Strongly recommanded
study literature:
Hans Behrbohm, Oliver Kaschke, Tadeus Nawka,Andrew
Swift: Ear, Nose, and Throat Diseases: Founding Authors W.
Becker, H.H. Naumann, C.R. Pfaltz (Paperback) Publisher: Thieme
Publishing Group; 3rd Revised edition edition (12 Aug
2009). 471 pages , Language English. ISBN-10:
313671203X, ISBN-13: 978-3136712030.
Ear I
Ass.prof. P. Smilek, MD, Ph.D.
ENT Clinic of Masaryk university, Brno
Faculty St. Ann Hospital
Head: Ass.prof. Gál Břetislav, MD, Ph.D.
Pekařská 53, Brno , 656 91
The hearing and balance system
The hearing and balance system localized in temporal bone
The hearing system
Two main subdivisions:
Peripheral Part
▪ external, middle and inner ear
▪ auditory nerve
Central Part
▪ central hearing pathways
▪ subcortical and cortical auditory centers
Anatomic boundary - entry the VIIIth nerve into brainstem.
Function of hearing system
– The external and middle ear transport the stimulus
– cochlea distributes the stimulus
– the sensory cells transform the stimulus
External ear
Auricle – abundantly formatted cartilage (localization, protection)
External meatus (meatus acusticus externus)
External part
▪ cartilage
▪ Lined with skin and down (tragi) and sebaceous gland – cerumen
Internal part
▪ Temporal bone
▪ Lined with thinned epidermis (skin)
– curved cartilaginous mobile part –
must be drawn upward and posteriorly (in adults)–
to bring the same axis
External meatus skin has 10x higher growth potential
than middle ear mucose membrane – theory of development
of acquired cholesteatoma
Middle Ear
Middle Ear cavity
– summary name for the whole pneumatic system of temporal bone: tympanic cavity, cells of proc.
mastoideus and Eustachian tube (tubotympanal and tympanomastoideal segment)
Middle Ear
Tympanic membrane (membrana tympani) - a sound pressure receptor
and transformer
Inclination and declination angle to meatus axis, surface 55 mm2
– sulcus tympanicus; incissura tympanica Rivini
– anulus fibrocartilagineus (fixing of tymp.membrane)
pars tensa
▪ Three layers:
– external- epidermis (stratum cutaneum)
– middle– fibrous layer (str. fibrosum)
– internal– epithelium (str. mucosum)
pars flaccida (membrana Shrapnelli)
▪ Surface 5 mm2 in superior part of ear drum
▪ Fibrous layer is almost missing (lower strength)
Tympanic cavity (Cavum tympani; shape of
biconcave lens) 6 walls
Paries:
▪ membranaceus
▪ labyrinthicus
▪ tegmentalis
▪ jugularis
▪ mastoidea
▪ caroticus
Lateral projection of Ear drum divides tympanic cavity
Into: 1,2 epitympanic recess
3 mesotympanum
4 hypotympanic recess
Tympanic cavity – medial wall
Middle ear
Tympanic cavity (cavum tympani)
ossicular chain:
▪ malleus
▪ incus
▪ stapes
Hearing function of tympanic cavity
(transfer system)
1. Compensation of loss of acoustic energy (ear- liquid):
a/ tympanic membrane - oval window 14x
b/ lever-action system of ossicles 1,3x
c/ lever-action system due to uneven incurvation of ear drum, all together
amplification is 30-35dB
2. Mutual change of deviation and pressure acoustic vibration .
Gas = great deviation, low pressure.
Liquid = low deviation, great pressure .
Eustachian tube
• Ventilation function - it serves to
equalize the pressure between
middle ear and the nasopharynx
• Drainage function – removal of
secretion from middle ear cavity
• Protective function - before
secretion penetration into middle
ear cavity (microbial barrier guard
system in epipharynx vs sterile
tympanic cavity)
Membranous labyrinth (hearing and balance)
▪ Cochlear Duct (ductus cochlearis)
▪ Saccule and Utricle (saculus et utriculus)
▪ Membraneus semicircular Ducts (canales semicirculares)
Cross-section of Cochlear Duct (dct.
Cochlearis)
A snail shell in
shape,
two and half
turns
Cochlear duct cross-section, organon
spirale Corti
membrana basilaris, reticularis, tectoria
HEARING FUNCTION - COCHLEA
Cochlear function:
•Change of mechanic vibration on
neural excitation
•Basic frequency analysis
Vibration conduction from the ear
drum through cochlea, Organon
Corti
Outer hair cells (OHC) = servomechanism
for inner hair cells (IHC)
Cochlear septum
System of 3 membranes – membrana
basilaris, reticularis, tectoria
Principle of tonotopy
– as higher frequency, the acustic
pressure balanced near to stapes.
High frequency are perceived in basal
thread, low frequencies in apical
thread.
Wave hydrodynamic theory of hearing (von Bekesy
theory of „traveling wave“; still valid ☺)
▪ Acoustic tension is led from ear drum through ossicles into oval window.
▪ Liquid is je not compressible, pressure changes are equalized on round window
membrane, which vibrate in anti phase to stapes.
▪ Acoustic pressure is equalized on cochlear septum and it create wave.
▪ a sound impulse sends a wave sweeping along the basilar membrane. ... And as Helmholtz
had postulated, Bekesy found that the high-frequency tones were perceived near the base
of the cochlea and the lower frequencies toward the apex." (principle of tonotopy).
▪ „ traveling wave“ leads to shift of tectorial membrane of Organon Corti in relation to
basilar membrane and deflection of hairs of sensory cells (opening of iont channels)
▪ Thus the mechanic energy is changed into electric potential in VIII cranial nerve.
Vestibular system
Basic function
1. Equilibrium of human body in stand
and in walking
2. Stabilization of retinal picture and
keeping visual sharpness in
movement
Equilibrium
Three afferent sources of equilibrium:
eye, proprioception and vestibularsemicircular
system.
Basic reflex circles
▪ vestibulo-ocular reflex (VOR)
▪ Vestibulo-spinal reflex (VSR) - help
keep head and body in upright
position due to vestibulospinal
system.
On keeping balance : Interaction of eye, vestibular-semicircular system, proprioception X
vestibular nuclei and cerebellum
Vestibulo-occular reflex
Stabilisation of retinal picture. Create movement of eye,
which are opposite to movement of head in some plains.
Nystagmus – conjugated, coordinated eye movement
around a specific axis. The movement consists of
rhythmically alternating slow – and fast beating phases.
The direction of the fast components determines the
laterality of the nystagmus.
Membranous labyrinth
▪ Vestibular apparatus localized in pyramis ossis temporalis; membranous labyrinth:
saccule, utricle and three semicircular canal; filled with endolymph.
▪ Every semicircular canal begins with pars ampullaris with ampullary crest, sense organ
is static macula (macula statica utriculi et saculi).
Section of semicircular canal, schema of membranous labyrinth ( with one canal), sensory organs.
Genesis of receptor potential
Ampullary crests (cristae ampulares) and maculae utricle and saccule
are created by supporting cells and hair cells. On their surface lie the
otoliths (statoconia) – calcium carbonate crystal.
Linear acceleration changes the otolith
pressure, deflecting the sensory hairs.
This stimulates the sensory cell by
altering the resting potential.
Diagnosis, vestibular function tests
History – subjective feeling of dizziness, time of start and duration…
Evaluation of reflexes – spontaneous vs. experimentally provoked
(calorisation, rotation)
▪ Nystagmus (vestibulo-ocular reflex) Detail evaluation of eye movement electronystagmography,
video oculography (preferred)
▪ Vestibule-spinal reflexes:
– Hautant test (spontaneous deviation test),
– Romberg test (patient is asked to stand in basic position/wide stance, and to close
eyes. A check is to see whether there is unsteadiness or a tendency to fall.)
▪ Vestibule-cerebellar reflex
– Barany test (finger-nose pointing test) ; posturography
Vestibular function Tests
▪ Head shaking nystagmus – spontaneous Nystagmus can be provoked by
gentle, passive, horizontal shaking of the patients head
▪ Unterberger test, walk „on the rope“
▪ Stabilometric plain - static and dynamic (vestibule-spinal reflexes)
▪ Head impulse test: – in long lasting dizzines. From mild eccentric head
position we provide passive quick rotation movement from side to side,
patient fixis our tip of nose….
Vertigo (dizziness)
the outcome of the functional tests is to determine whether it is peripheral
or central vertigo. Peripheral vertigo is troublesome but not life-threatening,
while central vertigo can be life-threatening.
• Periferal type – feeling of rotation of itself body or surroundings, direction
of rotation is usually into healthy part, loss of stability or feeling of
swimming
• Central type – ineptitude by walk, inability of walk, vertigines with aura
(EPI), disorder of vision "black outs" – diplopia is seen by disorder of
oculomotory.
Differential diagnosis peripheral vs. central vestibular
syndrome
Symptom Peripheral (harmonic) VS Central VS
Nystagmus
Horizontal rotatory on side of most reactive
labyrinth
Other then horizontal rotatoric: vertical, „gaze“
nystagmus, rebound nystagmus etc)
Tonic deviation
On side of weak labyrinth (to affected ear) in
relation to position of head
Without to relation to head position
Eye fixation In absence of eye fixation nystagmus is growing In absence of eye fixation nystagmus not changed
Cranial nerves Without lesions (excl.: n. VII) Laesion of cranial nerves present
Cerebellar symptoms Not present Could be present
Disturbance of occulomotoric function
Not present
Could be present
Hearing disorder
Usually Could be present Usually Not present
Central compensation
Gradually compensation, harmonic symptoms:
intensity of vertigo correlates with nystagmus
intensity and tonic deviations
Not present, disharmonic symptoms
History of ear disease
Hearing
disorder
Otorhoea
Ear discharge
Tinnitus
Pain Dizzines
Physician itself is a „remedy“. (Michael Balint)
Ear evaluation, oto(mikro)scopy
▪ Aspection and palpation
– Auricle shape, deformities
– Skin lesions, scars (also retroauriculars)
– Discharge from external meatus
– Pain in pressure on tragus (by otitis externa)
– Pain in pressure on processus mastoideus (by mastoiditis acuta)
▪ Otoscopy and oto(micro)scopy evaluation
– Ear speculum
– Illuminated otoscope, pneumo-otoscopy
– Otomicroscope, endoscope
Otoscopy
eye evaluation of
deeper parts of
external meatus
and ear drum
The cartilaginous part of
ext. meatus is stretched
by pulling the auricle
upward and backward
„Normal“ ear drum
• Grey colour
• Without perforation
• Bezold´s trias
Prominentia mallearis
Stria mallearis
Light reflex
Otoscopy – tympanic membrane
quadrants and zones
Basic pathologic finding on tympanic
membrane
▪ Changes on the tympanic membrane: Injection of the vessels
▪ Position of the tympanic membrane
– bulgging due to exudate - hyperemia, moist infiltration and opacity of the
surface, the contours of the handle of malleus and short process
disappear
– retraction - injection of blood vessels
▪ integrity of the tympanic membrane perforations –
– after injury
– inflammatory - acute
- chronic - central (mesotympanic)
- marginal (peripheral)
▪ changes after inflammation: thickening of the tympanic membrane, scars
▪ changes behind the ear-drum: middle ear effusion, fluid level, air bubbles
Retraction of the ear drum, pressure equalizing tube
Retrakční kapsa ve Schrapnel. blance, perforace v zad. hor. kv. s cholest. hmotami
Various types of ear drum perforations
Peripheral perforation
Central perforation
Periopheral and central
perforation
Ear drum injury
Siegl´s ear speculum
Siegl´s ear speculum
Radiographs in
Schüller wiev
Radiographs in Schüller wiev
Radiographs in the Stenver view
Schema of CT of ossicular chain
and middle ear cavity
Canalis Fallopi
Hearing disorder according to place of lesion
▪ External ear – conductive hearing loss
▪ Inner ear sensorineural intracochlear
hearing disorder
▪ Central pathways – retro cochlear hearing
disorder
Hearing disorder
(Hypacusis)
Senzorineural
Hypacusis perceptiva
Weber lat. to better hearing
Rinne posit
Schwabach shortened
Cochlear RetrokochleárníRetro (supra) cochlear
Conductive hearing disorder
Hypacusis conductiva
Weber lat to worse hearing
Rinne negat
Schwabach prolonged
Mixed hearing disorder
Hypacusis mixta
Schwabach shortened
Rinne negat
Classification of basic type of hearing dysfunction
according to place of lesion
Evaluation of hearing function
We evaluate on growing level of objectivity:
▪ „Classical“ hearing test
▪ Audiometry
▪ Objective evaluating methods
– tympanometry
– evoked potentials
– otoacoustic emissions
Classical hearing test (speech test,
tuning fork tests)
Important part of hearing tests:
+ quick, easy, cheap, information about understanding speech
– only for orientation
Tuning fork tests:
– Rinne
– Weber
– Schwabach,
Gellé, …
Basic types of hearing disorder
P L
4 V 10
O,5 Vs 10
W
+ R +
zkr. Sch norm
Hypacusis perceptiva (Sensorineural deafness)
Weber unto better hearing ear
Rinne posit
Schwabach shorter
Retrocochlear
P L
4 V 10
3 Vs 10
W
–– R +
prod. Sch norm.
Hypacusis conductiva (Conductive hearing loss)
Weber unto worse hearing ear
Rinne negat
Schwabach longer
Hypacusis mixta (Mixed hearing loss)
Schwabach shorter
Rinne negat.
Pure-tone audiometry
An audiometer is an electric tone generator used to determine
the hearing threshold for pure tones; generates tones of
specific frequency (Hz) and intensity (dB).
▪ audiometric room
▪ Air conduction:
→ headphones
▪ Bone conduction:
→bone vibrator
Normal range – until 20 dB loss
Symbols for record of audiometric
evaluation
right left
Air conduction
Bone conduction
The speech field
Region of the best sensitivity for hearing
Hearing loss (Hypacusis)
Conductive Sensorineural Mixed
Speech audiometry
Patient repeats words which are
reproduced. One correctly
repeated word means 10% of
comprehension from one set. It
is evaluated on increasing levels
of intensity till 100% of
comprehension or maximally
possible per cent of
comprehension.
Comprehensionin%
Speech sound level in %
Sensorineural hearing loss
Conductive hearing loss
Normal hearing
Tympanometry
The greater the pressure differential (before and behind ear drum), the greater is the
impedance of tympanic membrane and more acoustic energy is reflected back into external
meatus. The level of testing tone in meatus is measured by sensitive microphone .
Tympanometry
Evoked response
audiometry (ERA)
▪ Human brain works with bioelectric impulses, not sound.
▪ bioelectric impulses could be measured as an electric
potential
▪ conditions: motoric and psychic rest of patient, camera silent,
electric interference suppression of the room
▪ Patient repeatedly exposed to an acoustic stimulus, an EEG is
recorded. Averaging – the individual response can be
distinguished by mathematical analysis of numerous individual
evoked potentials
Evoked response audiometry (ERA)
▪ Cochlear potentials, electrocochleography (Ecochg): latency window
0-4 ms. Probe – in externeal meatus or on promontorium)
▪ Early potentials (brain stem, BERA): 10-12 ms.
▪ Middle potentials MERA (middle latency evoked response
audiometry : 40-60 ms – suitable for processing (steady-state evoked
potentials)
▪ Late potentials (cortical, CERA-cortical evoked response
audiometry): to 200 ms. Before application CI or hearing aids.
BERA, BAEP (brainstem auditory evoked potentials)
▪ Early potentials (brain stem, BERA): 10-12 ms.
▪ Complex 7 peaks, so called Jewett waves, most
important I-III.
▪ Fixed elektrods temporal, occipital and referent forhead,
given earphone
▪ Susp. rektrocochlear laesion – dysmorphy of Jewett
complex, missing or shift of latency V wave.
▪ Senzitivity and specifity for dg vestib schwanoma 70-80
%
Auditory evoked potentials BERA
– prolonged latency of 0,2 ms – suspection
on small schwanoma n. VIII
Patient repeatedly exposed to an acoustic stimulus, an EEG is
recorded. Averaging – the individual response can be
distinguished by mathematical analysis of numerous
individual evoked potentials
Middle potentials MERA
Steady-state evoked potentials (SSEP)
▪ Other names: ASSR (auditory steady-state responses), AMFR (amplitude
modulated frequency responses) – processing of signals of middle electric
response.
▪ Fully automatized
▪ Good correlation with pure tone audiometry
▪ Outcome of measurement – objective frequency – specified threshold
audiometry, estimation audiogram
Otoacustic emision (OAE)
▪ Sound result from spontaneous or provoked activity of outer hair sells
organon Corti.
▪ Spontaneus OAE arise itself, sign of normal function of Corti organ,
present in childhood
▪ Evoked OAE
– Tranziently evoked otoacustic emision (TEOAE)- as response on acoustic stimulus
– Distors products (DPOAE) – emission response on 2 simultaneous perceived tons of
nearby freqency and intensity
▪ Usage newborn screening of hearing function and frequency
specified determination of hearing threshold
Sensorineural hearing loss
According to type of audiometry curve:
• Basocochlear
• Pankochlear
• Apicocochlear
• Mediocochlear
According to
lesion localisation:
• Cochlear
• Retrocochlear
Cochlear lesion
- bothering, but not life threating
Retrocochlear lesion
- bothering, but also they could life threaten
Sensorineural hearing loss
(intra) cochlear
= damage of cochlear structures
Etiology:
– Presbyacusis
– Heredo-degenerative
– Nois damage
– Toxic damage
– Menier´s disease
– Acute sensorineural hearing loss
… etc.
Sensorineural hearing loss
retro- (supra-) cochlear
= damage of structures proximal from cochlea
Etiology:
Demyelization - atherosclerosis
- sclerosis multiplex
Inflammation - borreliosis
- neuro-viruses
- meningitis
- meningoencephalitis
Tumors -vestibular schwannoma
- meningioma
- other tumors of cerebellar angle
Trauma - commotion, contusion
- scull base fractures
Differencial diagnosis
cochlear/retrocochlear
1. Subjective tests:
- time demanding
- active cooperation of pt
- complicated for understanding
- relatively low validity
2. Objective tests :
- time usually not so demanding
- demand only passive patient cooperation
- expansive technical equipment
- high validity
Subjective tests
Based on proof of:
mask effect of noise
recruitment phenomena
wearisomeness of hearing organ
Recruitment phenomena
= abnormal increase of loudness in above-threshold in damage of OHC
and normal function IHC.
Fowler test; convergence of perceptions
SI-SI Short Increament Sensitivity Index
short time 1 dB increase of intensity 20 dB above treshold (20x)
assuredly recognize
Langebeck test
= increase ability to mask tons by hum in
supracochlear hearing loss. Thresholds
are higher about more than 10 dB as
level of ripple.
Noise
audiometry
Langebeck test
Supracochlear hearing
loss