Downbeat nystagmus without ataxia as an early manifestation of spinocerebellar ataxia, autosomal recessive type 10 (SCAR10): a case report.
Hunter Stearns, Aimen Vanood, Karissa N Arca et al.
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Case in brief
A 23-year-old female with a history of migraine presented with a four-month history of progressive vestibular dizziness. Neurological examination revealed downbeat nystagmus without ataxia. MRI showed severe cerebellar atrophy, and genetic testing identified a pathogenic variant in the ANO10 gene, confirming a diagnosis of Autosomal Recessive Spinocerebellar Ataxia Type 10 (SCAR10).
What made this case unusual
This case is notable for the presentation of SCAR10 with downbeat nystagmus as the sole neurological finding, without accompanying cerebellar ataxia, highlighting a potential early marker of the disease.
Diagnostic / clinical pearl
Clinicians should consider genetic testing for SCAR10 in patients presenting with downbeat nystagmus, even in the absence of ataxia, as it may indicate early neurodegenerative changes.
Why it matters
Recognizing downbeat nystagmus as a potential early sign of SCAR10 can facilitate timely diagnosis and management of this rare condition.