F benoudiba hearing sense organ jfim hanoi 2015
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hearing sense organ imaging
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F benoudiba hearing sense organ jfim hanoi 2015
- 1. F. Benoudiba, JL Sarrazin, A Ladoux, JB Billaud, D Ducreux Neuroradiology Department CHU Kremlin Bicêtre hearing: Sense organ Hanoi, nov 2015
- 2. • 3 distinct parts • The acoustic meatus • Pinna • External acoustic meatus • Acoustic wave propagation • Protection of the middle ear and resonance Anatomy and physiology of hearing
- 3. • Eardrum • Middle ear • Contents: • Auditory ossicles Amplify the vibration of the eardrum • Malleus, uncus and stapes • Eustachian tube: connecting the middle ear to the rhinopharynx: equalizing air pressure on both sides of the eardrum • Adaptation of impedance • Transformation vibration wave to mechanical energy Middle ear
- 4. • Mastoid • Communication with the mastoid air cells and the epitympanic recess • windows • Round window • Oval window Middle ear
- 6. • Vestibule and semi circular canals: Balance • Cochlea • Hearing part of the inner ear • 35mm long • Spiral around a bony structure • 2 spires 1/2 • 2 scala separated by the spiral lamina • Filled with peri lymph Stapes Fenestra vestibuli Apex of cochlea Scala vestibuli Scala Tympani Organe of Corti Inner ear
- 7. • Scala Media • Triangular-shaped duct • contain the organ of hearing: Organ of Cort • Filled with endolymph Organe of Corti Scala vestibuli Scala tympani Inner ear
- 8. • Organe of Corti Tectorial membran Outer hair cells(10500) 3 rows (W) Inner hair cells (3500 fibers) 1 row Cochlear nerve 10/CCI Basilar membran Inner ear Reissner’s membran
- 9. Central auditory system : Cochlear Nucleï Posterior Nucleus Anterior nucleus Unilateral afferents Sound intensity, fréquency and duration
- 10. Cochlear Nucleus: superior olivary complex Bilatéral Information • Spatial location • Binaural interaction • Motor response to a sound
- 12. Inferior Colliculus Ø Crossroad between acsending and descending fibers Ø Complex auditory information Ø located just below the visual processing centers
- 13. Auditory Thalamus Medial geniculate nucleus Posterior group of thalamus Reticular nucleus § Auditory lateralization
- 15. Hemispheric inter connexion 1. Anterior commissure of the cerebrum connecting the temporal lobe 2. Auditory tract over corpus callosum MRI auditory system
- 16. SOUND: Air pressure vibration Vibration of the eardrum MAE Sound =Mechanical Energy focus Ossicles amplification Endolymph fluid agitation Hydraulic pressure OHC: amplification IHC: frequency Cochlear nerve = Electrical energy Electrochemical signals to brain Physiology of Audition
- 17. • Cochlea tonotopy: • Cochlea is capable of exceptional sound analysis, in terms of both frequency and intensity. • Higher frequencies cause movement in the base of the cochlea, and deeper frequencies work at the apex. • Cochlear nuclei tonotopy • Apex fibers: surface of nucleus • Base fibers: depth of nucleus Physiology of Audition
- 18. Physiology of Audition Auditory messages are conveyed permanently to the brain via two types of pathway: the primary auditory pathway which exclusively carries messages from the cochlea the non-primary pathway (also called the reticular sensory pathway) which carries all types of sensory messages.
- 19. a b c d e Neurophysiology of audition • Primary auditory cortex: tonotopic representation. Topographic map of cochlea • Stimulation:auditory hallucinations contralateral ear • Secondary auditory cortex: spatial localisation of sound, memory audition • Stimulation: auditory illusions • Broca’s area: articulation of speech • Wernicke’s area: speech perception
- 20. Neurophysiology of audition • Some examples in music: • Left hemisphere : rythm • Right hemisphere : Melody et Harmony • Primary auditory cortex: height and sound volume • Secondary auditory cortex: Harmony, Melody and Rythm • Motor cortex: vocals and playing an instrument • Hippocampus: memory • Cerebellum: rythm pathways (beat the measure, tapping the feet to the beat) Corpus callosum
- 23. • Medical history • Uni or bilateral deafness • Acquired, evolutive • Otoscopy • Tympanometry • Acoustic reflex (if recruitment: endo cochlear lesion) • Audiometric tests: • Rinne CA>CO Nl ou SP CO>CA ST • Weber: Nl: vibration both ear ST: sick side SP: healthy side Clinical diagnosis
- 24. • Audiogram: • Tonal : graph • Vocal : patient’s ability to understand words AEP: Electric activity cochlea Clinical diagnosis ST SP S Mixte Unconformity tonal and vocal: retro cochlear lesion brainstem
- 25. HEARING LOSS • A number of pathological, genetic and epigenetic factors can cause hearing loss • May involve any part of the sensory structure • 3 types Conductive earing loss EAM ME Sensorineural : Inner ear, IAM, central Mixed : SP + Conductive
- 26. Imaging Deafness Conductive Sensorineural CT IV - Cone beam MRI IAM Inner ear Brain +/- CT Malformations Trauma otosclerosis
- 27. Conductive earing loss: causes Mechanical obstruction Infectious Tumor Trauma Earwax, external epidermal Cholesteatoma Malformation Coforign body Exostosis et osteoma EMO External otitis Benign Malignant • EAM
- 28. Conductive earing loss: causes Malformation Inflammatory • Middle ear Ossicles windows Chronic Suppurative otitis tympanosclerosis Cholesteatoma
- 29. Conductive earing loss: causes Otosposclerosis Traumatic • Middle ear Tumor Meningioma Adenoma Paraganglioma Hémangioma VII Schwanomma VII
- 30. Sensorineural earing loss: causes Inner ear Malformation • Cochlea • Aquecduct dilatation Otosclerosis Paget Osteogenesis imperfecta Labyrinthic schwanomma Labyrinthic hemorrage Traumatic Presbyacousia Toxics Endolymphatic papilloma
- 31. Sensorineural earing loss: causes MAI Malformation Agenesia, hypoplasia CN Infectious Schwanomma Meningioma Lymphoma Metastasis Inflammatory
- 32. Sensorineural earing loss: causes PCA Schwanomma VIII, VII, IX,X,XI,XII Cystic lesions EC, AC Meningioma Lipoma Aneurysm Cartilaginous tumor (chondroma, chondrosarcoma)
- 33. Sensorineural earing loss: causes Central Traumatic Inflammation ischemic Infectious Siderosis Dementia Parkinson
- 34. Central deafness • Surdité Verbale: • Impossibilité de reconnaître les mots entendus. • Possibilité de parole spontanée • Atteinte bilatérale cortex temporal. • Agnosie auditive: • Impossibilité de reconnaître les sons et bruits environnants. • Infarctus capsules externes ou corps genouillés • Amusie • Impossibilité de reconnaître la musique
- 35. • The auditory system has a complex organization • It revolves around a dual relationship : • Anatomical structure with perceptual function • Complex structure combining perception and cognition. • The deafness causes are many and varied and a good knowledge of anatomy , physiological , clinical and para-clinical and etiological diagnostic will approach adapted diagnosis to a single symptom but with multiple etiologies.