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.
A 1969 study of 30 patients with increased ICP who deteriorated after LP attempted to identify the clinical features of patients who were at greatest risk for this complication [ 59 ]. The following findings were noted: 73 percent had focal findings on neurologic examination (including dysphagia, hemiparesis, and cranial nerve palsies); 30 percent had documented papilledema prior to the LP; and 30 percent had evidence of increased ICP on plain skull films (erosion of the posterior clinoid processes). Deterioration occurred immediately in one-half of the patients, with the remainder declining within 12 hours.
Rare but life-threatening complications from epidural analgesia include the following: (1) maternal convulsions or cardiovascular collapse after unintentional direct intravenous injection of a local anesthetic and (2) total spinal anesthesia following unintentional subarachnoid injection of local anesthetic. Slow, incremental administration of the local anesthetic with appropriate maternal and fetal monitoring will produce signs and symptoms of subarachnoid or intravenous injection before serious consequences occur. Many physicians administer an epidural “test dose” (., 3 mL of percent lidocaine [Xylocaine] with epinephrine 1:200,000) to detect subarachnoid or intravenous placement of the catheter.