The presence of neurological clinical manifestations suggestive of a posterior cerebral circulation stroke in association with the finding of areas of restricted diffusion on MRI of vertebrobasilar vascular distribution, as well as a contrast media filling defect of the basilar artery on DSA are the most important findings to support an acute basilar artery occlusion (BAO). 

However, other findings favoring acute BAO such as the hyperdense basilar artery on non-contrast CT, as well as contrast filling defects of the basilar artery on CTA and DSA in the presence of an unremarkable anterior cerebral circulation were also in keeping with acute BAO.

Lastly, acute BAO has been described to be tied to a very high mortality and poor functional outcome, even when successful arterial rencalization is achieved. The fact that this patient went on to develop significant cytotoxic edema, obstructive hydrocephalus, and brain herniation leading to her death despite having been adequately treated via mechanical thrombectomy is also in keeping with the clinical course of acute BAO.