<P> 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 . </P> <P> For some procedures, the anaesthetist may choose to combine the rapid onset and reliable, dense block of a spinal anaesthetic with the post-operative analgesic effects of an epidural . This is called combined spinal and epidural anaesthesia (CSE). The practitioner may insert the spinal anaesthetic at one level, and the epidural at an adjacent level . Alternatively, after locating the epidural space with the Tuohy needle, a spinal needle may be inserted through the Tuohy needle into the subarachnoid space . The spinal dose is then given, the spinal needle withdrawn, and the epidural catheter inserted as normal . This method, known as the "needle - through - needle" technique, may be associated with a slightly higher risk of placing the catheter into the subarachnoid space . </P> <P> Epidural steroid injection may be used to treat radiculopathy, radicular pain and inflammation caused by such conditions as spinal disc herniation, degenerative disc disease, and spinal stenosis . Steroids may be injected at the cervical, thoracic, lumbar, or caudal / sacral levels, depending on the specific area where the pathology (disease, condition, or injury) is located . </P> <P> In addition to blocking the nerves which carry pain, local anaesthetic drugs in the epidural space will block other types of nerves as well, in a dose - dependent manner . Depending on the drug and dose used, the effects may last only a few minutes or up to several hours . Epidural analgesia typically involves using the opiates fentanyl or sufentanil, with bupivacaine or one of its congeners . Fentanyl is a powerful opioid with a potency 80 times that of morphine and side effects common to the opiate class . Sufentanil is another opiate, 5 to 10 times more potent than Fentanyl . Bupivacaine is markedly toxic if inadvertently given intravenously, causing excitation, nervousness, tingling around the mouth, tinnitus, tremor, dizziness, blurred vision, or seizures, followed by depression: drowsiness, loss of consciousness, respiratory depression and apnea . Bupivacaine has caused several deaths by cardiac arrest when epidural anaesthetic has been accidentally inserted into a vein instead of the epidural space . </P>

Where is an epidural placed in the spine