PMC8769435_01
Intraoperative view of left superficial temporal artery (STA)-middle cerebral artery (MCA) bypass (A). The frontal branch of the STA was anastomosed to the M4 segment of the left MCA. The arrow indicates the site of anastomosis. Indocyanine green video-angiography confirmed the patency of the bypass (B). Magnetic resonance (MR) angiography 1 day after the surgery, indicating left STA-MCA bypass as high-signal intensity (arrow) (C). [123I] iodoamphetamine single-photon emission computed tomography (123I-IMP-SPECT) before and 1 and 7 days after surgery, showing local cerebral hyperperfusion and concomitant decrease in the cerebral blood flow (CBF) at the splenium (D). The numbers represent the quantitative CBF values (ml/100 g/min) by the auto-radiographic method. Values in the parenthesis indicate the relative CBF ratio compared with the preoperative value. Temporal profile of MR images. Diffusion-weighted image (DWI) at 2 days after the surgery (E), DWI (F) and apparent diffusion coefficient (G) at 5 days after the surgery, and T2-weighted image (H) at 14 days after the surgery, together indicating the reversible ischemic lesion at the splenium. Catheter angiography before (I) and after (J) the surgery, showing regression of the posterior pericallosal artery after the surgery.
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Intraoperatively, the stump of the left STA was anastomosed to the M4 segment of the left MCA (Fig. 1A and 1B). Postoperative magnetic resonance (MR) angiography confirmed patent STA-MCA bypass (Fig. 1C). Although asymptomatic, local CBF increased by over 150% from the preoperative CBF value, and a paradoxical decrease in the CBF value at the splenium was evident on N-isopropyl-p-123I-IMP-SPECT (Fig. 1D) on postoperative day (POD) 1, while no parenchymal lesions were found on MR imaging (Fig. 1E). Diffusion- weighted MR imaging revealed a high-signal- intensity lesion with a low apparent diffusion coefficient at the splenium (Fig. 1F and 1G). We confirmed the amelioration of local CHP and the paradoxical decrease in the CBF at the splenium by 123I-IMP-SPECT on POD 7 (Fig. 1D), and of the splenium lesion on POD 14 on MR imaging (Fig. 1H). Catheter angiography 2 months after revascularization surgery confirmed the marked regression of posterior-to-anterior collaterals via the posterior pericallosal artery, suggesting the dynamic watershed shift between blood flow supplies from the posterior and anterior circulation (Fig. 1I and 1J).