Chronic Dilatation of Superficial Temporal Artery and Middle Meningeal Artery Associated with Development of Collateral Circulation After Bypass Surgery for Moyamoya Angiopathy

Abstract

Dilatation of the superficial temporal artery (STA) and middle meningeal artery (MMA) were occasionally observed after bypass surgery for moyamoya angiopathy. The purpose of this study was to examine the correlation between angiographic outcomes and magnetic resonance imaging (MRI), specifically focusing on the postoperative dilatation ratio of the STA (rSTA) and MMA (rMMA). Fifty-six hemispheres in 36 consecutive patients who underwent revascularization for moyamoya angiopathy were evaluated. All patients underwent angiography and MRI before surgery and during the chronic phase. Angiographic outcomes were classified as good or poor according to the extent of the blood supply through direct or indirect bypass. The rSTA and rMMA was calculated in time-of-flight magnetic resonance angiography (MRA). The signal changes of ivy signs and flow voids in basal ganglia were also evaluated. Postoperative collaterals through direct and indirect bypass was good in 30 (53.6%) and 33 (58.9%) patients, respectively. The mean rSTA and rMMA were 36.04 ± 28.79% and 29.15 ± 22.01%, respectively. Ivy signs and flow voids were decreased in 9 (16.1%) and 26 (46.4%) patients, respectively. Univariate analyses demonstrated no significant correlation between the angiographic outcomes and postoperative signal changes on MRI. However, rSTA was significantly correlated with good collaterals through direct bypass (P= 0.04), whereas rMMA was significantly correlated with good collaterals through indirect bypass (P < 0.001). MRA may be an alternative to angiography. Both rSTA and rMMA estimated the development of collaterals after bypass surgery for moyamoya angiopathy.