Lumbar Puncture
What is a lumbar puncture?
A lumbar puncture is the insertion of a needle into the fluid space within the spinal canal. It is termed a “lumbar puncture” because the needle goes into the lower back called the lumbar area.
Why is this done?
It is most commonly done for diagnostic purposes, namely to obtain a sample of the fluid in the spinal canal (cerebrospinal fluid) for tests to detect infection and/ or presence of cancer cells.
How is this procedure performed?
You will most commonly be lying down sideways for the procedure. After local anaesthesia is injected into the lumber area, a needle is inserted in between the bony blocks (vertebrae) into the spinal canal. The needle is usually placed between the 3rd and 4th lumbar vertebrae. The spinal fluid pressure can then be measured. Cerebrospinal fluid is then removed for tests.
What are the risks of a lumbar puncture?
As with any medical procedure, complications may occur. Some of the most common and important complications following lumbar puncture are:
Backache
Headache
Bleeding
Infection
Neurological deterioration
Backache
The doctor will numb the skin of your lower back before insertion of the needle. However, mild lower back discomfort, generally lasting one or two days, might still occur. This is easily treated with simple pain medications.
Headache
Occasionally, a headache follows lumbar puncture. This is the most common complication following a lumbar puncture, but occurs in less than one of ten procedures. The headache can occur from hours up to a day or so after the procedure. Remaining recumbent and avoiding walking until six hours after the procedure may reduce the likelihood of headache. Drinking adequate water may also help reduce the incidence or severity of headaches. Pain medications can usually relieve the headache.
Bleeding
As with any procedure involving puncture with a needle, bleeding may occur at the procedure site. Bleeding is usually minimal in lumbar puncture, except when disorders of the blood clotting system are present. Occasionally a blood clot that has formed under the skin at the site of the procedure called a haematoma may cause prolonged pain. The risk of this happening can be reduced by lying flat for six hours after the procedure.
Infection
Rarely, an infection may develop at the procedure site. In order to reduce the chances of infection, the skin of your lower back will be cleaned with a sterilizing agent. However, it is possible that infection may still occur.
Neurological deterioration
In very rare situations, neurological deterioration may follow lumbar puncture. This only occurs if the cerebrospinal fluid pressure is high and becomes reduced during the procedure, causing a part of the brain to sink into an area of the skull resulting in coma and possible life-threatening event. The chance of any such adverse change developing can be assessed by clinical examination and/ or radiological procedures performed prior to the lumbar puncture.