Any unnecessary and uncontrollable loss of spinal fluid while doing lumbar puncture for any purpose is undesirable. With the ordinary type of spinal tap needle the stylet has to be withdrawn completely to obtain spinal fluid or to make a spinal fluid pressure determination; and, to stop the flow, the stylet has to be reintroduced. This often causes an appreciable loss of cerebrospinal fluid. Also, with the needles in common use, spinal fluid will often flow along the under surface of the needle for a variable distance before it drops into a collecting test tube or ampule, and in this way there is a spill. It occurred to me that it might be of advantage to attempt to prevent this loss of cerebrospinal fluid by designing a needle that would perhaps control more accurately the escape of cerebrospinal fluid.
The needle is the stereotyped lumbar puncture needle, to which an