Postoperative Dilatation of Superficial Temporal Artery Associated with Transient Neurologic Symptoms After Direct Bypass Surgery for Moyamoya Angiopathy

OBJECTIVE: In moyamoya angiopathy, transient neurologic symptoms (TNS) are occasionally observed after superficial temporal artery (STA)-middle cerebral artery direct bypass surgery. The purpose of this study was to investigate the correlation between TNS and postoperative magnetic resonance imaging as well as perform a perfusion study. METHODS: We reviewed 52 hemispheres in 33 consecutive patients with moyamoya angiopathy. TNS were defined as reversible neurologic dysfunction without any apparent intracranial infarction or hemorrhage. All patients underwent magnetic resonance imaging and single-photon emission computed tomography before and within 5 days after surgery. Maximum diameter of STA on time-of-flight magnetic resonance angiography and the dilatation ratio of STA were calculated. The presence of signal changes on fluid-attenuated inversion recovery images and regional cerebral blood flow were also evaluated. RESULTS: TNS were observed in 13 of 52 (25%) cases 1-16 days after surgery. The mean preoperative STA dilatation, postoperative STA dilatation, and dilatation ratio of STA were 1.33 mm +/- 0.27, 1.67 mm +/- 0.30, and 29.31% +/- 28.13%. Postoperative intraparenchymal cortical hyper-intensity lesions and high-intensity signals in the cortex sulci (ivy sign) were detected in 24 (46.2%) cases and 29 (55.8%) cases, respectively. Univariate analyses demonstrated no association between TNS and postoperative signal change on fluid-attenuated inversion recovery images as well as cerebral blood flow. Only >1.5-fold dilatation of STA was significantly correlated with TNS (P < 0.0001). CONCLUSIONS: STA dilatation was correlated with TNS after direct bypass surgery for moyamoya angiopathy.