Proximal ligationとSTA-MCA bypassで治癒し得た外傷性頭蓋外内頸動脈解離性動脈瘤の1例

A case of traumatic extracranial internal carotid artery dissecting aneurysm treated by proximal ligation and STA-MCA bypass

I．はじめに

　外傷性頭蓋外内頸動脈瘤は，高位に位置することが多いため直達手術は困難であり^4,13），またその大部分が解離性動脈瘤であるため，血行再建術を併用した治療法が中心となる．今回われわれは，頸部内頸動脈結紮と浅側頭動脈—中大脳動脈バイパス（STA-MCA bypass）を併用し，治癒し得た外傷性頭蓋外内頸動脈解離性動脈瘤の1例を経験したので，その発生機序，治療法について考察を加え報告する．

We present a case with the traumatic extracranial in-ternal carotid artery dissecting aneurysm.

A 21-year-old man was involved in a motorcycle acci-dent, resulting in multiple injuries but no apparent head and neck injuries. Head CT was normal on his admis-sion. He was discharged from his local hospital 3 weeks after the accident without any neurological deficits.

Five weeks after the accident, he suddenly presented with a motor aphasia and a right hemiparesis. CT and MRI showed infarctions in the left para-Sylvian and the left angular areas.

The patient was treated with urokinase and osmotic diuretics, but these were not effective and she died on the eleventh day after admission. Autopsy revealed that the bilateral internal carotid artery was occluded by fresh thrombi at the carotid bifurcation. The mitral valve was thickened by fibrous adhesion, and this was thought to indicate mitral stenosis. MRI before onset had shown flow void sign in the bilateral internal caro-tid artery. From the clinical course, and radiological and autopsy findings, we consider this case to be one of simultaneous bilateral carotid occlusion due to car-diogenic thrombi. Previous cases of bilateral carotid occlusion are reviewed and discussed. Angiography showed a left ex-tracranial carotid artery dissecting aneurysm at the level of C1 vertebral arch. The patient was initially managed by an anticoagulant agent, but he suffered from another transient ischemic attack due to distal embolism from the aneurysm. Balloon occlusion test of the left ICA was performed under monitoring EEG, SEP. Mean stump pressure (MSP) revealed 60mmHg, and MSP/Mean systematic blood pressure revealed 67%.

We judged that the left ICA ligation was a safe method to treat this patient, however, considering the patient's age and the side of the lesion, left STA-MCA bypass and ligation of the left ICA were carried out in one stage.

Postoperatively, the patient did not show any cere-bral ischemic complications and angiography showed disappearance of the aneurysm and patency of the bypass. The left MCA territories were filled well by cross circulation and the bypass.