What's the difference between dizziness, vertigo and light headedness?



The Dizziness, Balance, and Falls Center at the Michigan Ear Institute has been recognized internationally as an outstanding clinical program for the diagnosis and treatment of balance disorders. After diagnosing the balance problem various treatment modalities including medical, surgical, and vestibular rehabilitation can improve overall balance function. Common balance disorders we see include Meniere's disease, benign positional vertigo, vestibular neuritis, post traumatic dizziness, among other processes.

Dizziness and Balance Disturbances
Dizziness is a general term for many different symptoms. While it generally means an abnormal sensation of motion, it can also mean imbalance, lightheadedness, blacking out, staggering, disorientation, weakness and other sensations. Symptoms can range from mild and brief to severe spinning sensations accompanied by nausea also known as vertigo. For clarity the definitions we use to talk about dizziness are used.

  • Dizziness - A general term for all abnormal symptoms of balance and stability.
  • Imbalance - Inability to keep one's balance especially when standing.
  • Lightheadedness - The feeling of nearly passing out, similar to the feeling you might have if you hold your breath for a long time.
  • Vertigo - The sensation that you or your surroundings are moving or spinning or whirling.

Balance requires the interaction between many different organs and systems in the body. The brain is the central processing center for all balance information coming from the senses and for all information going out to the muscles of balance. Input comes from three main areas: vision, the balance portion of the inner ear, and the touch (from the feet and joints). Vision is an important cue to the brain which tells us if we are moving relative to our surroundings.

Anatomy
There are two parts of hearing: mechanical and nerve (or electric). The mechanical part of hearing picks up sound from the outer ear canal and then vibrates the ear drum and the three tiny hearing bones in the middle ear. The inner ear looks a bit like a snail. It has two halves which are connected and are filled with fluid. The coil or cochlea takes care of the nerve part of hearing. Like a telephone it takes the vibration and turns it into an electric signal that is then relayed to the brain.

The other half of the inner ear is the balance or vestibular system. There are three balance canals, each set in different directions that respond to rotational movement of the head. Depending on which way you turn fluid, called end lymph, move within the canals and send the direction to the brain by way of the vestibular nerve.

There are also 2 small compartments that have sensory cells that are covered with small calcium crystals in a gelatin matrix. These compartments are responsible for sensing linear movement, such as swaying, rocking or bouncing movements. When the crystals of this compartment are dislodged, they may cause BPPV (benign paroxysmal vertigo).

The inner ear fluid undergoes a natural recycling every day. It is made from the brain's spinal fluid and is absorbed by the endolymphatic sac. In Meniere's syndrome the sac fails to absorb enough fluid. This increases inner ear pressure resulting in dizziness and hearing loss.

Also in close association with the ear is the facial nerve. It helps move the face and also provides for some of the taste to the tip of the tongue.

Maintenance of Balance
Balance is maintained by the interactions in the brain of nerve impulses from the inner ear, the eye, the neck muscles, and the muscles and joints of the limbs. A disturbance in any of these areas may result in the subjective sensation of dizziness or unsteadiness. General disturbances of body function may lead to dizziness by interfering with coordination of the impulses of the brain.

Causes of Dizziness
Dizziness can be grouped into types by the portion of the entire balance system that is not working properly. The different portions include the inner ear, the brain, the eyes and the limbs (neck, back, and leg muscles and joints which react to keep us upright).

Inner Ear Dizziness
Half of the inner ear is used for hearing (the cochlea) and the other half is used for balance (the labyrinth). If the labyrinth or the nerve that connects it to the brain is malfunctioning, dizziness can result. Many types of maladies occur in the inner ear to cause dizziness, including Meniere's syndrome, labyrinthitis, positional vertigo, and vestibular neuritis, migraine and tumors of the inner ear nerves. These usually cause imbalance, vertigo (spinning), and nausea. It can also be accompanied by tinnitus and hearing loss, if the nearby cochlea is also affected. These diseases will be further explained.

Central Dizziness
Central dizziness is caused by problems in the balance portion of the brain. Anytime this portion of the brain is not working properly, dizziness can occur. Symptoms usually include lightheadedness, disorientation, imbalance, and sometimes even blacking out. Causes of central dizziness include low blood sugar, low blood pressure to the brain, strokes, multiple sclerosis, migraine headaches, head injury, tumors, and the aging process, among others. Treating these types of dizziness usual involves treating the problem which is causing the brain to not work properly.

Muscle-Joint Dizziness
This type of dizziness is uncommon. If the muscles, joints or touch sensors of the limbs are not working well, it becomes difficult for the body to react to motion, and makes it difficult to remain upright. Causes of muscle-joint dizziness include muscular dystrophy; sever diabetes, arthritis, joint replacements, and injuries. Symptoms are usually imbalance and unsteadiness.

Visual Dizziness
Eye muscle imbalance and poor vision can make one's balance worse. The brain relies on information from the eyes to help with balance. Car sickness or sea sickness are types of visual dizziness because the eyes are constantly adjusting to a moving visual field and confuses the balance part of the brain. This can lead to dizziness, nausea and vomiting.

Diagnostic Tests
Dizziness can be caused by numerous disturbances to any of many different parts of the body. Based upon your history and physical findings your physician may require further tests to complete a full evaluation. The tests necessary are determined at the time of examination and may include hearing and balance tests, imaging (CT or MRI scans), blood tests, and ultrasound tests. A general physical exam and neurological tests may also be needed.

The most common test for dizziness is the electronystagmogram (ENG) or videonystagmogram (VNG). In these tests the strength of the inner ear is tested as well as the coordination of eye movements. They involve watching the eye movements after placing warm or cool air into the ear canal. This usually causes a normal sensation of brief dizziness. It is important not to be taking any medications which can affect the test such as Valium, Antivert, alcohol and others. When scheduling this test make sure to ask if your medications will impact the outcome of the tests.

Other tests that are done for dizziness are the electrocochleography (ECoG) and Vestibular evoked myogenic potentials (VEMP). These painless tests may be useful in determining the cause of dizziness in complex cases.

The object of this evaluation is to be certain that there is no serious or life threatening disease and to pinpoint the exact site of the problem. This lays the groundwork for effective medical or surgical treatment.

Diagnosis can often be difficult. Frequently multiple tests must be conducted. Patience and understanding is necessary on the part of the doctor and patient alike.


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