Down beat nystagmus could be due to-a) Cerebellar lesionb) Arnold - Chiari malformationc) Optic neuritisd) Pontine lesion
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.
ac
a
ab
bc