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Low-pressure
headaches result when cerebrospinal fluid is removed during a spinal
tap (lumbar puncture) or leaks out because of a cyst or tear. Loss
of this fluid, which flows around the brain, reduces pressure around
the brain.
A headache commonly occurs after a spinal tap, usually hours to a day or two afterward. The procedure removes some cerebrospinal fluid. Cerebrospinal fluid flows through a channel between layers of tissue (meninges) that cover the brain and spinal cord and fills spaces within the brain. Removal of some cerebrospinal fluid reduces pressure around the brain, causing headaches, which can be severe. Young, small people are most likely to be affected.
Sometimes cerebrospinal fluid leaks because a cyst in the meninges bursts or the meninges are torn (as can occur when the head or face is injured). Rarely, a cyst may burst when people cough or sneeze.
Low-pressure headaches are intense. They occur when people sit or stand and may be relieved by lying flat. People usually also have a stiff, painful neck and may vomit.
Diagnosis
Doctors base the diagnosis on the symptoms and the situation. If people have had a spinal tap, the diagnosis is usually obvious, and testing is rarely needed. If not, imaging tests, such as magnetic resonance imaging (MRI), may be done.
Treatment
Doctors advise people who have had a spinal tap to lie flat. They are given fluids (by mouth or, if very dehydrated, intravenously), mild analgesics, and caffeine. An elastic binder may be wrapped around their abdomen. It can help increase pressure of the fluid around the brain. If the headache persists after a day of such treatment, a small amount of the person's blood can be injected in the space between the spine and the meninges in the lower back. This procedure is called an epidural blood patch. The blood plugs the hole made by the spinal tap.
A blood patch may also be effective for a leak. Surgery for a leak is rarely required.
Last full review/revision April 2008 by Stephen D. Silberstein, MD
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