Anatomy/Physiology Flashcards
(129 cards)
What is the function of the GJB2 gene?
It encodes a gap junction protein that transmits ions
The gradient across the stria vascular is is maintained by:
Na-K pumps
A 23yo w/late-onset congenital syphilis presents to clinic after a hearing test that showed b/l symmetric moderate SNHL. He reports experiencing vertigo when he was next to the stage at a rock concert the previous week. In regard to middle ear anatomy, which of the following have to be present for him to experience this phenomenon?
Tullio phenomenon - inflammatory lesions of the labyrinth (gummas) lead to labyrinthine fistulas, endolymphatic hydrops w/eventual degeneration of the membranous labyrinth. Also loss of type II hair cells in the semicircular canals and otoliths in otosyphilis.
Aminoglycoside ototoxicity is most commonly associated with damage to which ofc the following sites within the inner ear?
Outer hair cells
Aspirin and other salicylate use can cause severe tinnitus and reversible SNHL, however, it is expected to recover within __.
72hrs (3d)
Describe the acoustic reflex.
Upon exposure to a loud noise (typically w/in the 70-100dB range, there is contraction of b/l stapedius muscles, innervated by the facial nerve.
(Stapes bones are shown as a stirrup-shaped stick figure).
A patient undergoes acoustic reflex threshold testing as part of a possible retrocochlear pathology workup. A 70dB click is applied to activate the afferent limb of the reflex. The efferent limb is measured by:
Assessing changes in TM compliance - contraction of the stapedius muscle decreases the TM compliance as a protective measure.
Two types of nerve cells comprise the cochlear nerve afferents ___.
Type I (95%) and Type II (5%).
Type I cochlear nerve afferent cells are ___ and synapse directly on ___.
Type I cochlear nerve afferent cells are Bipolar and synapse directly on the body of a single Inner hair cell.
Type II cochlear nerve afferent cells are ___ and branch to synapse onto ___.
Type II cochlear nerve afferent cells are Pseudounipolar and branch to synapse onto multiple Outer hair cells..
Streptomycin and Gentamicin are known as mostly ___ agents compared to Neomycin, Amikacin, Tobramycin and Kanamycin that are primarily ___.
Streptomycin and Gentamicin are known as mostly Vestibulotoxic agents compared to Neomycin, Amikacin, Tobramycin and Kanamycin that are primarily Cochleotoxic.
An intact sound transmission mechanism (__) must be present to test for the Tullio phenomenon.
Intact TM, ossicular chain, and mobile footplate
Describe recruitment in the setting of SNHL.
Recruitment = increase in perception of loudness of sound in an ear with SNHL (damaged/ineffective hair cells “recruit” adjacent hair cells w/normal fxn., which then respond to that signal - resulting in narrowing range btwn. softest sound a person can hear and loudest sound a person can tolerate). B/c the defect is with the hair cells, recruitment is a sign of cochlear pathology.
The absence of recruitment in the setting of an ear w/sensorineural HL suggests a ___.
Retrocochlear lesion
The basic pathway for cochlear afferent fibers is:
Inner/Outer hair cells -> cochlea -> cochlear nerve -> cochlear nuclei -> superior of ovary complex -> lateral lemniscus -> inferior colliculus -> auditory cortex
A 70dB click is applied to activate the afferent limb of the acoustic reflex. The efferent limb is measured by ___.
Assessing changes in the TM compliance.
(The contraction of the stapedius muscle decreases TM compliance as a protective measure).
Patient states “she hears her footsteps loudly when she walks,” name this finding.
Autophony
-
- aural pressure
- hyperacusis
- unstable gait
- sound or pressure evoked vertigo
Vestibular manifestations of Superior SSCD include:
- autophony
- pulsatile tinnitus
- aural pressure
- hyperacusis
- unstable gait
- sound or pressure evoked vertigo
Vestibular manifestations of Superior SSCD include:
- autophony
- pulsatile tinnitus
-
-
- unstable gait
- sound or pressure evoked vertigo
Vestibular manifestations of Superior SSCD include:
- autophony
- pulsatile tinnitus
- aural pressure
- hyperacusis
- unstable gait
- sound or pressure evoked vertigo
Vestibular manifestations of Superior SSCD include:
- autophony
- pulsatile tinnitus
- aural pressure
- hyperacusis
-
-
Vestibular manifestations of Superior SSCD include:
- autophony
- pulsatile tinnitus
- aural pressure
- hyperacusis
- unstable gait
- sound or pressure evoked vertigo
Pulsatile tinnitus can occur due to ___.
Exposure of the canal to changes in CSF pressure, or to the flow of adjacent blood vessels.
Audiogram results of a patient w/SSCD:
Most commonly: symmetric hearing
Also: Conductive HL w/larger low-frequency air-bone gaps and supranormal bone conduction
Acoustic reflex testing in a patient w/SSCD:
Acoustic reflex testing is normal.
A patient with SSCD will have ___ ECOG and ___ VEMP testing results.
Elevated ECOG, SP/AP ratio >0.4.
Low threshold VEMP w/high amplitudes.