MRI - Infarct, cerebellar: This 80-year-old man presented with difficulty walking and nausea. Examination revealed left-beating nystagmus and left-sided appendicular and truncal ataxia. The FLAIR-weighted axial MR image on the left shows high signal intensity within the left cerebellum in the distribution of the posterior inferior cerebellar artery. The lesion exerts some mass effect with slight distortion of the fourth ventricle. The corresponding diffusion-weighted image on the right shows high signal intensity within the same distribution.