Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo which is experienced as the illusion of movement. Symptoms are due to inner ear dysfunction. Otoliths become detached from the macula (the utricle-based receptor for detecting head position and movement) into the semicircular canals. These are affected differentially due to anatomy:
Posterior semicircular canal - 85-95% of patients.
Inferior semicircular canal - 5-15% of patients.
Anterior semicircular canals - very rare.
Hair cells embedded in otoliths are stimulated as they are pulled/pushed by the flow of endolymph through the semicircular canals following head movement and terminate as movement ceases. Detached otoliths may continue to move after the head has stopped moving and vertigo results from the conflicting sensation of ongoing movement with other sensory inputs.
Most BPPV is idiopathic. Causes can be attributed in about 40% and include:
Head injury.
Spontaneous degeneration of the labyrinth.
Post-viral illness (viral neuronitis).
Complication of stapes surgery.
Chronic middle ear disease.