Dura to spinal cord distance at different vertebral levels in children and its implications on epidural analgesia: A retrospective MRI-based study.

Abstract

The distance from the dura to spinal cord is not uniform at different vertebral levels. The dura to spinal cord distance may be a critical factor in avoiding the potential for neurological injury caused by needle trauma after a dural puncture. Typically, the greater the dura to spinal cord distance, the larger the potential safety margin. The objective of our study is to measure dura to spinal cord distance at two thoracic levels T6 -7 , T9 -10 , and one lumbar level L1 -2 using MRI images. Eighty-eight children under the age of 8years old qualified for the study. The distance from dural side of ligamentum flavum to the posterior margin of the spinal cord was defined as dura to spinal cord distance. Sagittal T2 -weighted images of the thoracic and lumbar spine were used to measure the dura to spinal cord distance at the T6-7 , T9-10 , and L1-2 interspaces. Measurements were taken perpendicular to long axis of the vertebral body at each level. The dura to spinal cord distance was 5.9 ± 1.6mm at T6-7 (range: 1.4-9.9mm), 5.0 ± 1.6mm at T9-10 (1.2-8.1mm), and 3.6 ± 1.2mm at L1-2 (1.2-6.8mm). There were no evident differences in dura to spinal cord distance by gender, age, height, or weight. The present study reports that the largest dura to spinal cord distance is found at the T5-6 level, and the shortest dura to spinal cord distance at the L1-2 level. There appears to be substantially more room in the dorsal subarachnoid space at the thoracic level. The risk of spinal cord damage resulting from accidental epidural needle advancement may be greater in the lumbar region due to a more dorsal location of the spinal cord in the vertebral canal compared to the thoracic region.