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). Cerebral spinal fluid is produced by the choroid plexus, in the ventricles, or hollow spaces, in your brain. CSF is completely replaced every few hours and carries away waste material.

Cerebrospinal fluid, artwork
SCIEPRO / Getty Images

Analysis of the Cerebrospinal Fluid – Lumbar Puncture Procedure

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.

During a lumbar puncture a long, thin, hollow needle is inserted between spaces in your spinal cord to obtain a sample of fluid. You may feel some pressure and a little 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 do develop a headache, it may last up to a couple of days after the test. If your headache lasts for more than a week you should contact your healthcare provider.

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

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

Diseases Detected With a Lumbar Puncture

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

Hemorrhagic diseases that can be determined by an analysis of the cerebrospinal fluid include intracranial bleeding due to stroke, high blood pressure, and aneurysm.

Immunological disorders can disrupt the central nervous system with inflammation, production of antibodies, and the destruction of the myelin sheathing around the nerves. Common immunological disorders include:

Primary tumors of the brain or spine can be detected with an analysis of the cerebrospinal fluid. It can also detect cancer that has metastasized to other areas of the central nervous system. A lumbar puncture is very important for people who may have a 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.

Common Symptoms of Brain Tumors Affecting the CSF

Often the symptoms of a brain or spinal cord tumor vary. Cancer may cause an increase in the pressure in the skull or block the flow of spinal fluid. This may cause headaches, confusion, problems with balance, or walking. It may also cause problems with bladder control. These are symptoms that may prompt a lumbar puncture and CSF analysis to be done.

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.

Was this page helpful?
7 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. Johns Hopkins Medicine. Lumbar puncture.

  2. 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

  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. NIH National Institute of Neurological Disorders and Stroke. Brain and spinal cord tumors: Hope through research.

  7. 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

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