Hearing Loss Flashcards
Know the common causes of hearing loss
What are the main types of hearing loss?
Sensorineural- cochlear or medial to this. Bone conduction and air conduction are equally reduced
Conductive- any pathology from the middle ear laterally. Bone conduction is in tact.
Mixed
What are some causes of conductive hearing loss?
External canal obstruction- wax, pus, debris, foreign body, congenital abnormality
Drum perforation- trauma, barotrauma, infection
Problems with ossicular chain-(otosclerosis, infection, trauma)
Dysfunction of Eustachian tube- E.g. Middle effusion that can occur with nasopharyngeal carcinoma
What are some causes of sensorineural deafness?
Ototoxic drugs (streptomycin, vancomycin, gentamycin, chloroquine, vinca alkaloids)
Post infective- meningitis, measles, flu, herpes, syphilis
Cochlear vascular disease
Trauma
Presbyacusis (loss with ageing)
Acoustic Neuroma
Multiple sclerosis
Brain metastases
If unilateral SNHL exclude dangerous conditions- acoustic neuroma (MRI), cholesteatoma, effusion from nasopharyngeal cancer
What are some causes of acute conductive hearing loss?
Perforation of the ear drum Foreign body Trauma Barotrauma Infection- Otitis media/externa
What are some causes of chronic conductive hearing loss?
Otosclerosis
Otitis media with effusion (Glue ear)
Cholesteatoma- erosive and destructive process (characteristic smelly discharge)
What process is occurring in otosclerosis?
New bone is formed around the stapes foot plate which reduces the movement of the stapes and so leads to conductive hearing loss
What is the cause of otosclerosis?
This condition is hereditary: Autosomal Dominant inheritance with incomplete penetrance
50% have a family history, 85% are bilateral
When do symptoms of otosclerosis usually present?
Early adult life
Accelerated by pregnancy
What other features might people with otosclerosis?
Tinnitus (in around 75%)
Vertigo- transient vertigo is common
What is Schwartze’s sign? What condition is it seen in?
Schwartze’s sign is seen in otosclerosis
It is a pink tinge to the typanic membrane
It is also called Flemingo’s pink sign
What unique feature is seen on pure tone audiometry bone conduction for otosclerosis?
Carhart’s Notch
A drop is seen at around 2,000Hz for bone conduction
What is the treatment for otosclerosis?
Hearing aids
Surgery- stapedectomy or stapedotomy to replace the fixed stapes
Cochlear implant is another option if severe
Note- The stapes is the smallest bone in the body
What is presbyacusis?
Sensorineural hearing loss that is age related, bilateral and seen at high frequency
What might a person with presbyacusis describe?
Hearing is often reduced at higher frequencies
This therefore makes speech difficult to hear and a patient may describe people around them mumbling
Hearing is most problematic with background noise
What is the treatment for presbyacusis?
Hearing aids
Cochlear implant
What are some important things to investigate for if unilateral SNHL?
If unilateral SNHL exclude dangerous conditions- acoustic neuroma (MRI), cholesteatoma, effusion from nasopharyngeal cancer
What is sudden onset SNHL defined as?
Loss of 30 or more dB in 3 continuous pure tone frequencies over 3 days
Is sudden onset SNHL usually bilateral or unilateral?
Unilateral
What should be done if a patient presents with new onset SNHL?
Immediate referral to a specialist for investigation
What are some causes of sudden onset SNHL?
Noise exposure, ototoxic drugs (e.g. gentamycin), acoustic neuroma, mumps, MS, vasculopathy, TB).
If no cause found (~90%)- Idiopathic Sudden SNHL
What is the treatment for idiopathic sudden SNHL?
Always refer sudden onset sensorineural hearing loss urgently
High dose steroids (presumed inflammatory cause)- Prednisolone
What is an acoustic neuroma?
Subarachnoid tumour that is benign, slow growing and causes problems due to local pressure
Usually arise from the Schwamm cell layer of the vestibular nerve- also called a vestibular schwannoma
What symptoms can an acoustic neuroma cause?
Unilateral tinnitus
Unilateral Sensorineural deafness- difficulty hearing speech
Raised ICP signs- papiloedema (blurring of vision), headaches, nausea, vomiting
Cranial nerve compression of:
V- Parasthesia/Numbness of face
CN IX- X- Dysphasia, Hoarse voice
What investigations should be carried our if acoustic neuroma is suspected?
Request an MRI (with gadolinium contrast) for all those with unilateral tinnitus or SNHL
