Evaluation of conus medullaris level in newborn infants

Purpose: Previous studies have reported that the conus medullaris (CM) is located between T12 and L2 in most adults, but no significant ascent has been observed during childhood. There is evidence that the normal position of the CM in an adult is acquired at birth in the majority of cases. Studies have shown that there are differences in CM levels in neonates. This situation causes problems for interventional procedures in the neonatal period. The aim of this study is to determine CM levels in preterm/term neonates using ultrasound (US).Materials and Methods: Newborn infants (gestational age: 24-43 weeks) admitted to the neonatal intensive care unit between March 2020 and June 2021 were evaluated for CM levels by the postnatal US. Infants with central nervous system abnormalities, dysmorphic features, somatic or various genetic diseases, or their parent's refusal to participate were excluded from the study.Results: Of the 189 neonates infants included in our study, 85 (44.6%) were female, 104 (55.4%) were male, 139 (73.54%) were preterm (24-36 weeks), and 50 (26.46%) were term (37-42 weeks) neonates. As a result of the US performed on the first day of 189 neonates, CM levels, 31 (16.4%) were L1, 31 (16.4%) were L1-2, and 71 (37.6%) were L2. There is a strong correlation between birth weight and birth week (r 0.84). There is a negative relationship between birth weight and CM level (r-0,20), gestational age, and CM level (r-0,23).Conclusion: Conus medullaris level was negatively correlated with gestational age and increased with advancing gestational age. In addition, the CM level shows a slower rise at 28-40 weeks of postmenstrual age and reaches the normal level (L1-L2) in the neonatal period, as in adults. Knowing the level of the CM in the newborn period will ensure that spinal procedures such as lumbar puncture to be applied to the spinal region can be performed safely.