Hearing Loss

Question	Answer
Describe the structures involved in hearing & how they transmit sound to the brain.	External ear canal (transmits vibrating column of air) -> Ear drum (vibrates & transmits movement to ossicles) -> Ossicles (lever action vibrates oval window) -> Oval window/cochlea (converts vibrations to electrical signals) -> Auditory nerve (transmits signals to cortex) -> Auditory cortex (located in temporal lobe - perception of sound) ENTAAG p10.
What are the two categories of hearing loss & what are the causes of each.	* Conductive hearing loss (interruption to the mechanism in the external and/or middle ear prevents conduction to the cochlea - if functioning well will still recieve some sound still perceived): > Congenital - ossicular abnormality, pinna abnormality (microtia, anotia), external auditory canal abnormality (atresia) > Acquired - wax, otitis externa, foreign body, glue ear, chronic suppurative otitis media, otosclerosis, ossicular disruption (trauma, iatrogenic) * Sensorineural (if mechanism is interrupted at the cochlea or in the auditory nerve - hearing loss may be complete & difficult to Rx): > Congenital - syndromic, non-syndromic genetic, gestational infxn (toxoplasmosis, rubella, CMV, herpes) > Acquired - perinatal (hypoxia, jaundice), infxn/inflammatory (meningitis, mumps), trauma (noise, surgery, etc), drugs, neoplasia (vestibular schwannoma), idiopathic, presbyacusis ENTAAG p14.

Resource summary

	Created by Andrew Street about 8 years ago