Vol. 93 No.3 March　2000

Clinical Features of Direction-Changing Positional Nystagmus

 Mamoru Suzuki (Tokyo Medical University)

           There are two major types of direction-changing positional nystagmus, namely, apogeotropic and geotropic nystagmus. Both peripheral and central lesions are involved in there two types of nystagmus. Peripheral lesions include various types of disorders such as Ménière’s disease, sudden deafness, vestibular neuritis, and BPPV. In our series, there were 30 peripheral, 8 central, and 8 unknown lesions. On occasion, nystagmus is so intense that a surgical procedure is indicated. The present case is a 63-year-old woman who had a disabling positional vertigo for a period of 4 months. She showed intense direction-changing apogeotropic nystagmus. Conservative treatments failed to resolve her vertigo. From the findings of the nystagmus, cupulolithiasis of the right lateral semicircular canal was suspected. Plugging of the lateral canal was performed, which successfully eliminated the nystagmus and positional vertigo. Positional vertigo can sometimes be disabling and unresponsive to conservative therapy. Careful analysis of the nystagmus may allow selection of an appropriate treatment.

Key words: positional nystagmus, cupulolithiasis, canal plugging