What is it like to have a lumbar puncture?

6 December 2021

A woman who underwent a lumbar puncture during her diagnosis for MS (multiple sclerosis) shares her personal account of the process.

What do I need to prepare in advance?

Assuming that this is not an emergency, you will have been given a date and time for your lumbar puncture. If that does not suit you, you can ring up and ask to change it. If you can't make it, let the hospital know - I have always found them very helpful.

The hospital usually sends information about what to expect and what to bring with you. You may be at the hospital for a few hours, but you are not likely to have to stay overnight.

You may want to wear clothes that are suitable for resting in bed and take things you can do whilst resting. You don't usually have to stop eating or drinking before the test. In fact it may help avoid or reduce any post procedure headache if you are well hydrated. You should take all your medicines, unless told not to do this.

Whether you want someone with you on the day of the test is a personal choice. You may not feel able to go home by yourself and it is not recommended to drive yourself home afterwards, so having someone to go home with you or to take you home may be sensible.

What happens at the hospital?

The doctor (or other professional) doing the test will discuss with you what they are going to do. When talking to you, they must check who you are and say who they are. They will explain what they are proposing to do, how they expect to do it, why they think it is appropriate for you, what the common complications are and, if there are any, significant possible complications. This is your opportunity to ask questions. They will also ask you to sign a form consenting to the procedure that they have described to you.

The cerebrospinal fluid (CSF) is the fluid that surrounds the brain and spinal cord, all within a thin membrane sack (the dural sac). The dural sac is entirely surrounded by the spine, passing through holes in the back of each vertebra. Samples are usually taken from the lower back, in the bottom part of the dural sac, where there is generally a good amount of CSF around the nerves that go to the legs.

When everything is ready to start, the doctor will ask you to get into a position that curls your lower back. This may be lying on your side in a sort of foetal position with your knees up and head down, or sitting up in a chair with your head down towards your knees, possibly leaning over a pillow to get the shape. These positions mean that the spaces between the bony vertebrae in the lower back are as wide as possible, giving a bigger target to aim for. This makes the procedure easier.

Getting a sample of cerebrospinal fluid (CSF) is a bit like getting a sample of blood for a blood test. A needle needs to be put in the right place and the fluid can be allowed to flow out or removed with a syringe. When getting a sample the needle has to go between two adjacent vertebrae, through the protective dural membrane and into the CSF.

The doctor will clean your lower back to avoid infection, using iodine or another liquid. This is usually rather cold and iodine leaves a yellowish stain, which may get on your clothes. They will probably then put sterile paper or material sheets around your back.

Some local anaesthetic will be put into your skin through a small needle. This stings but only for a moment. They will probably put more in a bit deeper to numb the underlying tissues, which you may or may not feel. The anaesthetic works within seconds, but if you are feeling sharp pains during the lumbar puncture, tell them and they can give you more.

The needle used to collect the CSF is very thin - much thinner than the sort of needle used for a blood test - and may need to be quite long. When the doctor is putting the needle in, it may feel as if someone is pushing on your back, though some people feel nothing.

There are lots of nerves within the fluid in the spinal canal but usually they have room to move out of the way. If one of the nerves is touched, it can give you a nasty ache or pain, usually in your leg.

Once the needle is in the right place, it takes a few seconds to get the sample. It is important to stay as completely still as possible for the time of collection of the sample, but this is only is a minute or two.

Then the needle is removed. The tiny hole in the membrane caused by the lumbar puncture usually seals itself, although this seal is not very strong. Immediately after the test you will be told to keep still and move carefully.

What happens afterwards?

You will probably be told to stay lying flat in bed for an hour or so, possibly up to six hours. If things are straightforward, you may be able to leave after two or three hours.

Because of the loss of the fluid and the change in the pressure around the brain, a post-procedure headache is common. Unfortunately it can be very unpleasant indeed, but not everyone gets one. The body replaces the missing CSF, but this does take a day or so. The doctor may suggest taking some simple pain relief on the off chance, or they may prefer you to wait until you get a headache.

The other common side effect is to have mild swelling and back pain around the area where the sample was taken. This should clear up within a couple of days.

It is helpful to stay well hydrated after the test and it is probably a good idea to take things a bit gently for a day or so. Some people find that caffeinated drinks like tea or cola help as well.

You should be supplied with information about what to do if there are any other problems. For example, if the swelling at the puncture site gets worse or leaks fluid, or you have a severe headache that doesn't get better with simple painkillers.

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