461 hearing disorders

Auricle

Pinna

Temproalmandibular joint (TMJ)

Produces a refer pain perceived in the ear

Otalgia

Ear pain

Condyle

Protrusion of the mandible that rests right below the osseocartliginous junction

Ear canal

External auditory meatus (EAM)

External auditory canal (EAC)

Extends inward at a slight upward angle

In small children, angles downward

Tympanic membrane

Begins forming my the end of the second fetal month

TM annulus

Develops in the third fetal month

Layers of TM

Form from different layers of the pharyngeal arches

Ectoderm, endoderm, mesoderm

Conductive hearing loss

When conditions occur that might interfere with or block normal sound vibrations transmitted throng the outer (and/or middle) ear

Also arises from disorder of the middle ear

Microtia

Pinna may be very small in size

Anotia

Pinna may be entirely absent

Microtia grade 1

Smaller than normal Pinna but the ear has mostly normal atonomy

Microtia grade 2

Part of the ear looks normal, usually lower half

Canal may be normal, small, or completely closed

Microtia grade 3

Small remnant of “peanut-shaped” skin and cartilage

There is no canal, called aural atresia

Microtia grade 4

Complete absence if both external ear and ear canal, also called “anotia”

Atresia

The lack of canalization

May occur in cartilaginous portion, bony portion, or both

May occur in both ears

May occur in isolation or with other abnormalities

Stenosis

Narrowing of the EAC

Does not directly cause hearing loss, but can be easily clogged by earwax/debris

Collapsing of the canal

Does not directly cause hearing loss, but can be easily clogged by earwax/debris

External otitis

Infection in the EAC

Commonly caused by bacterial infections

Osteomas

Growth in the EAC

Bony tumors, singular in growth, unilateral

Exostoses

Growth in the EAC

Outward projection of multiple growths, bilateral

Cerumen impaction

Earwax

Wax occlusion of the EAC may cause hearing loss

Amount of hearing loss is directly related to the amount of occlusion

Losses range from very mild to moderate

Tympanic membrane perforation

Excessive pressure

Direct trauma

Sudden pressure changes

Rapid changes in the EAC

Tympanoplasty

Surgical reconstruction of the TM

Graft tissue is taken from the temporalis fascia

Graft patch is placed over the defect

Tympanosclerosis

Thickened or scarred TM due to infection and/or perforation

Eustachian tube

Purpose is to equalize the pressure in the middle ear to the outside world and to the external auditory canal to maximize sound transmission

Disorders of the middle ear

Dysfunction in the middle ear that results in a conductive component to hearing loss

Eustachian tube dysfunction (ETD)

Results in decreased pressure in middle ear cavity

Patulous Eustachian tube

E-tube is chronically open

Otitis media

Infection of the mucous membrane lining the middle ear

Serous otitis media

Accumulation of fluids secreted by the mucous membrane that are normally drained from the middle ear

Mucoid otitis media

Thick mucous secretions accumulate in the middle ear

Suppurative otitis media

Chronic infection of the middle ear without an intact TM

Pressure equalizing (PE) tube

Functions as an artificial e-tube

Drains fluid

Mastoiditis

Serious bacterial infection in the mastoid bone

Facial palsy

Damage to the facial nerve causing paralysis of one side of the face

Cholesteatoma

Build up of keratin in the middle ear

Otosclerosis

Spongy bone growth over stapes footplate that fixates at the oval window

Carhart’s notch

Bone conduction threshold decreases at 2000Hz and then rises again

Stapedecromy

Stapes is removed and replaced by prosthesis

Cochlea

Bony snail like structure

The organ of hearing

Auditory portion of the inner ear

Vestibular

Houses organs of equilibrium

Balance portion of the middle ear

Endolymph

Found in the scala media, utricle, saccule, and semicircular canals

High in sodium and low in potassium

Periymph

Found in the scala vestibule snd scala tympani

High in sodium, low in potassium

Organ of corti

End of organ hearing

Lies on top of the basilar membrane along the scala tympani

Contains sensory cells that are covered by tectorial membrane

Basilar membrane

Contains the auditory hair cells in its fibrous layer

Tectorial membrane

Gelatinous flap covering the tops of the stereocilia of the outer hair cells

Sensory loss

Damage to the hair cells

Neural loss

Damage to the auditory nerve

Sensory/neural hearing loss

Congenial or perinatal

Presbycusis

Hearing loss due to natural aging

Sudden SNHL

Hearing loss that develops instantly or over the course of a few days

noise induced hearing loss

Hearing loss due to noise exposure

Ototoxic hearing loss

Hearing loss due to exposure to drugs or chemicals that are toxic to the inner ear

Semi circular canal dehiscence

weakening of the bones that covers the semi circular canals, which can cause a third window affect

Ménière’s disease

Characterized by sudden attacks of vertigo, “roaring” tinnitus, aural fullness, and fluctuating hearing loss

Auditory nerve lesions

Result in hearing losses that are classified as sensorineural

signs and symptoms include

Unilateral tinnitus

high frequency SNHL

asymmetric SNHL

WRS score is worse than expected

Acoustic neuroma/vestibular schwannoma

Benign tumor on the auditory nerve

Progressive and slow

10% are sudden

WRS typically lower than expected

Auditory neuropathy spectrum disorder (ANSD)

Normal outer hair cell function with dyssynchronous firing of the auditory nerve

Progressive and slow

10% or sudden

WRS typically lower than expected

Non-organic hearing loss

Hearing loss without any organic disorder or with insufficient pathological evidence to explain the extent of the loss

SRT better than PTA

Half word responses during SRT

Rhyming responses during WRS

inconsistency between thresholds

Inconsistency between behavioral tests

“The patient is lying” - professor wu

The stenger test

When two tones are of the same frequency are introduced simultaneously into both ears, only the louder tone is perceived

Superior oilivary complex (SOC)

Receives input from the ipsilateral and contralateral cochlear nuclei

Lateral lemniscus

Major pathway for the transmission of impulses from the ipsilateral lower brain stem

Inferior colliculus

Receives afferent stimulation from both superior olivary complexes

Medial geniculate body

Last subcortical relay station for auditory impulses

Heschl’s gyrus

Area of auditory reception

Central auditory processing disorder (CAPD)

Individuals present difficulty interpreting auditory information without an accompanying hearing loss Symptoms include:

Difficulty hearing speech in noisy environments

Difficulty maintaining attention

Problems locating the source of the sound

Difficulty following directions

Commonly asking for information to be repeated

Inability to detect subtle changes in town

Distracted and inattentive behavior

Difficulty learning to read

Academic difficulties, including poor reading and spelling

CAPD Environmental modifications

Improve signal clarity

Preferential seating

Use of FM system

CAPD compensatory strategies

Strengthen auditory skills

Teach active participation in addressing difficulty

CAPD Direct remediation techniques

Address specific deficits

Improve auditory performance (auditory training programs)