You spin me right round baby, right round, like a dysfunctioning vestibular system baby, right round

If you’ve managed to get past the frankly vertigo-inducing title then please enjoy a little introduction into the balance system, vertigo and some common dizziness-related questions, including the one about alcohol.

What do we mean by balance?

When people feel dizzy, unbalanced or vertiginous, they often blame their ears. But actually, our balance is maintained by a sophisticated integrated system with input from FOUR areas:

1) Vision

2) The vestibular system (this is located in the bony labyrinth of the inner ear, next to the cochlear which is the organ of hearing)

3) Propriceptive system (anything you can feel with your body but especially the soles of the feet)

4) Superficial sensory system, such as smell

All of this information is collated and integrated in the brain, and that is how we know where we are standing in relation to everything else – we refer to this as maintaining equilibrium. If any one of these inputs is impaired, this will lead to abnormal perception.

The semantics involved in defining balance are often varied: dizzy, unbalanced, off-balance, giddy, unsteady. But when the vestibular system is involved in the cause of unbalance, we refer to the sensation as vertigo. Vertigo is essentially the illusion of movement.

Why are older people more prone to falls?

Older people often need to walk with a stick. People sometimes think this is to do with their inner ear balance or even their hearing – it’s not. It’s because leg muscles and joint function deteriorate with age leading to altered input from the proprioceptive system. This makes them feel unbalanced and they are more prone to slipping over.

Why do I get motion sickness?

Motion sickness is due to a conflict of sensory input. Input from the vision system says you’re not moving but input from the proprioceptive and vestibular system says you are moving. The resulting nausea is essentially the brain reacting adversely to this conflict.

Why do eyes flicker back and forth when looking out of a train window?

The brain processes information from all balance-maintenance inputs in order to maintain equilibrium. One of its roles is to maintain visual stability. When someone looks out of a fast-moving train, everything is moving so quickly it’s hard to maintain focus on one object. This causes the brain to make reflexive counter eye movements to (try to) maintain visual stability. The movement is called nystagmus.

Why do I feel dizzy if I lie down after drinking alcohol?

Firstly, we need to understand a little about the anatomy of the vestibular system. Within the vestibular system are hair cells. These hair cells, unlike the hair cells in the cochlear, are sensitive to direction. The vestibular system is essentially a set of motion sensors that gives the brain information on head movements with respect to gravity. The brain uses this information to keep us from falling over.

The hair cells of the vestibular system are surrounded by a jelly-like mass called the cupula and this in turn is surrounded by endolymph fluid. The hair cells move backwards and forwards and the way in which the fluid surrounding the cupula is disturbed indicates to the brain which way the head is moving.

Toxins in alcohol change the gravity of the cupula with respect to the surrounding fluid of the vestibular labyrinth. Normally, the density of the cupula is the same as the surrounding fluid so lying on your side doesn’t make you feel dizzy. But with the toxins from alcohol causing it to become gravity-sensitive, lying on your side when drunk will cause the cupula to tilt, causing dizziness and a spinning sensation.

It can be solved momentarily by ‘hair of the dog’. The toxins from the hair of the dog will temporarily re-equalize the gravity of the cupula with respect to the surrounding fluid. But all you’re really doing is prolonging the recovery time.

So the moral of this story is (other than don’t drink alcohol because it’s bad for you) don’t lie on your side when you’re inebriated, and don’t bother with hair of the dog.

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