Hearing loss Flashcards
Conductive and Sensorineural Hearing Loss
Bilateral vs. Unilateral Hearing Loss
Bilateral = Both ears affected.
Unilateral = One ear affected
Conductive hearing loss is a what problem?
outer/middle ear problem
= preventing sound from reaching the inner ear
Sensorineural hearing loss is a what problem?
inner ear/ auditory nerve damage
= preventing sound signals from being sent to the brain
What do the three different types of tympanograms represent?
(1) Type A curve
= normal tympanogram
(2) Type B (flat) curve:
= Normal canal volume – otitis media with effusion
= High canal volume – tympanic membrane perforation
(3) Type C curve
= eustachian tube dysfunction
Why are audiograms important in diagnosing hearing loss?
Identifies the type of hearing loss (conductive, sensorineural, or mixed)
What is conductive hearing loss?
A condition where sound waves are obstructed in the outer or middle ear, leading to reduced hearing ability
Examples of conductive hearing loss
- Earwax blockage (outer ear)
- Otitis Media with Effusion (OME) (fluid in the middle ear)
- Middle ear congestion
(fluid or pressure build-up) - Perforated eardrum
- Otosclerosis (stiffening of the stapes)
What are the key audiogram findings in conductive hearing loss?
(1) Air conduction thresholds
= Elevated causing poorer hearing meaning sound is blocked
(2) Bone conduction thresholds
= Normal, which means inner ear function is fine
(3) Air-Bone Gap
= Significant (≥ 15 dB) indicating conductive loss
(4) Frequency affected
= Typically affects low frequencies more than high
What is sensorineural hearing loss (SNHL)?
Damage to the inner ear (cochlea) or auditory nerve, leading to impaired sound transmission to the brain
Examples of Sensorineural Hearing Loss
- Noise-induced hearing loss
- Presbycusis
(age-related hearing loss) - Vestibular schwannoma
(tumour on CN VIII) - Meniere’s disease
What are the audiogram findings in sensorineural hearing loss?
(1) Air and bone conduction thresholds
= Both are elevated equally meaning no air-bone gap
(2) Configuration
= Typically sloping, affecting high frequencies more
(3) Speech discrimination
= Often disproportionately reduced compared to pure-tone thresholds
What findings would you expect to see on audiogram in sensorineural hearing loss?
Sensorineural hearing loss on an audiogram presents with loss of hearing at high frequencies
What does the presence or absence of an air-bone gap indicate?
(1) Presence of an air-bone gap (≥ 15 dB)
= Conductive hearing loss.
(2) Absence of an air-bone gap
= Sensorineural hearing loss.
(3) Mixed hearing loss
= Features of both (elevated air and bone thresholds with an air-bone gap)
What are the causes of bilateral hearing loss?
Sudden onset - Ear wax
Gradual onset -
(1) Middle-ear effusion/glue ear
(2) Presbycusis (elderly)
(3) Noise-induced hearing loss
What are the causes of unilateral hearing loss?
Sudden-onset
(1) Middle-ear effusion (after URTI)
(2) Trauma to middle ear
(eg, tympanic membrane perforation, ossicular injury)
(3) Vascular/autoimmune
(normal tympanic membrane!)
Gradual-onset
(1) Ear wax
(2) Nasopharyngeal carcinoma
(Chinese ethnicity, effusion, lymph nodes)
(3) Otosclerosis
What clinical features would you expect to see in patients with tympanosclerosis?
You would expect to see chalky white patches on the tympanic membrane
Tympanogram findings for Type B (flat curve) are what?
Middle ear congestion or fluid
= OME or Eustachian tube dysfunction
Tympanogram findings for Type C (negative pressure) are what?
Eustachian tube dysfunction
What is an example of Mixed Hearing Loss?
Otosclerosis affecting both the stapes and cochlea - if cochlear involvement occurs
A 3-year-old boy presents with speech and language delay to the GP clinic. The father states that he is most concerned about his son’s hearing and sometimes finds that the child does not respond to his name. He denies otalgia, dizziness and balance issues. There is no family history of hearing problems
The GP refers the patient for audiometry testing. The right ear tympanogram demonstrates a flat (type B) tympanogram curve. The left ear audiogram is normal.
What is the single most likely diagnosis?
Right middle ear congestion
A 25-year-old man presents to his GP complaining of a deterioration in hearing in his right ear. He reports that this occurred after a head injury sustained while playing rugby. The observations for this patient are normal. He has no past medical history of note.
What is the single most likely cause of this deterioration? and why?
Perforated tympanic membrane
= Perforated tympanic membrane is the most common cause of hearing impairment post head injury
What does Rinne’s Test compare?
Compares air conduction (AC) and bone conduction (BC)
What is the result of a normal Rinne’s Test?
AC > BC (positive Rinne)
= which suggests normal or sensorineural hearing loss
What does an abnormal Rinne’s Test (BC > AC) indicate?
BC > AC (negative rinne)
= indicates conductive hearing loss, such as in otosclerosis or otitis media
What is the purpose of Weber’s Test
Weber’s Test assesses the lateralisation of sound to determine the type of hearing loss
What does a normal Weber’s Test show?
A normal Weber’s Test shows that sound is heard equally in both ears
What does Weber’s Test show in conductive hearing loss?
The sound is heard louder in the affected ear
What does Weber’s Test show in sensorineural hearing loss?
The sound is heard louder in the unaffected ear
In Bilateral hearing loss what does Weber’s test look like for both conductive or sensorineural hearing loss?
Sound is heard equally in both ears. (bad)
No lateralisation
Something blocking sound (eg, fluid, earwax) suggests what
Conductive Hearing Loss
Damage to the inner ear or auditory nerve (eg, from ageing or loud noise) suggests what?
Sensorineural Hearing Loss
How is Rinne’s test performed?
(1) Rinne’s test is performed with a vibrating tuning fork placed first on the mastoid process
(2) Then parallel to and ~3cm away from the external ear canal
(3) The patient is asked which of the two positions sounds louder
How is Weber’s test performed?
(1) Weber’s test is performed with a vibrating tuning fork placed on the midline
(2) typically on either the forehead or the vertex
(3) The patient is asked whether the sound is heard loudest on one side or equally on both sides
What is the most common cause of symmetrical bilateral hearing loss in older adults?
Presbycusis
A 53-year-old male presents to the clinic complaining of a four-month history of progressive hearing loss. His past medical history includes hypertension, heart failure and hypercholesterolaemia.
He had a bout of pneumonia three months ago, which resolved after antibiotics. He is currently taking furosemide, simvastatin and ramipril.
Which drug is responsible for his hearing loss?
Furosemide
air conduction is better than bone conduction in both ears suggests what?
Normal hearing
A 40 year old guitarist plays for a heavy metal band. He complains of hearing loss in both his ears that is affecting his work. He also experiences constant ringing in his ears that is worse when he is trying to fall asleep. He started wearing ear defenders two years ago. Audiometry confirms the most likely diagnosis.
What is the most appropriate management option?
Hearing aids
A 23-year-old swimmer presents to her GP 14 days after attending with right-sided ear pain, otorrhoea and hearing loss. Ciprofloxacin ear drops were prescribed, and the pain has resolved. She states that she has a race in 7 days’ time, and is anxious to ensure that she is medically fit to compete.
On examination, the affected ear is clear of debris, is not erythematous, and the tympanic membrane can be visualised. Weber’s test does not lateralise to either side. Air conduction is louder than bone conduction bilaterally.
What is the most appropriate next step in her management?
Reassurance
= Normal hearing
1. Rinne result
= Air conduction > bone conduction bilaterally
- Weber result: same in both ears
A 55-year-old man reports gradual hearing loss in his right ear. On examination:
Rinne’s test:
1. Left ear: air conduction > bone conduction
2. Right ear: air conduction > bone conduction
Weber’s test
1. Lateralises to the left side
What do these tests imply? and explain why
Right sensorineural hearing loss
Explanation:
- Rinne is positive in both ears, which rules out conductive hearing loss. It can be normal or sensorineural
- Weber lateralising to the left means either left conductive or right sensorineural hearing loss.
- But Rinne is positive (no conductive loss), so the only explanation is sensorineural loss in the right ear
A 31-year-old man presents to your clinic complaining of ongoing hearing loss, otalgia and tinnitus bilaterally.
Upon examination, otoscopy shows some wax in the canals and normal tympanic membranes. Weber’s test demonstrates no lateralisation and Rinne’s test is positive bilaterally, yet a coarse hearing test shows hyperacusis bilaterally.
You note this patient was previously diagnosed with a testicular seminoma now in remission, treated with orchidectomy and cisplatin-based chemotherapy.
Given the above, what is the most appropriate next management step?
Adults are generally required to have had a failed trial of hearing aids before having a cochlear implant
= Therefore refer to an ENT for further evaluation of acoustic hearing aids
What is considered normal hearing on an audiogram?
Anything above the 20 dB line is considered normal hearing
What does it indicate if both air and bone conduction are impaired on an audiogram?
sensorineural hearing loss
What does it indicate if only air conduction is impaired, but bone conduction is normal?
conductive hearing loss
What is considered mixed hearing loss on an audiogram?
both air and bone conduction are impaired, but air conduction is worse
What type of hearing loss is indicated on an audiogram when air and bone conduction thresholds are reduced but at the same level, with no air-bone gap?
Sensorineural hearing loss
What to do if a patient presents with sensorineural hearing loss?
Refer urgently to ENT and start high-dose oral steroids
What are the contraindications to consider for cochlear implants?
- Lesions of cranial nerve VIII or in the brain stem causing deafness
- Chronic infective otitis media
- Mastoid cavity
- Tympanic membrane perforation
- Cochlear aplasia
A patient complains of ringing in the ears with no external sound. What’s the term for this?
Tinnitus
