What phenomenon occurs when a person experiences vertigo triggered by changes in head position?

Benign Paroxysmal Positional Vertigo (BPPV) is the correct answer as it specifically describes a condition where vertigo is triggered by changes in head position. This occurs due to the displacement of small calcium carbonate crystals (otoconia) within the inner ear. When the head moves, these particles disrupt the normal fluid movement in the semicircular canals, leading to a false sense of spinning or vertigo.

In contrast, labyrinthitis refers to an inflammation of the inner ear structures, often resulting in hearing loss and balance issues but not specifically related to positional changes. An aneurysm involves a bulging blood vessel and does not directly cause positional vertigo. Meniere's disease, characterized by episodes of vertigo, hearing loss, tinnitus, and a feeling of fullness in the ear, is not specifically triggered by head position but rather is thought to be related to changes in inner ear fluid dynamics. Therefore, BPPV is distinct in its mechanism and trigger, making it the phenomenon associated with positional vertigo.