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PART I  DIZZY SPELLS THAT OCCUR WITH A CHANGE IN POSITION This page intentionally left blank Benign Paroxysmal Positional Vertigo Within a few seconds of changing position (lying down, turning in bed, or bending the head backward while sitting or standing), you feel a wave of vertigo that typically lasts 10 to 30 seconds. You may also feel dizzy all day long. But this is a dif­fer­ ent, milder kind of dizziness, typically a motion sickness. Vertigo that is triggered by a change in head position is called positional vertigo. Benign paroxysmal positional vertigo (BPPV) is the most common type of positional vertigo, but it is not the only type. BPPV is a distinct diagnosis with known cause (see below), while positional vertigo is a symptom with many ­ causes. ­ After lying down or turning over in bed, a person with BPPV feels that the world seems to move or spin. In some cases, a person with BPPV may feel that an object in the room, such as an alarm clock, appears to jump up and down rhythmically. As noted in the introduction, ­ there are two types of motion sensors in the inner ear: the otolith organs, which are sensitive to gravity, and the semicircular canals, which are sensitive to rotation of the head. BPPV occurs when the tiny stones, “otoliths” (also called otoconia), sitting on top of the otolith organs become dislodged and fall into one of the CHAPTER  1 Dizz y Spells with a Change in Position 18 semicircular canals. Normally, the semicircular canals are not sensitive to changes in the direction of gravity that occur with head position change, but when the “heavy” otolith debris enters a semicircular canal, the canal becomes sensitive to gravity. Movement of debris within a semicircular canal activates the sensors in the semicircular canal, sending a signal to the brain to indicate that you are spinning in the plane of the canal. The vertigo sensation is brief (seconds) since the debris stops moving when it ­ settles. The debris almost always gets trapped in the posterior semicircular canal ­ because of its position in the inner ear. That BPPV was a benign disorder originating from the inner ear was first reported in the early 1950s. Initially, BPPV was thought to result from damage to the otolith organs since they­ were the ones sensitive to gravity. However, doctors performing postmortem studies of ­ people who had had BPPV noticed otolith debris in the semicircular canals. They proposed the theory of “canal lithiasis” (stones in the canal). This term is ordinarily written in a shortened form as canalithiasis. Based on this theory, in the late 1980s, John Epley, an otolaryngologist in Oregon, introduced a ­ simple positioning maneuver designed to “roll” the otolith debris out of the canal (now called the Epley maneuver), curing positional vertigo. For several years ­ after the Epley maneuver was introduced,­ there was ­ great skepticism within the medical community regarding its effectiveness. Such ­ simple cures just ­ don’t exist in medicine. By the turn of the ­ century, a few skeptics remained, but most had jumped on the bandwagon ­ after seeing how dramatic the cure can be. The American Acad­ emy of Neurology and the American Acad­ emy of Otolaryngology and Head and Neck Surgery recently published position papers strongly endorsing the Epley treatment maneuver for BPPV. Put simply, it Benign Parox ysmal Positional Vertigo 19 works! (See “What Is the Best Treatment for BPPV?” ­ later in this chapter.) What happens to the debris once it is out of the canal and back into the chamber containing the otolith organ (called the utricle)? It may continue to float around and ­ later reenter the canal, it may dissolve in the inner ear fluid, or it may be incorporated into the inner ear membrane. We know relatively­ little about how the debris is eliminated although the calcium concentration of the inner ear fluid seems to affect ­ whether the debris ­ will dissolve. So we know that otolith debris that is rich in calcium becomes dislodged from the otolith organ and ­ causes BPPV. But why does it become dislodged? One obvious cause is a blow to the head that is forceful enough to dislodge the otoliths. BPPV is common ­ after major head injuries. The most common risk­ factor for developing BPPV, however, is normal aging. The otoliths are less tightly bound to the under­ lying sensory cells as we age. Approximately one in five ­ people in their eighties ­ will develop BPPV. By contrast, when we see BPPV in young...

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Additional Information

ISBN
9781421420912
Related ISBN
9781421420905
MARC Record
OCLC
964524376
Pages
208
Launched on MUSE
2016-12-10
Language
English
Open Access
No
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