Mnires
Disease
General
Discussion
Mnires Disease
is a disorder of inner ear. There is commonly episodic vertigo, imbalance,
nausea and vomiting, tinnitus, and a feeling of fullness or pressure in the
ear. Fluctuating hearing loss. Attacks can be typically preceded in one or both
ears by aching or feeling of fullness. Average attack can be two to four hours
followed by a period of tiredness and a need for sleep for several hours.
Weeks, months or even years may pass between episodes, usually free of symptoms
but may note mild imbalance or tinnitus. Around 75% confined to one ear and
most cases have a progressive hearing loss in the affected ear. This disease is
considered to result from fluctuating pressure of a fluid (endolymph) within
the inner ear. The cause of the disease is unknown. The loss of hearing is over
time. There are periods of vertigo or dizziness with tinnitus (ringing,
buzzing, humming in the ear) with the feeling of fullness or pressure in
affected ear.
Initially,
hearing may return to normal then get worse, get better and so on. Hearing may
never return to normal limits but changes go back and forth between
mild/moderate hearing loss. Usually the loss is greater in the low frequencies.
May complain of some or all of the following:
Greater sensitivity to noise or sounds
Nausea
Vomiting
Rapid heart action
Rapid pulsation of heart
Complete mental or physical exhaustion
Hearing one sound as two
General weakness
Sweating
Symptoms may
occur together or separately. For some, symptoms exist to some degree at all
times. Episodes usually occur suddenly and are often preceded by a decrease in
hearing, increased fullness feeling, tinnitus in affected ear and change in
quality of the pre-existing symptoms. An attack may go within one hour or may
continue for hours or days. Some have long periods between episodes - some more
frequently. Mnire's disease refers to amount of one of the inner ear fluids
(approx 50% cases of unknown cause). Associated with physical trauma (fracture
of temporal bone or concussion of balance organ), elevated blood fat, viral
infection.
There are four
subvarieties of Mnire's disease - improved hearing during and immediately
following attack (Lermoyezs syndrome). Sudden falling down that lasts for
short time only (Tumarcinn's syndrome). Low frequency hearing loss, but no
dizziness (Cochlear hydrops). Dizziness, but no hearing loss (Vestibular
hydrops). Audiologist often consulted to complete hearing and balance evaluation,
electrocochleography (ECOG), electronystagmography (ENG), posturography and
Auditory Brainstem Response (ABR). Mnire's disease also called idiopathic
endolymphatic hydrops. One of most common causes of dizziness originating in
inner ear - typically between 20 to 50 years of age. Men and women equally
affected.
Vertigo defined
as sensation of movement when no movement occurring. May also occur in CNS
disorders.
Dysequilibrium
(off-balance sensation). This lasts 20 mins to two hours or more. Off balance
may last several days afterwards. May be intermittent hearing loss early in
disease, especially low frequencies, but fixed hearing loss involving tones of
all pitches commonly develops in time. Loud sound may be uncomfortable and
appear distorted in affected ear. Tinnitus pressure feeling may come and go
with changes in hearing, occur during or just before attacks or be constant.
Symptoms of Mnire's disease may be minor nuisance or become disabling,
especially if attacks of vertigo are severe, frequent and occur without
warning. Audiometric examination typically indicates sensory type hearing loss
in affected ear. ENG to evaluate balance function. Darkened room. Eyes and ears
work in coordinated manner through nervous system. Eye movements used to test
balance system. In about 50%, balance reduced in affected ear (ie. 50% it is
not). CT or MRI to rule out tumour (rare) on hearing or balance nerve but
symptoms similar to Mnire's disease. acoustic neur(in)oma.
Endolymphatic
shunt or decompression procedure - inner ear operation directs fluid from inner
ear into cerebrospinal fluid around brain or into mastoid and done to improve
inner ear drainage. Usually preserves hearing. Vertigo controlled ;n half to
two-thirds cases. Control not always permanent but recovery time short.
Selective vestibular neurectomy - major procedure, working next to brain stem.
Like 'unplugging phone' - cuts nerve sending faulty information. Balance nerve
cut as it leaves inner ear to brain. Vertigo commonly cured and hearing
preserved in most cases. Labyrinthectomy and Vlllth nerve section - balance and
hearing mechanism destroyed in inner ear on one side. Only considered if poor
hearing in affected ear. Results in highest rate of control of vertigo attacks.
Head noise - Annoying
but rarely a sign of a serious problem. Causes of tinnitus (ringing in the
ear/s):
http://www.mayoclinic.com/health/menieres-disease/DS00535
Common source of
dizziness is Mnire's disease. Sudden attack or 'spell' includes vertigo
(often with nausea and vomiting). May occur once a year or every day and may
last 20 mins to one-day. Usually begins in adulthood and equally among men and
women. May return to normal after a spell and may gradually worsen with
repetitive episodes. Most people ultimately lose much if not all hearing in
affected ear. Can develop into other ear to some degree. Problem of tiny
fluid-filled semicircular canals (vestibular labyrinth) of inner ear that
controls balance. Only a few drops of fluid in these canals so balance of
pressure and electrolytes in the fluid is critical. Too much fluid produced or
isn't reabsorbed quickly enough - or combination of both. Build up of fluid and
pressure causes vestibular nerve to send false signal to brain indicating
spinning or falling. Cause unknown. Diagnosis tends to be by exclusion.
Otolaryngology
Wide variation of
symptoms, difficult to diagnose. Inner ear and not brain (Mnire 1861). Four
major symptoms - vertigo, hearing loss, tinnitus and pressure in ears. All
symptoms tend to occur intermittently and are variable in severity. Sometimes,
only two or three of symptoms are present. Vertigo my last minutes to hours,
leaving patient feeling tired and unsteady. Most middle aged but can occur in
very young and elderly. Symptoms do not always correspond to medical text book
description. Underlying cause unknown but fluid pressure build up of inner ear
results in symptoms of Mnire's. Also fluid pressure build up can occur in
spinal fluid (hydrocephalus) and in the eye (glaucoma) or arteries (high blood
pressure). As fluid pressure increases over time damage occurs to nerve endings
of the inner ear.
Many cases
referred to ear specialist. Audiogram, ENG, ABR (tumour may mimic Mnire's
disease). ECOG - most specific test for endolymphatic hydrops or Mnire's
disease. SHA (sinusoidal harmonic acceleration, rotary chair). Posturography -
helpful in diagnosis of inner ear membrane rupture (perilymph fistula). Two
surgical procedures - Shunt Endolymphatic Mastoid Shunt Valve. Non destructive.
Small incision behind ear and brain not involved. RVS (Retrolabyrinthine
Vestibular Nerve Section). All symptoms are unpredictable - vertigo, tinnitus,
hearing loss. Frequency, duration and intensity vary. Some may feel slight
vertigo several times a year, or tinnitus while sleeping. Hearing tends to
recover after attack but over time becomes worse.
Change in fluid
volume within portion of inner ear known a labyrinth. Two parts - bony
labyrinth and membranous labyrinth. Latter encased by bone necessary for
hearing and balance and is filled by fluid called endolymph. Head motion causes
endolymph to move. This causes nerve receptors in membranous part to send
signals to brain about body motion. The increase in endolymph can cause the
labyrinth to balloon or dilate.
Condition known as endolymphatic hydrops.
Possible that
rupture of the membranous labyrinth allows endolymph to mix with perilymph -
another inner ear fluid occupying space between membranous labyrinth and the
bony inner ear. This mixing may cause symptoms of Mnire's disease. Possibly
also viral infection implicated? Symptoms can suddenly arise daily or once a
year. Vestibular nerve serves balance and sends distorted messages to brain.
Balance nerve very close to facial nerve. Hearing loss can be sensory arising
from inner ear or neural arising from hearing nerve. ABR measures electrical
activity in hearing nerve and brain stem can differentiate and be useful
between two types of hearing loss. An ECOG (records electrical activity of
inner ear in response to sound) can help confirm diagnosis.
To test
vestibular or balance system, calric testing done. Flood ears with warm and
cool water. Results in nystagmus (rapid eye movements) that can help diagnose
balance disorder. Tumour growth can produce symptoms similar to Mnire's
disease so MRI useful test to determine whether tumour causing vertigo and
hearing loss. In USA about. 0.2% population affected. Two in three cases affect
one ear only. Progressive hearing loss in affected ear - not fatal. Acute
attack believed to result from fluctuating pressure of fluid within inner ear.
Most often attributed to viral infection of the inner ear or head injury.
Periodic
admixture of perilymph and endolymph often kills hair cells in the inner ear.
Gradual process over years. Results frequently in unilateral deafness. Cochlear
(hearing) hair cells are most sensitive. Vestibular hair cells seem more
resilient. Mechanical disruption also likely an effect with dilation of the
utricle (upper chamber of the inner ear from which arise the semicircular
canals) and saccule (lower chamber of the auditory vescicle, small cavity
containing fluid) of the ear being a well known pathological finding. This may
result in gradual onset of a chronic unsteadiness, even when not having an
attack. Also reasonable explanation for periodic attacks of BPPV (Benign
Paroxysmal Positional Vertigo - causes severe vertigo when head held in certain
position). Also likely that may be rupture of the suspensory system for the
membranous labyrinth. No evidence t.hat diseases kills cochleovestibular nerve.
Most people with this disease are over 40 - equal to male/female. No cure but
manageable. There are several blood tests which can be used to identify this
disease along with hearing testing. ENG test and MRI head scan. Acute symptoms
of Mnire's disease are episodic.
Hydrops diet -
fluid-filled hearing and balance structures of inner ear normally function
independent of the body's overall fluid/blood system. Normal ear fluid
maintained at constant volume and contains specific concentrations of sodium,
potassium, chloride and other electrolytes. This bathes sensory cells of inner
ear and allows normal function. Injury or degeneration of these structures,
independent control lost and volume and concentration of inner ear fluid
fluctuates with changes in body's fluid/blood. This fluctuation causes symptoms
of hydrops - pressure or fullness in the ears, tinnitus, hearing loss,
dizziness and imbalance.