Download Other examples of complex waves

Hearing disorders of the middle ear

Tympanic membrane:
1.
Perforations
2.
Tympanosclerosis: Thickening/Scarring
http://www.ent-usa.com/eardrum_and_middle_ear.htm
http://www.bestforhearing.com/images/normal-ed.jpg
http://www.hmc.psu.edu/ume/fcmonline/case32/images/normal-ear.jpg
TM Perforation
http://www.ghorayeb.com/files/TYMPANIC_PERFORATION_LEFT_LABELED.jpg
TM Perforation
http://texasearcenter.com/userfiles/Image/tmp-1.jpg
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Consequences

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Mild hearing loss
Treatment

In some cases, spontaneous recovery (depends on
location)

Myringoplasty: Surgical reconstruction
Middle ear cavity

Otitis media: Very common (~70% of children in the U.S.)
 Infection of the mucous membrane lining the middle ear
Predisposing factors:

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Poorly functioning Eustachian tubes
Barotrauma
Abnormal functioning of mucous membrane cilia
Anatomical deformities
Gender and demographic factors
Exposure to toxic fumes
TM Retraction
http://img.medscape.com/pi/emed/ckb/otolaryngology/834279-858557-860080-860208.jpg
Acute OM
http://www.mdconsult.com/das/book/body/161330440-2/0/1608/f4-u1.0-B978-1-4160-2450-7..50641-1..gr3.jpg
Acute OM
http://upload.wikimedia.org/wikipedia/commons/5/58/Otitis_media_entdifferenziert2.jpg
Acute OM
http://knol.google.com/k/-/-/Y0fzk46N/nxV32A/AOM.jpg
Possible mechanisms

Through ruptured tympanic membrane

Through Eustachian tube

Through blood
Characteristics of otitis media infection

Two types: Acute and chronic

Rapidly progressive

Negative pressure in middle ear because of ET malfunction

TM is retracted and appears red

Pain, high temperature, pus accumulates in middle ear mucosa

In severe cases, TM ruptures due to pressure.

If left untreated, can progress to mastoid air cells and cause
mastoiditis.
http://www.ent-usa.com/eardrum_and_middle_ear.htm
Consequences

Flat conductive hearing loss (degree depends on
the amount of fluid)

Low static compliance
Type B tympanogram
Absent reflexes
Absent OAEs
High latencies for all ABR peaks

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Treatment

Antibiotics

Surgery

Myringotomy and suction

Mastoidectomy (if infection has spread to mastoid
region)

Tympanoplasty
PE Tubes
http://www.pedisurg.com/PtEducENT/tube_in_TM.jpg
Complications of otitis media

Cholesteotoma: Sac-like growth due to presence of skin in the
middle ear.

Dangerous, progressive, highly erosive

Foul-smelling discharge (otorrhea)

Treatment: Surgical removal
http://www.ent-usa.com/eardrum_and_middle_ear.htm
Cholesteatoma
http://chicagoear.com/med_info/images_med_info/cholesteatoma.jpg
Cholesteatoma
http://www.earsurgery.org/images/Photo-31%20copy.jpg
Cholesteatoma
http://my.clevelandclinic.org/PublishingImages/Head_Neck/cholesteatoma
.jpg
Facial palsy

If erosion of bone occurs, facial nerve may be exposed.

Partial/Full paralysis of one side of the face.

Treatment: Surgery
Eustachian tube problems

Cause: Infections, allergies, blockage due to
overgrown adenoids, structural problems.

Consequences: Negative middle ear pressure,
retracted TM.

Audiometric findings: Mild conductive hearing
loss, normal static compliance, type C
tympanogram.
Methods to open ET


Valsalva: Close nostrils and cheek and blow out.

Toynbee: Close nostrils and swallow
Complications of ET malfunction:

Serous effusion
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Mucous otitis media
Otosclerosis

Causes: Hereditary in 70% of cases.

Progressive in nature
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Higher incidence in women, adults.

Clinical manifestation: Spongy bone formation
over the stapes footplate. Footplate becomes
fixed in the oval window.
Other clinical signs

Progressive hearing loss

Tinnitus
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Difficulty hearing while chewing

Very vascular promontory, rosy glow through TM
(Schwartze sign)

Paracusis willisii: Speech easier to understand in the
presence of background noise.
Audiometric findings

Low frequency conductive hearing loss with airbone gap.
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As disease progresses, hearing loss spreads to
high frequencies.

Bone conduction is affected, primarily at 2000
Hz (called Carhart’s notch).
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Type As tympanogram, absent reflexes
Treatment

Earlier: Surgery to free immobilized stapes footplate. Not very successful.

Fenestration (new window created in lateral semicircular canal).
Effects of fenestration: ~ 25 dB hearing loss to total hearing loss,
vertigo, tinnitus, poor word recognition scores, facial paralysis, repeated
infections of cavity

Stapes mobilization: Middle ear cavity exposed through incision in TM.
Effects: Immediate improvement in hearing, however, refixation of
stapes often occurred.

Most successful treatment: Stapedectomy. Replaced with prosthesis
Modification: Stapedotomy
Inner ear

Series of interconnecting canals or
‘labyrinths’ in the temporal bone

Two types:

Osseous
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Bony
Bigger cross-sectional area
Contains fluid called perilymph
Membraneous
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Soft tissue
Situated within the bony
labyrinth
Contains fluid called endolymph
http://research.meei.harvard.edu/Otopathology/3dmodels/download.html