Cerebrospinal Fluid (CSF) Analysis

What is a cerebrospinal fluid (CSF) analysis?

A cerebrospinal fluid (CSF) analysis tests a sample of your CSF for diseases that affect the brain and spinal cord, which make up your central nervous system. Your central nervous system controls and coordinates everything you do, including your ability to move, breathe, see, think, and more.

CSF is a clear, colorless, watery fluid that flows in and around your brain and spinal cord. CSF acts like a cushion that helps protect them from sudden impact or injury. It also removes waste products from the brain and helps your central nervous system work properly.

The CSF normally has substances like water, vitamins, and nutrients in it and is free of cells, proteins, and toxins (a type of poison). Certain diseases of the brain and spinal cord and other conditions that affect the central nervous system can cause a change in the amount of CSF you have or what substances are in your CSF. A CSF analysis is a group of tests that use a sample of your CSF to help diagnose these types of diseases.

Other names: Spinal Fluid Analysis, CSF Analysis

What is it used for?

A CSF analysis is used to measure different substances in your CSF. It may include tests to diagnose:

• Infectious diseases of the brain and spinal cord, including meningitis (inflammation of the brain and spinal cord) and encephalitis (inflammation of the brain). CSF tests for infections look at white blood cells, bacteria, and other substances in the CSF.
• Autoimmune disorders, such as Guillain-Barré Syndrome (a rare disorder where the immune system attacks the nerves that connect the brain and spinal cord to the body) and multiple sclerosis (MS; a nervous system disease of the brain and spinal cord). CSF tests for these disorders look for high levels of certain proteins in the CSF.
• Bleeding in the brain.
• Brain tumors, including from cancers in other parts of the body that may spread to the central nervous system.
• Alzheimer's disease, the most common form of dementia, which includes memory loss, confusion, and changes in behavior.

Why do I need a CSF analysis?

Your health care provider may order a CSF analysis if you have:

• Symptoms of an infection or bleeding in the brain or spinal cord
• Symptoms of an autoimmune disorder, such as multiple sclerosis (MS)
• Had a brain injury or an injury to your spinal cord
• Have cancer that may have spread to your central nervous system
• Symptoms that may be from another central nervous system condition, such as headaches

Symptoms of a brain or spinal cord infection include:

• Fever
• Severe headache
• Seizures
• Stiff neck
• Nausea and vomiting
• Sensitivity to light
• Double vision
• Changes in behavior
• Confusion

Symptoms of MS often vary and come and go, or they may steadily get worse. They may include:

• Blurred or double vision
• Tingling, numbness, or pain in the arms, legs, body, or face
• Painful muscle spasms
• Weak muscles, often in the hands and legs
• Dizziness, balance problems, or clumsy movement when walking
• Bladder control problems
• Fatigue
• Problems thinking or learning new things

What happens during a CSF analysis?

To get a sample of CSF, a provider will do a procedure called a spinal tap, also known as a lumbar puncture. A spinal tap is usually done in a hospital. During the procedure:

• You will lie on your side or sit on an exam table.
• A provider will clean your back to disinfect it and inject an anesthetic into your skin, so you won't feel pain during the procedure. Your provider may put a numbing cream on your back before this injection.
• When the area on your back is completely numb, your provider will insert a thin, hollow needle between two vertebrae in your lower spine. Vertebrae are the small backbones that make up your spine.
• Your provider will withdraw a small amount of CSF for testing. This will take about five minutes.
• You'll need to stay very still while the fluid is being withdrawn.
• Your provider may ask you to lie on your back for an hour or two after the procedure. This may prevent you from getting a headache afterward.

Will I need to do anything to prepare for the test?

You don't need any special preparations for a CSF analysis, but you may be asked to empty your bladder (pee) and bowels (poop) before the test.

Are there any risks to the test?

There is very little risk to having a spinal tap. You may feel a little pinch or pressure when the needle is inserted. After the test, you may feel some pain or tenderness in your back at the site where the needle was inserted.

You may also have some bleeding at the site or get a headache. The headache may last for several hours or up to a week or more, but your provider may suggest treatment to help relieve the pain.

What do the results mean?

A CSF analysis may include a variety of different tests on your sample. So, the measurements on your test results will depend on which tests were done. Your provider can explain what your results mean.

In general, your CSF analysis results may show that you have an infection, an autoimmune disorder, such as multiple sclerosis (MS), or another disease or injury of the brain or spinal cord. Your provider will likely order more tests to confirm your diagnosis.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a CSF analysis?

Some infections, such as meningitis caused by bacteria, are life-threatening emergencies. If your provider suspects you have bacterial meningitis or another serious infection, you may need to start medicine before you have a final diagnosis.