[Benign paroxysmal positional vertigo. Differential diagnosis of posterior, horizontal and anterior canalolithiasis]

Evidence is presented that all typical features of benign paroxysmal positioning vertigo can be explained by canalolithiasis rather than by cupulolithiasis. A free floating clot of "heavy" inorganic particles gravitates to the most dependent part of the canal as soon as the patient's head is moved in a way that alters the angle between the canal's plane and the gravity vector. Based on the canalolithiasis mechanism we describe how characteristics of the thus elicited nystagmus differ if the posterior, the horizontal or the anterior semicircular canal is causative.