Posterior Communicating Artery

The posterior communicating artery is a small blood vessel which lies near the base of the brain and bridges the larger posterior cerebral arteries. These arteries, together with the anterior cerebral arteries and anterior communicating artery, form a ring of blood vessels called the Circle of Willis.

The posterior communicating artery supplies much of the blood to the hippocampus and nearby structures in the medial temporal lobe.

Posterior communicating artery Aneurysm

A stroke or aneurysm which impedes blood flow through this artery can deprive and damage these regions, which are critical for the formation of new memory. The result can be anterograde amnesia: the inability to form new memories.

If the damage is relatively limited to the hippocampus and nearby structures, there may be little or no effect on intelligence, attention, judgment or personality; only memory is seriously impaired.

Further Reading:

Article : "VASCULAR DEMENTIA"