Spinal fluid fills the space around the brain and spinal cord. This fluid acts as a cushion. During a spinal tap (lumbar puncture) procedure, a needle is passed through the skin and the membrane around the spinal cord in the lower back. This allows the doctor to remove a small sample of spinal fluid. This fluid provides important information about the health of your brain and spinal cord. Normally, as the needle is removed, the puncture hole seals off and no more fluid comes out. But sometimes the hole does not seal correctly and spinal fluid leaks into the nearby tissues.
If you lose too much spinal fluid from a leak at the puncture site, the spinal fluid pressure goes down and a headache occurs. This headache may be mild or severe. The pain is often worse when you sit or stand and gets better or goes away when you lie down. There may also be dizziness, nausea, and blurred vision. The headache often goes away in 24 hours. No treatment is needed unless the headache is very severe or lasts longer than 24 hours. You may need a blood patch if the headache does not get better after 24 hours.