Superficial temporal artery dilation and the risk of transient neurological events after revascularization for moyamoya disease: Impact of preoperative PCA stenosis.

OBJECTIVE

The superficial temporal artery (STA)-to-middle cerebral artery (MCA) anastomosis is an established revascularization procedure for moyamoya disease (MMD), although transient neurological events (TNEs) are occasionally observed postoperatively. Postoperative dilation of the STA, reflecting the development of bypass blood flow, has been proposed as one of the potential causes of TNEs. However, no definitive biomarker has yet been identified to predict which cases will exhibit marked STA enlargement following revascularization for MMD.

METHODS

This study analyzed 40 hemispheres in 28 consecutive patients with MMD who underwent STA-MCA anastomosis between January 2015 and March 2023. Detailed changes in STA diameter were assessed using magnetic resonance angiography (MRA) before and after bypass surgery, and their association with the occurrence of TNEs was evaluated. In addition, we examined whether variations in the preoperative angioarchitecture influenced postoperative STA caliber changes.

RESULTS

TNEs occurred in 11 hemispheres (27.5%). The median STA dilation ratio was significantly higher in the TNE group than in the non-TNE group (33 [IQR 12.5-67.5] vs. 7 [IQR 0.6-22], p < 0.01). Hemispheres with posterior cerebral artery (PCA) stenosis also showed significantly greater STA dilation (p = 0.03).

CONCLUSION

Postoperative dilation of the STA following STA-MCA bypass for MMD can be detected noninvasively using MRA and may serve as a potential imaging marker of TNEs. Although both PCA stenosis and STA dilatation can be regarded as markers of disease progression, a potential association may exist between these two phenomena. However, these findings are exploratory and require validation in larger studies before any definitive clinical implications can be drawn.