Objective: Drastic hemodynamic change can be expected after direct bypass surgery for moyamoya angiopathy (MMA). However hemodynamic hyperperfusion could be observed presumably because of the increased permeability of blood-brain barrier (BBB). The assessment of BBB related molecular proteins has never been investigated. The purpose of this study was to evaluate the perioperative serum levels of biomarkers representing BBB function in MMA patients based on the hypothesis that postoperative hemodynamic change may cause the instability of BBB.
Methods: A total of 13 hemispheres in 12 patients with MMA were prospectively investigated. A superficial temporal artery - middle cerebral artery direct bypass was performed in all cases. All patients had blood examinations before and postoperative day (POD) 1, 4 and 7, respectively. The serum levels of tight juction proteins (occludin [OCLN] and claudin 5 [CLDN5]) and an adherence junction protein (vascular endothelial [VE]-cadherin) were measured quantitatively using enzyme linked immunosorbent assay. The percent change of these proteins compared to preoperative was calculated.
Results: Successful patency of the direct bypass was obtained in all cases. No apparent hemorrhagic or ischemic changes were observed on CT and MR image in this study. The mean percent changes of OCLN, CLDN5 and VE-Cadherin on POD 1 were 523.3 ± 598.0%, 108.7 ± 297.0% and -23.9 ± 25.5%, respectively. The following changes of OCLN and CLDN were decreased; -7.7 ± 63.8% and 80.0 ± 320.9% on POD 4 and -9.1 ± 54.2% and 36.3 ± 209.1% on POD 7, respectively. On the other hand, there was no remarkable fluctuation on those of VE-Cadherin in this series. The serum levels of OCLN and CLDN5 on POD 1 were markedly elevated over 10 folds higher than baseline in two patients, who had transient neurological symptoms within 13 days after the surgery.
Conclusion: In patients with MMA undergone direct bypass surgery, drastic changes of biomarkers representing tight junction of BBB were observed. These preliminary results suggested that marked hemodynamic change and temporary neurological symptom in some patients might be associated with the instability of BBB after direct bypass surgery for MMA.