Central Positional Nystagmus Can Be the Sole Presentation of Cerebellar Nodulus Infarction.

Objectives: To draw attention to acute positional vertigo and central positional nystagmus (CPN) developing as the sole features of cerebellar nodulus infarction.

Background: The cerebellar nodulus is vascularized by the medial branch of the posterior inferior cerebellar artery, which also supplies the uvula, tonsil, tuber, and pyramid of the vermis, and the inferior part of the cerebellar hemisphere, making isolated cerebellar nodulus infarction extremely rare. CPN occurs after a change in head position with respect to gravity and is caused by pathologies involving the vestibulo-cerebellar pathways. CPN is rarely seen in isolation. Additional neurological signs and ocular motor abnormalities are generally present.

Methods: A 62-year-old man was admitted to the emergency department with acute-onset positional vertigo and CPN as the sole finding on examination. Cranial magnetic resonance imaging revealed an acute infarction involving the nodulus. Results: Infarcts restricted to nodulus can cause positional vertigo and CPN without any associated neurological signs or ocul ar motor abnormalities.

Conclusion: Though very rare, cerebellar nodulus stroke must be searched in patients with positional vertigo of acute onset and isolated CPN on examination.