Hearing Loss Flashcards
what are the different types of hearing loss?
conductive
sensorineural
mixed
what is the pathophysiology of conductive hearing loss?
impaired sound transmission via the external canal and the middle ear ossicles to the foot of the stapes
Inner ear can still analyse signal
what are the different causes of conductive hearing loss?
o External canal obstruction
o Drum perforation
o Problems in the ossicular chain
o Inadequate eustachian tube ventilation of the middle ear
what are the causes of external canal obstructive causes in conductive hearing loss?
wax, pus, debris, foreign body, development anomalies, otitis externa, exostosis (suffers ear, abnormal bone growth in ear canal, gradual hearing loss), tumour, stenosis
what are the causes of drum perforation causes of conductive hearing loss?
trauma, barotrauma, infection
what are the causes of ossicular chain problems in conductive hearing loss?
otosclerosis, infection, trauma, otitis media, cholesteatoma, middle ear tumour, congenital malformation
what will an audiogram in conductive hearing loss show?
impairment in all frequencies
what is the management of conductive hearing loss?
treat underlying cause - will respond to treatment
surgical, pharmaceutical, supportive
what is the pathophysiology of sensorineural hearing loss?
results from defects central to the oval window in the cochlea (sensory), cochlear nerve (neural), or rarely, more central pathways
signal cannot be transmitted to brain
what are the causes of sensorineural hearing loss?
o genetic, congenital, presbycusis (age related), acquired (nose induced) o Ototoxic Drugs o Post Infective o Cochlear vascular disease o Meniere’s disease o Trauma o Rare
what are the ototoxic drugs associated with sensorineural hearing loss?
streptomycin, vancomycin, gentamicin, chloroquine and hydroxychloroquine, vinca alkaloids)
what are the post infective causes of sensorineural?
meningitis, measles, mumps, flu, herpes, syphilis (damage cochlear)
what are the rare causes of sensorineural hearing loss?
acoustic neuroma, B12 deficiency, MS, brain mets
what is important to exclude in sensorineural hearing loss?
If unilateral exclude acoustic neuroma, cholesatoma , effusion from nasopharyngeal cancer
what is the shape of the audiogram in sensorineural hearing loss?
sloped
what is the pharmaceutical management of sensorineural hearing loss?
vitamins, vasodilators, anti-inflammatories
what is the definition of sudden hearing loss?
loss of >30dB in 3 contiguous pure tone frequencies over 3 days
Hearing loss may be sudden and abrupt, or rapidly progressive
what is the management of sudden hearing loss
depends on cause, high dose steroids (prednisolone), hyperbaric O2 therapy
what are the different kinds of hearing aids?
conventional
bone anchored hearing aids
cochlear implant s
what are the different types of conventional hearing aids?
Behind the ear (BTE)
In the Ear (ITE)
In the canal (IC)
what are the features of BTE hearing aids?
consists of a case hanging behind the pinna
case is attached to an earmold by a tube or wire
tube or wire courses from superior-ventral protion of pinna to choncha, where the earmold inserts into external auditory canal
what is the structure of BTE hearing aids?
case contains the electronics, controls, battery + microphone
when at BTE hearing aids used?
good in severe hearing loss, versatile, good balance between ease and appearance
what are the features of ITE hearing aids?
Fit in the outer ear bowl (concha)
Custom made (mould taken)
what is the structure of ITE hearing aids?
made from silicone, being larger can hold extra features
when at ITE hearing aids used?
used in mild hearing loss, superior cosmesis, feedback is a problem
what are the advantages of Completely IC hearing aids?
- Fits deeper in ear canal
- Prevents wind noise + makes easier to use phone
- Larger models stop plugging feeling
what are the disadvantages of completely in canal hearing aids?
- Doesn’t have directional microphone + battery life short
* Trickier to use, not suitable for severe hearing loss
what are the advantages of invisible IC hearing aids?
- Fits deep in canal
- Custom made
- Use of venting + deep positioning = more natural
- Shape doesn’t block ear – sound collected more naturally to travel down canal
- More suitable middle age device due to fiddleness
what are the disadvantages of invisible in canal hearing aids?
• Not suitable for severe hearing loss
what is the description of bone anchored hearing aids?
comprise of a titanium screw abutment and an external hearing aid processor. Titanium screws can be implanted into bone and become firmly anchored. This enables them to have a hearing air attached and allow sound to be transmitted to the cochlea via bone conduction (via skull bones)
when are bone anchored hearing aids used?
patients with atresia of the ear canal, or in those who can’t have conventional aids e.g. continuous ear discharge
how do cochlear implants work?
o cochlear implants bypass the peripheral auditory system
o pick up sound and digitises it, converts said signals into electrical signals and transmits those to cochlear electrodes
o electrodes stimulate cochlear nerve to send signals to brain
what is structure the cochlear implants?
electrode array wrapped around cochlea, sound processor behind ear, coil that connects sound processor + electrodes
what is the pathophysiology of osteosclerosis
new bone is formed around the stapes footplate, which leads to it fixation and subsequent conductive hearing loss
what are cochlear implants used for?
non hearing children <3/4, adult who previously hear but can’t
what is the cause of otosclerosis?
autosomal dominant with incomplete penetrance
what are the clinical features of otosclerosis?
o conductive hearing loss (hearing better with background noise)
o young adults
o tinnitus and transient vertigo
o Pregnancy worsens symptoms
what do eardrums look like in otosclerosis?
looks normal (maybe light pink tinge (Scwartzes sign)
what does the audiometry look like in otosclerosis?
conductive pattern with dip at 2kHz (Caharts notch)
what is the management of otosclerosis?
o Hearing aid
o Surgery – stapedectomy, stapedotomy (microdrill of CO2 laser)
o Cochlear implant (if severe)
what is the pathophysiology of presbycusis?
Loss of hair cells on cochlear as age increases
what is the cause of prebycusis?
age related
what are the clinical features of presbycusis?
o SNHL
o Gradual, do not notice until hearing of speech is affected (loss of 3-4kHz)
o Most affected with background nose
what is the audiogram of presbycusis?
high frequencies lost first, low frequencies stay in normal range, no increased air-bone gap
what is the management of presbycusis?
hearing aids, no treatment to prevent worsening
what are the additional causes of SNHL?
Idiopathic
Noise Exposure
what are the features of idiopathic SNHL?
sudden deterioration, ear may feel blocked, tinnitus and vertigo
what is the cause of idiopathic SNHL?
viral infection or vascular event
what is the management of idiopathic SNHL?
bed rest and vasodilators
what are the clinical features of noise exposure SNHL?
tinnitus and “wooly ears”, bilateral
what is the audiometry of noise exposure SNHL?
loss of very high frequencies first, notch in audiometry
what is the management of noise exposure SNHL?
aural hearing aids
what is the pathophysiology of tinnitus?
o Spontaneous otoacoustic emissions, altered or increased spontaneous activity in the auditory nerve or central structures plastic reorganisation of central pathways, inappropriate feedback via descending pathways and auditory -limbic interactions
what is the clinical feature of tinnitus?
“ringing” – perception of sound in absence of auditory stimulation
what are the two types of tinnitus?
objective
subjective
what is objective tinnitus?
tinnitus that audible to examiner
what is subjective tinnitutis?
tinnitus that audible only to patient
how is tinnitus diagnosed?
audiometry, tympanogram
how is tinnitus managed?
o Treat underlying cause
o Symptom management – hearing aids, psychological support, CBT
what are the causes of objective tinnitus?
Vascular Disorders: pulsatile vibratory sounds from e.g. AV malformations, carotid pathology, glomus tumours
High outlet cardiac states – Paget’s, hyperthyroidism, anaemia
Myoclonus or palatal or stapedius/tensor tympani muscles
Patulous Eustachian Tube
what are the causes of subjective tinnuitits?
SNHL causing conditions – presbycusis, noise induced hearing loss, Menieres
Conductive hearing loss – impacted ear wax, otosclerosis
Ototoxic Drugs
Others: hypo/hyperthyroidism, diabetes, MS, acoustic neuroma, trauma, anxiety, depression
