Page 29 - Advances in Biomechanics and Tissue Regeneration

2.2 DIAGNOSING VESTIBULAR DYSFUNCTIONS 23

to be a valid research opportunity to test and validate hypotheses, such as the orientation and shape of the otolith
maculae.
The patient’s early evaluation also takes place in biomechanical concerns. In the last decades, research and study in
the field of otoneurology of patients suffering have been developed. The outcome of such research led to quick balance
recovery strategies development, preventing the onset or recurrence of vestibular disorders and consequently result-
ing in a fast reintegration to the daily routine.

2.2 DIAGNOSING VESTIBULAR DYSFUNCTIONS

The final goal of any health research project is to take a step into the quality improvement of the patient’s daily life.
A deep comprehension of the development of vestibular dysfunctions is a desirable start. In the present chapter, some
of the main diseases affecting the vestibular system and respective therapies will be discussed.
The literature shows that 85% of the balance dysfunctions could be related to the inner ear disorders [11], mainly
from the vestibular segment. People suffering from vertigo and dizziness have a higher risk of falls, so it is important to
develop mechanisms to decrease or even eliminate these symptoms. There are high mortality and morbidity rates asso-
ciated with falls in patients above 65years old. The accidents constitute the sixth cause of death in this age group; falls
are responsible for half of these episodes [12, 13]. Additionally, falls are one of the main causes of accidental bone frac-
tures in older patients. Furthermore, the healthcare related to these kinds of fracture involves high costs, which are
another strong motivation to decrease the number of people who suffer from dizziness [14].
Vertigo is one of the most common medical complaints, affecting approximately 20%–30% of the population world-
wide [15]. Vertigo may be present in patients of all ages, and its prevalence increases with age, being the most frequent
complaint in people over 70years old. Additionally, vertigo is about two to three times more predominant in women
than in men [16]. These numbers lead us to fathom the conditions behind the vestibular system failure. The vestibular
system degeneration associated with the decrease of the CNS capacities and the aging of the human body contribute to
balance changes. Other factors such as multiple and excessive medications expand the balance alterations, responsible
for the vertigo occurrence and for the imbalance of the geriatric population.
The circumstances regarding the orthostatic balance correspond to the body and view stabilization, ensuring the
maintenance of the gravitational center (GC) inside the sustentation polygon, either at rest or in motion [5, 17].
There are several reasons that could lead to a mismatch information between the systems in control of the balance
function. When it occurs, all the system breaks, leading to equilibrium loss, until the trigger is identified and starts to
compensate the central mechanisms to return balance. Consequently, vertigo can be defined as an illusionary sensation
of movement. However, it is often referred to the broadest sense of dizziness, imbalance, instability, or special disori-
entation [5, 17].
The classification of dizziness was first performed by Drachman and Hart following [18, 19], a categorization driven
by complaints of the patient, defined four categories of dizziness: presyncope (described as a feeling of imminent loss
of consciousness), imbalance (or apparent sense of falling, not exclusively associated with the movement), numbness
(described in Anglo-Saxon as light-headedness that does not present a clear definition or associated diagnosis), and
vertigo (defined as an illusion of movement, often with sense of rotation and with nausea and vomiting). The last is the
most prevalent cause of dizziness.
Vertigo can be caused by ear disorders, by the nerve connecting the ear to the brain, or even by the brain. Vertigo can
also be related to visual disorders or sudden changes in blood pressure. Brain-related causes are less commonly asso-
ciated with isolated vertigo and nystagmus but can still produce signs and symptoms. Many other conditions can
affect the inner ear and cause vertigo, like bacterial or viral infections, cancer, abnormal pressure, nervous inflamma-
tion, or toxic substances.
Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo, and it is described as a brief,
intense sensation of spinning that occurs when there are changes in the head orientation with respect to gravity [9].
The cause of BPPV is the presence of otoconia in the SCC, which are normally located in the macula of the otolith
organs, as explained in the previous section. If they fall from the utricle and become loose in the SCC, it will induce a
false spinning sensation with no head rotational motion actually occurring. The sensation is generated by the distinct
information sent to the brain by the two different systems, visual and vestibular [9, 20].
Therefore the BPPV diagnostic is obtained by the Dix-Hallpike maneuver, which consists of a specific set of move-
ments performed by an audiologist, where the presence of nystagmus confirms the disorder [21].

I. BIOMECHANICS