What patient factor led to performing a direct bypass rather than an indirect bypass for treatment of moyamoya?

The honest answer is that the evidence for selecting a direct or indirect bypass is limited and imperfect. There are no large randomized controlled trials and most data comes from retrospective cohort studies and meta-analyses. The key factors favoring direct bypass for moyamoya are age, cerebrovascular reserve, and size of the donor and recipient arteries. That said, I have a bias for direct bypass when possible. The best available evidence comes from meta-analyses, with the most cited being a 2022 Stroke publication (Nguyen et al., PMID 36134563) pooling comparative studies. It found that direct and combined bypass were superior to indirect bypass alone for:

• Early and late ischemic stroke reduction
• Late intracerebral hemorrhage
• Favorable ...