A 23-year-old female presented with motor TIA. Angiography disclosed nearly total occlusion of the distal ICA and severe MCA stenosis on the right side (Fig. 14.2a). Single-photon emission computed tomography (SPECT) showed decreased basal perfusion on the right side in the resting state and decreased vascular reserve capacity in the acetazolamide challenge test (Fig. 14.2b, c). The patient underwent STA–MCA bypass with EGDS on the right side. Follow-up angiography revealed anastomotic patency of the STA–MCA (Fig. 14.2d). Postoperative SPECT, 6 months after the procedure, showed improved basal perfusion with vascular reserve capacity (Fig. 14.2e, f). The patient remained asymptomatic during the follow-up of 6 months.