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DR. BANDAR MOHAMMED AL-QAHTANI, M.D KSMC. AUDIOLOGY IN ORL . Tympanic mem & Ossicular Amplification 22:1 in total 1.3:1 maleus to incus (lever action) 17 :1 TM surface to stapes footplate problem in transmission leads to CHL . Anatomy of hearing organ THE COCHLEA.
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DR. BANDAR MOHAMMED AL-QAHTANI, M.D KSMC AUDIOLOGY IN ORL
Tympanic mem & Ossicular Amplification22:1 in total 1.3:1 maleus to incus (lever action) 17 :1 TM surface to stapes footplateproblem in transmission leads to CHL
Traveling wave & Tonotopic organization Traveling wave & Tonotopic organization High frequency at base and low frequency at apexproblem inside the cochlea transmission leads to SNHL
Auditory Assessment Clinical vs audiometric tests Clinical : - finger friction - watch test - speech test - tuning fork test
Audiometric tests : subjective vs objective tests - pure tone audiometry - speech audiometry - impedance audiometry a-tympanometry b-acoustic reflex
AudiometricAssessment Pure Tone Audiometry Speech Audiometry Acoustic Immittance (impedance test ) Auditory Brainstem Responses Electrocochleography Otoacoustic Emissions
Pure Tone Audiometry Most common ,subjective test Air conduction testing Frequencies 125,250,500,1000,2000,4000,8000 HZ Bone conduction testing 250,500,1000,2000,4000 HZ
USES • As baseline test (pre op and post op) • To differentiate the conductive vs sensorineural pathway • The degree of handicap or heaing loss and which frequencies
Crossover Audiometric results are only valid when the results are actually of the test ear. Interaural attenuation reflects crossover. Air conduction from 40-80dB Bone conduction even at 0dB
Masking The audiometric technique used to eliminate responses by the non-test ear. An appropriate noise is presented to the non-test ear while the test ear is being tested. Masking level must exceed the non-test ear threshold, but not create crossover.
Speech Audiometry Determines how well a person hears and understands speech,subjective test. Spondee words SRT 50% of spondees SRT should be in close correlation with PTA +- 10 db of PTA. Discrimination score (DS) (90-100% in normal or conductive DS is 60-70 in sensory hearing loss
USES-malingerer patients-for fitting Hearing Aids-for cochlear implant patients-to differentiate cochlear than retro-cochlear lesion
Acoustic Immittance Impedance: resistance to acoustic flow,objective test Admittance: ease of acoustic flow Tested by: Tympanometry Acoustic Stapedial Reflex
A normal between 100-(-100) As stiff type otosclerosis or stiff TM. Ad flaccid type ossicular discontinuity B flat –fluid in ME or thick TM C more in negative –retracted TM
Acoustic Stapedial Reflex to elicit a stapedial muscle contraction, objective test. 3 primary acoustic reflex characteristics Presence or absence of the reflex Reflex threshold Reflex Decay It tests VIII,brain stem ,VII Good for screening in infants and malingerer
Acoustic Reflex Decay Measures the ability of the stapedius muscle to maintain sustained contraction. Lower frequency tone/noise for 10 seconds
Facial Paralysis Absent or abnormal stapedial reflex when the recording probe is ipsilateral to the side of the lesion. Can also be helpful in locating lesions proximal or distal to the stapedial muscle.
Eighth nerve lesions Absent reflexes when stimuli is presented to the affected ear. Reflexes in eighth nerve lesions are not dependent on the degree of hearing loss. Rapid reflex decay
Auditory Brainstem Responses Impulses that are generated by the auditory neural pathway that can be recorded on the scalp. objective test Not affected by sleep, sedation, or attention.
Bone Conduction ABR As reliable and repeatable as air conduction ABR. Particularly useful in structural abnormalities Canal Atresia or stenosis
ABR Primary goal is a clear and reliable Wave I Wave I : distal 8th nerve Wave II : proximal 8th nerve Wave III : cochlear nuclei Wave IV : SOC Wave V : Lateral Lemniscus
Otoacoustic Emissions Low energy sounds produced by the cochlear outer hair cells,objective test. Cochlear amplification. Spontaneous emissions Not present in greater than 25dB hearing loss. Evoked Emissions Transient evoked Distorted Product
OAE and middle ear pathology Transmission properties of the middle ear directly influence the OAE characteristics. Otitis media Newborns Tympanic membrane perforations