Bilateral paroxysmal positioning nystagmus.

The term "bilateral paroxysmal positioning nystagmus" (BPPN) refers to the occurrence of paroxysmal positioning nystagmus when the patient's head is placed in both right and left head-hanging positions. BPPN was found in at least 15% of 114 patients with benign positional vertigo. Head injury, central nervous system disease or both were causative in over half of patients with the finding. In some instances, paroxysmal positional nystagmus may be found when the abnormal ear (side) is uppermost rather than directed toward the floor; this fact may have important implications if singular neurectomy is to be performed.