44 - Hearing and Hearing Disorders Flashcards
What are the bones the tympanic membrane puts in motion after transferring vibrations?
malleus, incus and stapes
What direction does sound through air move through the cochlea?
from the base to the apex
What region of the cochlea do high frequency tones maximally displace?
basilar membrane near the BASE of the cochlea
Where is maximax membrane displacement in the cochlea for low frequency waves?
at the apex of the cochlea
What is ostosclerosis?
bony overgrowth of stapes at its point of attachmetn to teh cochlea that causes ossicles to stiffen and fail to transmit sound vibrations from the tympanic membrane.
What is Meniere’s disease?
vertigo, fluctuating sensorneural hearing loss and tinnitus due to decreased resorption of endoylymphatic fluid, casuing a hydrops with high pressure, and rupture in the membranes separating endolymph from perilypmh. The sudden change in vestibular cochlear pressure and in their firing electrical properties causes symptoms. Symptoms remit between attacks and patients can be symptom free for a year or more but with progression, there is persistent hearing loss and continous tinnitis.
What is presbyacusis?
age-related hearing loss that is gradual and progressive (mostly high frequency sounds)
What drugs cause ototoxicity?
aminoglycosides (gentamicyin), Lasix, salicylates, quinine and cancer drugs like cisplatin
Why is hearing loss less commonly seen from brain parenchyma diseases?
because the central auditory pathways cross over at many locations between the medial geniculate neucleus of thalamus and the Heschl’s gyrus.
How will conductive hearing loss present on audiogram?
fairly equal threshold elevation for each frequency
How does ostosclerosis present on audiogram?
will cause fixation of footplate of stapes and result in greater threshold elvation for lower frequencies.
How will middle ear effusion present on audiogram?
greater elevation of thresholds in higher frequencies
How will sensorinueral hearing loss present on audiogram?
steadily rising threshold elevations for increasing frequencies. (higher frequncies are harder to hear)
How will Meniere disese present on audiogram?
thresholds elevated more in lower frequencies.
Why do you get hearing loss but not vertigo with acoustic neuroma? what type of hearing loss is it?
sensorineural hearing loss due to compression of CN VIII. It is such a slow compression thought that brain has plenty of time for central compensation when vestibular input decreases on the affected side.
