Chemistry - CSF
Key points
- This test is an analysis of cerebral spinal fluid (CSF).
- A lumbar puncture (spinal tap) is the most common means of CSF collection.
- Be prepared to sign a consent form and to remain in the hospital for at least 6 to 8 hours after the test.
- The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust.
Alternative names
CSF chemistry
Definition
This test is an analysis of cerebral spinal fluid (CSF). CSF bathes, cushions, and protects the brain and spinal cord. It flows around the skull and spine in the subarachnoid space (the area immediately surrounding the brain and spinal cord).
CSF chemistry test identifies chemicals such as proteins and glucose levels, which can help diagnose certain disorders and diseases.
How the test is performed
A lumbar puncture (spinal tap) is the most common means of CSF collection. Generally, this is performed as follows: You are positioned on your side with your knees curled up to your abdomen and your chin tucked in to your chest. Local anesthetic is injected over the lower spine. The spinal needle is inserted, usually between the 3rd and 4th lumbar vertebrae, and fluid is withdrawn for testing. You will be asked to remain flat, or nearly flat, for 6 to 8 hours after the test.
Alternative methods of obtaining CSF are rarely used, but they may be recommended if you have a problem such as lumbar deformity or infection, which would make lumbar puncture impossible or unreliable:
- Cisternal puncture involves insertion of a needle below the occipital bone (back of the skull). This procedure can be hazardous because the needle is inserted close to the brain stem.
- Ventricular puncture is even more rare, but may be indicated when sampling of CSF is necessary in people with possible impending brain herniation. It is usually performed in the operating room. A hole is drilled in the skull and a needle is inserted directly into the lateral ventricle of the brain.
The CSF is then sent to the laboratory for evaluation.
How to prepare for the test
Be prepared to sign a consent form and to remain in the hospital for at least 6 to 8 hours after the test.
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
- Infant test or procedure preparation (birth to 1 year)
- Toddler test or procedure preparation (1 to 3 years)
- Preschooler test or procedure preparation (3 to 6 years)
- Schoolage test or procedure preparation (6 to 12 years)
Written and revised by
David Cohen, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
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