ENT Flashcards
(149 cards)
Hearing aid vs cochlear implant
Hearing aids amplify sounds, whereas cochlear implants bypass the outer and middle ear to directly stimulate the auditory nerve.
List the differentials for dizziness/vertigo
- Ménière’s disease.
- Benign paroxysmal positional vertigo (BPPV).
- Postural hypotension.
- Vestibular neuritis.
- Labyrinthitis.
- Acoustic neuroma.
- Posterior circulation stroke syndrome (POCS).
What are the 2 main causes of hearing loss?
- Conductive hearing loss: problem with sound travelling from the environment to the inner ear.
- Sensorineural hearing loss: problem with the sensory system or vestibulocochlear nerve in the inner ear.
Name the 3 sections of the ear
- Outer ear
- Middle ear
- Inner ear
Function of semicircular canals?
Sense head movement (the vestibular system)
What is the function of the cochlea?
Converts the sound vibration into a nervous signal, to be transmitted by the vestibulocochlear nerve.
Name the 3 bones of the middle ear
Malleus, incus and stapes
Sudden onset hearing loss (< 72 hours) requires what?
A thorough assessment to establish cause.
Describe some symptoms which may occur alongside hearing loss
- Tinnitus.
- Vertigo (the sensation that the room is spinning).
- Pain (may indicate infection).
- Discharge (may indicate an outer or middle ear infection).
- Neurological symptoms.
Which tests are used to differentiate between sensorineural and conductive hearing loss?
Weber’s test and Rinne’s test
Describe Weber’s test
To perform Weber’s test:
- Strike the tuning fork to make it vibrate and hum.
- Place it in the centre of the patient’s forehead.
- Ask the patient if they can hear the sound and which ear it is loudest in.
Normal: patient hears the sound equally in both ears.
Sensorineural hearing loss: sound louder in the normal ear (quieter in the affected ear). The normal ear is better at sensing the sound.
Conductive hearing loss: sound louder in the affected ear. This is because the affected ear ‘turns up the volume’ and becomes more sensitive, as sound has not been reaching that side as well due to the conduction problem. When the tuning fork’s vibration is transmitted directly to the cochlea, rather than having to be conducted, the increased sensitivity makes it sound louder in the affected ear.
Describe Rinne’s test
To perform Rinne’s test:
- Strike the tuning fork to make it vibrate and hum.
- Place the flat end on the mastoid process.
- Ask the patient to tell you when they can no longer hear the humming noise.
- When they can no longer hear the noise, remove the tuning fork (still vibrating) and hover it 1cm from the same ear.
- Ask the patient if they can hear the sound now.
- Repeat on the other side.
Normal: AC > BC. ‘Rinne’s positive’.
Sensorineural hearing loss: AC > BC.
Conductive hearing loss: BC > AC. ‘Rinne’s negative’.
Outline the causes of sensorineural hearing loss
- Sudden sensorineural hearing loss.
- Presbycusis (age-related hearing loss).
- Noise exposure.
- Ménière’s disease.
- Labyrinthitis.
- Acoustic neuroma.
- Neurological conditions (e.g. stroke, multiple sclerosis or brain tumours).
- Infections (e.g. meningitis).
- Medications: loop diuretics (e.g. furosemide), aminoglycosides (e.g. gentamicin), chemotherapy (e.g. cisplatin).
Outline the causes of conductive hearing loss
- Ear wax.
- Infection (e.g. otitis media or otitis externa).
- Fluid in the middle ear (effusion).
- Eustachian tube dysfunction.
- Perforated tympanic membrane.
- Otosclerosis.
- Cholesteatoma.
- Exostoses.
- Tumours.
What is audiometry and audiograms?
- It involves testing a patient’s hearing by playing a variety of tones and volumes using headphones (air conduction) and a bone conduction device (oscillator).
- Audiometry results are recorded on an audiogram.
- Audiograms can help identify and differentiate conductive and sensorineural hearing loss.
- Hearing is tested to establish the quietest volume (dB) at which a patient can hear each frequency (Hz).
What is the medical term for age-related hearing loss?
Presbycusis
What type of hearing loss is presbycusis?
Sensorineural
Which sound pitch does presbycusis mostly affect?
High-pitched sounds
What are the causes of presbycusis?
- Loss of hair cells in the cochlea.
- Loss of neurones in the cochlea.
- Atrophy of the stria vascularis.
- Reduced endolymphatic potential.
What is a key risk factor for presbycusis?
Exposure to loud noise over time.
Describe the presentation of presbycusis
- Gradual, insidious and bilateral hearing loss.
- Loss of high-pitched sounds e.g. speech.
- May be associated tinnitus.
How would you diagnose presbycusis?
Audiometry
Describe the management of presbycusis
- Hearing aids.
- Cochlear implants (in patients where hearing aids are not sufficient).
Define sudden sensorineural hearing loss (SSNHL)
Hearing loss over less than 72 hours. It is most often unilateral and permanent or resolve over days to weeks.