 - Intrathecal administration, through a lumbar puncture spinal tap: A spinal tap also called a lumbar puncture is when fluid surrounding the spinal cord is removed by inserting a needle into the lower back. The affected area is numbed with local anesthetic during the procedure. It can also be used to give chemotherapy. The number of doses you receive will depend on how many doses the study doctor thinks is needed. Occasionally, a sample of the fluid obtained from the spinal taps may be tested for leukemia. 