title: Visual Suppression is Impaired in Spinocerebellar Ataxia Type 6 but Preserved in Benign Paroxysmal Positional Vertigo.
abstract: Positional vertigo is a common neurologic emergency and mostly the etiology is peripheral. However, central diseases may mimic peripheral positional vertigo at their initial presentation. We here describe the results of a visual suppression test in six patients with spinocerebellar ataxia type 6 (SCA6), a central positional vertigo, and nine patients with benign paroxysmal positional vertigo (BPPV), the major peripheral positional vertigo. As a result, the visual suppression value of both diseases differed significantly; e.g., 22.5% in SCA6 and 64.3% in BPPV (p < 0.001). There was a positive correlation between the visual suppression value and disease duration, cerebellar atrophy, and CAG repeat length of SCA6 but they were not statistically significant. In conclusion, the present study showed for the first time that visual suppression is impaired in SCA6, a central positional vertigo, but preserved in BPPV, the major peripheral positional vertigo, by directly comparing both groups. The abnormality in the SCA6 group presumably reflects dysfunction in the central visual fixation pathway at the cerebellar flocculus and nodulus. This simple test might aid differential diagnosis of peripheral and central positional vertigo at the earlier stage of disease.
authors: Neurology, Internal Medicine, Sakura Medical Center, Toho University, Sakura, 564-1 Shimoshizu, Sakura 285-8741, Japan. neuro-mkishi@sakura.med.toho-u.ac.jp.
authors: Masahiko
authors: M
authors: Kishi
authors: Neurology, Internal Medicine, Sakura Medical Center, Toho University, Sakura, 564-1 Shimoshizu, Sakura 285-8741, Japan. sakakibara@sakura.med.toho-u.ac.jp.
authors: Ryuji
authors: R
authors: Sakakibara
authors: Department of Otolaryngology, Sakura Medical Center, Toho University, Sakura 285-0841, Japan. tomoe@med.toho-u.ac.jp.
authors: Tomoe
authors: T
authors: Yoshida
authors: Department of Otolaryngology, Sakura Medical Center, Toho University, Sakura 285-0841, Japan. masa@med.toho-u.ac.jp.
authors: Masahiko
authors: M
authors: Yamamoto
authors: Department of Otolaryngology, Sakura Medical Center, Toho University, Sakura 285-0841, Japan. mitsuya.suzuki@med.toho-u.ac.jp.
authors: Mitsuya
authors: M
authors: Suzuki
authors: Clinical Physiology Unit, Sakura Medical Center, Toho University, Sakura 285-8741, Japan. kataoka@sakura.med.toho-u.ac.jp.
authors: Manabu
authors: M
authors: Kataoka
authors: Neurology, Internal Medicine, Sakura Medical Center, Toho University, Sakura, 564-1 Shimoshizu, Sakura 285-8741, Japan. osirukooomori@yahoo.co.jp.
authors: Yohei
authors: Y
authors: Tsuyusaki
authors: Neurology, Internal Medicine, Sakura Medical Center, Toho University, Sakura, 564-1 Shimoshizu, Sakura 285-8741, Japan. tateno@med.toho-u.ac.jp.
authors: Akihiko
authors: A
authors: Tateno
authors: Neurology, Internal Medicine, Sakura Medical Center, Toho University, Sakura, 564-1 Shimoshizu, Sakura 285-8741, Japan. f-tateno@sakura.med.toho-u.ac.jp.
authors: Fuyuki
authors: F
authors: Tateno
keywords: benign paroxysmal positional vertigo; flocculus; nodulus; spinocerebellar ataxia 6; visual suppression test