Can a small posterior communicating artery cause headaches?

Yes, a small posterior communicating artery (PComA) can cause headaches. The PComA is a small blood vessel that connects the internal carotid artery to the posterior cerebral artery. It is located at the base of the brain, near the pituitary gland. If the PComA is too small, it can cause insufficient blood flow to the brain, which can lead to headaches. Additionally, a small PComA can also cause compression of the surrounding nerves, which can also lead to headaches.