Study of the biomechanical mechanisms of benign paroxysmal positional vertigo.

From a biomechanical point of view, the process of Benign paroxysmal positional vertigo (BPPV) includes 2 fluid¯solid coupling effects: the interaction between particles and endolymph and the interaction between endolymph and cupula. The interaction between the canaliths and the wall would affect the coupling effects. This study aimed to investigate the entire process of cupula motion caused by canaliths motion and the influence of canalith particles composition. A biomechanical numerical model was established to simulate the canalith falling process and study the influence of canalith diameter, number, and initial falling position on cupula movement. Simultaneously, the relationship between cupula displacement and the nystagmus signal was analyzed in BPPV patients. The results revealed that the particle velocity was proportional to the particle diameter. The pressure difference between the two sides of the cupula was directly proportional to the canalith diameter and number. The degree of vertigo was positively related to the slow angular velocity of the nystagmus and, therefore, reflected canalith number and diameter. The BPPV latent period and vertigo duration were inversely related to particle diameter. Thus, the number of particles, particle radius, and initial falling position affected cupula movement, which was reflected in the nystagmus.