Ontario Clinical Practice Exam

Benign Paroxysmal Positional Vertigo (BPPV) is primarily caused by the displacement of otoconia crystals, which are tiny calcium carbonate crystals located in the otolith organs of the inner ear. Under normal conditions, these crystals help the brain to perceive the position and movement of the head relative to gravity. However, when these otoconia become dislodged—often due to head trauma, aging, or other factors—they can migrate into one of the semicircular canals, leading to abnormal signaling to the brain. This results in the characteristic episodes of vertigo that occur when the head is moved in certain positions.

Understanding this mechanism is crucial, as the other options generally do not relate directly to the pathophysiology of BPPV. For instance, infections of the inner ear can cause various types of vertigo but typically involve different mechanisms and symptoms. Vestibular nerve damage and neurological disorders might contribute to broader vestibular dysfunction, but they are not primary causes of BPPV specifically. Therefore, the displacement of otoconia crystals directly addresses the fundamental issue underlying BPPV, making it the primary cause.