Impact of Combined Direct and Indirect Revascularization on Preoperative Middle Meningeal Artery Collaterals in Moyamoya Angiopathy

Introduction: The middle meningeal artery (MMA) is an important source of collaterals in moyamoya angiopathy. We sought to evaluate the impact combined revascularization may have on existing middle meningeal artery collaterals in patients with moyamoya angiopathy.

Methods: A retrospective review of adult patients carrying a diagnosis of moyamoya disease or moyamoya syndrome undergoing combined direct and indirect revascularization from 2011 to 2021 was performed. Direct revascularization was performed with the frontal branch of the superficial temporal artery (STA) to a suitable cortical middle cerebral artery recipient. Indirect revascularization consisted of encephaloduroarteriosynangiosis with the parietal branch of the STA and dural inversion. Preoperative catheter-based angiograms were reviewed and patients with MMA collaterals were identified. Postoperative angiograms were reviewed to evaluate graft patency and alterations in MMA collaterals. Postoperative outcome data included modified Rankin score (mRS) as well as ischemic and hemorrhagic events.

Results: 62 patients with moyamoya angiopathy were identified with 80 hemispheres undergoing combined revascularization. 13 patients (20.9%) had preoperative MMA collaterals. The majority of the collaterals arose from the anterior division of the MMA (69.2%). 3 hemispheres (23.1%) had collaterals from both anterior and posterior MMA divisions. 1 hemisphere had only posterior division collaterals. Post-revascularization, 2 patients suffered hemorrhages with one patient expiring. There were no postoperative ischemic events in any patient. 9 patients had post-revascularization angiograms with 6 hemispheres (66.7%) demonstrating increased MMA collaterals. 60% of the hemispheres that maintained patency of the direct graft demonstrated increased MMA collaterals compared to 75% of the hemispheres with direct graft occlusion. 3 patients that had improvement in their mRS score all had increased MMA collaterals but varied direct graft patency.

Conclusion : The MMA remains an important source of collaterals in patients with moyamoya angiopathy undergoing combined revascularization. Further studies are necessary to evaluate the optimal revascularization strategy in this specific patient population.