Vertigo and vestibular abnormalities in spinocerebellar ataxia type 6
Spinocerebellar ataxia type 6 (SCA6) is a calcium channelopathy due to a pathological CAG repeat expansion in CACNL1A4. Patients frequently describe paroxysmal vertigo early in the disease course, but it is not clear whether this is central or labyrinthine in origin. To address this issue we studied 21 SCA6 patients. Symptoms of vertigo were defined using a structured questionnaire. Signs were recorded during a standardised bed-side vestibular examination that included systematic positional testing with Frenzel goggles.
Brief, recurrent attacks of vertigo occurred in 13 patients, usually preceding the onset of ataxia. Nystagmus was observed behind Frenzel goggles in 14 patients, and was induced either during positional testing, or head shaking in 20 patients. Only one patient had findings typical of benign paroxysmal positional vertigo (BPPV). Combined downbeat and horizontal gaze-evoked nystagmus (“side-pocket”) was the most common form, occurring most commonly in supine and head-hanging positions, and following horizontal head-shaking. Nystagmus beating away from the ground (apogeotropic) occurred in 9 patients as they lay on their side.
In conclusion, vertigo and abnormalities on bedside vestibular examination are common in SCA6, with forms of nystagmus typical of cerebellar, rather than labyrinthine, disease. These findings demonstrate phenotypic overlap between SCA6 and episodic ataxia type 2, which are both due to mutations in CACNL1A4.
Key wordsspinocerebellar ataxia stereopsis nystagmus ocular motility vertigo vestibular
Unable to display preview. Download preview PDF.
- 1.Zhuchenko O, Bailey J, Bonnen P, Ashizawa T, Stockton DW, Amos C, Dobyns WB, Subramony SH, Zoghbi HY, Lee CC (1997) Autosomal dominant cerebellar ataxia (SCA6) associated with small polyglutamine expansions in the alpha 1A-voltagedependent calcium channel. Nat Genet 15:62–69PubMedCrossRefGoogle Scholar
- 4.Leigh RJ, Zee DS (2006) The Neurology of Eye Movements (Book/DVD). Oxford University Press, New YorkGoogle Scholar
- 7.Takahashi H, Ishikawa K, Tsutsumi T, Fujigasaki H, Kawata A, Okiyama R, Fujita T, Yoshizawa K, Yamaguchi S, Tomiyasu H, Yoshii F, Mitani K, Shimizu N, Yamazaki M, Miyamoto T, Orimo T, Shoji S, Kitamura K, Mizusawa H (2004) A clinical and genetic study in a large cohort of patients with spinocerebellar ataxia type 6. J Hum Genet 49:256–264PubMedCrossRefGoogle Scholar
- 9.Brandt T, Dieterich M, Strupp M (2005) Vertigo and Dizziness: Common Complaints. Springer, New YorkGoogle Scholar