Hearing Loss Flashcards
Which anatomical structures may be damaged in sensorineural hearing loss (SNHL)?
Hair cells of the organ of Corti in the cochlea
CNVIII
Auditory cortex
Give some examples of genetic causes of SNHL?
Huge number of syndromes:
- Connexin 26 GJB2 deafness
- Waardenburg’s
- Stickler
- Usher’s
- Pendred’s
Which antenatal factors might causes SNHL in a newborn?
Maternal infection –> rubella, chicken pox, HIV, CMV, streptococcus
Drug/alcohol misuse during pregnancy
What are some acquired causes of SNHL?
Presbyacusis Noise-induced hearing loss Inflammatory Trauma Autoimmune Tumours Meniere's disease Drugs
What is presbyacusis?
Age related high frequency SNHL
- loss of hair cells and neurones
What are the features of noise induced hearing loss?
Tinnitus common
Typically worst at 4kHz on audiogram
What are some causes of inflammatory SNHL?
Meningitis - important to identify in children who have had meningitis
What are the features of autoimmune SNHL?
Rapidly progressing, fluctuating, unilateral SNHL
Associated with vertigo and tinnitus
–> RA, GPA, sarcoidosis
Which tumours might cause SNHL?
Vestibular schwannoma
Meningioma
What are the features of a vestibular schwannoma?
Unilateral SNHL
What investigation should be done in a patient with unilateral SNHL?
MRI –> T1 weighted, gadolinium enhancement of CP angle + internal acoustic meatus
How is a vestibular schwannoma managed?
Yearly MRI to monitor for growth
If growing persistently:
- stereotactic radiosurgery
- surgical removal
What type of hearing loss is seen in Meniere’s?
Low frequency SNHL
Which drugs can cause SNHL?
Aminoglycosides e.g. gentamicin
Some chemotherapy agents
Which investigations should be done in someone presenting with hearing loss?
Pure tone audiogram (PTA) + Rinne/Weber
–> used in conjunction to see if SNHL or CHL
MRI if unilateral SNHL
How is Weber’s carried out and how are the results interpreted?
512Hz tuning fork in middle of forehead
If louder in one ear
–> conductive loss in that ear or
–> sensorineural loss in other ear
How is Rinne’s carried out and how are the results interpreted?
Tuning fork held against mastoid process (bone) and in from of external auditory canal (air) - which is louder?
- air louder than bone –> normal (+ve test)
- bone louder than air –> conductive loss in that ear (-ve test)
If Weber’s is central and Rinne’s in +ve bilaterally (AC>BC), what is the interpretation?
Normal or Bilateral SNHL (presbyacusis)
If Weber’s is louder in right ear and Rinne’s is +ve left and -ve right, what is the interpretation?
Conductive hearing loss right ear
If Weber’s is louder in the right ear and Rinne’s is +ve right and -ve left, what is the interpretation?
SNHL left ear
What are the management options for SNHL?
Open fitting hearing air –> mild hearing loss
Mould hearing aid
Cochlear implant –> profound SNHL where conventional hearing aids don’t help
How might hearing loss present in young children?
Developmental delay
Behavioural problems
How is hearing loss identified in newborns?
Newborn screening exam - automated otoacoustic emission
If fails twice –> automated auditory brainstem response audiogram
If fails –> audiology for further testing
How is SNHL in a newborn managed?
Early aids/cochlear implants to improve communication outcomes
- cochlear implantation age > 2 –> poorer outcomes
- if deaf from birth, implantation > 5 is not worthwhile as too late for brain auditory centres
What are the causes of conductive hearing loss and which parts of the ear do they affect?
Ear canal: - congenital: atresia - acquired: stenosis, otitis externa, wax Ear drum: - perforation, cholesteatoma Middle ear space: - otitis media with effusion (glue ear) - acute otitis media Ossicles: - congenital, trauma, otosclerosis
What causes otosclerosis?
Fixation of the stapes footplate
What are the features of otosclerosis?
Gradual onset conductive hearing loss with normal otoscopic appearance
More common in women –> progresses more rapidly during pregnancy
What is the treatment for otosclerosis?
Surgery –> stapedectomy
or hearing aids
How is otosclerosis investigated?
PTA –> 2kHz raised bone conduction threshold (Carhart notch)
CT
What are the management options for excessive wax occluding the ear canal?
Topical ear drops –> warm olive oil, sodium bicarbonate
Microsuction
Jobson Horne wax probe
Syringing
