To the Editor:

Patients with Moyamoya disease have abnormal intracranial blood vessels [Online Resource 1], the presence of which results in frequent strokes. Anesthesia further enhances the risk. We report cerebral oxygen saturation (rSO2) observations using noninvasive near-infrared spectroscopic (NIRS) cerebral oximetry during a cesarean delivery (CD) under combined spinal epidural anesthesia in a Moyamoya case.

A 30-year-old G1P0 Moyamoya patient had an elective CD at 37 weeks. Her rSO2 was monitored using an NIRS cerebral oximeter. Eight milligrams of intrathecal heavy bupivacaine was sufficient for an optimum block. An intravenous bolus of 5 IU oxytocin at a volume of 5 ml was injected over a span of 1 min immediately following the delivery. Her rSO2 remained normal (60–75 %) and was relatively higher after the delivery [Online Resource 2]. We postulate that the increase in rSO2 after the delivery resulted from oxytocin-induced cerebral vasodilatation.

Oxytocin leads to dilatation or constriction in a myriad of blood vessels [1]. It has a vasopressin-like weak vasoconstrictive effect, and some reports [2] suggest that it may reduce cerebral blood flow (CBF), although other articles suggest an increase in CBF in experimental animals [3]. The rSO2 monitoring in obstetric anesthesia is currently scarce. We propose that rSO2 should be monitored in Moyamoya patients undergoing anesthesia, particularly when oxytocin is administered.