Impact of craniotomy area on improvement of cerebral blood flow in combined revascularization surgery for moyamoya disease

To investigate factors associated with improvements in cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) after combined revascularization surgery for moyamoya disease, with special attention to the size of craniotomy. We retrospectively analyzed 35 hemispheres in 27 patients with adult and older pediatric moyamoya disease. CBF and CVR were measured separately in the MCA and ACA territories from acetazolamide-challenged single-photon emission computed tomography before and after 6 months postoperatively, and associations with various factors were analyzed. Postoperative CBF improved in patients with lower preoperative blood flow in both ACA and MCA territories. Postoperative CVR improved in 32 of 35 patients (91.4%) in the MCA territory and in 30 of 35 patients (85.7%) in the ACA territory, with more prominent improvement in the MCA territory than in the ACA territory (MCA territory 29.7% vs ACA territory 21.1%, p = 0.015). Craniotomy area did not correlate with postoperative CBF and only MCA territory was associated with good (≥30%) CVR improvement (odds ratio 9.33, 95% confidence interval 1.91–45.6, p = 0.003). Postoperative CBF improved in adult and older pediatric cases, reflecting preoperative CBF. Postoperative CVR improved in most cases, although the degree of improvement was more prominent in the MCA territory than in the ACA territory, suggesting a contribution of the temporal muscle. Large craniotomy area was not associated with improved blood flow in the ACA territory and should be applied prudently.