Reflexes related to the inner ear
Timothy C. Hain, MD •
Page last modified:
August 23, 2020
VOR (vestibulo-ocular Reflex)
- Stabilizes eye in space
- Necessary to see while head is in motion.
- Rotational movement in 3D includes roll, pitch and yaw.
- Linear movement along the same axes.(heave -- up/down, surge-- front/back, sway -- side-side)
- demands for otolith ocular reflex scale with point of regard.
- Disorders include
- Bilateral loss
- Test for bilateral loss with the DIE (Dynamic Illegible 'E' test)
- Distance vision with head still
- Distance vision with head moving (horizontal or vertical, 1-2
hz)
- Normal: 0-2 lines change.
- Abnormal: 4-7 lines drop with movement
- Other tests of lesser utility
- OCR
- Head-thrust (HIT) test -- catch-up saccades for high speed head movements.
- Ophthalmoscope test -- relative retinal movement when head is rotated.
- Head-shaking test -- reduced amplitude of VOR.
- Unilateral loss or imbalance
- Test for unilateral loss at bedside with head-shaking nystagmus
or vibration
- Head-shaking is about 75% sensitive to unilateral loss
- Vibration is about 95% sensitive to unilateral loss
- Test for imbalance by assessing spontaneous nystagmus
- This test works best acutely (i.e. in the first few days)
- VEMP test for unilateral saccule loss or unilateral utricular loss.
- VHIT test
- In horizontal planee, can detect unilateral loss.
- Cross-coupling
- Linear->angular
- Manifests as positional nystagmus
- Test with positional testing such as Dix-Hallpike test
- Angular->angular
- Called "perverted nystagmus", sometimes seen with caloric or head-shaking.
VSR (Vestibulo-spinal reflex)
- Stabilizes body
- Helps maintain desired orientation to environment
- Test for VSR using Romberg test
- Eyes Closed Tandem Romberg (6 seconds)
- Eyes Open Tandem Romberg
- Eyes Closed Regular Romberg Eyes
- Open Regular Romberg
- Other tests of uncertain utility