Temporary Steno-occlusive Change in the Donor Artery During Mouth Opening (Big Bite Ischemic Phenomenon) After Superficial Temporal Artery to Middle Cerebral Artery Bypass in Adult Patients with Moyamoya Disease and Atherosclerosis.

BACKGROUND: Superficial temporal artery (STA) to middle cerebral artery (MCA) bypass is one of the most common surgical procedures performed for direct extracranial (EC) to intracranial (IC) bypasses. We describe a temporary steno-occlusive change in the STA that was caused by mouth opening after the STA-MCA bypass (so-called big bite ischemic phenomenon) in an adult patient with moyamoya disease. The aim of this study was to assess the incidence of this phenomenon in patients with atherosclerosis.

METHODS: Adult patients with ischemic cerebrovascular disease who underwent STA-MCA anastomosis were included in this study. Ultrasound examinations were postoperatively performed on 62 sides to determine whether mouth opening affected the blood flow of the donor STA and resulted in any ischemic symptoms within 1 min. Computed tomography angiography was performed during both mouth opening and closing when blood flow changes were recognized in the donor STA.

RESULTS: During wide mouth opening, steno-occlusion of the donor STA occurred in 8 of the 62 affected sides (12.9 %), which included 3 of the 47 sides (6.4 %) in patients with atherosclerosis and 5 of the 15 sides (33.3 %) in patients with moyamoya disease.

CONCLUSION: Steno-occlusion of the donor STA occurred during wide mouth opening in 12.9 % of the sides of adult patients who had undergone STA-MCA anastomosis. This phenomenon was more common in patients with moyamoya disease than in patients with atherosclerosis.