TY - CHAP M1 - Book, Section TI - Caudal Anesthesia A1 - Barrie, Jamie A1 - Jivan, Kuntal A2 - Freeman, Brian S. A2 - Berger, Jeffrey S. PY - 2014 T2 - Anesthesiology Core Review: Part One Basic Exam AB - In neonates and infants, the conus medullaris is located at L3, which is more caudal than in adults (L1). Because of the difference in the rates of growth between the spinal cord and the bony vertebral column, the conus medullaris reaches L1 at approximately 1 year of age. Thus, lumbar puncture for subarachnoid block in neonates and infants should be performed at L4-L5 or L5-S1 so as not to injure the spinal cord. The midline approach is preferred over paramedian because the vertebral laminae are poorly calcified in neonates and infants.The sacrum is narrower and flatter in neonates. This difference affects the approach to the subarachnoid space from the caudal canal. It is much more direct in neonates than in adults. The needle must not be advanced deeply in neonates because dural puncture is much more likely.The distance from the skin to the subarachnoid space in neonates is approximately 1.4 cm, progressively increasing with age. The ligamentum flavum is much thinner and less dense in children than adults, which makes it more difficult to detect engagement of the epidural needle and results in unintended dural puncture.Cerebrospinal fluid (CSF) volume per percentage of body weight is greater in infants than in adults. This may account for the comparatively larger doses of local anesthetics required for surgical anesthesia with subarachnoid block.A caudal block may be contraindicated in the presence of a deep sacral dimple because this may indicate the presence of spina bifida occulta, thus greatly increasing the probability of dural puncture. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/04/23 UR - accessanesthesiology.mhmedical.com/content.aspx?aid=1102567554 ER -