Wide Arterial Sparing Encephalo-Duro-Synangiosis for Moyamoya: Surgical Technique and Outcomes

Abstract

Background: Moyamoya is managed by surgical revascularization, but no standardized method has yet been universally adopted.

Objective: To describe a new indirect bypass technique for pediatric moyamoya, wide arterial sparing encephalo-duro-synangiosis (WASEDS), which provides a much wider area of revascularization with minimal compromise to the middle meningeal arterial tree compared with traditional procedures. Initially used as a salvage technique after failed encephalo-duro-arterio-synangiosis, its success later motivated its use as a first-line procedure.

Methods: Clinical and radiographic records of patients who underwent WASEDS for moyamoya from 2009 to 2020 were reviewed. Brain perfusion relative cerebral blood volume on the side of the WASEDS procedure was calculated. Two-tailed paired t tests were performed to identify the statistically significant differences ( P ≤ .05).

Results: WASEDS was successfully performed on 8 patients for a total of 14 cerebral hemispheres. Age ranged from 2 to 25 years. There were no mortalities. The average clinical and radiographic follow-up was 49.79 months (range 2-126 months), demonstrating improvement in neurological condition and no postoperative stroke and significant diminution or cessation of transient ischemic attacks in all patients. Relative cerebral blood volume increased 9.24% after the WASEDS procedure ( P = .012). There were no neurological complications. There were 2 pseudomeningoceles related to the extensive dural openings.

Conclusion: WASEDS is a safe and effective indirect revascularization technique for both primary and salvage techniques. It provides an extensive area of cortical revascularization with no compromise of the middle meningeal vasculature and subjective reports of early improvement in cognition and behavior. The main disadvantage is elevated risk of pseudomeningocele secondary to the large craniotomy.

FIGURE 1.

Surgical images of the final product of wide arterial sparing encephalo-duro-synangiosis. Dural slits along most of the large-sized and medium-sized middle meningeal artery branches were created, followed by arachnoid opening (see Video).

FIGURE 2.

Post-wide arterial sparing encephalo-duro-synangiosis angiography performed on patient 7. A, AP and B, lateral right ECA injections and C, AP and D, lateral left ECA injections. Diagnostic images demonstrate extensive collateral formation, left greater than right. The cause of the asymmetry is unclear and may not only depend on technical issues but also on preoperative ischemia severity and other biological factors. Regardless, both hemispheres showed improved perfusion, and the patient had 1 postoperative transient ischemic attack, otherwise made significant clinical improvement. AP, anterior-posterior; ECA, external carotid artery.

FIGURE 3.

MR perfusion images of patient 1. Pre-WASEDs and post-WASEDS CBV perfusion maps with increased bilateral CBV post-WASEDs (yellow arrows). CBV, cerebral blood volume; WASEDS, Wide arterial sparing encephalo-duro-synangiosis.

FIGURE 4.

Three-year-old boy (case 8) with several months of intractable headaches, intermittent emesis, and severe anger issues, all of which improved markedly within weeks of bilateral wide arterial sparing encephalo-duro-synangiosis, and progressively resolved over 2 years. Note significant enlargement of the middle meningeal arteries (A, preoperative magnetic resonance angiography and B, postoperative magnetic resonance angiography).

FIGURE 5.

MR perfusion images of patient 1. Pre-EDAS images demonstrate prolonged FMT in both hemispheres. After EDAS, there is improvement in the left hemisphere but persistent FMT prolongation on the right, predominantly in the parietal and occipital regions. Imaging 4 months after WASEDS shows significant improvement in left hemisphere perfusion and bilateral interval improvement in FMT. CBV, cerebral blood volume; EDAS, encephalo-duro-arterio-synangiosis; FMT, first-moment transit time; WASEDS, wide arterial sparing encephalo-duro-synangiosis.