A Case of Non-junctional Posterior Communicating Artery Aneurysm Forming Kissing Aneurysms with an IC-PC Aneurysm

We report a case of unruptured “true posterior communicating artery” (Pcom) aneurysm associated with ruptured internal carotid-posterior communicating artery (IC-PC) aneurysm in a 72-year-old woman, treated successfully by direct surgery. Left internal carotid angiography and three-dimensional CT angiography revealed an IC-PC aneurysm 8 mm in maximum diameter protruding inferolaterally, with a small bulge on the Pcom side which was regarded as part of the IC-PC aneurysm. Intraoperative inspection revealed that the prominence initially thought to be part of the IC-PC aneurysm was a true Pcom aneurysm forming a kissing aneurysm pair with the IC-PC aneurysm. The 2 aneurysms were completely dissected and both were clipped. This is the first reported case of kissing aneurysms of the IC-PC aneurysm and true Pcom aneurysm. A true Pcom aneurysm forming kissing aneurysms with IC-PC aneurysm, as in the present case, may be difficult to diagnose preoperatively. Careful intraoperative observation and complete dissection are therefore important for a good outcome.