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Background and Aims This study determined whether scalp nerve block (SNB) could reduce the incidence of postoperative symptomatic cerebral hyperperfusion syndrome (SCHS) in adult patients who underwent after superficial temporal artery (STA)–middle cerebral artery (MCA) anastomosis for moyamoya disease (MMD).

Methods Patients undergoing STA-MCA anastomosis for MMD were retrospectively divided into SNB (n = 167) and control (n = 221) groups depending on whether SNB was performed at the end of surgery. Inverse probability of treatment weighting was used to balance the two groups. The primary outcome measure was the incidence of postoperative SCHS.

Results The incidence of postoperative SCHS was not different between the SNB and control groups (62 [37.1%] vs 100 [45.2%], P = 0.133), but its duration was shorter in the SNB group (3 [2–6] vs 5 [3–7] d, P = 0.014). The SNB group had lower pain scores (postoperative day [POD] 0: 2 [1–3] vs 3 [1–4], P = 0.004; POD 1: 2 [1–2] vs 2 [1–3] d, P = 0.039) and systolic blood pressures (POD 0: 129 [121–137] vs 139 [130–149] mmHg, P < 0.001; POD 1: 125 [117–136] vs 131 [124–139] mmHg, P < 0.001) and shorter lengths of intensive care unit (1 [1–2] vs 2 [1–2] d, P < 0.001) and hospital (10 [9–13] vs 10 [8–14] d, P = 0.044) stays.

Conclusions Despite some benefits, SNB did not reduce the incidence of SCHS after STA–MCA anastomosis for MMD.