A graphical representation of the inner ear. The pink disc on the right is the eardrum, which lies between the inner ear and the ear canal (the 'ear hole' that exits through the side of the skull). The blue organ that looks like a snail's shell is the cochlea. The pink organ is known as the hammer, the yellow as the anvil, and the white as the stirrup.

The human balance system is sometimes referred to as the sixth sense. Many people don't give it a second thought, but without our sense of balance it becomes difficult to get around, live independently and carry on with simple daily activities.

Balance disorders can have a serious impact, particularly on an older person's life. They are one of the reasons that older people have falls, for example, which can result in serious injuries such as broken bones. Approximately nine per cent of those aged 65 or older will require medical attention for an injury related to a fall at some point in their senior years, according to statistics gathered by the National Institute on Deafness and Other Communication Disorders in the United States.

Having good balance means that one is able to control and maintain their position whether moving or still, and while moving over various types of terrain. It sounds simple, but it's actually a rather complex feat.

Balance relies on a combination of several factors. The inner ear, eyes, muscles and joints need to work together to transmit reliable information to the brain, helping it co-ordinate the body's movement and orientation in space.

If the system becomes damaged, a person may suffer from dizziness, imbalance, or vertigo. While many systems play a role in helping us keep our balance, a balance disorder is most commonly caused by a disturbance in the inner ear.

The ear's crucial role

The human ear has three main mechanisms. The first is the external, which is the part of our ear that we can see. The middle ear's main function is to transmit sound from the outer ear to the inner ear.

Finally, there's the inner ear, also known as the labyrinth, located deep inside of our skull. It is divided into the cochlear organ, which is responsible for hearing, and the vestibular organ that is responsible for our balance.

It is the vestibular organ that tells our brain about the movements and position of our head. In each vestibular organ there are three sets of semi-circular canals that detect when you move your head around. There are also two structures called the 'otoliths' that tell the brain when the head is moving and its position relative to the pull of gravity.

Balance disorders

There are many types of balance disorders, and the severity of the symptoms and the ability to accurately describe them can be overwhelming.

Kevin Hatt, 50, from Ottawa, developed a balance disorder after a bout of progressive multifocal leukoencephalopathy (PML) in 2000. "Uneven sidewalks or a slope will cause my balance to become unsteady, pitching me to the ground," Hatt said.

"Crossing streets is nerve-racking for me. My legs are trying to over-compensate because of the unsteadiness in my brain, [and] I often end up staggering," he added. "I find that using an escalator involves watching and timing my step onto it, and having to deal with the moving stairs is a problem as well as the stepping off."

Most cases of dizziness that cause imbalance, stumbling and difficulty in walking result from vestibular organ disorders. Dizziness, for example, occurs when the left and right side of the balance organs are not working together in equilibrium. This can lead the brain to the development of new patterns of movements in order to compensate for the internal changes in the ear — those who suffer from balance disorders often avoid certain head movements that are apt to lead to dizziness.

The most common balance disorder among older adults is benign paroxysmal positional vertigo. BPPV causes the individual to experience brief feelings of intense dizziness when they change the position of their head, get out of bed, or reach up for something in a cupboard. The cause is unknown.

Labyrinthitis is a balance disorder caused by an infection in the inner ear or the labyrinth organ that helps us maintain our balance.

Ménière's disease affects adults of any age. It causes a person to experience a feeling of fullness in the ear, tinnitus, vertigo and hearing loss that comes and goes.

Other cases of vertigo, not due to the vestibular system can be caused by neurological damage affecting the brain stem as a result of disease (such as multiple sclerosis) or injury.

Cardiovascular problems like high blood pressure and anemia can cause strokes that result in balance disorders, according to the Canadian Health Network.

Bacterial or viral illness or a reaction to certain medications can damage the inner ear, as well. It's a good idea to ask your doctor if any of the medications that you take are ototoxic, or damaging to the inner ear.

Diagnosis

Diagnosing balance disorders is a complex process.

"Because the term dizziness is used so frequently it is important to know when to seek medical assistance," said Marilyn Tutt, a clinical audiologist specializing in vestibular function at the Charlton Audiology Clinic in Hamilton, who specializes in the area of vestibular function. "The term dizziness has no definitive meaning. There are a number of medical conditions that can cause 'dizziness.' One of the difficulties that arise in the assessment of vestibular function lies in the fact that the symptoms may mimic other disorders that can be life-threatening or debilitating."

There are diagnostic tests available to determine if the loss of balance is caused by a problem in the vestibular system, or whether doctors should check for something else.

Tests for the vestibular system include a procedure called electronystagmography (ENG), which takes an electronic recording of your eye movements. Your balance system is located primarily in the inner ear, but works in concert with the brain, the brain stem, the eyes and sensory nerves throughout the body — each of the centres transfers information with the others. When the system is working properly, you maintain your balance. By stimulating your nervous system in various ways that usually affect your balance and then carefully measuring your eye movements, an expert can tell if there are any abnormalities to the vestibular system.

In addition to ENG, rotation tests are another way of evaluating how well the eyes and inner ear work together. The technician records eye movements while the head is moving at various speeds. This provides further information, beyond the ENG, about how well the balance organs are operating, particularly as it relates to the eye muscles.

Computerized dynamic posturography (CDP) is a test of postural stability that provides information about motor control or balance under varying environmental conditions. CDP tests the relationship amongst all three of the balance system workings: The eyes, the somatosensory system (which is the sensory input from the eyes, the muscles and joints, and the vestibular system), and the vestibular system. It measures the person's response to environments in which the amount of reliable information from the eyes and somatosensory system is varied.

Auditory hearing tests may also be required for an accurate diagnosis.

Audiometry is the measurement of hearing function. Several different audiometry tests, performed by an audiologist, may be required. These tests are carried out in a sound-treated room with a set of headphones that allow voice contact with the audiologist through a microphone. The tests include pure-tone audiometry, speech audiometry, acoustic reflex, electrocochleography, otoacoustic emissions, and auditory brainstem response tests.

Other tests like magnetic-resonance imaging (MRI) or a computerized tomography (CT) scan of the brain can also be done to evaluate a patient.

Treatment

The type of treatment prescribed for vestibular disorders depends upon the individual's symptoms, medical history, diagnostic test results and a physical examination by a qualified doctor.

"In my experience I have found that the word dizziness is a generic term," Hamilton Health Sciences' Tutt said. "It is often used to describe symptoms such as lightheadedness, swimming sensation, motion sickness and general malaise, as well as symptoms such as a sensation of motion or imbalance. One of the difficulties that arises in the assessment of vestibular function lies in the fact that the symptoms may mimic other disorders that can be life-threatening or debilitating. Once a person has experienced severe acute onset of dizziness and imbalance they will often be seen to rule out such causes as stroke, heart attack, MS or migraines."

Different types of exercises, a change in diet (reducing sodium to cut the risk of stroke, for example), surgery or treatment for any underlying disease that may be contributing to the balance disorder can help. Patients may be referred to an otolaryngologist, a doctor who treats problems in the ears, nose, throat, head and neck.

It is important to remember that the balance system is complex. The ear is important, but the entire system must also rely on what we see in relationship to where we are. The brain needs to know things such as how the feet and the legs are positioned with regards to the ground and how the head is positioned with the shoulders and the chest. There are many things that can go wrong, but our brain can also control balance by using various bits of information it has available to it at any point in time. So a loss of balance can definitely be disabling, but is often treatable.

"A large percent of dizzy patients can be diagnosed and treated successfully," Tutt said. "However there are some cases that cannot be treated as successfully as others. The treatment may be one of management, one of libratory procedures, one of diet, one of vestibular rehabilitation performed by qualified physiotherapists, or one of surgery."

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