Abstract
A case of a true posterior communicating artery aneurysm is presented. A 51-year-old woman was admitted to our hospital with sudden severe headache. Subarachnoid hemorrhage in the left Sylvian fissure was recognized on CT scan and an aneurysm, 4×5mm in size, was revealed by angiography on the left posterior communicating artery (P co A) itself 5 mm distal from the origin of P co A. During the surgery, the aneurysm was found projecting toward out of upward on the curved portion of P co A, 5mm distal from the carotid artery. The neck of the aneurysm was narrow, but since a few perforating arteries were found very close to the neck, the neck clipping sparing them was very difficult. The patient was discharged from the hospital without neurological deficit.
The incidence of true P co A aneurysm is rare with reports of 0-3.3% among all intracranial aneurysms. As the surgical treatment of this aneurysm, proximal ligation of the carotid artery or the posterior communicating artery is not effective to prevent the rerupture of the aneurysm because rich collateral blood flow comes from the circle of Willis. In saccular aneurysms, neck clipping is performed with relative ease, but careful attention must be paid not to injure the perforating arteries from P co A close to the neck, which feed the thalamus, hypothalamus, internal capsule, etc. In some cases, trapping of aneurysm must be performed for unavoidable reasons such as broad aneurysmal neck or fusiform aneurysm. However, since the blood flow of perforating arteries is interrupted by this procedure, the appearance of severe neurological deficits is not rare.
