Progression of severe basilar artery stenosis to occlusion is a well-recognized phenomenon, but regression of a severe basilar artery atherothrombotic lesion has not been described previously.

Two patients with a symptomatic severe basilar artery occlusive lesion showed substantial angiographic improvement after 3 months of anticoagulation in one case and 4 months after superficial temporal artery to superior cerebellar artery bypass in the other case. The findings in these cases indicate that clinical improvement in similar cases may reflect recanalization of a basilar artery occlusive lesion. The uncertain natural history and potential for regression of symptomatic basilar artery atherothrombosis make the authors hesitant to recommend posterior circulation revascularization immediately after such lesions are first demonstrated angiographically ¹⁾.