ANALYZING THE EARLY CLINICAL AND IMAGING OUTCOMES OF STA-MCA BYPASS SURGERY VIA THREE-DIMENSIONAL VOLUMETRIC MEASUREMENT IN PATIENTS WITH INTRACRANIAL ATHEROSCLEROSIS

Background: Intracranial atherosclerotic disease (ICAD) is a leading cause of ischemic stroke and remains associated with high morbidity and mortality. Although recent studies suggest that superficial temporal artery to middle cerebral artery (STA–MCA) bypass may benefit patients with hemodynamic compromise, its clinical efficacy remains a matter of controversy. Objective: We aimed to evaluate the effectiveness of STA-MCA bypass surgery in patients with ICAD, focusing on both clinical outcomes and cerebral hemodynamic imaging using 3D volumetric analysis. Methods: Six patients with ICAD who underwent STA-MCA bypass surgery were selected using predefined criteria. Clinical outcomes were retrospectively reviewed using the National Institutes of Health Stroke Scale (NIHSS) and the Modified Rankin Scale (mRS). Imaging outcomes were examined by analyzing the brain lesion area and perfusion using computed tomography perfusion (CTP). Statistical significance was analyzed using paired rank-sum and Friedman tests. Results: In all cases, the primary diagnosis was ischemic stroke with significant stenosis of the internal carotid or middle cerebral artery. All patients demonstrated patent grafts, and no ischemic events occurred within 30 days after surgery. However, one patient had a postoperative asymptomatic acute subdural hematoma. All patients showed stable or improved neurological and functional outcomes after 30 days. Median NIHSS scores remained stable (pre-op 1.50 [0.00–7.50] vs. 30 days 1.50 [0.00–5.25], p = 0.368), while median mRS scores showed a non-significant trend toward improvement (pre-op 1.50 [0.75–3.50] vs. 30 days 1.00 [0.00–3.00], p = 0.082). Volumetric perfusion analysis demonstrated reductions in lesion volumes for CBF (66.40 [43.35-145.70] → 28.55 [19.85-111.28] mL), MTT (220.75 [101.60-337.05] → 143.00 [39.93-242.35] mL), and Tmax (265.45 [145.53-333.63] → 212.40 [101.08-260.20] mL) on CT perfusion immediately postoperatively and at short-term follow-up, although these changes did not reach statistical significance (p = 0.068 for all). CBV lesion volume also decreased slightly (1.15 [0.25–5.51] → 0.00 [0.00–2.54] mL, p = 0.109). Conclusion: Our results suggest that STA-MCA bypass surgery may offer clinical and hemodynamic benefits for ICAD patients who are unresponsive to medical and endovascular treatments. In this study, improved NIHSS and mRS scores, as well as hemodynamic parameters, were observed using CTP. Performing volumetric measurements may support the assessment of imaging outcomes. Given the small sample size and short follow-up period, these findings should be interpreted with caution. Large-scale and long-term studies are warranted to validate our findings and optimize ICAD treatment strategies.