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


CONCLUSIONS
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.
*Department of Neurosurgery, and ‡Center for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, Illinois.
Sepideh
S
Amin-Hanjani
Amritha
A
Singh
Hashem
H
Rifai
Keith R
KR
Thulborn
Ali
A
Alaraj
Victor
V
Aletich
Fady T
FT
Charbel
D000328:Adult; D002533:Cerebral Angiography; D002548:Cerebral Revascularization / Q000379:methods*; D006801:Humans; D018810:Magnetic Resonance Angiography; D008875:Middle Aged; D009072:Moyamoya Disease / Q000000981:diagnostic imaging* / Q000601:surgery*; D012189:Retrospective Studies