Changes of flow pattern after extracranial intracranial arterial bypass in patients with artherosclerotic cerebral ischemia and moyamoya disease

동맥경화성 뇌허혈 환자 및 모야모야병 환자들에서 두개강 내-외 혈관문합수술 후 혈류 흐름의 변화

Objective : Extracranial-intracranial arterial bypass (EIAB) has proved to be useful in selected patients with artherosclerotic cerebral ischemia and moyamoya disease. But neurological deterioration (ND) after EIAB has occasionally been reported in spite of successful EIAB. We have performed EIAB in 150 patients with artherosclerotic cerebral ischemia and moyamoya disease during the recent 8 years. We analyzed the patients who exhibited ND after successful EIAB was performed for a selected group of patients with artherosclerotic cerebral ischemia and moyamoya disease. Methods : Among 150 patients, the cause of the hemodynamic ischemia was atherosclerotic in 90 and moyamoya disease in 60. Eighteen patients experienced ND after successful EIAB. There were 14 patients with temporary neurologic deficit and 5 patients had a permanent deficit. We divided these 18 patients into two groups. Group 1 revealed relative hyperperfusion of a chronically hypoperfused area of the brain after successful EIAB. Group 2 showed hypoperfusion of the brain by the change of the flow pattern after successful EIAB. Results : Of the 18 patients who experienced ND after successful EIAB, 8 patients belonged to group 1 and 10 patients belonged to group 2. We divided group II into four subgroups according to angiographic flow patterns. The first subgroup (2 patients) showed delayed filling of one division out of two divisions of the middle cerebral artery. The second subgroup (3 patients) showed collision between the orthograde flow and the retrograde flow from the grafted vessel, which resulted in more profound hypoperfusion. The third subgroup (2 patients) exhibited a complete occlusion of the preoperative stenotic artery. The fourth subgroup (3 patients) included the cases with marginal hypoperfusion in the periphery of the perfused region from the grafted extracranial artery. Conclusion : EIAB is a reliable, reasonably safe method for establishing new pathways of collateral circulation to the brain. However, this operation can have potential complications according to the relative hyperperfusion or hypoperfusion that's due to the altered flow pattern after the bypass.