Preoperative transdural collateral vessels in moyamoya as radiographic biomarkers of disease

OBJECTIVE The prevalence of angiographically evident preoperative transdural collateral vessels in moyamoya is not well documented. The authors hypothesized that transdural collaterals could be used as radiographic biomarkers of disease, and that their presence is associated with more advanced moyamoya arteriopathy at diagnosis, which is a harbinger of more frequent operative complications and a predictor of better long-term angiographic results following surgery. METHODS The study consists of a single-institution case series of patients with moyamoya who underwent pial synangiosis between 2005 and 2013. RESULTS Moyamoya was diagnosed in a total of 204 patients (n = 121 [59%] female, 83 [41%] male); the average age at surgery was 9.5 years (range 0.4–35 years). Radiographically, 154 (75%) had bilateral disease for a total of 308 affected hemispheres; 152 (75%) had radiographic stroke; and 190 (93%) had “ivy sign” on FLAIR MRI, indicating slow flow. Of the 358 hemispheres, 324 were treated operatively. On preoperative angiography, 107 patients (52%) had transdural collaterals in 176 affected hemispheres (49%). The Suzuki stage was higher in patients with collaterals (3.4 vs 3.0, p = 0.002). Of 324 treated hemispheres, 84 (26%) had collaterals within the surgical field. Complications included 12 strokes (3.7% stroke rate/hemisphere), with 5 (42%) directly attributable to interruption of transdural collaterals. On 1-year postoperative arteriograms available in 222 hemispheres, Matsushima grades trended better in patients with preoperative collaterals (1.5 vs 1.8 [A = 1, B = 2, C = 3]; p < 0.003). CONCLUSIONS Transdural collaterals are present in nearly half of all preoperative arteriograms in patients with moyamoya. These collaterals are more common in advanced disease, are associated with stroke as a perioperative complication, and may suggest increased capacity to produce surgical collaterals postoperatively. These data support the utility of preoperative arteriography.