ENT - Hearing Loss Flashcards
What are the main types of hearing loss?
Conductive hearing loss - problem with sound traveling from the environment to the inner ear.
Sensorineural hearing loss - problem with the sensory system or vestibulocochlear nerve in the inner ear.
Sections of the ear.
Symptoms associated with hearing loss.
- tinnitus
- vertigo
- pain
- discharge
- neurological symptoms
What examination can be used to differentiate between sensorineural and conducting hearing loss?
NB: Spiderman shoots a web (Weber’s) right into the middle of someones face.
Normal hearing - findings.
a) Rinnes test
b) Weber’s test
a) AC > BC
b) no lateralisation
Sensorineural hearing loss - findings.
a) Rinnes test
b) Weber’s test
b) AC > BC (false normal in affected air)
b) sound lateralises to the normal ear
Conductive hearing loss - findings.
a) Rinnes test
b) Weber’s test
a) BC > AC in affected ear
b) sound lateralises to the affected ear
Causes of adult-onset sensorineural hearing loss.
- presbycusus (age-related)
- Ménière’s disease
- labyrinthitis
- acoustic neuroma
- neurological conditions (e.g. stroke, multiple sclerosis, brain tumour)
- infections (e.g. meningitis)
- medications
What medications can cause sensorineural hearing loss?
- furosemide
- gentamicin
- cisplatin
Causes of conductive hearing loss.
- ear wax
- infection (e.g. otitis media, otitis externa)
- fluid in middle ear
- Eustachian tube dysfunction
- perforated tympanic membrane
- otosclerosis
- cholesteatoma
- exostoses
- tumours
What is audiometry?
Testing a patient’s hearing by playing a variety of tones and volumes using headphones, and an oscillator.
It can help identify and differentiate conductive and sensorineural hearing loss.
Which symbols are used to plot on an audiogram?
a) left-sided air conduction
b) right sided air conduction
c) left sided bone conduction
d) right sided bone conduction
a) X
b) O
c) ]
d) [
What audiometry findings are consistent with normal hearing?
All reading will be between 0 and 20 dB
What audiometry findings are consistent with sensorineural hearing loss?
Air conduction and bone conduction are more than 20dB.
This may affect one side, one side more than the other or both sides equally.
What audiometry findings are consistent with conductive hearing loss?
Bone conduction readings are normal (0-20dB).
Air conduction readings more than 20dB.
What audiometry findings are consistent with mixed hearing loss?
Both air and bone conduction readings >20dB.
There will be a difference of >15dB between air and bone conductance (BC > AC)
Pathophysiology of presbycusis.
Age-related loss of hair cells and neurones in the cochlea results in a sensorineural hearing loss.
It tends to affect high-pitched sounds first, with a gradual and symmetrical hearing loss.
Presbycusis - risk factors.
- increasing age
- family history
- loud noise exposure
- diabetes
- hypertension
- ototoxic medications
- smoking
Symptoms of presbycusis.
Gradual and insidious hearing loss:
- high pitched sounds first
- speech difficult to hear
- missing details of conversations
- tinnitus
NB: Patients may present with concerns about dementia, when the issue is hearing loss.
Diagnosis of presbycusis.
Audiometry
Sensorineural hearing loss pattern; worsening hearing loss at higher frequencies.
Management of presbycusus.
Support the person to maintain normal functioning:
- reduce ambient noise during conversations
- hearing aids
- cochlear implants
What is sudden sensorineural hearing loss?
Hearing loss over less than 72 hours, unexplained by other causes.
Causes of sudden sensorineural hearing loss.
- idiopathic (>90%)
- infection
- ménière’s disease
- ototoxic medications
- multiple sclerosis
- stroke
- acoustic neuroma
Investigations of sudden sensorineural hearing loss.
Audiometry.
MRI or CT head may be used if a stroke or acoustic neuroma are being considered.
Management of acute sensorineural hearing loss.
Immediate referral to ENT for assessment.
Idiopathic SSNHL can be treating with steroids under the guidance of ENT:
- oral
- intra-tympanic
What is an acoustic neuroma?
A benign tumour of the Schwann cells surrounding the vestibulocochlear nerve.
Acoustic neuromas occur at the _____ angle.
Cerebellopontine angle.
Acoustic neuromas are usually unilateral.
What is the association of bilateral acoustic neuromas?
Neurofibromatosis type II
Symptoms of acoustic neuroma.
Gradual onset of:
- unilateral sensorineural hearing loss
- unilateral tinnitus
- dizziness or imbalance
- fullness in the ear
They can also be associated with facial nerve palsy if the tumour grows large enough to compress the facial nerve.
Investigating acoustic neuroma.
Audiometry revealing a sensorineural pattern of hearing loss.
Brain imaging (MRI or CT) to establish a diagnosis.
Management of acoustic neuroma.
Conservative management with monitoring if there are no symptoms.
Surgery to remove the tumour (partial or total removal).
Radiotherapy to reduce the growth.
Risks associated with treatment of acoustic neuromas (radiotherapy or surgery).
Vestibulocochlear nerve injury:
- permanent hearing loss
- dizziness
Facial nerve injury:
- facial weakness
Facial nerve pathway.
- Exits brainstem at cerebellopontine angle
- Passes through temporal bone and parotid gland
- Divides into branches*
*To Zanzibar By Motor Car
Function of the facial nerve.
Motor:
- facial expression
Sensory:
- taste from anterior 2/3 of tongue
Parasympathetic:
- submandibular and sublingual salivary gland
- lacrimal gland
How to differentiate between UMN and LMN facial nerve palsy.
UMN - forehead sparing - urgent referral with suspected stroke.
LMN - forehead not spared.
Causes of UMN facial nerve palsy.
- stroke
- tumour
- motor neurone disease
Treatment of Bell’s palsy.
The majority of patients fully recover over several weeks; a third are left with some residual weakness.
NICE recommend considering prednisolone as treatment.
Lubricating eyedrops; eye can be taped closed at night.