Lumbar puncture

Why a lumbar puncture may be used

A lumbar puncture is often used to diagnose certain conditions that affect the brain and spinal cord. 

Some of these conditions are described below.


Meningitis is the inflammation of the membrane layers that cover the brain and spinal cord. It can develop from a number of different causes, including infection by bacteria or viruses. Bacterial meningitis can be serious and even life threatening.

A lumbar puncture is needed to diagnose the condition and ensure appropriate treatment is started.

Subarachnoid haemorrhage

subarachnoid haemorrhage occurs when a blood vessel within or underneath the brain bursts (ruptures). The condition is usually diagnosed using a computerised tomography (CT) scan, but in some instances it may be necessary to perform a lumbar puncture as well to detect the presence of blood in the cerebrospinal fluid (CSF).

A diagnosis is important because there is a risk of further haemorrhages. Treatment is available to prevent this. 

Guillain-Barré syndrome

Guillain-Barré syndrome is a rare condition that causes inflammation of the nerves that supply the arms and the legs. A lumbar puncture is needed to check the protein level in the CSF, which is usually higher than normal in people with this condition.

Providing treatment

As well as being used to diagnose conditions, a lumbar puncture is sometimes used to administer treatments by injecting medication into the cerebrospinal fluid. Such medications include antibiotics to treat bacterial meningitis and chemotherapy medicines to manage certain types of cancer that affect the central nervous system.

Lumbar punctures can be used to administer a spinal anaesthetic so that operations on the lower half of the body can be carried out without the need for a general anaesthetic.

A lumbar puncture can also be used to relieve a pressure build-up within the skull known as raised intracranial pressure by removing some CSF. This can provide short-term relief of symptoms until a more permanent treatment for the underlying problem can be provided.

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