Balance Information

Dizziness, Vertigo, Motion Intolerance

The primary organ of equilibrium in the human body is located in the inner ear which serves as both the sensory organ for spatial orientation and head movement as well as hearing.  If for any reason there is an abnormal increase or decrease in the signal being sent to the brain, from any of the balance canals, the brain will perceive this as an exaggeration or hallucination of motion.  The result is what we commonly term dizziness or vertigo. 

Illness, infections, disease, head trauma, and the natural aging process may cause changes in the equilibrium portion of the inner ear.  For others, motion sickness may be traced to their early childhood.  Motion intolerance may be experienced as either a sense of exaggerated motion or inability to watch moving objects while stationary. 

Although symptoms may only last for several days it is not uncommon, if left improperly diagnosed or treated, for them to linger for years.  The good news is that 90% of all causes of dizziness can be found through evaluation. Eighty-five percent are caused by inner ear disturbance and can be treated medically, surgically, or with Vestibular Rehabilitation. 

Assessing Dizziness

Dizziness is one of the most difficult complaints to assess because it is a subjective sensation that cannot be directly and objectively measured.  Dizziness frequently represents many separate overlapping sensations that can be caused by a multitude of different pathophysiologic processes.  Dizziness also is one of the most common patient complaints seen in ambulatory care today and therefore clinicians in almost all disciplines will be faced with evaluating this difficult problem.   Evaluation and treatment of patients with dizziness will differ significantly once the category of dizziness has been determined.  It is imperative that clinicians take a careful history to determine the type of dizziness prior to initiating further workup.  These patients are typically challenging from a diagnostic standpoint.  Their own difficulty in providing a clear and succinct history adds to this challenge.  It is helpful to have a solid understanding of the various types of dizziness in order to help obtain an informative history from patients.

True Vertigo Versus Other Types of Dizziness

While the description alone cannot make this important distinction between vertigo and other forms of dizziness, there are certain terms that are frequently associated with the description of different forms of dizziness.  A vestibular disorder is almost always described as a sensation of spinning and is accompanied by nystagmus that patients may report as a feeling that their eyes were rapidly snapping or jerking to and fro.  This will relate to a sensation that the environment around them is moving.  Patients with nonvestibular dizziness may describe a spinning sensation inside the head; they do not have nystagmus and thus do not report movement of the environment.  Those patients with vestibular dysfunction may equate the feeling to a sensation of having motion sickness and describe feelings of imbalance, as though they were falling or leaning to one side.  Those patients describing their symptoms with terms such as “lightheaded . . . swimming . . . giddiness . . . floating” most often have a nonvestibular etiology for their dizziness.  Psychophysiologic dizziness is suggested by a description of a feeling that they have left their body.  True vertigo is an episodic phenomenon compared to nonvestibular dizziness that is often described as a continuous sympton.

Vertigo is often aggravated by head movements, while nonvestibular dizziness can be aggravated by movement of targets in the visual field.  This is often obvious in patients who complain of dizziness stimulated by specific situations such as driving in traffic or shopping in a busy supermarket.  In cases where the dizziness is primarily related to positional changes, and postural hypotension has been ruled out, a vestibular lesion should be suspected.  The association of symptoms, such as nausea and vomiting or auditory or neurologic symptoms, is more likely to be seen with vestibular causes of dizziness.

Please visit the American Institue of Balance website for further information.

  www.dizzy.com