Biomedical Engineering Reference
In-Depth Information
2.1.1
Symptomatology
The symptoms or disorders associated with MS can be from various types such as
motor, sensory, cognitive [
27
] and psychosocial [
28
]. Vary widely from individual
to individual and also with the evolutionary stage of the disease [
29
]. The motor
symptoms include impaired speech and swallowing, bladder dysfunction, bowel
and sexual [
30
,
31
], fatigue [
32
], spasticity [
33
], tremor [
34
], muscle weakness,
paresis, clonus, impaired postural stability [
35
] and gait abnormalities, being a major
factor the ataxia [
36
]. Ataxic patients give priority to the maintenance of postural
stability by a propulsive movement, with increased proximal muscle activity, step
towards extending the medio-lateral and extended period of double support (which
corresponds to the time that both feet are in contact with support).
This type of gait ataxia identifies a incoordination in the lower limbs, in which
the angular displacements of joints are getting smaller with a consequent decrease
in gait speed [
37
]. Fatigue is another symptom that patients identify as one of the
most adverse factors for the activities of daily living, followed by bladder problems
and changes in postural stability. New evidence suggests that fatigue may be related
to dysfunction of the regulation of body temperature [
38
]. The bladder disorders
are highly disabling in daily life and spinal cord injuries appear to be the cause of
pelvic dysfunction. These disorders are characterized by urinary urgency as a result
of the Detrusor hyper-reflex or by decreasing the storage capacity of the bladder.
In sensory symptoms is identified the changes in vision, dizziness, paresthesia and
sexual dysfunction.
2.1.2
Types of Multiple Sclerosis
We consider that there are three major types of Multiple Sclerosis [
20
]: Relapsing-
Remitting, Secondary Progressive and Primary Progressive.
•
The Relapsing-Remitting type accounts for 25% of total cases and is character-
ized by an exacerbation of neurological symptoms lasting more than 24 h [
39
].
Typically occurs between several days to 2 weeks, followed by a complete or
nearly complete remission of symptoms. The frequency of relapses varies greatly,
but on average one case per year [
40
]. Especially with more severe relapses, there
may be long periods of recovery and the persistence of residual symptoms. Some
authors [
41
,
42
] consider that there must be at least a period of 30 days between
two exacerbations, to be considered two distinct relapses. The most frequent
symptoms in this type of MS are the visual and sensory disturbances. The patient
often resorts to an evaluation by a neurologist in the second or third relapse, with
the disease already installed in the progressive phase.
•
Secondary progressive type accounts for 60% of total cases and is a continuation
of relapsing-remitting [
43
]. It is characterized by a progression of relapses, with
worsening of symptoms with a minimum period of 6 months, in which may
occur another severe relapses [
44
]. In this type of MS disorders are frequently
associated with gait and motor abnormalities, such as paresthesia.
