CEREBROSPINAL FLUID TESTING

This test is performed in patients with a suspicion of neurological disease. It is used for identifying infectious brain diseases such as fungal disease (e.g. cryptococcus), viral disease (e.g. Feline Infectious Peritonitis), cancer (e.g. lymphoma) and meningitis.

A needle is passed into the fluid filled space around the spinal cord either at the top part of the neck (cisternal) or the lower spine (lumbar).

This procedure is typically performed following MRI or CT studies and is always performed under anaesthesia.

Once the fluid has been obtained it is sent to the laboratory for further testing. Results start to be received after 24 hours.

Overall risks of cerebrospinal fluid testing appear minimal in most cases. Patients with severe brain abnormalities or raised pressure within the brain appear to have the highest risk of complications. Complications may result in further deterioration of neurological signs after the procedure. If your feline clinician is worried about the risk, spinal fluid sampling may not be performed however this will be discussed with you at the time.

QUESTION AND ANSWERS - CSF TESTING

What is CSF?

Cerebrospinal fluid (CSF) collection is a test to look at the fluid that surrounds the brain and spinal cord.CSF acts as a cushion, protecting the brain and spine from injury. The fluid is normally clear.

How does CSF help make a diagnosis?

There are different ways to get a sample of CSF. Cisternal puncture (spinal tap) is the most common or a lumbar puncture (spinal tap) can be used. Cisternal puncture uses a needle placed below back of the skull. Lumbar puncture is more technically difficult as the space in cats is very small.
Your cat will have an anaesthetic to keep them still and they are positioned on their side. The area is clipped and cleaned and a spinal needle is inserted. Once the needle is in position, the CSF is collected.
The needle is removed and the area is cleaned. Your cat is then woken up from anaesthesia and monitored closely until they have recovered.
In some cases, special x-rays are used to help guide the needle into position. This is called fluoroscopy. or radiography. This is more common with lumbar punctures.

Are there risks associated with CSF collection?

Yes. This is a specialised procedure and complications are possible as the space is close to the brain stem. Our feline team perform these tests regularly and are very experienced so complications are rare. When they do occur it is typically in cats with severe neurological conditions prior to the procedure. These neurological diseases can result in raised pressures within the skull (raised intracranial pressure) and when CSF is removed, it can cause a shift in pressures that can result in compression of the brain by the base of the skull.
Performing advanced imaging prior to the procedure can help us to identify increased risk factors for this procedure and we may recommend the procedure is not performed if we think it maybe too risky. Fortunately complications associated with CSF collection are rare.

How long will it take to obtain results?

Cell counts and fluid analysis will take 24 hours. Advanced testing for infectious diseases (PCR) takes 7-10 days.

All cats require anaesthesia for CSF testing. They are closely monitored throughout by our highly experienced and trained team.

CSF can contain infectious agents such as this purple circle which is a fungal infection called cryptococcus.

Normal spinal fluid contains low numbers of cells. This CSF sample is from a cat with a severe ear infection that spread into their brain. There are are large number of white cells (the ones with purple in the centre) that are commonly increased with severe infections or inflammation.

After the sample is obtained your cat will be recovered from their anaesthetic and closely monitored until they are recovered.