Cat & Dog - Cerebrospinal Fluid Collection and Testing

What is cerebrospinal fluid (CSF)?

Cerebrospinal fluid (CSF) is formed within the brain.  It circulates through the spaces both within and surrounding the brain and around the spinal cord.  A major function of CSF is to protect the brain and spinal cord, acting as a cushion or shock absorber.

What is the purpose of CSF testing?

Due to its intimate contact with the nervous tissue of the brain and spinal cord, examination of CSF often gives important clues to diagnosis with patients showing clinical signs of inco-ordination, fits (seizures), paralysis, etc.

How is CSF collected?

General anaethesia is usual since a special needle has to be inserted into the spinal canal.  The sample can be obtained either from a site just behind the head (cerebellomedullary cistern) or just in front of the pelvis (lumbar cistern).

The procedure is similar to that of taking a blood sample.  Only a small quantity of CSF is required (usually 2-3 ml).

Are there any risks are involved with CSF collection?

Risks involved with general anaesthesia have to be considered.  These are usually minimal since this is a short procedure.  If we have any concerns we will discuss these with you and may advise some additional pre-anaesthetic tests.

In addition there are certain risks specific to CSF collection which must be considered:

1. Damage to nerve tissue due to needle insertion.
2. Introduction of infection.
3. Problems that can sometimes occur if the CSF pressure is very high.

We will discuss any concerns and explain more fully if required.

How does CSF investigation help?

Laboratory examination of the sample will give an indication of the various constituents and highlight any abnormalities.  Sometimes bacteria, other infective organisms or abnormal cells (such as cancer cells) are isolated which can lead to a swift specific diagnosis.  Alternatively specific antibody tests may be necessary in some cases to establish if infections such as toxoplasmosis or ehrlichiosis are present.

Does CSF evaluation often provide a definite diagnosis?

This is possible (such as in cases of meningitis, toxoplasmosis, etc.).  More usually it will provide further evidence to support the most likely diagnosis based upon the age, breed and clinical signs being shown by the patient.