Vertigo is the hallucination of movement. Typically this is the sensation of the room spinning violently and often associated with symptoms such as nausea and vomiting.

One of the typical causes of vertigo is an imbalance in the messages sent from both inner ears to the brain. The inner ear has two important functions  - hearing and balance reception.

Each inner ear has three canals each of which is full of fluid. Any movement of the head causes movement of the fluid contained within these canals, and any movement results in a complex set of information being sent from each of these balance organs to a central part of the brain called the cerebellum. Apart from the inner ears, the eyes are also important in gathering information of the body’s position in space as are certain organs in the muscles and joints (the balance organs work like a waiter with a glass of water in each hand).

Together messages from the stretch receptors in the joints as well as the eyes and inner ears give information to the brain so that the brain understands the person’s position in space and any movement they may be undergoing.

An imbalance of information from one ear to the other causes the brain to react in a violent and uncomfortable manner. This is the typical cause of the vertigo most patients suffer. It is a symptom of the brain’s confusion with the head’s position in space.

There are many causes for the inner ear on one side not to function normally; this can include infections, a build up of fluid within the ear (Menieres’s disease), injury to the head or ear and an uncommon but serious cause is a small growth on the nerve.

The first priority of evaluation of people with dizziness is to exclude a serious lesion within the nerves leading from the balance apparatus to the brain. This will initially take the form of a hearing test and if there is any imbalance between hearing on one side to the other this often gives a clue as to problems going on within the inner ear balance apparatus. Sometimes the patient may need to have further more sophisticated tests including balance testing.

The typical balance test performed for patients with vertigo is an ENG (Electronystagmography). This is effectively a hearing test for the balance apparatus of the ear. The procedure involves irrigation of cold and warm air in both ear canals. This sets up in the normal ear convection currents that will give rise to the sensation of vertigo (as there is a message only from one ear at a time – the ear on the other side is not being stimulated) so that the brain gets confusion from mismatched inputs.  If this test is performed and there is no response then clearly the inner ear on that side is not working normally. This helps us to define were the problem is in the ear and also which side it is.

Symptomatic treatment will be tailored to the cause of the balance disturbance. One of the common causes of balance disturbances is benign positional paroxysmal vertigo. This is the displacement of some small crystals that exist within the inner ear and movement of the head causes these to be dislodged. As it is only affecting one ear and not the other, this leads to a mismatch or imbalance in the information sent to the brain and again vertigo is the result. This is a very common and not terribly disabling cause of dizziness, it can be treated by some positional exercises and some manoeuvres on some occasions to manoeuvre these crystals into a more satisfactory position.

Menieres’s disease is again a common cause of imbalance often associated with ringing in the ears and hearing loss. There may or may not be a positive family history. It is thought by many people that this is in part due to a build up in fluid in the inner ear and often sufferers are required to undergo a dietary salt reduction regime and possibly some fluid tablets.

Acoustic neuroma is a very uncommon but serious cause of balance disorder, it is often associated with a hearing loss. There are several screening tests for this but ultimately a MRI (Magnetic Resonance Imaging) performed at one of the major metropolitan hospitals is the only way for being reasonably certain that an acoustic neuroma is not the cause of the problem. Patients with a high suspicion for an acoustic neuroma based on results of audiology tests would generally be recommended to undergo a MRI scan.

Labyrinthis is another cause of dizziness, this thought to be due to either a viral infection of the inner ear or the nerve leading from the inner ear. As it affects only the labyrinth (i.e. the balance of the ear) there is no associated hearing loss. This can occur on a recurring basis but generally speaking the severity of it subsides within three to four months.

Apart from peripheral labyrinth (i.e. inner ear) some more centrally placed problems can cause balance disturbance. Problems in the brain or the brain stem typically cause disequilibrium and unsteadiness rather than true rotatory vertigo. Common causes of this include insufficient blood supply to the nerves responsible for balance (vertebrobasilar ischaemia), viral infections and hypotension.

It should be recognised that brain tumours are a very uncommon cause of vertigo without any other symptoms.

Many of the causes of vertigo are not serious, but worrying and inconvenient. Sometimes we can’t be entirely sure of the cause, but a range of tests will generally identify any issues of concern. In most situations the vertigo will get better over several months as the brain adapts or compensates to the imbalance between the ears.

*These notes are an outline only and should be expanded on in discussion with Dr Nicholson.

Illlustration Credit: Otalaryngology - Head and Neck Surgery, Missouri, USA, 1993 Mosby-Year Book, Inc

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