The nerve cells in these structures send a continu-
ous stream of signals to the movement centers of
the brain, which in turn direct the muscles to
respond in ways that keep the body upright and
stable. This flow of communication takes place
immeasurably fast and without conscious aware-
ness, as long as all components of the system are
functioning properly.
Situational disruptions of vestibular functions
(such as a carnival ride creates) resolve sponta-
neously when the stimulatory overload stops and
the body returns to normal functions, though
residual sensations of NAUSEAor queasiness may
remain. Pathologic disruptions—changes brought
about by damage or disease—often result in per-
sistent balance disturbances, the key symptom of
which is vertigo.
Relieving Vertigo
Situational vertigo, such as from spinning in cir-
cles, resolves itself when the environmental stim-
ulation stops. When vertigo is pathologic, certain
ANTIHISTAMINE MEDICATIONS, commonly marketed
for relief of motion sickness, often provide relief.
Researchers do not know the mechanisms
through which antihistamines intercede with
vestibular functions. Most antihistamines that can
relieve vertigo also cause substantial drowsiness,
making them unsuitable in situations that require
alertness and concentration.
Maintaining the focus of the eyes on the direc-
tion of movement can help stabilize the vestibular
system. This method provides additional informa-
tion to the brain via sight about the body’s posi-
tion and movement. It also is a diagnostic device
in helping distinguish the nature of the dysfunc-
tion: vestibular or neurologic. Many people obtain
relief from ACUPUNCTUREand acupressure. Pressure
bands are available that activate the acupuncture
points on the inner wrists; rubbing the earlobes
activates the acupuncture points there.
Surgical interventions may become necessary
to treat severe, unremitting vertigo that becomes
disabling. These are procedures of final resort, as
they create permanent disruptions in the vestibu-
lar system such as severing the vestibular nerve or
removing the labyrinthine structures of the inner
ear. Because the function of hearing also uses
these structures, surgical interventions are typi-
cally viable options only when there is also pro-
found and irreversible HEARING LOSS.Preventing Vertigo
Situational vertigo is preventable by avoiding the
circumstances that cause it. Pathologic vertigo
results from underlying disease processes that
often are not possible to mitigate. Methods such as
focusing the eyes in the direction of movement
can sometimes minimize a vertigo episode. Some
vertigo is positional, so avoiding the positions pre-
vents the vertigo. Quick movements of the head,
particularly upward, are known to bring on ver-
tigo in many conditions in which vertigo occurs
(such as Ménière’s disease).
Space flight is providing an ideal opportunity
for researchers to study the mechanisms of bal-
ance and vertigo, as nearly all astronauts experi-
ence vertigo under the extreme gravitational and
centrifugal forces to which leaving and reentering
the earth’s gravitational field subjects them as well
as the absence of gravity during space flight. The
normally functioning vestibular system uses grav-
ity as its point of reference for determining the
body’s position and movement. Researchers hope
that gaining understanding of how the body
adapts to the absence of gravity will shed light on
how the vestibular system functions as well as
dysfunctions, leading to new preventions and
treatments for vertigo and the conditions for
which it is a symptom.
See also ACOUSTIC NEUROMA; BENIGN PAROXYSMAL
POSITIONAL VERTIGO(BPPV); LABYRINTHITIS.vestibular neuronitis A dysfunction of the
vestibular system that causes sudden and severe
VERTIGO(sensation of spinning) with accompany-
ing NAUSEA, VOMITING, and balance disturbances.
The prevailing view is that viral infections cause
vestibular neuronitis. Because hearing remains
unaffected, doctors believe the INFECTIONinflames
the vestibular NERVE, the branch of the eighth cra-
nial nerve (vestibulocochlear nerve) leading from
the vestibular structures to the BRAIN. INFLAMMA-
TIONcauses the vestibular nerve to transmit con-
fused and erroneous signals to the brain. The
brain responds to the incoming signals as thoughvestibular neuronitis 61