The caudal approach to the epidural space involves the use of a Tuohy needle, an intravenous catheter, or a hypodermic needle to puncture the sacrococcygeal membrane . Injecting local anaesthetic at this level can result in analgesia and/or anaesthesia of the perineum and groin areas. The caudal epidural technique is often used in infants and children undergoing surgery involving the groin, pelvis or lower extremities. In this population, caudal epidural analgesia is usually combined with general anaesthesia since most children do not tolerate surgery when regional anaesthesia is employed as the sole modality.
In fact, the anatomical studies have demonstrated that after the radicular medullary arteries enter the neuroforamen in the anterior aspect of exiting nerve root and dorsal root ganglion, they often travel a distance superiorly and laterally in the lateral epidural space to join the anterior spinal artery supplying the anterior two thirds of the spinal cord. Additionally, in about 63% of cases of cadaver studies, there is a posterior branch of the radicular medullary artery going to the dorsal aspect of the cauda equina. It is conceivable that the epidural needle in the interlaminar lumbar epidural steroid injection will very likely encounter the radicular medullar artery in the lateral aspect of the epidural space or midline posterior epidural space.