What is the pathophysiology of vertigo?

Updated: Feb 15, 2018
  • Author: John C Li, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

To understand pathophysiology, an understanding of normal SCC anatomy and physiology is necessary. Each inner ear contains 3 SCCs oriented in 3 perpendicular planes; the SCCs mediate spatial orientation. Each canal consists of a tubular arm (crura) that sprouts from a large barrellike compartment, much like the handle of a coffee mug sprouts from the mug. Each of these arms has a dilated (ampullary) end located near the top or front portion that houses the crista ampullaris (nerve receptors).

The crista ampullaris has a sail-like tower, the cupula, that detects the flow of fluid within the SCC. If a person turns suddenly to the right, the fluid within the right horizontal canal lags behind, causing the cupula to be deflected left (toward the ampulla, or ampullopetally). This deflection is translated into a nerve signal that confirms the head is rotating to the right.

In simple terms, the cupula acts as a 3-way switch that, when pressed one way, appropriately gives the body a sensation of motion. The middle or neutral position reflects no motion. When the switch is moved the opposite way, the sensation of motion is in the opposite direction.

Particles in the canal slow and even reverse the movement of the cupula switch and create signals that are incongruous with the actual head movements. This mismatch of sensory information results in the sensation of vertigo.


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