Vestibular System Anatomy & Physiology Techniques Flashcards

The cervico-ocular reflex (COR) contributes to gaze stabilization during:

Answer: Slow, low-frequency head movements in patients with bilateral vestibular loss

The COR, driven by neck proprioceptors, contributes most at low frequencies and plays a compensatory role in patients with bilateral vestibular hypofunction when the VOR is absent.

The crista ampullaris within each semicircular canal is embedded in a gelatinous structure called the:

Answer: Cupula

The cupula is the gelatinous flap that spans the ampulla and moves in response to endolymph flow, deflecting the hair cell stereocilia of the crista ampullaris.

Ewald's Second Law states that in the horizontal canal, ampullopetal flow causes a response that is:

Answer: Stronger than the response to ampullofugal flow

Ewald's Second Law states that ampullopetal flow (excitation) in the horizontal canal evokes a stronger response than ampullofugal flow (inhibition), reflecting asymmetric canal dynamics.

The ocular tilt reaction (OTR) seen with a unilateral otolith or vestibular nucleus lesion includes which combination of signs?

Answer: Ipsilesional head tilt, skew deviation, and ocular counter-rolling toward the lesion

A unilateral peripheral OTR includes ipsilesional head tilt, skew deviation (lower eye ipsilesional), and ocular counter-rolling with the top pole of the eyes rotating toward the lesion.

The subjective visual vertical (SVV) test measures a patient's ability to align a rod with true vertical, and peripheral vestibular lesions typically cause the perceived vertical to be:

Answer: Tilted ipsilesionally (toward the lesion side)

After a unilateral peripheral vestibular lesion, the SVV tilts toward the affected (ipsilesional) side because loss of utricular input creates an asymmetric gravity signal.

The video head impulse test (vHIT) evaluates VOR function by measuring:

Answer: Eye velocity relative to high-frequency, high-velocity head impulses using a high-speed camera

vHIT uses a high-speed camera to measure eye velocity during brief high-acceleration head impulses, quantifying VOR gain and detecting catch-up saccades indicative of canal hypofunction.

Central vestibular lesions can be distinguished from peripheral lesions by the finding of nystagmus that:

Answer: Changes direction with gaze direction and is not suppressed by fixation

Direction-changing nystagmus with gaze (gaze-evoked nystagmus) that is not suppressed by fixation suggests a central lesion, unlike peripheral nystagmus which is unidirectional and fixation-suppressed.