Abstract
Through the angiographical study of the progress in pediatric moyamoya disease, a typical clinical model of a chronic progressive ischemia in the young brain, we proposed a hypothesis that the brain is surrounded by several systems of collateral networks arranged in rather concentric fashion and that the anatomical characteristics of the head prevent the use of some of the systems as collaterals at early stage of cerebral ischemia. The anatomical characteristics include the presence of a watery layer of subarachnoid space between the cortical and dural vessels and a bony closed box intervening between the dural and scalp arterial networks. They isolate the brain from the abundand blood flow of the external carotid system as if they were the moat (subarachnoid fluid layer) and the walls (skull) of a castle.
Based upon these concepts, we have developed a surgical procedure, the encephalo-duro-arterio-synangiosis (abbreviated as EDAS) for the treatment of moyamoya disease in children. This operation surmounts the above mentioned two obstacles to the formation of the collaterals to the brain via the external carotid system, by perforating the castle walls and bridging the moat by wound granulation without injuring the already formed natural collarerals.
We performed this operation on 70 sides in 38 pediatric moyamoya patients and various degree of revascularisation of the brain was obtained in 100% of the cases with proportionate improvements of the symptoms.
According to the philosophy as stated above, EDAS should be available not only for the moyamoya disease but also for the chronic ischemia to the brain other than moyamoya disease. Accordingly, we prformed this operation to a patient who presented with acute infantile hemiplegia and revealed to have a complete obstruction of the left carotid artery at C1 portion. This patient showed marked revascularisation of the left hemisphere by the implanted left STA 10 months after the operation. This is one of the clinical evidences that spontaneous EC/IC anastomoses can be formed in other ischemic condition than moyamoya disease just by surmounting the above mentioned two obstacles by surgical procedure.
We conclude that an indirect EC/IC anastomotic procedure like EDAS can be applicable to other cerebrovascular ischemic conditions than moyamoya disease.
