What is my vestibular system?

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My vestibulo-what?!

Most people take their vestibular system for granted, not even knowing it exists until something goes wrong!  

Your vestibular system consists of two tiny organs that reside in each of your inner ears.  Their main purpose is to:

• help keep your balance as you move throughout your day.  

Each inner ear sends signals to your brain to tell it what kinds of movements your head is making, as well as tell it if you are speeding up or slowing down.   

This not only helps keep you upright, but it also helps keep your eyes focused on what you are looking at as you move.

A simple example would be if you are looking at your friend while shaking your head side to side as if to say no - a healthy vestibular system helps to keep your eyes targeted at your friend, while your head rotates side to side. 

The inner ear has two methods of sensing movement.  

• The first method uses 3 fluid filled canals in each inner ear.  The inner ear uses the movement of the fluid to gage what direction your head is moving.  
• The other method uses tiny calcium crystals that are resting on a sticky gel on the floor of the vestibular organ.  The inner ear senses what speed your head is moving or slowing by noticing when these heavy crystals begin to push forward and back on the jelly floor.

How does the vestibular system cause vertigo?

In a healthy vestibular system, the two inner ear vestibular organs send matching or complementary signals to the brain.  

For example, of you are running forwards, both the left and right inner ear will tell your brain you are moving forward at the same speed.   If you are shaking your head NO, the left and right inner ear will send equal and opposite signals to your brain as the right ear swings forward and the left ear swing back in equal distance and arc. 

Vertigo occurs when there is a mismatch of signals to the brain from the left and right inner ear.  

There are several reasons that a mismatch can happen.  

Vestibular Neuritis 

Damage to the vestibular nerve from Vestibular Neuritis (a viral infection) is one example.  The signals from the affected side will not be as strong or as clear as the opposite side causing a continuous wave of vertigo that can last a few days until the infection subsides. 

Benign Paroxysmal Positional Vertigo (BPPV)

Another trigger of vertigo is Benign Paroxysmal Positional Vertigo (BPPV) which causes short vertigo attacks with certain head positions.  The tiny calcium crystals that are meant to stay on the floor of the inner ear become trapped in the fluid filled canals. 

Because the crystals are heavier than the fluid, they cause the fluid to move differently on that side, causing the mismatch in signals from the opposite side.  Vertigo occurs for several seconds after a head movement until the crystals settle. 

Menières disesase

In Menières disesase, vertigo is thought to be caused by excess fluid in the vestibular organ on one side, which increases the pressure inside the inner ear causing a change in the signal to the brain, and thus another mismatch causing a vertigo spell.  Menières disease vertigo attacks often cause a few hours of continuous vertigo and nausea until the pressure subsides.