Neurology Specialist Care Centre
What is a lumbar puncture?
A lumbar puncture is a medical procedure, carried out to obtain a sample of cerebrospinal fluid for analysis, or to measure the pressure of the cerebrospinal fluid, or both.
In the cavities of the brain, about a pint of cerebrospinal fluid is produced every day; this fluid surrounds the brain and the spinal cord and is then taken up into the blood stream again. When a lumbar puncture is carried out, a needle is used to obtain cerebrospinal fluid from the lower level of the spine, because this is where it can be obtained most easily and safely.
How is a lumbar puncture done?
A special, fine, hollow needle goes through the skin in the lower back, into the lower spine. The cerebrospinal fluid comes out through the needle and a few drops are collected and sent to the laboratory. Sometimes, a pressure gauge is attached to the needle in order to measure the pressure of the cerebrospinal fluid; and sometimes the lumbar puncture is done only to gauge the fluid pressure or to release some fluid to reduce pressure.
We use a local anaesthetic injection on your back, in order to numb the area. Sometimes it is not easy for the doctor or nurse to locate the place where the needle should be inserted, and several attempts may be undertaken.
Another doctor may be called to assist, but in some cases the procedure has to be abandoned. The doctors will discuss with you when and if the lumbar puncture should subsequently be repeated.
Preparation for the test
Prior to your lumbar puncture, your doctor or nurse will fully explain the procedure in detail and discuss any worries you may have. You will then be asked for your consent to ensure that you fully understand the test and the implications.
The intended benefits
A lumbar puncture can be used as a diagnostic investigation to look for evidence of inflammation, infection or bleeding. It can also be used therapeutically in conditions where the cerebrospinal fluid pressure is thought to be elevated.
We believe that in your case, the procedures intended benefits outweigh the small risk.
Why do I need a lumbar puncture?
The exact reasons for you having a lumbar puncture will be explained by the doctor requesting the procedure.
The reason why cerebrospinal fluid is required for these tests is because it is the fluid which has come into closest contact with the brain itself. By analysing the cerebrospinal fluid they will have more information about possible diagnoses and how that may affect your brain.
What happens to me during the lumbar puncture?
A lumbar puncture is usually carried out on the Neurology Day Case Unit or a ward.
You will be asked to lie on the bed on your side and to curl up.
The nurse will help you to keep in the correct position. The doctor or nurse will feel your lower back and locate the correct space between the vertebrae (the bones of the spine). Sometimes, the lumbar puncture will be done in a sitting position.
The doctor or nurse will clean the skin around this area. A local anaesthetic will be injected into the skin at the site of the lumbar puncture. The doctor or nurse will then insert a needle into the space between the vertebrae (spine). If required, a pressure gauge will be attached to that needle to read the pressure. Then, cerebrospinal fluid will be collected into special containers and sent to the laboratories to be examined.
Usually, a blood sample will be taken as well and be sent to the lab alongside the cerebrospinal fluid.
What are the risks?
It is unusual for something to go wrong, but occasionally one of the following may occur:
- Headache and, or nausea are common after a lumbar puncture and can last between 2 to 7 days. If you do develop a headache please lie flat.
- Transient leg or back pain at the site of the lumbar puncture is also common.
- Small risk of blood clot or bruising in the back.
- Complications such as bleeding into the spinal fluid and nerve irritation.
- Infection which can lead to long term neurological problems.
This is uncommon but does occur in rare cases.
What happens after the lumbar puncture?
The doctor or nurse will use a plaster to cover the site where the needle entered the skin. You will be encouraged to drink plenty of fluids and lie flat when you get home.
When you get home
Patients will usually be able to go straight home after a lumbar puncture (unless, of course, the lumbar puncture was done during an in-patient admission). If you should develop pain at home, take paracetamol, if no contraindications, according to the instructions on the pack.
It is alright for you to work the day following the procedure, if no low pressure headache is experienced. However, you may want to avoid strenuous activities for a few days after your lumbar puncture.
What happens next?
The samples are analysed in different laboratories. Some of the tests are done very quickly within a few hours, but others take longer for the results to come back. Sometimes this takes up to 10 weeks.
All results will be reported automatically to your general practitioner, and they will be discussed with you at your next clinic appointment. If you wish, you may contact your consultant earlier about the results.
If you would like to phone us, but do not have the contact number for your consultant, just ring the switchboard on 01642 850850, and ask to be put through to your consultant’s secretary.
South Tees Hospitals NHS Foundation Trust would like your feedback. If you wish to share your experience about your care and treatment or on behalf of a patient, please contact The Patient Experience Department who will advise you on how best to do this.
This service is based at The James Cook University Hospital but also covers the Friarage Hospital in Northallerton, our community hospitals and community health services.