Assessment of donor-vessel after STA-MCA bypass for moyamoya disease using handheld Doppler to confirm bypass patency and predict perioperative hyperperfusion

The study included 12 hemispheres of 9 patients with moyamoya disease who underwent direct-indirect revascularization. The parameters (peak systolic velocity (PSV), mean flow velocity (MV), resistance index (RI), flow volume (FV)) of the superficial temporal artery (STA) on the operated side were measured using a handheld Doppler before and after surgery in all the patients. The examination was conducted in a similar manner on postoperative day (POD)1 on 9 sides of 7 patients except for 3 sides of the first 2 patients. Patency of the superficial temporal artery-middle cerebral artery (STA-MCA) bypass was confirmed by magnetic resonance angiography (MRA) performed on all 12 sides of 9 patients within the first 2 PODs. There was a statistically significant increase in the PSV (<i>p</i> = 0.0201) and the MV (<i>p</i> = 0.0110) and a decrease in the RI (<i>p</i> = 0.0177) in the STA after surgery when compared with those measured before surgery. None of the changes from the immediate postoperative period to POD1 were statistically significant. Postoperative transient neurological events (TNEs) occurred in 3 patients (25 %) in the first 2 weeks, and all of them were attributed to hyperperfusion. The FV of the three sides associated with TNEs was significantly higher than that of the nine sides that were not (<i>p</i> = 0.0273). From the early stage after moyamoya disease bypass surgery, it was clarified that the parameter of the STA changed in which the PSV and the MV increased and the RI decreased. It was clarified that the increase in the FV, which is the blood flow rate that flows through the STA in the immediate postoperative period, may be a predictor of the development of hyperperfusion during the perioperative course.