Sudden Sensorineural Hearing Loss

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					Sudden Sensorineural Hearing
What is sudden sensorineural                   Scientists are focusing on two main
hearing loss?                                  theories as to why sudden hearing loss
                                               occurs in these unknown cases. The first
Sensorineural hearing loss may be either       is that it may be of viral origin, as some
sensory (affecting the sense organ of          viruses are known to damage the
hearing in the cochlea) or, less               hearing, and a viral infection seems to
commonly, neural (affecting the nervous        precede the hearing loss in some people.
pathways which connect the cochlea to          The second theory is that it may be due
the hearing centres in the brain).             to some vascular defect (relating to blood
Generally, sensorineural hearing loss is       vessels), but there is no conclusive proof
described as sudden if you notice a drop       at present to support either view.
in your hearing instantaneously or over a      In the 15 per cent of cases where it is
short period not exceeding three days.         possible to establish a firm cause of
You may notice a popping sound when it         SSHL the cause may be due to the
happens, or you may detect it when you         following:
first wake up or use the ear in a testing
situation, like making a phone call.           Infections
Sudden sensorineural hearing loss              Meningitis is one of the commonest
(SSHL) is considered a medical                 causes of severe or profound acquired
emergency and you will need to contact         deafness in babies and children, though
your doctor immediately. It currently          cases are falling due to the availability of
affects about 20 in every 100,000 people.      vaccines. Hearing loss due to meningitis
As middle ear infection or accumulation of     usually affects both ears (bilateral).
fluid behind the tympanic membrane             Anybody who has suffered from
(eardrum) can also occur rapidly, causing      meningitis, especially a child, should have
a temporary conductive hearing loss, and       their hearing tested as soon as possible
these conditions are more common than          after recovery.
SSHL, it is important to obtain a specialist   Measles and mumps are also associated
examination with hearing tests, to             with SSHL. In measles, the loss is usually
distinguish them from SSHL.                    moderate to profound and affects both
What causes sudden                             ears, whereas in mumps it usually affects
                                               only one ear. The herpes zoster virus
sensorineural hearing loss?                    may, on rather rare occasions, cause
In 85 per cent of cases of sudden              sudden hearing loss accompanied by
sensorineural hearing loss the cause is        weakness of the facial muscles and
unknown. These cases are referred to as        vertigo. This so-called Ramsay Hunt
idiopathic. In the majority, the hearing is    syndrome may affect adults who have
affected in only one ear (unilateral) and      been close to children with chicken pox,
may return to normal or near normal in 70      which is caused by the same virus.
per cent of cases.                             Some infections are confined to the ear
                                               itself. Labyrinthitis is an inflammation of
the inner ear, caused by bacterial or viral   against the risks to hearing, and these
infection, which can cause dizziness,         issues should be discussed with a
tinnitus (noise heard in the ear or head      specialist.
with no external source), and can lead to     Barotrauma
sensorineural hearing loss, but usually
only in one ear. Bacterial labyrinthitis      Barotrauma may occur when the ear is
often results in permanent hearing loss.      exposed to sudden pressure changes,
                                              possible when flying or diving.
One common cause of bacterial
labyrinthitis is an existing chronic middle   Most commonly, the middle ear is
ear infection, often with cholesteatoma       affected, causing a conductive hearing
(invasion of skin into the middle ear)        loss. It is rarer for the inner ear to be
invading the cochlea.                         involved, but sensorineural hearing loss
                                              can occur if the membrane of the round
Head injuries                                 window (one of the two windows which
Head injuries, especially those associated    separate fluid in the inner ear from air in
with a fractured skull, may produce           the middle ear) ruptures, causing a
profound and often permanent hearing          leakage of perilymph (one of the inner ear
loss. Even where there is no fracture,        fluids).
sensorineural hearing loss may occur,         Ototoxicity
caused by damage to the central nervous
system or the inner ear itself.               Sudden sensorineural hearing loss is
                                              sometimes attributed to ototoxic drugs
Noise                                         (drugs that may damage the inner ear)
Hearing loss caused by exposure to loud       however, the deafness related to
noise is usually gradual in onset and can     ototoxicity is more often gradual than
be prevented by avoiding noisy situations     sudden, and is often preceded by tinnitus.
or wearing appropriate ear protection.        Drugs that are known to cause
However, sudden hearing loss may occur        permanent hearing loss are usually given
from exposure to excessively loud noises,     only when no other alternative exists for
for example from blast injuries (from a       treating a life-threatening disease.
nearby explosion) or from firearms or
fireworks, especially in enclosed spaces.     If the prescription of such a drug is
                                              necessary, the potential effect on hearing
The degree of hearing loss can range          should be explained by the patient’s
from total, permanent deafness in one or      doctor and the hearing monitored
both ears to a relatively minor high          regularly during treatment.
frequency loss.
                                              Ménière’s Disease
Where minor, hearing may recover
spontaneously in time. For more               Ménière’s affects about one in every two
information about the effects of noise, see   thousand adults in the UK. It is a disease
the Deafness Research UK factsheets on        associated with later life, usually starting
this topic.                                   between the ages of 30-50 years.
Ear surgery                                   It is characterised by severe attacks of
                                              vertigo combined with fluctuating
Sensorineural hearing loss may occur          deafness, tinnitus and a feeling of
after any surgical procedure on the ear,      pressure in the affected ear. Attacks often
and the degree of risk depends on many        start without warning and can lead to loss
factors. These include the nature of the      of confidence, anxiety and sometimes
procedure, the underlying disease and         depression.
the skill of the surgeon.
                                              Other causes
The hearing loss may occur immediately,
in the few days following the operation, or   Less common causes of sudden
even many years later. It is important to     sensorineural hearing loss include an
balance the potential benefits of surgery     acoustic neuroma, which is a benign
(non-malignant) tumour. The hearing loss      may be prescribed and some weeks may
associated with acoustic neuroma is           pass before a correct diagnosis is made.
usually gradual and often unnoticed, but      If you can’t see your GP, and you have a
may be sudden in as many as 10% of            severe sudden hearing loss, you should
cases.                                        go to your nearest hospital accident and
Even rarer is the neurological condition of   emergency department.
multiple sclerosis, in which ‘plaques’ of
the disease may affect parts of the           How can sudden sensorineural
brainstem associated with hearing. The        hearing loss be treated?
diagnosis of this condition is made by        As with any medical condition, treatment
electrical tests of brainstem function and    depends upon the cause, when the cause
a magnetic resonance imaging (MRI)            is known. As the cause is not known in so
scan, and fortunately the hearing often       many cases of Sudden Sensorineural
recovers spontaneously.                       Hearing Loss, the treatment strategies
Immunological disorders                       may vary, being dependent on the
                                              doctor’s observation and experience.
Disorders affecting the immune system
may have a role in causing sudden             Treatment strategies used can include
sensorineural hearing loss but the link is,   steroids, vasodilation (treatment to relax
at best, uncertain.                           blood vessels), antiviral agents, diuretics
                                              and low-salt diets. The most often used of
There is a certain amount of debate over      these is high-dosage steroid therapy
the diagnosis of the condition known as       either given orally or intravenously (into
Autoimmune Inner Ear Disease (AIED),          the bloodstream). However, after a
its relationship with sudden deafness, and    course of treatment between 30 and 50%
potential treatments, but it probably         of patients show no response.
accounts for less than one per cent of all
cases of hearing loss.                        New research suggests that better results
                                              are obtained if a course of intravenous
What should you do if you lose                steroids is followed up by a course of
your hearing suddenly?                        intratympanic steroids (steroids
                                              administered directly into the middle ear),
As a sudden hearing loss can return to
                                              but further trials are required to establish
normal or near normal in some cases, it
                                              a firm evidence base.
may be tempting to adopt a ‘wait-and-see’
policy. However, if you think you have a      Some viral infections respond to anti-viral
sudden hearing loss in one or both ears,      agents like acyclovir, and for the Ramsay
you should be seen by a specialist as         Hunt syndrome, short-term treatment with
soon as possible because even where a         steroids and acyclovir is justified if started
cause is unknown any treatment may be         early enough, as it may lead to a reversal
more successful the earlier it is given.      of the hearing loss to near-normal
You should go to your GP (family doctor)
and ask for an urgent referral to an ear,     There is no evidence of cardiovascular
nose and throat (ENT) specialist. It is       disease in the majority of patients
especially important to make your GP          suffering from SSHL, but there are certain
aware that the hearing loss was sudden        ‘vascular’ conditions which may
to ensure you receive prompt medical          occasionally cause sudden deafness.
attention.                                    These include reduced blood flow in the
Family doctors may not have the facilities    cochlea and disorders of coagulation
to distinguish SSHL from the commoner         (clotting) of the blood.
conductive, middle ear hearing loss, and      Research is being carried out on the
if an incorrect assumption is made that       potential value of carbogen inhalation in
the deafness is caused by a fluid build up    such cases, carbogen being a mixture of
or a middle ear infection; decongestants      95% oxygen and 5% carbon dioxide.
Sudden sensorineural hearing                    Coping with sudden
loss with a known cause                         sensorineural hearing loss
In many cases of Sudden Sensorineural           When a hearing loss occurs suddenly, the
Hearing Loss, there is no effective             shock and sense of loss can be
treatment for the hearing loss itself, but      overwhelming.
further loss may be reduced and                 If you experience a sudden hearing loss,
occasionally hearing may even be                you may go through a range of emotions
restored by preventive measures. For            including denial, hope (for a cure or
example, the adverse effects of drugs           improvement), anger, isolation,
that can cause hearing loss may be              acceptance, embarrassment and resolve.
halted and to some extent reversed if the
patient stops taking that particular drug       Other people may react to your hearing
(in consultation with a medical adviser)        loss by feeling awkward, embarrassed or
and replaces it with a different agent.         unsympathetic. You may feel
                                                embarrassed about it yourself. It is
Similarly, the risk of noise-induced            important to be open and honest with the
hearing loss can be greatly reduced by          people around you, and explain what you
appropriate ear defenders, and the use of       want them to do.
helmets in certain sports and by motor
cyclists undoubtedly reduces the risk of        With time, and with the right sort of
deafness in skull fractures due to head         professional support, as well as the
injuries.                                       support of your friends and family, you
                                                should find that you become more skilled
Finally, timely surgery for the ‘dangerous’     at being aware of your environment and
type of middle ear infection will prevent       communicating. As your skills grow you
what is called suppurative labyrinthitis,       will feel more in control and you might
which occurs if the infection spreads to        find that you are able to adapt your
the inner ear.                                  leisure interests, social life and hobbies to
When a perilymph leak (a leak of one of         your hearing loss.
the inner ear fluids) is suspected, bed rest    There are many sources of information
is advised for up to five days. If there is     and advice available to help adjust if it
no improvement in the hearing after that        seems that the hearing loss is permanent.
period, surgical exploration of the ear is      This includes guidance on equipment and
needed, with repair of the leak when            devices available, and implications for
possible.                                       employment and benefits.
In cases of Ménière’s Disease, most             A wide range of services and support,
forms of medical treatment are aimed at         including rehabilitation courses can also
controlling the crippling attacks of vertigo,   be accessed. Hearing Therapists and
while preserving the hearing if at all          lipreading classes can be valuable
possible. In severe cases, if attacks           sources of support. Details of relevant
persist despite medication, a consultant        organisations to contact are given below.
may advise surgery.
A number of different operations have           Coping with permanent hearing
been devised, some to reduce pressure           loss
in the inner ear, others to diminish or         Hearing Aids
abolish the abnormal impulses passing
from ear to brain. For more information         When treatment is impossible or
about Ménière’s Disease, see the                ineffective, most patients whose hearing
Deafness Research UK factsheet on this          loss is diagnosed as permanent can be
topic.                                          helped by a hearing aid or aids and/or by
                                                other assistive devices. Hearing aids are
                                                available free of charge through the NHS
                                                and to receive one, patients are generally
referred within their local hospital to an    Assistive Devices
audiologist.                                  Even when a hearing loss is relatively
The type of hearing aid prescribed will       mild, people with sudden sensorineural
depend on the severity of the hearing         hearing loss often have difficulty hearing
loss, the frequencies affected and            high frequency sounds such as
whether one or both ears are affected. On     telephones, doorbells and alarm clocks,
the NHS, the main type of hearing aid is      but may find it unnecessary to wear a
worn behind the ear.                          hearing aid all the time.
For people with one-sided deafness there      To help, there is a wide range of special
is a particular type of hearing aid known     equipment available, such as amplified
as a CROS (Contralateral Routing of           doorbells, vibrating alert systems, loop
Signals) aid which can be of benefit in       systems and headphones. Social
certain situations where the microphone       services may help to pay for, or provide,
is located on the side of the worse ear       equipment. For more information contact
and the signal from it is fed to the better   your local social services department.
ear.                                          The Government’s Access to Work
There is also a BICROS aid in which the       scheme may help to pay for equipment
better ear receives an additional signal      you need for work or for job interviews.
from a second microphone placed on the        There are also a number of suppliers
better-hearing side. These systems can        from whom you can purchase equipment.
mean that users are able to hear sounds
directed to the impaired ear more easily,     See contact details below.
without turning the better ear towards the    Lipreading
sound, and they also provide extra cues
for locating the direction of sound           In combination with an efficient hearing
sources.                                      aid, lipreading plays an important part in
                                              helping people with acquired hearing loss
Another hearing aid suitable for single       to communicate better and regain
sided sensorineural hearing loss is a         confidence.
bone anchored hearing aid (BAHA),
which transfers sound through bone            Learning to lipread is challenging, but it is
conduction. It works by stimulating the       worth persevering, as the improvement in
cochlea of the normally hearing ear giving    communication can be significant.
users the sensation of hearing sounds         Lipreading classes can also be very good
from the deaf side.                           places to meet other people who have
An operation is required which takes          had similar experiences. Lipreading
approximately thirty minutes to insert a      classes are usually offered at local adult
small titanium implant into the mastoid       education centres and/or colleges.
bone behind the ear. The site is then left    If you have difficulty finding a class,
for three months allowing the implant to      contact the Association of Teachers of
fuse with the skull bone in a process         Lipreading to Adults (ATLA) whose
known as osseointegration before the          address is given below.
hearing aid (a small rectangular box) can
be attached and easily removed for            Hearing Therapy
sleeping and bathing.                         A qualified Hearing Therapist can play a
There are a number of hospitals in the UK     vital role in helping someone with an
where the BAHA procedure is currently         acquired hearing loss. They use a variety
performed and where a person would            of methods to work out an individual
need to be referred for assessments. Part     programme for each patient to assist
of the assessment involves a trial of the     them in managing their hearing loss,
device on a headband which can give a         improving their communication skills and
good idea of whether this type of aid will    enabling them to participate fully in their
be helpful.
daily activities. Hearing Therapists can
       •   help with hearing aids;
       •   auditory training (working with the
           remaining hearing);
       •   counselling both for the deafened
           person and their family
       •   advice about environmental aids;
       •   lipreading instruction; and
       •   tinnitus management.
Some Hearing Therapists may also
specialise in cochlear implants, helping
with balance problems or working with
patients with learning disabilities or dual
sensory loss.
Although not all NHS Trusts employ
Hearing Therapists, most are situated in
either the Audiology or Ear, Nose and
Throat departments of hospitals.
Cochlear Implants
The cochlear implant is one of the major
scientific triumphs of the last few
decades. They are increasingly being
used to help adults with acquired total or
profound hearing loss in both ears, as
well as in children born profoundly deaf or
acquiring deafness before the
development of speech.
They work by electrically stimulating the
auditory nerve (nerve of hearing) to give
the user a sense of sound, and, in the
case of a child born profoundly deaf, the
potential to understand speech and to
learn to speak.
Although cochlear implants are available
through the NHS, rigorous assessment is
undertaken to ensure that each recipient
meets certain referral criteria. These
criteria change over time and may vary
between cochlear implant centres.

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