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: à headphones § Bone conduction: àbone 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