Download Dizziness And Syncope

Dizziness and Syncope
Jong-Ling Fuh, MD
1. Vestibular Neuritis and Labyrinthitis
a. Etiology： viral infection of the vestibular nerve.
The vestibular nerve carries information from the inner ear about head
movement. When one of the two vestibular nerves is infected, there is an
imbalance between the two sides, and vertigo appears.
The virus that causes the infection is thought to be usually a member
of the herpes family, the same group that causes cold sores in the mouth
as well as a variety of other disorders.
b. Nnomenclature：neuritis（damage to the nerve）, neuronitis （damage
to the sensory neurons of the vestibular ganglion）
c.
Labyrinthitis
generally viruses cause the infection, but rarely labyrinthitis can be the
result of a bacterial middle ear infection.
hearing may be reduced or distorted in tandem with vertigo.
Both vestibular neuritis and labyrinthitis are rarely painful -- when
there is pain it is particularly important to get treatment rapidly as there
may be a treatable bacterial infection or herpes infection.
d. Symptoms：dizziness or vertigo, disequilibrium or imbalance, and nausea.
Acutely, the dizziness is constant. After a few days, sudden movements
often only precipitate symptoms. A sudden turn of the head is the most
common "problem" motion. While patients with these disorders can be
sensitive to head position, it is generally not related to the side of the
head, which is down, but rather just whether the patient is lying down or
sitting up.
e. Pathology：Single case report--viral infection of Scarpa's ganglion (the
vestibular ganglion). There was loss of hair cells, "epithelialization" of the
utricular maculae and semicircular canal cristae on the deafferented side,
and reduced synaptic density in the ipsilateral vestibular nucleus.
f.
Vestibular neuritis often spares part of the vestibular nerve, the
inferior-division. Because the inferior division supplies the posterior
semicircular canal and saccule, even a "complete" loss on vestibular
testing may be associated with some retained canal function.
g. Prevalence：About 5% of all dizziness (and perhaps 15% of all vertigo) is
due to vestibular neuritis or labyrinthitis. It occurs in all age groups, but
cases are rare in children.
h. Signs：spontaneous nystagmus, and unsteadiness Occasionally other
ocular disturbances will occur such as skew deviation and asymmetric
gaze evoked nystagmus.
i.
Examination
Acutely, in uncomplicated cases, while a thorough examination is
necessary, no additional testing is usually required.
It is not possible on clinical examination to be absolutely certain that
the picture of "vestibular neuritis" is not actually caused by a brainstem
or cerebellar stroke, so mistakes are possible. Nevertheless, this
happens so rarely that it is not necessary to perform MRI scans or the
like very often.
If symptoms persist beyond one month, reoccur periodically, or
evolve with time, testing may be proposed.
(a). an audiogram and an ENG. An audiogram is a hearing test to
distinguish between vestibular neuritis and other possible diagnoses
such as Meniere's disease and Migraine.
(b). MRI scan：if there is any reasonable possibility of a stroke or brain
tumor. Occasionally one can visualize the inflammation of the
vestibular nerve.
©. Blood tests for diabetes, thyroid disorders, Lyme disease, collagen
vascular disease and syphilis are sometimes performed, looking for
these treatable illnesses. However, it is rare that these are ever
positive.
j.
Treatment: The vestibular neuritis is treated symptomatically, meaning
that medications are given for nausea (anti-emetics) and to reduce
dizziness (vestibular suppressants).
k.
Prognosis
It usually takes 3 weeks to recover from vestibular neuritis or
labyrinthitis.
Some persons experience persistent vertigo or discomfort on head
motion.
In the great majority of cases (at least 95%) vestibular neuritis it is a
one-time experience. Rarely the syndrome is recurrent.
2. BENIGN PAROXYSMAL POSITIONAL VERTIGO (BPPV)
a. Etiology：otoconia which are small crystals of calcium carbonate derived
from a structure in the ear called the "utricle", was collected within a part
of the inner ear. While the saccule also contains otoconia, they are not
able to migrate into the canal system. The utricle may have been
damaged by head injury, infection, or other disorder of the inner ear, or
may have degenerated because of advanced age.
b. Prevalence
About 20% of all dizziness is due to BPPV.
About 50% of all dizziness in older people is due to BPPV.
c.
Symptoms： dizziness or vertigo, lightheadedness, imbalance, and
nausea. Symptoms are almost always precipitated by a change of
position of the head with respect to gravity. Getting out of bed or rolling
over in bed is common "problem" motions. An intermittent pattern is
common. BPPV may be present for a few weeks, then stop, and then
come back again.
d. Causes
The most common cause of BPPV in people under age 50 is head
injury.
In older people, the most common cause is degeneration of the
vestibular system of the inner ear.
In half of all cases, BPPV is called "idiopathic," which means it occurs
for no known reason.
Viruses affecting the ear such as those causing vestibular neuritis,
minor strokes such as those involving anterior inferior cerebellar artery
(AICA) syndrome", and Meniere's disease are significant but unusual
causes.
Occasionally BPPV follows surgery, where the cause is felt to be a
combination of a prolonged period of supine positioning, or ear trauma
when the surgery is to the inner ear.
e. Diagnosis：
Often, the diagnosis can be made with history and physical
examination. Most other conditions that have positional dizziness get
worse on standing rather than lying down (e.g. orthostatic hypotension).
Electronystagmography (ENG) testing may be needed to look for the
characteristic nystagmus.
f.
Differential Diagnosis：There are some rare conditions that have
symptoms that resemble BPPV. Patients with certain types of central
vertigo such as the spinocerebellar ataxias may have "bed spins" and
prefer to sleep propped up in bed. These conditions can generally be
detected on a careful neurological examination and also are generally
accompanied by a family history of other persons with similar symptoms.
g. Prognosis：BPPV has often been described as "self-limiting" because
symptoms often subside or disappear within six months of onset.
Symptoms tend to wax and wane.
h. Treatment：The Epley maneuver is also called the particle repositioning,
canalith repositioning procedure, and modified liberatory maneuver. It
involves sequential movement of the head into four positions, staying in
each position for roughly 30 seconds. It is very effective, with roughly an
80% cure rate. The recurrence rate for BPPV after these maneuvers is
about 30 percent at one year, and in some instances a second treatment
may be necessary.
3. Meniere's disease
a. History：In 1861, the French physician Prosper Meniere described a
condition, which now bears his name. Meniere's disease is a disorder of
the inner ear, which causes episodes of vertigo, tinnitus, a feeling of
fullness or pressure in the ear, and fluctuating hearing loss.
b. Symptoms
preceded by fullness in one ear, hearing fluctuation or changes in
tinnitus.
A Meniere's episode generally involves severe vertigo (spinning),
imbalance, nausea and vomiting.
The average attack lasts two to four hours.
An unusual sensitivity to visual stimuli is common.
"otolithic crisis of Tumarkin"：a sudden fall that may occur without
warning. These are attributed to sudden mechanical deformation of the
otolith organs (utricle and saccule), causing a sudden activation of
vestibular reflexes. Patients suddenly feel that they are tilted or falling
(although they may be straight), and bring about much of the rapid
repositioning themselves. This is a very disabling symptom as it occurs
without warning and can result in severe injury. Often destructive
treatment (e.g. labyrinthectomy or vestibular nerve section) is the only
way to manage this problem.
Meniere's episodes may occur in clusters; that is, several attacks may
occur within a short period of time. However, years may pass between
episodes. Between the acute attacks, most people are free of symptoms
or note mild imbalance and tinnitus.
c.
Prevalence
affects roughly 0.2% of the population.
Meniere's disease usually starts confined to one ear but it often
extends to involve both ears over time so that after 30 years, 50% of
patients with Meniere's have bilateral disease. Some authors suggest that
the prevalence of bilaterality is as low as 17%. Silverstein suggested that
75% of persons destined to become bilateral do so within 5 years.
d. Prognosis
In most cases, a progressive hearing loss occurs in the affected
ear(s).
A low-frequency sensorineural pattern is commonly found initially, but
as time goes on, it usually changes into either a flat loss or a peaked
pattern.
e. Mechanism
result from fluctuating pressure of the fluid within the inner ear.
A system of membranes, called the membranous labyrinth, contains a
fluid called endolymph. The membranes can become dilated like a
balloon when pressure increases. This is called "hydrops". One way for
this to happen is when the drainage system, called the endolymphatic
duct or sac is blocked. In some cases, the endolymphatic duct may be
obstructed by scar tissue, or may be narrow from birth. In some cases
there may be too much fluid secreted by the Stria Vascularis.
Hydrops is not found in all persons with Meniere's disease, and
hydrops is also commonly found (6%) on autopsy studies of persons who
had no Meniere's type symptoms.
Abnormally enlarged fluid pathways into the ear such as the vestibular
aqueduct or cochlear aqueduct may also be associated with Meniere's
like symptoms. Enlarged vestibular aqueducts are one of the most
commonly identified inner ear bony malformations in children with
sensorineural hearing loss of unknown cause. The vestibular aqueduct
extends from the medial wall of the vestibule to the posterior surface of
the petrous temporal bone. Most persons with enlarged vestibular
aqueducts with ear disorders have hearing loss, but occasionally there is
an association with vestibular problems.
Recently attention has been mainly focused on the immunologic
function of the endolymphatic sac -- immune disease may contribute to a
substantial percentage of Meniere's disease.
For the most part the underlying cause of Menieres disease is
unknown. It is most often attributed to viral infections of the inner ear,
head injury, a hereditary predisposition, and allergy.
Conventional thought is that repeated attacks of Meniere kill hair cells
in the inner ear. This is a gradual process over years, but frequently
resulting in unilateral functional deafness. Cochlear (hearing) hair cells
are the most sensitive. Vestibular hair cells seem more resilient but there
is also a slow decline in the caloric response in the diseased ear over
roughly 15 years.
Mechanical disruption of the inner ear is also likely with dilation of the
utricle and saccule of the ear being a well-known pathological finding of
Meniere disease. The saccule may dilate so that in later stages, it is
adherent to the underside of the stapes footplate. This mechanical
disruption and distortion of normal inner ear structures may result in the
gradual onset of a chronic unsteadiness, even when patients are not
having attacks. Finally, it also seems likely that there may be rupture of
the suspensory system for the membranous labyrinth. This might create
some mechanical instability of the utricle and saccule and consequently
some chronic unsteadiness.
f.
Prevalence
affects about 2 out of 1000 people.
The majority of people with Menier's disease are over 40 years of age,
with equal distribution between males and females.
g. Diagnosis
is based on a combination of the right set of symptoms (usually
episodic dizziness and hearing disturbance)
hearing tests (audiometry) which document that hearing is reduced
after an attack, and then gets better, and exclusion of alternative causes.
an ENG test, several blood tests (ANA, FTA), and an MRI scan of the
head. Electrocochleography (ECOG) is helpful in difficult cases.
h. Treatment
Between attacks, medication may be prescribed to help regulate the
fluid pressure in your inner ear, thereby reducing the severity and
frequency of the Meniere's episodes. Diamox is the most common
medication for this purpose. Verapamil (typical dose: 120 SR) sometimes
reduces the frequency of attacks.
The hydrops diet regimen will probably be recommended.
In extremely severe cases, treatments that deaden the inner ear such
as gentamicin injections or surgery may be considered. This is a last
resort for persons who have severe attacks, which are disabling. At
present, gentamicin is favoredfor most instances where destructive
treatments are being considered. Injections of gentamicin are given
through the eardrum, through a small hole or through a small tube. This
procedure allows one treat one side alone, without affecting the other.
Typically about four injections are given, over a period of a month.
Dizziness may reoccur one year later, requiring another series.
surgical treatment - vestibular neurectomy or vestibular nerve
section is very effective in eliminating vertigo but much higher risk than
gentamicin injection.
Another operation, called a labyrinthectomy is recommended in
persons who have lost all usable hearing or in whom vestibular nerve
section is considered too dangerous. Again, this procedure seems most
applicable to situations where gentamicin has failed.
A third procedure, the endolymphatic shunt procedure, is used by
some doctors to relieve pressure in the inner ear.
4. Perilymph Fistula
a. Etiology
an abnormal opening in fluid filled inner ear.
There are several possible places that there can be an opening-between the air-filled middle ear/mastoid sinus, into the intracranial cavity, or
into other spaces in the temporal bone. In most instances it is a tear or defect
in one or both of the small, thin membranes between the middle and inner ears.
These membranes are called the oval window and the round window. Another
possible location for an abnormal communication is in the bone of the ear (the
otic capsule).
b. Symptoms
pressure in the ear or loud noises which can cause strong vertigo,
nystagmus, vertigo, imbalance, nausea, and vomiting.
Some people experience ringing or fullness in the ears, and many
notice a hearing loss.
Valsalva induced dizziness -Some people with fistulas find that their
symptoms get worse with coughing, sneezing, or blowing their noses,
as well as with exertion and activity.
Tullio's phenomenon：use of ones own voice or a musical instrument
will cause dizziness
c. Prevalence：Whatever the cause, perilymph fistula is a very rare condition
compared to most other causes of dizziness and hearing loss.
d. Cause
Head trauma is the most common cause of fistulas, usually involving a
direct blow to the ear.
following rapid or profound changes in intracranial or atmospheric
pressure, such as may occur with SCUBA diving. Forceful coughing,
sneezing or straining as in lifting a heavy object may rarely cause a fistula.
Ear surgery, particularly "stapes" surgery, often causes fistula.
present from birth (usually in association with deafness)
cholesteatomas
superior canal dehiscence syndrome：the bone between the ear and
brain area is missing or thin. Roughly 2% of persons at autopsy are found
to have thinning of bone, which is thought to predispose them to this
syndrome.
e. Examination
A fistula test - recording of eye movements while pressurizing each ear
canal with a small rubber bulb.
A positive test is good grounds for surgical exploration.
In window fistulae, a positive test may consist only of a slight
nystagmus after pressurization.
In superior canal dehiscence, a strong nystagmus may be
produced.
Positive pressure or Valsalva against pinched nostrils produces
downbeating nystagmus, with a torsional fast phase consistent with
stimulation of the affected ear.
Negative pressure or Valsalva against a closed glottus may
produce upbeating nystagmus and nystagmus beating with the
torsional fast phase in the opposite direction.
Audiometry and an "ENG" - to establish the side, and to exclude other
potential causes of symptoms. Audiometry may show a sensorineural
hearing loss.
An ECOG (ectrocochleography) - diagnose Meniere's disease, which is
a common alternative source of pressure sensitivity.
An MRI and/or a temporal bone CT scan - to exclude other possibilities.
CT of the temporal bone is very accurate in identifying canal
fistulae. CT should be done of the temporal bone with at least 1 mm
resolution.
MRI is not the best test for fistulae because it doesn't show the
bone and resolution is not as good as CT scan. However, MRI is the
best way of showing other possibly confounding problems such as
tumors or multiple sclerosis plaques.
CT cisternography with a spinal injection of a contrast material
- to
detect CSF leak. The head is tilted down for 3 minutes with the patient
prone, and a CT scan is done with high resolution cuts (spiral), in the
coronal plane immediately after the prone positioning, to cover the frontal
sinus through the mastoid sinus region.
Air in the labyrinth (pneumolabyrinth) is the most convincing finding of
fistula.
Middle ear effusions may also be suggestive of fistula.
f. Treatment
In many cases, a window fistula will heal itself if your activity is restricted.
In such cases, strict bed rest is recommended for one week or more to give
the fistula a chance to close.
It is usual to wait 6 months before embarking on surgical repair, given
that hearing function is reasonable and is stable or improving.
With respect to air travel, while it is certainly safest to avoid air travel
altogether, in some instances it may be unavoidable. In this case, we
suggest using a nasal decongestant at least one half hour prior to landing.
If a patient has a canal fistula, the symptoms are significant and have
not responded to the conservative approach outlined above, or if the
patient has a progressive hearing loss, surgical repair of the fistula may be
required. For canal fistulas, surgery generally involves plugging of the
canal. For a window fistula surgery involves placing a soft-tissue graft over
the fistula defect in the oval and/or round window. Otic capsule fistula does
not, in general, heal by itselves. Unfortunately, surgical procedures are not
well worked out. Patients are often reoperated when it is decided that the
graft has failed.
5. Motion Sickness
a. Symptoms/sign：nausea, disorientation and fatigue that can be induced by
head motion. The first sign is usually pallor. Yawning, restlessness and a
cold sweat forming on the upper lip or forehead often follow. As symptoms
build, an upset stomach, fatigue or drowsiness may occur. The final stages
are characterized by nausea and vomiting.
b. Prevalence
Nearly anyone can be made motion sick by an appropriate stimulus,
except for individuals with no vestibular system.
prevalence was about 28%
females were more susceptible than males
Individuals with more active occupations are less susceptible.
c.
Mechanism：In order for the body to determine where it is at all times, the
brain combines visual information, touch information, inner ear information,
and internal expectations. Under most circumstances, the senses and
expectations agree. When they disagree, there is conflict, and motion
sickness can occur.
d.
Acquired susceptibility
Persons with an inner ear disturbances, especially a recent one, may be
intolerant to activity in general
People with migraine are apt to get motion sick.
Persons with rare, central nervous system disorders of the part of the
brain that processes signals from the inner ear may also be unusually
susceptible to motion sickness.
e.
mal de debarquement ：Certain individuals who are constitutionally
susceptible to motion sickness and can develop seasickness on ships, and a
prolonged land sickness, when they get off the ship.