The main clinical manifestations of the spinocerebellar ataxias (SCAs) result from the involvement of the cerebellum and its connections. Cerebellar activity has been consistently observed in functional imaging studies of olfaction, but the anatomical pathways responsible for this connection have not yet been elucidated. Previous studies have demonstrated olfactory deficit in SCA2, Friedreich's ataxia and in small groups of ataxia of diverse aetiology. The authors used a validated version of the 16-item smell identification test from Sniffin' Sticks (SS-16) was used to evaluate 37 patients with genetically determined autosomal dominant ataxia, and 31 with familial ataxia of unknown genetic basis. This data was also compared with results in 106 Parkinson's disease patients and 218 healthy controls. The SS-16 score was significantly lower in ataxia than in the control group (p<0.001, 95% CI for β=0.55 to 1.90) and significantly higher in ataxia than in Parkinson's disease (p<0.001, 95% CI for β=−4.58 to −3.00) when adjusted for age (p=0.001, 95% CI for β=−0.05 to −0.01), gender (p=0.19) and history of tobacco use (p=0.41). When adjusted for general cognitive function, no significant difference was found between the ataxia and control groups. This study confirms previous findings of mild hyposmia in ataxia, and further suggests this may be due to general cognitive deficits rather than specific olfactory problems.
- Movement disorders
- cerebellar ataxia
- cerebellar degeneration
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Funding This work was funded by the Reta Lila Weston Trust for Medical Research. Dr Laura Silveira-Moriyama is beneficiary of a Reta Lila Weston Fellowship, receives a grant from Parkinson's UK, and travel grant from UCB and Teva. Dr Moscovich reports no disclosures. Dr Munhoz reports no disclosures. Dr Ashizawa is funded by NINDS grant RC1NS068897, National Ataxia Foundation, Marigold Foundation. Dr Teive received personal compensation for educational activities with Allergan, Boehringer, Ingelheim, Ipsen, Novartis, and Roche, and serves as an editorial board member of Parkinsonism and Related Disorders, Journal of Neurology Research, Parkinson's Disease, Current Neurology and Neuroscience Reports, and Arquivos de Neuropsiquiatria. Dr Carvalho reports no disclosures. Dr Raskin reports no disclosure. Liu reports no disclosure. Dr Lees is funded by PSP Association, Weston Trust - The Reta Lila Howard Foundation grant, is a member consultant of Genus, advisory board of Novartis, Teva, Meda, Boehringer Ingelheim, GSK, Ipsen, Lundbeck, Allergan, Orion, BIAL, Noscira, Roche and received honoraria from Novartis, Teva, Meda, Boehringer Ingelheim, GSK, Ipsen, Lundbeck, Allergan, Orion, BIAL, Noscira, Roche. Dr Barbosa received personal compensation for educational activities from Boehringer- Ingelheim. Dr Ranvaud reports no disclosure. Dr McFarland reports no disclosure.
Competing interests None.
Ethics approval Ethics committee at the Federal University of Parana General Hospital.
Provenance and peer review Not commissioned; externally peer reviewed.