Spinal cord: blood flow

“The blood supply to the spinal cord depends on a single anterior spinal artery and bilateral posterior spinal arteries. The arteries arise from the circle of Willis and receive reinforcements during their descent in the spinal canal. The posterior spinal arteries receive regular contributions from radicular arteries, but the single anterior spinal artery, which supplies the anterior two thirds of the spinal cord, receives only sporadic reinforcement. Anterior spinal artery syndrome, which may result from arterial compression, hypotension, or embolization is characterized by a predominantly motor deficit, with or without loss of pain and temperature sensation, but with sparing of vibration and joint sensations, which are transmitted in the posterior columns. The condition has been reported among obstetric patients with particular risk factors (see later).[6,9,181] One report described a series of accidents[182]: A parous woman received epidural analgesia with lidocaine, then bupivacaine with epinephrine, followed by 2-chloroprocaine when she required urgent cesarean delivery. Hypotension due to blood loss from a placenta previa and a ruptured uterus was followed by typical irreversible anterior spinal artery syndrome. Hypotension due to blood loss is likely to cause a greater degree of ischemia than that due to vasodilation, and the use of epinephrine may have contributed to the adverse outcome in this case.”