Measurement of Hearing Quiz 2 - Otoscopy

Direction

Anterior

Direction

Posterior

Direction

Inferior

direction

lateral

medial anatomical position

dorsal anatomical position

superior anatomical position

ventral anatomical position

coronal anatomical section

sagittal anatomical section

Transverse anatomical sections

peripheral system

-outer ear

-middle ear

-inner ear

-auditory nerve

• proximal or cochlear end of the 8th cranial nerve

Central system

-Eighth cranial nerve/vestibulocochlear nerve

• Distal/brainstem end

-Auditory brainstem nuclei (central)

-Auditory cortex (central)

What do systems do audiologists assess?

peripheral and central auditory system function and more!

Test battery goals

-Diagnose HL and, if HL is present, determine its degree, configuration, and type, and aid in determining a site of lesion and pathology

Primary audiology tests

-case history

-otoscopy

-immittance

• tymps, acoustic reflexes, reflex decay

-Pure tone audiometry

• air and bone conduction

-Speech testing

• SRT and word rec

-Other physiological and behavioral measures

• OAEs, stenger and tuning fork tests

Where is the bulk of the peripheral auditory system housed?

within the temporal bone

temporal bone

5 sections of the temporal bone

-squamous

-mastoid

-tympanic part/portion

-styloid process

-petrous (pyramid)

squamous portion of temporal bone

mastoid portion of temporal bone

mastoid

-forms portion of EAC

-used in BC testing

-honeycombed

• prone to infection

tympanic part/portion of temporal bone

styloid process

Styloid process

attachment point for tongue and larynx muscles

Petrous pyramid

-very hard

-contains inner ear and internal auditory canal

petrous pyramid portion

outer ear consists of…

-pinna (auricle)

-External auditory meatus (ear canal)

-tympanic membrane?

Construction of the pinna

-primarily constructed from elastic cartilage

• also contains some muscle tissues (most are non functioning)

-Fat pad in the lobule

A

Helix

B

Tragus

C

Inter-tragal notch

D

Anti-tragus

E

Concha (bowl)

F

Anti-helix

G

Triangular fossa

H

Scaphoid fossa

External ear canal structure

-Cartilage support for outer 1/3 of length

• contains hairs and sebaceous (oil) and veruminour (wax) glands

-Bony support for inner 2/3 of length

• can be painful here

-In total ~2.5-3.5 cm long in adults

• ~1.4 cm at birth

-EAC is not straight!

• S-Shaped with 2 bends in the canal

  • Seeing the eardrum can be a challenge

Functions of the outer ear

-protects more central structures

• curvy canals protect the middle and inner ear

• hair and wax impede access, keep skin moist and have antimicrobial protective characteristics

-Acts as a resonator

• provides a boost in sound level at some frequencies

• 15-20 dB gain in the 2-5 kHz region for frontal sounds

  • The size of the boost varies with sound source location

    • can help little with horizontal localization and a lot with vertical plane localization

Middle ear system consists of…

-tympanic membrane

-ossicles

• malleus

• incus

• stapes

-middle ear muscles

• stapedius

• tensor tympani

-eustachian tube

tympanic membrane function and structure

-function: convert sound waves in the air into vibrations of the middle ear ossicles

-structure:

• ~8-10 mm in diameter

  • ~.074 mm thick (very thin)

• Concave outward (not flat)

• tilted at ~55 degrees

2 main sections of the tympanic membrane

-Pars tensa (has 4 layers)

-Pars flaccida (only 2 layers)

• frequent site of pathologies

A

Pars flaccida

B

Pars tensa

C

Umbo (connection point of malleus

D

Light reflex (cone of light)

E

Long process of the malleus (e.g. handle/manubrium)

F

Lateral (short) process of the malleus

Quadrants of TM

-Umbo in the center

-handle of the malleus (manubrium) divides anterior and posterior sections

-line perpendicular to manubrium divides superior and inferior sections

1

Anterior-superior quadrant

2

anterior-inferior quadrant

3

posterior-inferior quadrant

4

posterior-superior quadrant

you need to be familiar with “normal” ears so you can:

-Identify conditions that warrant medical referral

-Identify conditions that may impact your diagnostic assessments

-Identify conditions that may impact your rehabilitative efforts

Purpose of otoscopy

-determine the need for medical referral

-identify conditions that may affect audiometric test results

Otoscopy results that lead to medical referral

-untreated pathology

• trauma to or blood/drainage in EAC

-Obstructions

• Foreign bodies or impacted cerumen in EAC

-Previously unidentified structural defects

• pits/tags/stenosis/growths

• perforations or other abnormalities of the TM

otoscopy results that lead to audiometric concerns

-collapsing EAC

-obstructions

• foreign bodies or impacted cerumen in EAC

-Stenotic (narrow) or atrenic (closed) EAC

-Pressure equalization (PE) tubes

Otoscopy procedures

-Always do otoscopy before starting any audiologic procedure involving the EAC

• Follow infection control procedures

  • hand washing and gloves if needed

  • clean specula (for each ear if needed)

• make sure the otoscope light is bright

-explain what you are doing and start with good ear first (always ask “do you have a better hearing ear?”)

-start exam with the outer ear and surrounding areas, then examine the ear canal, and finally examine the TM

Examine the outer ear

-Inspect pinna and area around, behind and adjacent to the pinna

• look for signs of ear surgery, inflammation, pits, and tags

-If possible, talk to your patient to explain what you are doing during this process

Pinnae and EAC deformities

-Pinnae and EAC deformities are often associated with conductive or mixed losses

• always suspect HL in persons with these anomalies

-May be observed alone or as one of multiple craniofacial anomalies

• often associated with genetic disorders

-If not previously identified - these finding warrant medical referral

• particularly for children

Examples of pinnae deformaties

-Anotia

-microtia

-pre-auricular sinus (pit)

-pre-auricular “tag”

Anotia

no pinnae

microtia

-very small or deformed pinnae

-can vary from mild (grade I) to severe (grade III)

Pre-auricular sinus (pit) and pre-auricular “tag”

-Pit: small depressions in the skin around the pinna that are suggestive of abnormal development during crucial time periods in utero

-Tag: additional skin protrusions

-in isolation, pits and tags may not warrant a medical referral

• if not previously identified:

  • note them in your report and encourage the patient to speak with their physician about the findings, particularly if identified in a child

• if found in conjunction with other flags, (eg. HL) then refer.

Otoscopy procedure for checking the ear canal and TM

-Use the pencil grip if feasible and brace fingers against the patient’s head

-begin with the outer ear then move to EAC

• Check for collapsing canal first, then

• gently pull up and back (on adults) on the pinna to straighten the EAC

  • pull pinna down and back for young children

  • systematically check EAC and all TM quadrants

Ear canal disorders

-stenosis: narrow EAC

• may or may not cause HL

-atresia: absent EAC

• blockage may be in the cartilaginous and/or bony portions of the canal

• results in conductive HL

skin disorders in the ear canal

-otitis externa

• acute or chronic

-Osteoma and exostoses

-excessive cerumen/wax

-collapsing ear canals

otitis externa/external otitis

-can be acute or chronic

• may be due to viral, bacterial, or fungal infection

-Painful with foul smelling discharge

-can spread to middle and inner ear if left untreated

• may cause HL if severe swelling occurs in the EAC

-Warrants medical referral!

Variations in cerumen

-a normal product of a healthy ear

• but in excess it can impact audiologic procedures

• effect on hearing varies from non to a large conductive loss (if ear is completely occluded)

-Only warrants referral is excessive and/or impacting your ability to complete testing

Foreign bodies

potentially warrants a referral. solid objects can become embedded in the skin and lead to infection and/or need for surgery

Collapsing canals

-more prevalent in elderly and infants/newborns

• typically benign

• if using supra-aural phones can lead to a “false” ABG (air bone gap) in audiometric testing

  • gaps up to 15-30 dB often high frequency conductive loss

-When using supra-aural headphones, check for collapsing canals during otoscopy

-Typically no referral unless collapsed all the time

Cysts

-benign sacs beneath the skin

-no referral

Tumors

-can be benign or malignant

-vascular or bony

-no referral

Osteomas and exostoses

-Most common bony outgrowths (tumor) in the EAC

-Often seen in cold water swimmers

-Usually benign, may need removal if causing EAC blockage or recurrent external otitis

-Typically no referral

Tympanosclerosis

-scarring on the ear drum

-Very common following ear disease (e.g. otitis media)

-May or may not affect hearing thresholds

-Typically no referral needed

TM perforation

-sometimes they are easy to see, other times not so much.

-if unidentified and/ active drainage, refer

-if longstanding, no referral

Middle ear fluid

-May or may not have active otitis media or hearing loss

-if causing pain, refer

-if unidentified and not sick, refer

-if unidentified and sick with treatment, no referral

Monomeric scar

-previous infection or perforation that is partially healed

-no HL and normal tests, no referral

ballooning monomers

without fibrous regions, skin can balloon on the TM

Atelctatic eardrum

-Extreme negative pressure, Eustachian tube dysfunction

-Not always necessary referral

PE tubes

-In and of itself do not require referral but underlying conditions may

Cholesteatoma

-middle ear pathology that may spread to the EAC and be visualized via otoscopy

• very serious

  • absolutely needs referral

Ossicles

-Purpose: transmit TM vibrations to the cochlea via the oval window

-Consists of the malleus, incus, stapes

-smallest bones in the body

• stapes ~3.5 mm (1/8th in)

-Held in space by ligaments & tendons of two ME muscles

• stapedius muscle

• tensor tympani muscle

Middle ear muscles

-Our focus is on the stapedius muscle

• smallest muscle in the body

• connects to the stapes

• innervated by the VII (facial cranial nerve)

-Both ME muscles may contract reflexively, in response to acoustic and nonacoustic stimuli

• loud sounds, puff of air, tactile stimulation

-Stapedius (acoustic) reflex-

• This reflex provides important diagnostic information

middle ear space

-the brain, arteries, veins, and several cranial nerves are in or near this space

• V (Trigeminal)

  • tensor tympani

• VII (facial)

  • stapedius muscle

  • chorda tympani branch

    • sensory information from tongue

• IX (glossopharyngeal)

  • tympanic branch

Middle ear functions

-Convert pressure variations in the air (sound waves) to mechanical vibration to stimulate the inner ear

-optimize energy transmission

• impedance matching function

• focuses sound energy on the oval window

-pressure equalization - eustachian tube

-protective mechanism (?)- acoustic reflex

Energy transmission in the middle ear

-We lose 99.9% of sound energy (~30dB) as sound waves are transmitted from air (ear canal) to fluid medium (cochlea)

• due to the “impedance mismatch”

-middle ear system compensates for this via:

• areal ratio difference (oval window is smaller so pressure is greater

• lever action

• curved membrane buckling

-and by focusing energy directly into the cochlea

Eustachian tube

-connects middle ear space to nasopharynx

• 3.5-4 cm long

• 45 degrees downward tilt in adults

• near horizontal in children

-provides aeration, drainage, and pressure equalization for ME

-opened by contraction of tensor palatini muscle

• innervated by the Vth (trigeminal) cranial nerve

-eustachian tube dysfunction may lead to middle ear effusion (fluid)

• particularly in children

Acoustic (stapedius) reflex

-acoustic contraction of stapedius muscle in response to a loud sound (>85 dB SPL)

• This stiffins the ossicles and attenuates sound flow

  • largest effect on low frequency sounds

-purpose is unclear

• protect the cochlea from loud sound?

• adjust ossicular chain to

  • maximize sound transmission at different levels?

  • aid in sound localization?

2 major components of the inner ear

-osseous labyrinth

• bony outer casing carved within the temporal bone

-membranous labyrinth

• encased within the bony labyrinth

3 main sections of the inner ear

-semicircular canals

• vestibular (balance) portion

-vestibule

• connects the cochlea and semicircular canals

-cochlea

• auditory portion

Membranous labyrinth

-size of a flattened pea (approx. 5 mm (h) x 9 mm (w) at base

-2 ¾ spiral turns in humans

-about 35 mm long if uncurled

-internally divided into 3 fluid filled sections

1

Scala media

• reissner’s membrane

• basilar membrane

• contains sensory organ of hearing (organ of corti)

2

Scala vestibuli

• stapes/oval window connection

3

Scala tympani

• round window connection

4

spiral ganglion

5

auditory nerve

6

helicotrema

1

scala vestibuli

2

scala tympani