Hearing Loss and Audiology - Cass Flashcards
A score less than 100% on the “word recognition” portion of an audiogram indicates possible damage to what structures?
IHC, VIII, Central auditory pathways
Word Recognition Score represents the ability to discrimination words presentenced at normal conversational loudness levels (0-100%). This is a critical part of the hearing assessment and represents the “neural” aspect of hearing ability.
Vibrating the skull vibrates the inner ear, thus bypassing what structures?
bypasses the eardrum, middle ear, ossicles
Name the three types of hearing loss, and describe each one (what anatomical structures are damaged).
Hearing loss can be characterized into three categories. Conductive, Sensory and Neural.
Conductive hearing loss involves disorders of the external ear canal, tympanic membrane, and middle ear ossicular chain that impair the transmission of sound (sound conduction) to the cochlea.
Sensory hearing loss involves the sensory transduction apparatus within the cochlea. Sensory hearing loss typically manifests with changes in pure tone hearing thresholds
Neural hearing loss involves disorders of the 8th nerve and central auditory pathways. The inner hair cell is often considered part of the neural component as it is directly linked to the auditory nerve. Neural hearing loss typically manifests as changes in word recognition scores or the clarity of hearing.
The term sensorineural hearing loss is used to describe the mixture of sensory and neural aspects of hearing loss we frequently observe.
What is indicative of conductive hearing loss on an audiogram?
ON THE TEST FOR SURE
Difference between AIR and BONE is Conductive loss – called an AIR/BONE GAP
What are 5 common causes of conductive hearing loss?
Otitis media
TM perforation
Cholesteatoma (abnormal skin growth in the middle ear behind the tympanic membrane)
Otosclerosis (hereditary disorder causing progressive deafness due to overgrowth of bone in the inner ear)
Congenital aural atresia
What is the most common pathology causing hearing loss?
Hair cell loss is by far the most common pathology causing hearing loss. Human hair cells do not have the ability to regenerate, thus once damaged they degenerate and are not replaced. There are approx 100,000 hair cells in the human cochlea, and that’s all you get.
What is presbycusis?
Age-related hair cell loss.
Noise is dangerous if:
You have to shout over background noise to be heard
The noise is painful to your ears
The noise makes your ears ring
You have decreased or “muffled” hearing for several hours after exposure
What is the most common cause of non-syndromic hearing loss?
The most common cause of non-syndromic hearing loss is connexion 26 hearing loss (10-20% of all genetic hearing loss)
A patient presents complaining of recurrent episodes of vertigo, sensorineural hearing loss, tinnitus and aural fullness. What is the diagnosis?
Endolymphatic hydrops refers to a pathologic condition characterized by expansion of the endolymphatic compartment of the inner ear. Reisners membrane has been massively displaced. Also refered to as Meneire’s disease.
What are 4 main causes of sensory hearing loss?
1) Hair cell loss (presbycusis, noise trauma, ototoxicity, genetic factors)
2) Endolymphatic Hydrops
3) Loss of endocochlear potential (failure of the stria vascularis)
4) Disordered inner ear homeostasis (generally a result of impaired blood flow, resulting in secondary failure of the stria vascularis)
What are 3 major causes of neural hearing loss?
8th nerve tumors
Auditory neuropathy
Multiple Sclerosis
What are hallmarks of neural hearing loss?
Hallmarks of neural HL are asymmetry of hearing between the two ear and reduced speech perception scores. In this case note the asymmetric right high frequency HL and reduced word recognition score of 80% in the right ear.
A temporary threshold shift that decreases hearing sensitivity to frequencies between 2000-400 Hz is most likely caused by:
Noise exposure.
Temporary threshold shifts decrease sensitivity to certain sound frequencies. If repeated, will recover for a time but hearing loss will eventually become permanent. Pattern of loss is between 2000-4000 Hz which is different than age-related hearing loss.f
Which of the following symptoms occurs LATE in the progression of a vestibular schwannoma? (Tinnitus, headache, hearing loss, vertigo, balance problems)
Headache.
Early signs of a Vestibular schwannoma are intracanalicular, only affecting the internal auditory canal (unilateral hearing loss and tinnitus, mild/fleeting vertigo, trouble with word recognition). Late signs are hydrocephalic, due to mass effects (facial numbness, ataxia, headache, vision loss, lower cranial nerve dysfunction, swallowing/speech problems, long tract signs, death due to brain herniation).
