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Combined Direct and Indirect Bypass for Moyamoya: Quantitative Assessment of Direct Bypass Flow Over Time

Amin-Hanjani, Sepideh MD*; Singh, Amritha BS*; Rifai, Hashem BS*; Thulborn, Keith R. MD, PhD; Alaraj, Ali MD*; Aletich, Victor MD*; Charbel, Fady T. MD*

doi: 10.1227/NEU.0000000000000139
Research-Human-Clinical Studies

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 to12 ± 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.

ABBREVIATIONS: EDAS, encephaloduroarteriosynangiosis

MCA, middle cerebral artery

QMRA, quantitative magnetic resonance angiography

STA, superficial temporal artery

*Department of Neurosurgery, and

Center for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, Illinois

Correspondence: Sepideh Amin-Hanjani, MD, FAANS, FACS, FAHA, Department of Neurosurgery, University of Illinois at Chicago, Neuropsychiatric Institute, Room 451N, 912 S Wood St, M/C 799, Chicago, IL 60612. E-mail:

Received February 09, 2012

Accepted August 09, 2013

Copyright © by the Congress of Neurological Surgeons