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.
Med Servis Mgr. Jaroslava Wilhelmová, Všetičkova 29,
602 00 Brno. Tel./fax. 05/43241146 .
Ear I
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 and balance system
Two main subdivisions:
Peripheral Part
▪ external, middle and inner ear
▪ auditory nerve
Central Part
▪ central hearing pathways
▪ subcortical and cortical auditory centers
▪ central balance mechanism
Anatomic boundary - entry the VIIth nerve into brainstem.
▪ The external and middle ear transport the stimulus
▪ cochlea distributes the stimulus
▪ the sensory cells transform the stimulus
External ear
Auricle – abundantly formatted cartilage
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
– curved cartilaginous mobile part –
must be drawn upward and posteriorly –
to bring the same axis
External meatus skin has 10x higher growth potential,
than middle ear linen – 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
– anulus fibrocartilagineus
pars tensa
▪ Three layers:
– external- epidermis (stratum cunateum)
– middle– fibrouas layer ,str. fibrosum
– internal– epitel, str. mucosum
pars flaccida (membrana Shrapnelli)
▪ Surface 5 mm2 in superior part of ear drum
▪ Fibrous layer is missing
1,2 epitympanic recess
3 mesotympanum
4 hypotympanic recess
Cavum tympani - (shape of biconcave lens)
6 walls
Paries:
▪ membranaceus
▪ labyrinthicus
▪ tegmentalis
▪ jugularis
▪ mastoidea
▪ caroticus
Middle ear
Tympanic cavity (cavum tympani)
ossicular chain:
▪ malleus
▪ incus
▪ stapes)
HEARING FUNCTION (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 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
SLUCHOVÁ FUNKCE (PERCEPČNÍ ÚSTROJÍ )
Cochlear function:
•Change of mechanic
vibration on neural
excitation
•Basic frequency analysis
Cochlear cross-section
Cochlear duct cross-section
Conduction of vibration from
tymp. membr. through cochlea,
Organon Corti
Outer hair cells (OHC) = servomechanism
for inner hair cells (IHC)
routing vibration from ear
drum through cochlea,
Organon Corti
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 whorl, low frequencies in
apical whorl.
Wave hydrodynamic theory of hearing
(von Bekesy theory of „traveling wave“)
▪ 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
▪ Thus the mechanic energy is changed into electric potential in VIII cranial nerve.
Vestibular system
Basic function
▪ Equilibrium of human body in stand and
in walking
▪ Stabilization of retinal picture and
keeping visual sharpness in movement
Basic reflex circles
▪ vestibulo-ocular reflex (VOR)
▪ Vestibulo-spinal reflex (VSR) - help keep
head and body in upright position due to
vestibulospinal system.
Equilibrium
Three afferent sources
of equilibrium: eye,
proprioception and
vestibular system.
Interaction of eye, vestibular-semicircular system, proprioception and cerebellum on
keeping balance
Vestibulo-occular reflex
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.
Section of semicircular canal, schema of membranous labyrinth ( with one canal), sensory organs.
Genesis of receptor potential
Ampullary crests and maculae utricle and saccule are created 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.
Vestibular function Tests
▪ History – subjective feeling of dizziness
▪ Nystagmus
▪ Vestibule-spinal and cerebellar reflexes:
– Hautant test (spontaneous deviation test),
– Romberg test,
– Barany test (finger-nose pointing test) ; posturography
▪ Head impulse test: from mild eccentric head position we
provide passive quick rotation movement from side to side.
Vestibular function Tests
▪ Head shaking nystagmus – spontaneous Ny can be
provoked by gentle, passive, horizontal shaking of the
patients head
▪ Detail evaluation of eye movement electronystagmography,
video oculography
▪ Unterberger test, walk „on the rope“
▪ Stabilometric plain - static and dynamic
Vertigo (dizziness)
• 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 Horizonttal rotatoric (olnz
horiyontal, 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 abscence of eye fixation nystagmus
is growing
In abscence of eye fixation nystagmus
not changejd
Cranial nerves Without laesion (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)
▪ Otoskopy and oto(mikro)scopy evaluation
– Ear speculum
– Illuminated otoscope, pneumo-otoscopy
– otomicroscope
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
Bezold´s trias
• Prominentia mallearis
• Stria mallearis
• Light reflex
Otoscopy – tympanic membrane
quadrants and zones
Normal ear drum
Basic pathologic finding on tympanic
membrane
• Injection of the vessels of the tympanic membrane
• (position) bulgging due to exudate - hyperemia, moist
infiltration and opacity of the surfice, the contours of the
handle of mellaeus and short process disappear
• retraction - injection of blood vessels
• (integrity) perforations –
• after injury
• inflammatory - acute
• - chronic - central (mesotympanic)
• - marginal (peripheral)
• (changes after infamm.) thickening of the tympanic
membrane, scars
• changes behind the ear-drum: middle ear efussion, fluid level,
air bubbles
Various types of ear drum
perforations
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
Schema of hearing organ:
▪ 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
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
Auditory evoked potentials
(BERA,CERA…)
– 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
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
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
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