiple Sclerosis (MS) affects about 2.5 million people in all world and is the most
common neurological disorder, with major incapacity in young adults, especially
in Europe and North America [
1
]. We know today that beyond the environmental
component, genetic factors have a large influence on the acquisition of the disease,
thus, susceptibility to the different responsibilities and racial heterogeneity of ethnic
groups, play an important role in the geographical distribution of the disease [
2
].
Globally, the median estimated prevalence of MS is 30 per 100,000 (with a range of
5-80). Regionally, the median estimated prevalence of MS is greatest in Europe (80
per 100,000), followed by the Eastern Mediterranean (14.9), the Americas (8.3), the
Western Pacific (5), South-East Asia (2.8) and Africa (0.3) [
3
].
The symptoms of MS are very diverse as the disease course. Some patients,
throughout their life, just have a small disability, although about 60% can no longer
walk in the next 20 years, after the diagnosis [
4
]. In the disease course, the life
expectancy is slightly changed, but the quality of life is seriously affected in recent
years. Patients with MS learn to live with the difficulties inherent to the disease
progression, but there is a big change in their plans, also in employment and hope
for the future. Many of these patients are young adults, in the beginning of their
careers and family building [
5
]. Another stressful aspect is the uncertainty about the
future. Many times after adjustment to disability from the last relapse of the disease,
a new relapse that causes more disability and limitation, requiring a new period of
adjustment and changes in daily life. MS is an inflammatory disease of the central
nervous system (CNS) associated with loss of motor and sensory function. These
symptoms results from white matter lesions, that causes destruction of axons and
myelin sheaths, with a consequent decrease in nerve impulses [
6
].
A major problem associated with this disease, is the alteration of postural stability
[
7
]. This change of stability puts individuals at risk of falling and serious injury,
complicating the handling of these patients, increasing their disability and causing
changes in the quality of life [
8
].
The responsible mechanisms for altering the postural stability in these patients
still not very clear. The cause of this instability may be due to an isolated lesion in
a single system or neuronal pathway, or often, due to multiple injuries affecting
two or more sensor motor systems [
7
]. If only one system is damaged, the the
compensation can be reasonably effective. In the case of many systems affected
compensation is more complex and it becomes increasingly difficult as the disease
progresses and becomes more severe. The postural stability and joint stability in
particular is essential to the success of human movements [
4
]. In an unstable system,
a small variation in initial condition, or a small external perturbation, may lead to an
