hearing loss Flashcards
causes of exostosis
repeated exposure to cold water and wind
what is exostosis
a benign bony growth in the external auditory canal, this is a form of conductive hearing loss
what is a cochlear implany
rgically implanted device that provides people with severe to profound sensorineural deafness with a modified sense of sound.
contradiction for cocnhlear implant
otitis media is a contraindication to a cochlear implant due to the risk of meningitis and tympanic membrane rupture.
Contraindications to consideration for cochlear implant:
Lesions of cranial nerve VIII or in the brain stem causing deafness
Chronic infective otitis media, mastoid cavity or tympanic membrane perforation
Cochlear aplasia
Relative contraindications:
Chronic infective otitis media or mastoid cavity infections
Tympanic membrane perforation
Patients that may be seen to demonstrate a lack of interest in using the implant to develop enhanced oral communication skills.
how to assess suitability for cochlear implant
n children, audiological assessment and/or difficulty developing basic auditory skills.
In adults, patients should have completed a trial of appropriate hearing aids for at least 3 months which they have been objectively demonstrated to receive limited or no benefit from.
causes if severe to profound hearing loss
In children
Genetic (accounts for up to 50% of cases).
Congenital e.g. following maternal cytomegalovirus, rubella or varicella infection.
idiopathic (accounts for up to 30% of childhood deafness).
Infectious e.g. post meningitis.
In adults Viral-induced sudden hearing loss. Ototoxicity e.g. following administration of aminoglycoside antibiotics or loop diuretics. Otosclerosis Ménière disease Trauma
prior to assess for the cochlear implant what should patients acheive
patients should have exhausted all medical therapies aimed at targeting any underlying pathological process contributing to the loss of hearing. In addition, they should have explored ‘conventional’ amplification strategies i.e. hearing aids and found the devices insufficient to allow functioning within daily life and/or support language development/maintenance.
what should still be survivng for an implant
y the destruction or degeneration of the organ of Corti, it is essential that there are surviving spiral ganglion neurons to ensure the success of the implant. An assessment of the patient anatomy should be undertaken by an experienced otolaryngologist/skull base surgeon.
complications of the implantation
infection, facial paralysis due to nerve injury intra-operatively, cerebrospinal fluid (CSF) leakage, and meningitis. To reduce the risk of meningitis as far as possible, it is recommended that all patients should have up-to-date vaccinations against Streptococcus and Haemophilus.
post op what happens for implants
Patients are discharged for the post-operative physical recovery of the implantation site and generally return to outpatient clinic 3-5 weeks post-op for device stimulation.
how does an implnat work
Externally, the microphone recognises the environmental sound and sends it to the sound processor. This, in turn, transforms the impulses received into a digital signal that which is then transferred to the transmitter coil. The transmitter coil conveys the signal to the internal components. Internally, a receiver, which magnetically connected to, and sits directly above the transmitter coil, and receives the impulses from the external apparatus which are then processed by a set of electrodes. The electrodes do the work that would be performed by the inner ear hair cells in a ‘normal’ ear. The brain can then process these signals to comprehend sound. Rechargeable batteries can be used to power the apparatus and life span depends upon usage and the individual device.
risk of sudden-onset sensorineural hearing loss
permanent hearing impairment
treatment of dden-onset sensorineural hearing loss
high-dose oral corticosteroids
features sudden-onset sensorineural hearing loss
sudden
fullness
not painful no vertigo
normal otoscope
what is presbycusis
Presbycusis describes age-related sensorineural hearing loss. Patients may describe difficulty following conversations
Audiometry shows bilateral high-frequency hearing loss
what is otosclerosis
Autosomal dominant, replacement of normal bone by vascular spongy bone. Onset is usually at 20-40 years - features include:
conductive deafness
tinnitus
tympanic membrane - 10% of patients may have a ‘flamingo tinge’, caused by hyperaemia
positive family history
drug ototxicity
Examples include aminoglycosides (e.g. Gentamicin), furosemide, aspirin and a number of cytotoxic agents
acoustic neuroma/ vestibular schwannomas
Features can be predicted by the affected cranial nerves
cranial nerve VIII: hearing loss, vertigo, tinnitus
cranial nerve V: absent corneal reflex
cranial nerve VII: facial palsy
Bilateral acoustic neuromas are seen in neurofibromatosis type 2
causes of perforated tympanic membrane
infection
barotrauma
direct trauma
features of a perforated TM
hearing loss
mild pain
management of perforated TM
no treatment is needed in the majority of cases as the tympanic membrane will usually heal after 6-8 weeks. It is advisable to avoid getting water in the ear during this time
it is common practice to prescribe antibiotics to perforations which occur following an episode of acute otitis media. NICE support this approach in the 2008 Respiratory tract infection guidelines
myringoplasty may be performed if the tympanic membrane does not heal by itself
what is auricular haematoma
occur after direct trauma to the ear and is due to a build up of blood between the cartilage and perichondrium. This can restrict blood supply and lead to necrosis of the connective tissue.
kicked in the ear
ear pain
persistent ringing
tender and swollen
auricular haematoma
management of auricular haematoma
auricular haematomas need same-day assessment by ENT
incision and drainage has been shown to be superior to needle aspiration
causes of tinnitus
meniere's otosclerosis acoustic neuroma hearing loss drugs - Aspirin/NSAIDs Aminoglycosides Loop diuretics Quinine
impacted ear wax
chronic suppurative otitis media
which durgs cause tinnitus
quinine aspirin NSAIDs aminoglycosides loop diuretics
when do you refer someone to ENT within 24 hours
Sudden onset (over 3 days or less) unilateral or bilateral hearing loss which has occurred within the past 30 days and cannot be explained by external or middle ear causes.
Unilateral hearing loss associated with focal neurology (such as altered sensation or facial droop).
Hearing loss associated with head or neck injury.
Hearing loss associated with severe infection such as necrotising otitis externa or Ramsay Hunt syndrome.
what is vestibular schwannoma (acoustic neuroma)
intracranial tumors
cerebellopontine angle tumors
history of vestibular schwannoma
vertigo
hearing loss
tinnitus
absent corneal reflex
why are these features seen in vestibular schwanomma
1) cranial nerve VIII: vertigo, unilateral sensorineural hearing loss, unilateral tinnitus
2) cranial nerve V: absent corneal reflex
3) cranial nerve VII: facial palsy
where are bilateral vestibular schwanommas seen
neurofibromatosis type 2
Ix of choice for vestibular schwanomma/acoustic neuroma
MRI of the cerebellopontine angle
what is exostosis
repeated exposure to cold water and wind which causes a benign bony growth in the external auditory canal, this is a form of conductive hearing loss
