People with IH are typically well acquainted with lumbar punctures (LP's) as a form of diagnosis and/or treatment of IH  (you may be more familiar with the term spinal tap). Both are one in the same. For people with IH, an LP is performed to obtain an opening pressure, which (when elevated) is often the means to diagnosis (when all other tests are inconclusive). It is also used to monitor your condition over time. The opening pressure is measured by a device called a manometer. The opening pressure is the amount of cerebrospinal fluid (CSF) that fills the manometer upon successful insertion of the needle. How is an LP Performed? This can vary from Doctor to Doctor, as well as where the LP is performed (Doctor's office vs. hospital). If you are anxious about the procedure, your Doctor may prescribe medication for you to take ahead of time to help you to relax (which is important during an LP). You will typically be advised to arrive one hour in advance of the procedure. A nurse will stand-by to assist (and are typically quite comforting). Commonly the patient will be asked to lie on their side in the fetal position. Some Doctor's may choose to position you in a sitting position, or on your stomach. Your Doctor may recommend you have your LP done via fluoroscopy (x-ray guided). The Doctor will cleanse the area first, and you may feel a cool, wet sensation. A sterile sheet will be draped over the area. Your Doctor may choose to use a numbing cream (patch placed on the lumbar region of your back about one hour prior to the procedure), or may inject it under your skin. You may feel a quick prick of the skin during injection. Once numb, a thin needle will be inserted into the interspace between the vertabra of your lumbar region. The size of the needle often depends on the Doctor's preference. Many people find decreased spinal headaches (a side effect of this procedure), when the Doctor uses a lower gauge needle. There has also been discussion of the position of the needle easing the puncture of the dura, and decreasing the chance of a post-LP headache (that is, going in at an angle as opposed to straight on). The needle will penetrate through the subcutaneous tissue, then the dura (membrane that surrounds and protects the spinal cord, in which the CSF is encased). You may hear a "pop", when the needle enters the dura. At this point the spinal fluid will begin flowing through the needle, measured by the manometer, and collected in plastic tubes to be sent off for testing. There should not be outright pain, but you will feel an intense pressure when the needle penetrates the dura. There may be numbness down your leg if the needle irritates a nerve root. Advise your Doctor of what you are feeling during the procedure! The needle is then withdrawn, pressure typically applied to the site, and often a small band-aid is applied. You will be advised to lie flat for a period of time (in some cases 6-8 hours), to avoid a post LP headache (this occurs when the CSF continues to leak from the site, and causes the pressure to drop too low). The procedure may take from 20-30 minutes. You should take it easy for the following 24 hours, and it is advisable if it's your first, that you take the day after off from work (as you may be unsure of what to expect). It is advisable to drink plenty of fluids 24 hours prior to an LP (though not too close - particularly if your Doctor wants you flat on your back for 8 hours!). You may be advised to consume extra caffeine following a spinal tap - caffeine helps to constrict blood vessels, thus speeding the process of closure to the puncture site. Many people swear by gatorade following an LP, to help balance lost fluids. Typically an opening pressure of 180mm's or higher (or 18cm's) is considered high, and an indication of IH. The level considered high often differs throughout medical literature. It is very important you obtain your opening pressure, for your own records and future reference. Your CSF will be sent to the lab for analysis. Absence of abnormalities coupled with a high opening pressure indicate IH.  Spinal Headache and Blood Patches If fluid continues to leak from the puncture site following an LP, you may experience a spinal headache. This is often described as "head pain like no other", and is typically worse when seated upright (relieved by lying down). There may be neck pain and vomiting in addition to the head pain. Spinal headaches typically present within five days of an LP. Call your physician if you experience a spinal headache, as they may be able to treat it quickly! Typically adequate hydration and bed rest will be recommended. In some cases a blood patch may be recommended. This is performed by inserting a needle into (or next to) the lumbar puncture site, withdrawing the patients blood from another region, and injecting it into the needle. This facilitates blood clotting and sealing of the lumbar puncture site (some Doctor's perform this routinely after an LP). Even when left untreated, a spinal headache typically dissipates in 5-7 days.      If you'd like to add any information or your own tips to this page, please contact habanno@comcast.net.