The posterior lumbar dural depth: an ultrasonographic study in children

Lumbar puncture or identification of the epidural space is technically more difficult in children. Prior obtained information regarding the distance from skin to the dura mater may be useful as leading to an increase in success. We studied the anatomy of the posterior lumbar spine at the L4-5 intervertebral space in 137 children, using ultrasonography. Children aged between 7 and 12 years in whom weight and height are in 3-97 percentiles (recommended for healthy Turkish boys and girls) were investigated. The measured distance from skin to dura mater was found significantly higher in girls (2.59 ± 0.44 cm) than boys (2.43 ± 0.46 cm) (p<0.05). Prediction of the posterior dural depth at L4-5 level was obtained using single linear regression equation. All demographic variables correlated significantly with the dural depth in both sexes. In girls the skin-duramater distance achieved highest correlation ranks with weight and body surface area (BSA): ‘dural depth’ (cm) = 1.094 + [0.048 x weight (kg)], r = 0.79, p<0.01 and ‘dural depth’ (cm) = 0.337 + [2.119 x BSA (m2)], r = 0.76, p<0.01). We concluded that the distance between the skin and the dura mater at the level of L4-5 interspace could be predicted using a statistical model based on the age, weight, height or BSA of children aged between 7-12 years old.