Combined direct and indirect bypass for moyamoya: quantitative assessment of direct bypass flow over time

Neurosurgery. 2013 Dec;73(6):962-7; discussion 967-8. doi: 10.1227/NEU.0000000000000139.


Background: The optimal revascularization strategy for symptomatic adult moyamoya remains controversial. Whereas direct bypass offers immediate revascularization, indirect bypass can effectively induce collaterals over time.

Objective: Using angiography and quantitative magnetic resonance angiography, we examined the relative contributions of direct and indirect bypass in moyamoya patients after combined direct superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass and indirect encephaloduroarteriosynangiosis (EDAS).

Methods: A retrospective review of moyamoya patients undergoing combined STA-MCA bypass and EDAS was conducted, excluding pediatric patients and hemorrhagic presentation. Patients with quantitative magnetic resonance angiography measurements of the direct bypass immediately and > 6 months postoperatively were included. Angiographic follow-up, when available, was used to assess EDAS collaterals at similar time intervals.

Results: Of 16 hemispheres in 13 patients, 11 (69%) demonstrated a significant (> 50%) decline in direct bypass flow at > 6 months compared with baseline, averaging a drop from 99 ± 35 to 12 ± 7 mL/min. Conversely, angiography in these hemispheres demonstrated prominent indirect collaterals, in concert with shrinkage of the STA graft. Decline in flow was apparent at a median of 9 months but was evident as early as 2 to 3 months.

Conclusion: In this small cohort, a reciprocal relationship between direct STA bypass flow and indirect EDAS collaterals frequently occurred. This substantiates the notion that combined direct/indirect bypass can provide temporally complementary revascularization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cerebral Angiography
  • Cerebral Revascularization / methods*
  • Humans
  • Magnetic Resonance Angiography
  • Middle Aged
  • Moyamoya Disease / diagnostic imaging*
  • Moyamoya Disease / surgery*
  • Retrospective Studies