Preparation
Sometimes, a computerised tomography (CT) scan of your brain may be carried out before a lumbar puncture to check that there's nothing wrong with the pressure inside the skull. If there is something wrong, it may be too dangerous to do a lumbar puncture because it could damage the brain.
A neurologist, who specialises in treating conditions of the brain and nervous system, or a doctor with expertise in emergency medicine will usually carry out the lumbar puncture.
They will explain why the procedure is required and any possible risks. You will then be asked to provide your consent to have the procedure.
If it is not possible for you to provide informed consent - for example, if you are unconsciousness or mentally confused - a lumbar puncture may be carried out if it's considered too dangerous to wait until you can give consent.
The procedure
You may be asked to lie on one side with your legs pulled up and your chin tucked in, so that your spine is curved. This will help separate the bones in your spine, allowing the needle to be inserted more easily. Sitting while bending forwards also works well.
An antiseptic solution will be applied to the skin at the base of your spine, which may feel cold. A local anaesthetic will then be used to numb the area of skin around your lower back.
If your child is having a lumbar puncture, they may be given medication to help keep them calm (a sedative) or be held in position. This is because it's very important to keep still during the procedure.
The doctor will push a hollow needle in between the two bones at the base of the spine and into the space around the spinal cord. The anaesthetic should help prevent you feeling any pain, although there may be some pressure as the needle is pushed in. Some people feel a sharp sensation in their back or leg.
After the needle has been inserted, a small amount of cerebrospinal fluid (CSF) will drip back into a sterile pot underneath the needle. Only a few millilitres of CSF are usually removed.
If the doctor needs to measure the pressure of the CSF, they will attach a special tube to the needle to check the pressure of the fluid coming out. Once the procedure is complete, the needle will be removed and a small plaster will be put on the skin.
The CSF sample will be sent to a laboratory to be tested. The lumbar puncture procedure usually takes about 45 minutes.
After the procedure
After having a lumbar puncture, you will be asked to lie flat on your back for a few hours. This can sometimes help prevent a headache developing.
How soon you can return home depends on why the lumbar puncture was carried out. If it's thought there may be a threat to your health, such as meningitis, you will probably need to stay in hospital as a precaution until the results of the tests are known.
However, if your condition is not thought to be serious, you will probably be able to leave hospital on the same day.
You can remove the plaster after 24 hours and you should drink plenty of fluids over the next few days. Do not drive for 24 hours after having a lumbar puncture.
If your child has had the procedure and the results show that nothing is seriously wrong, they will be able to go to school the following day. However, they should avoid playing sports or doing PE for a week.
