Cerebrospinal Fluid (CSF)

Cerebrospinal fluid (CSF) is a clear liquid made from filtered plasma. It surrounds, cushions, supports and protects your brain and spinal cord. It also delivers nutrients and helps remove waste.

Adults have about 150 milliliters or 5 ounces of CSF in their bodies. This is just enough fluid to fill a teacup.

Injuries or health conditions may affect how much your body makes or absorbs. If that happens, a healthcare provider can help you manage it.

What is the main function of cerebrospinal fluid?

The main functions of CSF include:

• Protecting your brain and spinal cord from injury
• Providing nutrients (like glucose, proteins and electrolytes)
• Removing waste from your brain

Other functions include:

• Balancing the weight of your brain and helping it float
• Keeping your brain’s temperature and pressure steady (homeostasis)
• Supporting immune system function by carrying immune cells and antibodies

Where is cerebrospinal fluid located?

Most of it (125 milliliters) surrounds your brain and spinal cord. It flows through the subarachnoid space. This is between two layers of protective membranes (meninges) and around the surface of your brain and spinal cord. The rest (25 ml) is in your brain’s ventricles. These are connected, fluid-filled cavities deep within your brain.

Where is CSF produced?

The choroid plexus makes cerebrospinal fluid. This is a group of cells and blood vessels in your brain’s ventricles. Your body makes 400 to 600 ml of CSF each day. It can only hold 150 ml at a time. This means your body absorbs and replaces it four to five times each day.

Flow of CSF

The fluid starts in your brain and flows through a series of connected spaces (ventricles). Then, it exits those spaces to freely move around your brain and spinal cord. It drains into your bloodstream and lymphatic system (like near your nose and along your spinal nerves).

What does CSF look like?

Typically, it has the following features:

• Clear
• No color
• Water-like texture

It may look different if you have an injury or underlying condition.

What are the common conditions that affect cerebrospinal fluid?

Common conditions that may affect CSF include:

• CSF leak: The fluid isn’t where it’s supposed to be in your body.
• Hydrocephalus: There’s too much fluid in your brain.
• Meningitis: An infection targets the meninges surrounding your brain and spinal cord.
• Pseudotumor cerebri: Too much fluid builds up in your skull and increases pressure.
• Subarachnoid hemorrhage: This is bleeding in the subarachnoid space.
• Syringomyelia: A spinal cord cyst damages nerves over time.

What are the signs or symptoms of CSF conditions?

Signs and symptoms vary based on the cause, but may include:

• Balance problems or difficulty walking
• Confusion
• Dizziness
• Headache
• Light sensitivity
• Loss of bladder or bowel control
• Muscle spasms
• Nausea or vomiting
• Neck pain or stiffness
• Numbness or tingling
• Seizures
• Vision changes

A healthcare provider can check the health of your CSF by performing a lumbar puncture.

While CSF is usually clear and colorless, it may be cloudy or red if you have an infection or spinal cord injury, for example.