ENT Flashcards
Mechanism of hearing
Pinna of ear —> auditory canal —> tympanic membrane —> ossicles to amplify sound (malleus, incus, stapes) —> cochlear —> cochlear nerve
What do the semicircular canals do?
Sense head movement
What does the cochlea do?
Convert sound vibration to nervous signal
Explain results of Weber’s test
(Shooting a web in the middle of someone’s face)
Normal = equal in both ears
Sensioneural = louder in normal ear
Conductive = louder in affected ear as volume has been “turned up”
Explain results of rinnes test
Normal = air > bone
Conductive = bone > air
Sensioneural Weber’s and rinnes?
Weber’s - heard louder in normal ear
Rinnes - normal ie air > bone
Conductive Weber’s and rinnes
Weber’s = louder in affected ear
Rinnes = bone > air
What does otosclerosis affect
Ossicles - mostly the stapes. A growth/stiffening of the ossicles which leads to an inability to amplify sound
What is the range of normal hearing ?
-10 to 20 decibels (dB)
What does the vestibulocochlear nerve do?
transmits nerve signals from the semicircular canals and cochlea to the brain
What are the small bones of the middle ear called, function?
malleus, incus and stapes
connect the tympanic membrane to the structures of the inner ear
What does the Eustachian tube do?
Connects the middle ear with the throat to equalise pressure
What is sudden sensioneural hearing loss?
hearing loss over less than 72 hours, unexplained by other causes.
This is considered an otological emergency and requires an immediate referral to the on-call ENT team.
When is a diagnosis of sudden sensioneural hearing loss made?
when someone rapidly (<72 hours) loses their hearing, and no conductive cause can be found
Causes of SSNHL?
Most cases (90%) of SSNHL are idiopathic, meaning no specific cause is found.
Other causes of SSNHL include:
Infection (e.g., meningitis, HIV and mumps)
Ménière’s disease
Ototoxic medications
Multiple sclerosis
Migraine
Stroke
Acoustic neuroma
Cogan’s syndrome (a rare autoimmune condition causing inflammation of the eyes and inner ear)
Investigations SSNHL?
Audiometry is required to establish the diagnosis. A diagnosis of SSNHL requires a loss of at least 30 decibels in three consecutive frequencies on an audiogram.
MRI or CT head may be used if a stroke or acoustic neuroma are being considered.
Management of SSNHL?
- Urgent referral to ENT
If underlying cause, treat that
If idiopathic
1. Steroids initiated by ENT team - oral or intratympanic
Presentation Presbycusis
age-related sensioneural hearing loss.
It tends to affect high-pitched sounds first and more notably than lower-pitched sounds.
The hearing loss occurs gradually and symmetrically.
May have associated tinnitus
Pathophysiology presbycusis
loss of the hair cells in the cochlea, loss of neurones in the cochlea, atrophy of the stria vascularis and reduced endolymphatic potential.
Risk factors for presbycusis
Age
Male gender
Family history
Loud noise exposure
Diabetes
Hypertension
Ototoxic medications
Smoking
Investigations presbycusis
Audiometry
Management presbycusis
Optimising the environment, for example, reducing the ambient noise during conversations
Hearing aids
Cochlear implants (in patients where hearing aids are not sufficient)
Triad of symptoms Ménière’s disease
Hearing loss
Tinnitus
Vértigo
Pathophysiology menieres
excessive buildup of endolymph in the labyrinth of the inner ear, causing a higher pressure than normal and disrupting the sensory signals. This increased pressure of the endolymph is called endolymphatic hydrops.
The typical patient is 40-50 years old, presenting with unilateral episodes of vertigo, hearing loss, and tinnitus.
Menieres
