* Lumbar puncture (spinal tap). During a lumbar puncture a small amount of the fluid that surrounds the brain and spinal cord, the cerebrospinal fluid, is removed and examined. In kids, a lumbar puncture is often done to look for meningitis, an infection of the meninges (the membrane covering the brain and spinal cord). Other reasons to do lumbar punctures include: to remove fluid and relieve pressure with certain types of headaches, to look for other diseases in the central nervous system, or to place chemotherapy medications into the spinal fluid. Spinal taps, which can be done on an inpatient or outpatient basis, might be uncomfortable but shouldn't be too painful. Depending on a child's age, the test may be done while the child is sedated.