November 15, 2013
Many people use “dizziness” and “vertigo” interchangeably. While the group of conditions known as vertigo produce dizziness sensations, not all dizziness is vertigo. Let us examine the difference in these terms.
Dizziness essentially refers to a sense of physical disorientation in space or illusory movement. There may also be a sense of “light-headedness”, where the person may suffer momentary altered sensations, such as blurred vision and difficulty maintaining balance. One such condition is known as orthostatic (or positional) hypotension, which is temporary low blood pressure in the head. The brain and sense organs of the head are the biggest consumers of the oxygen carried in the bloodstream. When the head rises (as from a bed) too rapidly, the resulting lack of oxygen reaching the head can momentarily cause a dulling of the senses and “dizziness”. This typically lasts for seconds. Similar sensations of unsteadiness can also be psychologically influenced, including those caused by fear of heights, bridges or enclosed spaces.
Vertigo, on the other hand, typically refers to a spinning sensation and is most often related to the main balance organs of the body, the ears. Benign Paroxysmal Positional Vertigo (BPPV) is a common condition that causes many people to avoid provoking movements, such as bending downward, lying back or rolling in bed. It is caused by an accumulation of mineral debris which has migrated from one part of the inner ear (the saccule) into one of the semicircular canals. These calcium-based otoliths “ear stones” are used to sense linear acceleration, as motion causes them to move toward, and bend, specialized cilia on balance receptors known as “hair cells”. When the acceleration signals from both ears match each other and reinforce what the eyes see, we sense acceleration. If the debris happens to block one of the semicircular canals and stimulate the sense organs incorrectly, the brain will receive mismatched signals about the head’s position or movement. Dizziness is the mind’s way of expression confusion with conflicting information.
Positional vertigo typically is triggered by movement or position. Its most common presentation, posterior canal BPPV, canalithiasis variant, is characterized by spinning dizziness, nausea, a twisting movement of the eyes and brief duration (15-30 seconds). The symptoms typically fatigue upon repetition, and repeated movements tend to result in milder dizziness.
The quickest, least invasive, most cost-effective and best treatment for positional vertigo is called a canalith repositioning maneuver. With versions named after researchers named Epley, Semont, Gans and others, the clinician uses gravity and the density of the particles to unblock the canals and allow the debris to clear into an area where it can be easily absorbed. Obviously no medication can specifically target crystalline debris in the inner ear, pick up the stones and remove them.