1. Impact of the Vestibular System on the Visual System

2. Anatomy of the Vestibular System

3. Types of Vestibular Input

4. Vestibular Canals

5. Vestibulo-Ocular Reflex

6. Demonstration of Normal VOR Response
Head moving
Eyes moving
Image on retina remains stationary

7. Demonstration of Abnormal VOR Response
Head moving
Eyes moving
Image on retina moving resulting in blur and smearing of image

8. Head Thrust Test 
This test is used to evaluate for unilateral vestibular function. In this test, the patient’s head is turned degrees from center and then rapidly rotated to the other side with the patient focusing on the examiner’s eyes. Patients with unilateral vestibular weakness will have a catch-up saccade when rotated rapidly.

9. Impact on Visual System
WHY WE GET DIZZY
During normal head rotations, the eye rotates opposite to the head, thus canceling the motion of the head. This tends to stabilize the image of the world on the retina.
VESTIBULAR INPUT WITHOUT VISION
During very prolonged head rotations with the eyes closed, the drive to the VOR stops (falsely telling the brain that one is stationary). If at this point you open your eyes, you see the world moving and you feel dizzy.
VISUAL SENSE OF MOTION WITHOUT VESTIBULAR DRIVE
Visual input on its own can drive the VOR (the optokinetic response). This visual input can elicit a false perception of motion. For example, a false sense of motion often occurs when looking out a car window and an adjacent car starts to move.
COMBINED VISUAL AND VESTIBULAR INPUT
During a prolonged head rotation in the light, both the signal from the cupula and visual input reaches the vestibular nuclei. Visual input builds up as the signal from the cupula dies away, thus compensating for the loss of cupula drive. Motion sickness occurs when the two signals are in conflict. Suppose you are inside the cabin of a boat during a storm. Your vestibular afferents are telling you that you are moving. Because you and the cabin are moving together, the visual system senses that you are not moving. To avoid motion sickness the best bet is to go out on the deck and look at the horizon. One theory for the feeling of nausea is that the brain interprets this conflict as poisoning and responds by eliciting vomiting to clear the poison.

10. Symptoms of a Vestibular Disorder
VERTIGO AND DIZZINESS
Spinning or whirling sensation; an illusion of movement of self or the world (vertigo)
Lightheaded, floating, or rocking sensation (dizziness)
Sensation of being heavily weighted or pulled in one direction.
BALANCE AND SPATIAL ORIENTATION
Imbalance, stumbling, difficulty walking straight or turning a corner
Clumsiness or difficulty with coordination
Difficulty maintaining straight posture; tendency to look downward to confirm the location of the ground
Head may be held in a tilted position
Tendency to touch or hold onto something when standing, or to touch or hold the head while seated
Sensitivity to changes in walking surfaces or footwear
Muscle and joint pain (due to struggling with balance)
Difficulty finding stability in crowds or in large open spaces
COGNITIVE
Difficulty concentrating and paying attention; easily distracted
Forgetfulness and short-term memory lapses
Confusion, disorientation, difficulty comprehending directions or instructions
Difficulty following speakers in conversations, meetings, etc., especially when there is background noise or movement
Mental and/or physical fatigue out of proportion to activity

11. Symptoms of a Vestibular Disorder
VISION
Trouble focusing or tracking objects with the eyes; objects or words on a page seem to jump, bounce, float, or blur or may appear doubled
Discomfort from busy visual environments such as traffic, crowds, stores, and patterns
Sensitivity to light, glare, and moving or flickering lights; fluorescent lights may be especially troublesome
Sensitivity to certain types of computer monitors and digital televisions
Tendency to focus on nearby objects; increased discomfort when focusing at a distance
Increased night blindness; difficulty walking in the dark
Poor depth perception
OTHER
Nausea or vomiting, "Hangover" or "seasick" feeling in the head
Motion sickness
Sensation of fullness in the ears
Headaches
Slurred speech
Sensitivity to pressure or temperature changes and wind currents
Pain, pressure, or other symptoms with certain dietary changes (e.g., high sodium)

12. VT Activities with Vestibular Integration
Mirror Fixations
Add a Balance Board or Physio-ball to any activity
Infinity Walk
Back to Back Ball Pass/ Over Head Through Legs Ball Pass
Fruit Ninja