Vestibular 3

1. When are we in balance?

We are in balance when the information from the three systems agree with each other. For example, suppose that you are in an elevator which looks outside (as in some expensive hotels) and you go up in that elevator. Then your eyes tell you that you are going up, your sacule feels that you are going up and the pressure sensors in your musculo-skeletal system informs the brain that the body is moving upwards.

2. Motion sickness

But if there is a conflict between the information received from one (or two) of the three systems, then we become violently sick: motion sickness. This is well known when one is on a boat in a choppy sea. Another current example is trying to read a book while riding in a car. Your eyes concentrate on the reading (stable) while your vestibular system and your proprioception inform you that you are constantly accelerating and decelerating. Good reason to become very very sick.

3. Symptoms:

The symptoms of motion sickness are quite severe:

1. nausea
2. vomiting
3. pallor
4. rapid breathing
5. sweating

4. Why so severe?

Body position is crucial fo survival. The brain needs to know all the time the exact position of its head, its limbs etc. It must be able to act immediately in the case of danger. If there is a conflict in the information it is receiving, it can then no longer react adequately to danger. Whatever causes this mis-information must STOP immediately. Hence, motion sickness is really incapacitating.

An example of an endolymphatic hydrops. This is a cross-section of a cochlea. Note that the membrane of Reissner is bulging out in the Scala Vestibuli because the pressure of the endolymphe (in the scale media) is too high.