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What is Down beat nystagmus could be due to-a) Cerebellar lesionb) Arnold - Chiari malformationc) Optic neuritisd) Pontine lesion and explain in detail?
Upbeat nystagmus → lesions of central tegmentum of brain stein.
Downbeat nystagmus → Cerebellar lesions and Arnold chiari syndrome. It is due to posterior fossa disease and compression at foramen magnum level.