[Three cases of carotid anterior cerebral anastomosis]

Three cases are presented with rare carotid-anterior cerebral anastomosis (anomalous ACA) originating from the internal carotid artery at the level of the origin of the ophthalmic artery, running first underneath and then between both optic nerves, and finally joining the anterior communicating artery. Case 1 (47 year-old woman) and case 2 (56 year-old man) were both admitted with subarachnoid hemorrhage from a ruptured aneurysm, which was located at the anomalous ACA (carotid-ACA anastomosis). Case (61 year-old man) was diagnosed as having left occipital intracerebral hematoma on CT, and bilateral anomalous ACA was found on angiograms. This anomalous ACA is very rare; only 21 cases have been reported in the literature. Several synonyms have been proposed as follows: 1) interoptic course of the anterior cerebral artery (ACA), 2) interoptic course of ACA, 3) an anomalous branch of the internal carotid artery (ICA) and 4) an anastomosis between the ICA and the ACA (carotid-ACA anastomosis). In cases with this carotid-ACA anastomosis, coexisting intracranial aneurysm has been reported. However, this is the first report of ruptured aneurysm located at the anomalous ACA itself. Case 1 and 2 were operated on through the ipsilateral pterional approach and the aneurysm was successfully clipped. Postoperative course was uneventful in each case. Case 3 was treated conservatively. From the angiographical and operative findings, we prefer to use "carotid-anterior cerebral artery anastomosis" as the medical terminology best suited to describe this condition.