Delayed reopening of a superficial temporal artery to middle cerebral artery bypass graft occluded by a white thrombus during surgery

Background: To the authors’ knowledge, reopening of a superficial temporal artery to middle cerebral artery (STA-MCA) bypass graft occluded by a white thrombus during the procedure and was observed several months after the surgery is relatively rare. Case Description: The authors encountered a case of moyamoya disease in an Asian female in her third decade of life, in whom a bypass recipient vessel was occluded by a white thrombus during surgery and remained occluded on magnetic resonance angiography (MRA) performed up to 6 weeks after the procedure. However, recanalization was confirmed by MRA performed 4 months after surgery. MRA performed 10 and 19 months after surgery revealed that the bypass vessel had grown thicker, and the ischemic symptoms experienced by the patient also improved. Conclusion: Whether this lesion is explained by reopening or angiogenesis, its pathophysiology remains controversial. The uninterrupted connection of occluded bypass vessel in STA-MCA bypass surgery in conjunction with surgical strategy of single bypass using only parietal branch of STA as donor and preserving blood flow of frontal branch to scalp may have made a positive impact on promoting the development of extracranial-intracranial bypass anastomosis in the chronic phase and should be considered.