Lumbar Punctures in Neonates: Improving Success Rates and Minimizing Pain

The purpose of this study is to compare two medications used to numb an infant's back when performing a lumbar puncture. A lumbar puncture (LP) is often needed in newborns to obtain cerebrospinal fluid (CSF). This is achieved by inserting a small needle between the infant's vertebrae. In the past, doctors did not know if newborns could feel the pain from a procedure like this in the same way that adults do. Investigators now know that the newborns do experience pain during this procedure, but we do not know the best way to control this pain. Investigators also think that when the newborns have pain, they move during the test. The movement can increase the chance of having blood mix with this normally clear fluid leading to limitations in our clinical application of these results. This study will compare the injected and topical forms of Lidocaine to see which gives us better pain control and more clear results. The investigators hypothesize that subcutaneous 1% Lidocaine, due to its deeper penetration, will be 25% superior to topical liposomal Lidocaine (LMX-4) in both the rate of clinically useful results and pain scores. The investigators hypothesize that both forms of Lidocaine will be 25% superior to our historical control cohort in the rate of clinically useful results.