γγThe tip of the basilar artery divides into the posterior cerebral artery and the superior cerebellar artery, which mainly supply the midbrain, thalamus, upper cerebellum, medial temporal lobe and occipital lobe.γγ(1) Eye movement and pupillary abnormalities: including partial or complete paralysis of one or both of the arteriolar nerves, manifested by impaired vertical eye movements, inability to see up or up or down, (2) Impaired consciousness: may be transient or last for several days, or may be recurrent, (3) contralateral hemianopia or cortical blindness, (4) there may be severe memory impairment (5) a few patients may have brainstem hallucinations, which often occur at dusk .