Role of scalp arteries in revascularization after side to side anastomosis in moyamoya disease patients

In our recent study, we introduced a novel side-to-side (S-S) bypass technique for adult moyamoya disease (MMD) patients. We aimed to validate the potential of this technique in enhancing postoperative revascularization. Patients undergoing S-S or end-to-side (E-S) bypass were enrolled, clinical data and angiography parameters were collected and compared. We included 44 E-S and 40 S-S MMD patients. There were no significant differences in basic characteristics and postoperative Matsushima grades between the two groups. However, in the S-S group, fewer patients had Matsushima grade D (0%) compared to the E-S group (11.4%, P = 0.028). The S-S group showed a greater occipital artery (OA) participation in revascularization (87.5% vs. 56.8%, P = 0.002) and higher postoperative caliber change ratio (CCR) of the superficial temporal artery (STA)-frontal branch (1.26 ± 0.43 vs. 1.04 ± 0.53, P = 0.038) compared to the E-S group. This difference was more pronounced in the subgroup with poor revascularization outcomes: in the S-S group, the CCR of the STA-frontal branch and the degree of participation in revascularization were 1.163 ± 0.168 and 58.8%, respectively, while in the E-S group, they were only 0.798 ± 0.494 and 6.7%. The S-S group also had a higher OA CCR (1.133 ± 0.257) and participation (82.4%) compared to the E-S group (0.941 ± 0.216 and 37.5%, respectively). In conclusion, the S-S bypass technique effectively utilizes scalp arteries, particularly the STA-frontal branch and OA, for direct revascularization via the preserved distal STA in adult MMD patients. Scalp arteries can serve as a supplementary source of donor arteries, especially beneficial for patients with suboptimal revascularization outcomes.