Lecture 6: Hearing Loss Flashcards
What are the 4 goals of evaluating potential hearing loss?
- Nature of impairment
- Severity of impairment
- Anatomy of impairment
- Etiology
What are the two main types of hearing loss?
- Conductive
- Sensorineural
When is hearing loss typically screened for?
- Birth
- Kindergarten
- Pre-employment/military physicals
When is an otoacoustic emission (OAE) test performed?
At birth to check for inner ear function.
Describe an otoacoustic emission test.
- Provider places a small earphone in the ear.
- Earphone plays a sound that should echo within the ear canal.
- Ear should send back in an echo
Can be performed while baby is sleeping, very quick.
What is an auditory brainstem response test? (ABR)
- Electrodes placed on forehead, and earphone in ears.
- Sound send through earphones, while the patch monitors brain function/response.
- Can check for abnormal sensorineural development.
If an infant fails a hearing screening, what is the protocol?
Need an EENT referral if the infant cannot pass a hearing test by the age of 3 months.
What signs might suggest that a baby has hearing loss?
- Not being startled by loud sounds
- Not turning towards a sound after 6mo
- Not saying single words like mama or dada by 1 year old.
- Turns head if sees you, but not if you only call out name.
- Seems to hear some sounds but not others.
How do we treat a child that has abnormal hearing screenings?
Visual reinforcement audiometry (VRA)
Must be 6m to 2y.
What is a VRA test?
- Patient sits in a booth while distracted.
- Patient trained to look towards the sound source.
- Rewarded if they look properly.
What is a conditioned play audiometry test? (CPA)
- Child performs an activity when a sound is heard.
2-5y old
What is a pure tone audiogram?
Test to see what a person’s hearing range is.
Tests decibels a patient can hear at certain frequencies.
How do we read an audiogram?
Y axis: intensity of sound in decibels.
X axis: pitch/frequency of sound.
What kind of sounds are at the top of an audiogram? Bottom?
Top: Whispers
Bottom: Jackhammer
What are the two types of conduction an audiogram can measure?
- Air conduction hearing using headphones.
- Bone conduction hearing using mastoid stimulators.
How do you read an audiogram?
Each frequency is plotted based on what decibel the patient could hear it at. Both ears are tested, generating a graph, which is then compared to a standard.
What is normal hearing range?
250-6000 Hz
-10 to 25 decibels.
0 decibels is the softest sound an average person can hear. Hearing something like -5 decibels on an audiogram just means you have very good hearing.
How many decibels different is profound hearing loss from regular?
Nearly 100 decibels less than the average.
AKA you need a sound at 100 decibels to hear it.
What is a tympanogram?
Measures mobility/compliance of the tympanic membrane and the small bones in the middle ear.
What are the 3 types of tympanograms and what do they represent?
- Type A: normal
- Type B: Abnormal finding, no compliance
- Type C: Abnormal finding, eustachian tube dysfunction.
What curves do each tympanogram type generate?
What does a Type A tympanogram indicate?
- Normal middle ear system without fluid and normal conduction.
- Maximal peak compliance (at 0 Pa)
What does a type B tympanogram indicate?
- No peak, non-mobile.
- Suggests severely restricted middle ear system.
- Often consistent with OM.
- Consistent with a middle ear pathology, such as effusion or perforation.
What does a type C tympanogram indicate?
- Indicator of eustachian tube dysfunction.
- Negative pressure in middle ear space, consistent with middle ear infection or cold-eustachian tube dysfunction.
- Consistent with a sinus, allergy, or end stages of a cold.
- Presents with an early peak.
What is Conductive hearing loss? What tests do we run?
When sound does not conduct efficiently through the outer ear canal to the tympanic membrane and ossicles, or middle ear.
Rinne Test: BC > AC
Weber test: Lateralized to defective ear.
Correct medically or surgically.
What is sensorineural hearing loss? What tests do we run?
Damage to inner ear/cochlea or nerve pathways. Loss of hearing higher pitched sounds.
Weber test: Lateralization to good ear
Rinne Test: AC > BC (but they stop hearing it really early. You can probably hear it as the tester still.)
Most common type of PERMANENT loss. Difficult to correct.
What are some examples of autosomal syndromes that cause hearing loss?
- Treacher Collins syndrome
- Crouzon syndrome
What is an example of an autosomal recessive syndrome that causes hearing loss?
Usher Syndrome
What is an example of a X-linked syndrome that causes hearing loss?
Alport syndrome.
airport = LAX (LINKED X)
What are the other hereditary causes of hearing loss?
- TORCH infections
- RH factor incompatibility
- Prematurity
- Anoxia
- Hyperbilirubinemia
What are the TORCH infections?
- Toxoplasma Gondii
- Other (Syphilis, Parvo B19, VZV, Listeria)
- Rubella
- CMV
- HSV2
What are the main/common ototoxic drugs?
- ASA
- Anti-malarials/tonic water
- LASIX
- Gentamicin/tobramycin
- Erythromycin
- Cisplantin/Carboplantin
- Mercury and Lead
What is the mnemonic for hearing loss drugs?
Medications Neglected Can Cause Loss Auditory-Vestibular System
* Malaria drugs: Quinine or Macrolide: erythromycin
* NSAID
* Cisplatin/Carboplatin
* Loop diuretics: Furosemide and ethacrynic acid
* Aminoglycosides: gentamicin/tobramycin
* Vancomycin/vincristine
* Salicyclic acid: ASA
What is otosclerosis?
- Disease of the ossicular chain in which the stapes affixes to the oval window.
- Presents as conductive hearing loss.
- It is an inherited, autosomal dominant disease!!
How does otosclerosis typically present?
- Progressive unilateral/bilateral conductive hearing loss.
- Improved hearing with BKG noise.
- Tinnitus
- Weber test should lateralize to defective ear
How is otosclerosis treated?
Stapedectomy or hearing aid if sensorineural loss has occurred.
What is a schwartz sign?
Red blush of the tympanic membrane over the promontory, often suggestive of otosclerosis.
What is presbycusis?
Age-related hearing loss.
How does presbycusis present?
- Progressive BILATERAL symmetrical sensorineural hearing loss.
- Most notable at high frequencies
- MOST SEVERE in males and often confused with noise-induced hearing loss.
What parts of the ear are generally affected in presbycusis?
Cochlea and ossicles.
What is the treatment for presbycusis?
- Hearing aids (common)
- Cochlear implants (severe)
- OTC CoQ10 (maybe)
What is an acoustic neuroma/vestibular schwannoma?
BENIGN tumor of the schwann cells (myelin forming) that occurs on CN8
How does an acoustic neuroma present?
- Unilateral, sensorineural hearing loss.
- Usually only affects CN8.
- Dizziness/balance problems.
How is an acoustic neuroma diagnosed? Treated?
MRI to locate it.
Treatment is either monitoring or radiation/surgery.
What is the pathophysiology behind noise-induced hearing loss? (NHL)
Permanent hearing impairment due to hair cell damage/death.
How loud do sounds need to be to cause NHL?
85+ decibels (lawnmower minimum)
What sound range does NHL ruin?
Bilateral hearing of 2000-4000 Hz?
How should we approach treatment of hearing loss in general?
- If due to cerumen impact or OM, treat there.
- If not easily remediable, refer to EENT since it may require time-sensitive treatment like corticosteroids.
When is routine auditory screening recommended?
- 65+
- Adults with previous exposure to injurious noise levels.
Where are the 4 types of hearing aids placed?
- Completely in the canal
- In the canal
- In the ear
- Behind the ear
What is the gold standard for auditory rehabilitation of advanced sensorineural hearing loss? (SNHL)
Cochlear implant
What is a cochlear implant?
- External microphone and speech processor under ear.
- Receiver underneath temporalis muscle.
- Internal receiver in the cochlea.
