The effectiveness of indirect revascularization on haemorrhagic moyamoya disease and the activities that trigger intracranial haemorrhage: a comprehensive study

PURPOSE: Revascularization surgery is the standard treatment for moyamoya disease (MMD); however, data on the effectiveness of indirect revascularization (IR) in haemorrhagic MMD (hMMD) are limited. This study aims to analyse the effectiveness of IR on hMMD. The activities that triggered the intracranial haemorrhage (ICH) were also identified to prevent the catastrophic haemorrhage in moyamoya patients. MATERIALS AND METHODS: From February 2016 to May 2025, 189 IR procedures were performed on 137 moyamoya patients by a single neurosurgeon. A standardized time-to-peak (TTP) scoring system, ranging 0-14 points, on magnetic resonance perfusion images and Matsushima grading on postoperative angiogram were used to evaluate the revascularization effect in all patients. Patients presented with ICH were included. Clinical and neuroimaging outcomes and risk factors for ICH were analysed. RESULTS: Ten consecutive patients were identified and included. The mean age of the first ICH was 36.1 ± 10.2 years. IR was performed in 14 cerebral hemispheres, however, two hemispheres were excluded due to short follow-up period. The mean age at surgery was 39.7 ± 12.2 years, and the average clinical follow-up period was 35.2 months. There were no haemorrhagic events occurring beyond the six-month postoperative period. The mean TTP scores improved from 9.25 ± 4.37 to 12.5 ± 1.57 after revascularization. Eight of 10 revascularized hemispheres that underwent postoperative angiographic study showed satisfactory revascularization (Matsushima grade A or B). The other two hemispheres that did not receive angiographic follow-up demonstrated a greater increase in TTP scores than those in Matsushima grade A. High-altitude exposure and alcohol-induced vomiting are two activities that triggered acute ICH in four of the 10 moyamoya patients. CONCLUSIONS: IR is a viable treatment for hMMD, providing satisfactory perfusion improvement and acceptable mid-term outcomes. High-altitude exposure and alcohol-induced vomiting should be avoided in patients with MMD.