Deafness Flashcards
What are the most common causes of hearing loss?
The most common causes of hearing loss are ear wax, otitis media and otitis externa.
Give examples of causes of deafness
- Presbycusis
- Otosclerosis
- Glue ear
- Meniere’s disease
- Drug ototoxicity
- Noise damage
- Acoustic neuroma (more correctly called vestibular schwannomas)
Briefly describe conductive deafness
There is impaired sound transmission via the external canal and middle ear ossicles to the foot of the stapes through a variety of causes. Causes of condutive loss:
- External canal obstruction
- Wax, pus, debris, foreign body and developmental anomalies
- Drum perforation
- Trauma, barotrauma and infection
- Problems with the ossicular chain
- Otosclerosis, infection and trauma
- Inadequate Eustachian tube ventilation of the middle ear
- E.g. with effusion secondary to nasopharyngeal carcinoma
Briefly describe sensorineural deafness
Results from defects central to the oval window in the cochlea (sensory), cochlear nerve (neural) or, rarely, more central pathways. Causes of sensorineural loss:
- Ototoxic drugs
- E.g. streptomycin, vancomycin, gentamicin, chloroquine and hydroxychloroquine and vinca alkaloids
- Postinfective
- Meningitis, measles, mumps, flu, herpes and syphilis
- Cochlear vascular disease
- Ménière’s
- Trauma
- Presbyacusis
What is the management if a patient presents with sudden sensorineural hearing loss?
Immediate specialist referral.
Starting regimen of oral prednisolone 80mg/24h for 7 days.
Briefly describe the key features of presbyacusis
Presbycusis describes age-related sensorineural hearing loss.
Patients may describe difficulty following conversations.
Audiometry shows bilateral high-frequency hearing loss.
Briefly describe the key features of otosclerosis
Autosomal dominant condition.
Replacement of normal bone by vascular spongy bone.
Onset is usually at 20-40 years and features include:
- Conductive deafness
- Tinnitus
- Tympanic membrane may have ‘flamingo tinge’
- 10% of patients
- Caused by hyperaemia
- Positive family history
Briefly describe the key features of glue ear
Also known as otitis media with effusion.
Peaks at 2 years of age.
Hearing loss is usually the presenting feature (glue ear is the commonest cause of conductive hearing loss and elective surgery in childhood).
Secondary problems such as speech and language delay, behavioural or balance problems may also be seen.
Briefly describe the key features of Meniere’s disease
More common in middle-aged adults.
Recurrent episodes of vertigo, tinnitus and hearing loss (sensorineural). Vertigo is usually the prominent symptom.
A sensation of aural fullness or pressure is now recognised as being common.
Other features include nystagmus and a positive Romberg test.
Episodes last minutes to hours.
What drugs cause ototoxicity?
Examples include aminoglycosides (e.g. gentamicin), furosemide, aspirin and a number of cytotoxic agents.
Briefly describe the key features of noise damage
Workers in heavy industry are particularly at risk.
Hearing loss is bilateral and typically is worse at frequencies of 3000-6000 Hz.
Briefly describe the key features of acoustic neuromas
Features can be predicted by the affected cranial nerves:
- Cranial nerve VIII: hearing loss, vertigo and tinnitus
- Cranial nerve V: absent corneal reflex
- Cranial nerve VII: facial palsy
Bilateral acoustic neuromas are seen in neurofibromatosis type 2.
What dangerous conditions need to be ruled out when a patient presents with deafness?
Exclude the dangerous (esp. if asymmetric):
- Acoustic neuroma
- Cholesteatoma
- Effusion from nasopharyngeal cancer
