Hearing loss Flashcards
Conductive and Sensorineural Hearing Loss (48 cards)
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
