Background: Moyamoya disease (MMD) involves progressive stenosis of intracranial arteries and
compensatory collateral vessel formation. While the single-barrel STA-MCA bypass remains
a cornerstone treatment, modifications such as the double-barrel bypass offer potential
advantages via higher postoperative flow and draw, although a longer operative time
is also required. Currently, there is a lack of consensus regarding the impact of
double-barrel bypass techniques on the incidence of postoperative stroke after direct
bypass for adult and pediatric patients with MMD.
Methods: We performed a PRISMA-compliant systematic review of MEDLINE and Embase from inception
through March 2024. A supplemental bibliography review in Google Scholar was also
performed to screen for additional candidate citations not captured by the primary
screen. Among 62 candidate citations, 16 underwent full-text review, and 5 met study
criteria and were included in a meta-analysis of proportions using random-effects
modeling. The supplemental screen yielded two candidate citations that were ultimately
included in the meta-analysis.
Results: The pooled odds ratio (OR) for postoperative stroke after single-barrel bypass as
compared to double-barrel bypass was 1.19 (95% CI = 0.3–4.73). Studies reported either
median or mean follow up times. Mean follow-up time was 20.2 months (range, 7–190)
based on data from two studies reporting mean follow-up times and two studies reporting
median follow-up times. One study did not report follow up time. Inter-study heterogeneity
was minimal (I
2 = 0%). In order to assess for latent confounding factors due to the inclusion of
mixed study populations that were majority MMD, a supplemental sensitivity analysis
was performed excluding Takanari et al (2015) and Cherian et al (2018). This yielded
a pooled OR of 1.12 (95% CI = 0.23–5.46), validating the findings of the primary analysis.
A second sensitivity analysis excluding studies with mean or median follow-up times
less than 12 months yielded similar results (OR: 1.16 (95% CI = 0.05–27.97). Funnel
plots and Egger’s test were negative for publication bias.
Conclusion: We report a novel meta-analysis comparing single-barrel and double-barrel techniques
for direct extracranial–intracranial bypass for the treatment of MMD. Double-barrel
techniques do not appear to provide additional postoperative stroke protection; however,
given the relatively limited follow-up times, these results may under-represent the
long-term benefits of a double-barrel bypass technique. Well-controlled long-term
studies are needed to better interrogate the optimal treatment strategies for this
vulnerable patient population.
