How I do it: combined direct (STA-MCA) and indirect (EDAS) EC-IC bypass

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EC-IC bypass for the treatment of a hypoperfused hemisphere is currently the treatment of choice for symptomatic moyamoya patients. Use of the combination of direct (STA-MCA) and indirect (an STA branch lay-on bypass and flipped dural flaps; EDAS) EC-IC bypass is advocated as the optimal treatment option as it allows immediate augmentation of flow in the postoperative period while allowing the brain to acquire additional indirect flow in the long term.


We describe the technical nuances of a combined direct and indirect bypass in a 41-year-old woman with moyamoya syndrome diagnosed with transient ischemic attacks (TIAs) and cognitive decline.


Combined direct and indirect bypass option should become a familiar treatment modality among vascular neurosurgeons.

Key Points

(1) Pay critical attention to not injuring the Superficial Temporal Artery, Parietal branch (STApb) while turning the skin incision anteriorly. Use the operating microscope to dissect the STApb.

(2) Always mark the origin of the Superficial Temporal Artery, Frontal branch (STAfb) on the skin so that its location can be anticipated during STApb dissection.

(3) When no frontal branch is available or if the frontal branch is of poor quality, the STApb can be used as a direct or indirect graft.

(4) A craniotomy should be done 2–3 cm posterior to the course of the STApb to allow for adequate exposure for an indirect graft.

(5) Manipulation of the donor vessels should be done with extreme care as spasm of the artery or intraluminal thrombosis may occur. Low cut flow in the direct graft should be interpreted with caution as vasospasm can result in significant temporary reduction of flow.

(6) Aggressive distal dissection of the direct donor is a must. The distal 1–2 cm of the vessel should be cleaned of any loose tissue and be fishmouthed prior to anastomosis.

(7) A blood-free field is mandatory. Perforators on the backside of the recipient should be sacrificed and cut to avoid backbleeding into the anastomotic segment during temporary occlusion.

(8) When recirculating after the anastomosis has been completed, open the temporary clips on the recipient first. Backflow into the donor segment confirms a patent anastomosis.

(9) Utilization of intraoperative angiography is not necessary as long as one utilizes flow measurements and ICG angiography.

(10) Take great care with the bone flap reconstruction and the skin closure as the grafts can easily be compressed or sutured. Create a generous craniectomy in the bone flap to avoid any graft compression.

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Correspondence to David J. Langer.

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Nossek, E., Langer, D.J. How I do it: combined direct (STA-MCA) and indirect (EDAS) EC-IC bypass. Acta Neurochir 156, 2079–2084 (2014).

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  • Combined
  • Direct
  • EC-IC Bypass
  • EDAS
  • Moyamoya