Spinal taps (lumbar punctures) help doctors diagnose many nervous system problems.

For this procedure, a needle is put into the lower back between the vertebrae to collect a sample of spinal fluid. The procedure usually takes approximately 30 minutes and does not require general anesthesia. Normal spinal fluid is clear and colorless. Abnormal fluid may appear cloudy, which can be a sign of an infection in the brain or spinal cord from meningitis, Lyme disease or some other inflammatory disease.