[Basilar artery occlusion after STA-SCA anastomosis; case report]

A case of basilar artery occlusion after STA-SCA bypass surgery is reported. The patient was a 56 year old male and presented a TIA of vertigo and speech disturbance. The preoperative angiogram revealed severe stenosis of the basilar artery in its midportion between the bifurcation of AICA and that of SCA. After surgery, the patient's clinical course was uneventful, but the angiogram showed that the previous stenotic segment of the basilar artery had been occluded and the distal portion of the basilar artery and its branches were perfused through the widely-patent STA-SCA bypass. About 6 months after the operation, the patient developed a pontine infarction in the right paramedian region, which was confirmed on MRI. The angiogram revealed that the occlusion of the basilar artery extended further proximally to a point just distal to the bifurcation of AICA. So it was suspected that the perforating branches of the basilar artery to the pons were occluded with the extension of the thrombosis of the basilar artery. The hemodynamic changes associated with the EC-IC bypass was thought to be responsible for the occlusion of the previous stenotic lesion.