Cerebrospinal Fluid

CSF cushions your brain protecting it from injury

Cerebrospinal fluid, also known as CSF, is a clear, colorless fluid that flows through the brain and spinal cord, surrounding and cushioning it from injury. CSF has the same consistency as water and delivers nutrients to your central nervous system (CNS). In addition, the choroid plexus produces cerebral spinal fluid in your brain's ventricles (hollow spaces). CSF is completely replaced every few hours and carries away waste material.

Cerebrospinal fluid, artwork
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Cerebrospinal Fluid Analysis

Examination of the cerebrospinal fluid helps to diagnose diseases, including infectious diseases of the central nervous system, causes of brain hemorrhages, immunological disorders, and cancer. Fluid is obtained by performing a lumbar puncture, also known as a spinal tap.

Lumbar Puncture

During a lumbar puncture, a long, thin, hollow needle is inserted between spaces in your spinal cord to obtain a fluid sample. You may feel pressure and a bit of soreness as the needle enters your body. After the fluid is removed, you will be asked to lie flat for an hour or more after the test. This is to prevent a headache. If you develop a headache, it may last up to a couple of days after the test.

The CSF is analyzed for its pressure, appearance, protein, glucose, cell count, and identification of cells. It is stained for microscopic examination and cultured to look for bacteria and other infectious organisms. Other chemistry tests include looking for tumor markers, amyloid beta 42 and tau protein in Alzheimer's disease, myelin essential protein in multiple sclerosis, and various other assays.

When to Call a Healthcare Provider

You should contact your healthcare provider if your headache lasts for more than a week.

If you develop a high fever, severe headache, sensitivity to light, vomiting, or tingling or numbness in your legs, you should contact your healthcare provider.

Purpose of CSF Analysis

Infectious diseases such as viruses, bacteria, fungi, and parasites can infect the central nervous system. The most common infections of the CNS include:

Cerebrospinal fluid analysis can identify hemorrhagic diseases such as intracranial bleeding due to stroke, high blood pressure, and aneurysms.

Immunological disorders can disrupt the central nervous system with inflammation, producing antibodies and destroying the myelin sheathing around the nerves. Common immunological diseases include:

Primary brain or spine tumors can be detected by analyzing the cerebrospinal fluid. It can also detect cancer that has metastasized to other areas of the central nervous system. A lumbar puncture is significant for people who may have brain lymphoma because the lymphoma cells often spread into the cerebrospinal fluid. CSF analysis can be used to determine the type and grade of cancer.

Injections Into the CSF for Treatment of Brain or Spinal Cord Cancer

A lumbar puncture may be used to deliver chemotherapy medication to treat brain or spinal cord cancer. This process is known as intrathecal chemotherapy. It is used in the treatment of some types of leukemia or lymphoma.

The procedure, which typically takes 20 minutes, includes numbing an area of skin over your spine. A needle will be gently inserted, and the chemotherapy will be injected through the needle into the CSF. A benefit of this process is that there are very few post-chemotherapy side effects. Some side effects may include a headache.


Cerebrospinal fluid plays an essential role in supporting the nervous system, including the brain and spinal cord. A lumbar puncture is a procedure that can access the CSF for a fluid sample for disease diagnosis.

A Word From Verywell

A lumbar puncture can identify infections in the CSF or serious diseases that effect the nervous system. Your healthcare provider will explain the details of the procedure if it is necessary. A severe headache is a possible side effect of a lumbar puncture and you should immediately notify your healthcare provider if this occurs.

Frequently Asked Questions

  • What are the three functions of the cerebrospinal fluid?

    Cerebrospinal fluid surrounds and cushions the nervous system, including the brain and spinal cord. CSF provides nutrients to the nervous system and removes waste.

  • What is the normal CSF pressure?

    The normal range of CSF pressure is 70 to 180 mm of H2O.

  • How do you know if you are leaking cerebrospinal fluid?

    The most common symptom of a CSF leak is a severe headache. Other symptoms are related to the location of the leak and can include:

    • Runny nose
    • Blurred vision
    • Loss of smell (anosmia)
    • Neck pain
    • Dizziness
    • Nausea and vomiting
    • Seizures
    • Pulsing ringing in the ears (tinnitus)
8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Hrishi AP, Sethuraman M. Cerebrospinal Fluid (CSF) analysis and interpretation in neurocritical care for acute neurological conditionsIndian J Crit Care Med. 2019;23(Suppl 2):S115–S119. doi:10.5005/jp-journals-10071-23187

  2. Johns Hopkins Medicine. Lumbar puncture.

  3. Dando SJ, Mackay-Sim A, Norton R, et al. Pathogens penetrating the central nervous system: infection pathways and the cellular and molecular mechanisms of invasionClin Microbiol Rev. 2014;27(4):691–726. doi:10.1128/CMR.00118-13

  4. Caceres JA, Goldstein JN. Intracranial hemorrhageEmerg Med Clin North Am. 2012;30(3):771–794. doi:10.1016/j.emc.2012.06.003

  5. Wang Y, Springer S, Zhang M, et al. Detection of tumor-derived DNA in cerebrospinal fluid of patients with primary tumors of the brain and spinal cordProc Natl Acad Sci U S A. 2015;112(31):9704–9709. doi:10.1073/pnas.1511694112

  6. Triarico S, Maurizi P, Mastrangelo S, Attinà G, Capozza MA, Ruggiero A. Improving the brain delivery of chemotherapeutic drugs in childhood brain tumorsCancers (Basel). 2019;11(6):824. doi:10.3390/cancers11060824

  7. Medline Plus. Cerebrospinal fluid (CSF) collection.

  8. Cleveland Clinic. Cerebrospinal fluid CSF leak.

Additional Reading
  • American Association for Clinical Chemistry, Lab Tests Online. CSF Analysis.

By Blyss Splane
Blyss Splane is a certified operating room nurse working as a freelance content writer and former travel nurse. She works as a freelance content writer for healthcare blogs when she's not spending time with her husband and dog.

Originally written by Lisa Fayed