Cerebrospinal Fluid (CSF) Analysis
What is a Cerebrospinal Fluid (CSF) Analysis?
Cerebrospinal fluid (CSF) is a clear, colorless, watery fluid that flows in and around your brain and spinal cord. Your brain and spinal cord make up your central nervous system. It controls and coordinates everything you do, including your ability to move, breathe, see think, and more.

Cerebrospinal fluid acts like a cushion that helps protect your brain and spinal cord from sudden impact or injury. The fluid also removes waste products from the brain and helps your central nervous system work properly.

A CSF analysis is a group of tests that use a sample of your cerebrospinal fluid to help diagnose diseases of the brain and spinal cord and other conditions that affect the central nervous system.

Other names: Spinal Fluid Analysis, CSF Analysis

What is it used for?
A CSF analysis is used to measure different substances in your cerebrospinal fluid. It may include tests to diagnose:

Infectious diseases of the brain and spinal cord, including meningitis and encephalitis. CSF tests for infections look at white blood cells, bacteria, and other substances in the cerebrospinal fluid
Autoimmune disorders, such as Guillain-Barré Syndrome and multiple sclerosis (MS). CSF tests for these disorders look for high levels of certain proteins in the cerebrospinal fluid.
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:

Severe headache
Stiff neck
Nausea and vomiting
Sensitivity to light
Double vision
Changes in behavior
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
Problems thinking or learning new things
What happens during a CSF analysis?
To get a sample of cerebrospinal fluid, 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 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 cerebrospinal fluid 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.
Cerebrospinal Fluid (CSF) Testing
Also Known As: CSF Analysis, Spinal Fluid Analysis
Board Approved
At a Glance
Why Get Tested?
To diagnose a disease or condition affecting the central nervous system such as meningitis, encephalitis, bleeding around the brain, cancer, or autoimmune disorder

When To Get Tested?
When your health care provider suspects that your symptoms are due to a condition or disease involving your central nervous system

Sample Required?
A sample of cerebrospinal fluid (CSF) collected by a health care practitioner from the lower back using a procedure called a lumbar puncture or spinal tap

Test Preparation Needed?
You will be instructed to empty your bladder and bowels prior to sample collection. It will be necessary to lie still in a curled-up fetal position during the collection and to lie flat and still for a time period after the collection.

What is being tested?
Cerebrospinal fluid (CSF) is a clear, watery liquid that flows around the brain and spinal cord, surrounding and protecting them. CSF testing is performed to evaluate the level or concentration of different substances and cells in CSF in order to diagnose conditions affecting the brain and spinal cord (central nervous system).

CSF is produced and secreted by the choroid plexus, a special tissue that has many blood vessels and that lines the small cavities or chambers (ventricles) in the brain. The total CSF volume is 3-5 ounces (90-150 mL) in adults and 0.3-2 ounces (10-60 mL) in newborns. CSF is continually produced, circulated, and then absorbed into the blood. About 17 ounces (500 mL) of CSF are produced each day. This rate of production means that all the CSF is replaced every few hours.

A protective, semi-permeable barrier separates the brain from the bloodstream. This blood-brain barrier allows some substances to cross and prevents other substances from crossing. Importantly, it helps keep large molecules, toxins, and most blood cells away from the central nervous system. Any condition that disrupts this protective barrier may result in a change in the normal level or makeup of CSF. Because CSF surrounds the brain and spinal cord, testing a sample of CSF can be very valuable in diagnosing a variety of conditions affecting the central nervous system.

Although a sample of CSF may be more difficult to obtain than, for example, urine or blood, the results of CSF testing may reveal more directly the cause of central nervous system conditions. The following are some examples:

Meningitis, an infection of the layers that cover the brain and spinal cord (meninges), and encephalitis, an infection in the brain
Autoimmune diseases that affect the central nervous system, such as multiple sclerosis
Cancers of the central nervous system or cancers that have spread to the central nervous system, such as leukemia
Alzheimer disease, an irreversible form of dementia
Common Questions
How is the test used?
Cerebrospinal fluid (CSF) testing may be used to help diagnose a wide variety of diseases and conditions affecting the brain and spinal cord (central nervous system). Some examples include:

Infections, such as meningitis and encephalitis—testing is used to determine if infection is caused by bacteria, viruses or, less commonly, by Mycobacterium tuberculosis, fungi or parasites, and to distinguish them from other conditions. CSF testing may also be used to detect infections of or near the spinal cord.
Bleeding (hemorrhaging) around the brain
Autoimmune disorders that affect the central nervous system, such as Guillain-Barré syndrome or multiple sclerosis
Tumors located within the central nervous system (primary) or cancers that spread to the central nervous system (metastatic cancer)
Alzheimer disease, an irreversible form of dementia
CSF testing usually involves an initial, basic set of tests performed when CSF analysis is requested:

CSF color, clarity and pressure during CSF collection
CSF protein
CSF glucose
CSF cell count (total number of cells present)
CSF differential cell count (numbers of different types of cells present)
If infection is suspected, CSF Gram stain, routine culture and molecular tests that detect the genetic material of any microbes present
A wide variety of other tests may be ordered as follow-up depending on the results of the first set of tests or the suspected diagnosis. The specific tests that are ordered depend on your signs and symptoms and the disease your healthcare practitioner suspects may be the cause. Each of these tests can be grouped according to the type of exam that is performed. For more, see Details on CSF Tests below.

When is it ordered?
CSF testing may be ordered when your health care practitioner suspects that you have a condition or disease involving your central nervous system. It may be ordered when:

You have suffered trauma to the brain or spinal cord
You have been diagnosed with cancer that may have spread into the central nervous system
Your medical history and/or signs or symptoms suggest a condition affecting your central nervous system. The signs and symptoms of central nervous system conditions can vary widely and many overlap with a variety of diseases and disorders. They may have sudden onset, suggesting an acute condition, such as central nervous system bleeding or infection, or may be slow to develop, indicating a chronic disease, such as multiple sclerosis or Alzheimer disease.
CSF testing may be ordered when you have some combination of the following signs and symptoms, especially when accompanied by flu-like symptoms that intensify over a few hours to a few days and fever:

Changes in mental status and consciousness
Sudden, severe or persistent headache or a stiff neck
Confusion, hallucinations or seizures
Muscle weakness or lethargy, fatigue
Nausea (severe or prolonged)
Sensitivity to light
Numbness or tremor
Difficulties with speech
Difficulty walking, lack of coordination
Mood swings, depression
Infants may be increasingly irritable, cry when they are held, have body stiffness, refuse food, and have bulging fontanels (the soft spots on the top of the head)
What does the test result mean?
CSF usually contains a small amount of protein and glucose and may have a few white blood cells.

Any condition that disrupts the normal pressure or flow of CSF or the protective ability of the blood-brain barrier can result in abnormal results of CSF testing. For detailed explanations of what various test results may mean, see the section below, Details on CSF Tests

What is a lumbar puncture (spinal tap) and how is it performed?
The lumbar puncture is usually performed while you are lying on your side in a curled up fetal position but may sometimes be performed in a sitting position. It is important that you remain still during the procedure. Once you are in the correct position, your back is cleaned with an antiseptic and a local anesthetic is injected under the skin. When the area has become numb, a special needle is inserted through the skin, between two vertebrae, and into your spinal canal. An “opening” or initial pressure reading of the CSF is obtained. The healthcare practitioner then collects a small amount of CSF in multiple sterile vials. A “closing” pressure is obtained, the needle is withdrawn, and a sterile dressing and pressure are applied to the puncture site. You will then be asked to lie quietly in a flat position, without lifting your head, for one or more hours to avoid a potential post-test headache.

The lumbar puncture procedure usually takes less than half an hour. For most patients, it is a moderately uncomfortable procedure. The most common sensation is a feeling of pressure when the needle is introduced. Let your health care provider know if you experience a headache or any abnormal sensations, such as pain, numbness, or tingling in your legs, or pain at the puncture site.

The lumbar puncture is performed low in the back, well below the end of the spinal cord. There are spinal nerves in the location sampled, but they have room to move away from the needle. There is the potential for the needle to contact a small vein on the way in. This can cause a “traumatic tap,” which just means that a small amount of blood may leak into one or more of the samples collected. While this is not ideal, it does occur a small percentage of the time. The evaluation of your results will take this into account.

What can be done about post-lumbar puncture pain?
Headaches are relatively common after a lumbar puncture and can occur immediately or up to a day or two after the sample collection. Lying flat after the procedure can help avoid and treat the headaches. Other potential treatments include drinking water (to stay hydrated), caffeine, and pain medication. Follow your healthcare practitioner’s recommendations and let them know if the pain persists.

Are there other reasons to do a lumbar puncture?
Yes. Sometimes it will be performed to introduce anesthetics or medications into the central nervous system. Sometimes, one or more lumbar punctures and removal of CSF may be used to decrease CSF pressure.

Why do I need a spinal tap? Why can’t my blood or urine be tested?
CSF is often the best sample to use for diagnosing conditions affecting your central nervous system because this fluid surrounds your brain and spinal cord. Central nervous system infections or diseases are most easily and rapidly identified by CSF testing, as these conditions typically lead to changes in the makeup of the spinal fluid. Tests on blood and urine may be used in conjunction with CSF analysis to evaluate your condition, however the evaluation of these specimens alone cannot be relied on to establish the presence of disease in the central nervous system.

What other tests may be done in addition to CSF testing?
Other laboratory tests that may be ordered along with or following CSF testing include:

Blood culture—to detect and identify bacteria or fungi in the blood
Culture and/or molecular testing of specimens collected from other possible sites of infection that led to meningitis or encephalitis
Blood glucose, total protein—to compare with CSF glucose and protein levels
CBC (complete blood count)—to evaluate cell counts in blood
Blood tests (serologic testing) to detect proteins released from disease-causing microbes (pathogens) or antibodies against a variety of pathogens, such as West Nile Virus and other arboviruses
CRP (C-reactive protein)—this is the preferred test to detect inflammation. An ESR (erythrocyte sedimentation rate) may be done instead if CRP is not available.
CMP (comprehensive metabolic panel)—a group of tests used to evaluate electrolyte balance and the health of your organs
Is there anything else I should know?
To help diagnose a central nervous system-related illness, a healthcare provider may want to know about recent vaccinations, sickness, contact with others who are ill, places you have traveled, signs and symptoms, and their duration.

Details on CSF Tests
CSF Physical Features (pressure and appearance)
Pressure of the CSF can be measured when opening (starting) and closing (finishing) the collection.

Increased CSF pressure may be seen with a variety of conditions that increase pressure within the brain or skull and/or obstruct the flow of CSF, such as tumors, infection, abnormal accumulation of CSF within the brain (hydrocephalus), or bleeding.
Decreased pressure may be due to dehydration, shock, or leakage of CSF through an opening (e.g., another lumbar puncture site or sinus fracture).
The appearance of the sample of CSF is usually compared to a sample of water.

Color of the fluid—normal is clear and colorless. Changes in the color of the CSF are not diagnostic but may point to additional substances in the fluid. Yellow, orange, or pink CSF may indicate the breakdown of blood cells due to bleeding into the CSF or the presence of bilirubin. Green CSF may also sometimes be seen with bilirubin or infection.
Turbidity—cloudy or turbid CSF may indicate the presence of white or red blood cells, microbes, or an increase in protein levels.
Viscosity—normal CSF will have the same consistency as water. CSF that is “thicker” may be seen in people with certain types of cancers or meningitis.
CSF Chemical Tests
Chemical tests detect or measure the chemical substances found in spinal fluid. Many of the substances in CSF are also in blood and the relative amounts in CSF and blood are often compared. Normally, levels of certain substances in CSF, such as protein and glucose, mirror the levels in blood.

CSF glucose—normal is about 2/3 the concentration of blood glucose. Glucose levels may decrease when cells that are not normally present use up (metabolize) the glucose. These may include bacteria, white blood cells, or cells shed by tumors.
CSF protein—only a small amount is normally present in CSF because proteins are large molecules and do not cross the barrier between the blood and brain easily. Decreases in CSF protein are not generally considered significant. Increases in protein are most commonly seen with:
Meningitis and brain abscess
Brain or spinal cord tumors
Multiple sclerosis
Guillain-Barré syndrome
If any of the initial tests are abnormal or if your healthcare practitioner has reason to suspect a specific condition, then additional testing may be ordered. This may include one or more of the following:

CSF protein electrophoresis—separates different types of protein; oligoclonal bands are often seen with multiple sclerosis and sometimes with other conditions.
CSF IgG (Immunoglobulin G)—increased in some conditions, such as multiple sclerosis, herpes encephalitis, connective tissue diseases
Myelin basic protein—seen when the covering of nerves (myelin) breaks down, such as with multiple sclerosis
CSF lactate—often used to distinguish between viral and bacterial meningitis; the level will usually be increased with bacterial and fungal meningitis while it will remain normal or only slightly elevated with viral meningitis.
CSF lactate dehydrogenase (LD, LDH)—used to differentiate between bacterial and viral meningitis; the level is usually increased with bacterial meningitis and not with viral meningitis; may also be elevated with leukemia or stroke.
Tumor markers—carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), and human chorionic gonadotropin (hCG) may be increased in cancers that have spread from other sites in the body (metastatic).
Amyloid beta 42 (Aß42) and tau protein—used in the evaluation of Alzheimer disease; in a symptomatic person, a low Aß42 CSF level along with a high tau level reflects an increased likelihood of Alzheimer disease.
Beta-2 transferrin—this is a protein present only in CSF. This test may be done if it is suspected that trauma to the central nervous system has caused a leak of CSF from the central nervous system. A sample of fluid leaking from the nose or ears is collected and tested. A positive test for beta-2 transferrin means the fluid is CSF.
Cell Counts, Differential and Microscopic Exam
Normal CSF has no or very few cells present and appears clear. A small drop of CSF is examined using a microscope, and cells are counted manually (or in some cases counted using an instrument). If the number of white blood cells present is very few (for example, 5 or less in an adult), the laboratory may or may not identify them or perform a cell differential (see below).

If white blood cells are numerous (such as greater than 5), a differential will most likely be done to determine the different kinds of white blood cells that are present. If cancer is suspected or has been previously diagnosed, a differential is always performed.

CSF total cell counts
Red blood cell (RBC) count—normally no red blood cells are present in the CSF. The presence of red blood cells may indicate bleeding into the CSF or may indicate a “traumatic tap” – blood that leaked into the CSF sample during collection.
White blood cell (WBC) count—normally very few white blood cells are present. A significant increase in white blood cells in the CSF can be caused by infection or inflammation of the central nervous system.
CSF white blood cell (WBC) differential—identifies and counts the different types of WBCs that are present. Small numbers of lymphocytes, monocytes (and, in neonates, neutrophils) are normal in a sample of CSF. There may be:
An increase in neutrophils with a bacterial infection
An increase in lymphocytes with a viral or fungal infection
Sometimes an increase in eosinophils with a parasitic infection
A slight increase in lymphocytes with immune disorders of the central nervous system, such as multiple sclerosis
Presence of abnormal WBCs with leukemia that has spread to the central nervous system
Abnormal cells from cancerous tumors present; if they are seen on a differential, CSF cytology will be performed (see below).
There may be an increase in the different types of WBCs with a variety of other conditions, including brain abscess, following seizures or bleeding around the brain, metastatic tumor, and inflammatory disorders such as sarcoidosis.

CSF cytology—a CSF sample is specially treated so that a microscope can be used to look for abnormal cells. This is often done when a central nervous system tumor or metastatic cancer is suspected. The presence of certain abnormal cells, such as tumor cells or immature blood cells, can indicate the type of cancer present.
Tests for Infections
Normally, CSF does not contain any bacteria, fungi, viruses or parasites.

If meningitis or encephalitis is suspected, select tests may be performed to detect and identify microbes. The selection of testing is frequently done based on signs and symptoms, the health of your immune system, and possible exposure to certain pathogens. Some of the more frequently performed tests are listed below.

CSF Gram stain—this test is always performed on CSF when infection is suspected. A sample of CSF is centrifuged and the concentrated portion is placed on a slide and treated with a special stain. A laboratory professional examines the slide using a microscope to look for bacteria or fungi, which can indicate bacterial or fungal meningitis.
CSF culture—culture is used to detect any bacteria or fungi in the sample. A negative culture does not rule out an infection because the microbes may be present in small numbers or unable to grow in culture due to prior antibiotic therapy.
Molecular testing of the CSF by polymerase chain reaction (PCR) assays can be performed to detect nucleic acid from various pathogens that may be present in the sample. This method detects bacterial, viral, fungal or parasitic genetic material (DNA, RNA) and is particularly helpful if the microbe does not grow in routine culture or if the patient has been on antibiotics.
Tests to detect antibodies produced by the immune system against specific disease-causing microbes may be helpful in infections where culture and molecular testing are insensitive (e.g., West Nile virus, Lyme disease that infects the nervous system, etc.).
Testing of CSF to detect proteins or antigens released by certain microbes, including the fungi Cryptococcus neoformans/gattii or Histoplasma capsulatum, may also be performed depending on exposure risk and signs and symptoms.
Other CSF tests for infectious diseases that are less commonly ordered include:

CSF AFB testing—used to detect infection with mycobacteria, such as Mycobacterium tuberculosis; molecular tests specific for M. tuberculosis may be performed when tuberculosis is suspected.
Tests for parasites—parasites may be detected in CSF with laboratory tests such as molecular tests, culture or microscopic exam. Infections of the central nervous system by parasites are rare and frequently are rapidly lethal. One example is an infection caused by the free-living amoeba, Naegleria fowleri, a single-cell parasite that can be found in warm water lakes and rivers. You can become infected if you swim in contaminated water and the parasite enters your respiratory system through your nose.
CSF syphilis testing (VDRL)—may be positive in people with neurosyphilis, which occurs when the syphilis bacterium infects the brain. A negative result does not necessarily rule out infection of the brain.
Cerebral Spinal Fluid (CSF) Analysis
Lumbar puncture
Detected diseases
Test analysis
What is a CSF analysis?

Cerebrospinal fluid (CSF) analysis is a way of looking for conditions that affect your brain and spine. It’s a series of laboratory tests performed on a sample of CSF. CSF is the clear fluid that cushions and delivers nutrients to your central nervous system (CNS). The CNS consists of the brain and spinal cord.

CSF is produced by the choroid plexus in the brain and then reabsorbed into your bloodstream. The fluid is completely replaced every few hours. In addition to delivering nutrients, CSF flows around your brain and spinal column, providing protection and carrying away waste.

A CSF sample is commonly collected by performing a lumbar puncture, which is also known as a spinal tap. An analysis of the sample involves the measurement of and examination for:

fluid pressure
red blood cells
white blood cells
other invasive organisms or foreign substances
Analysis can include:

measurement of the physical characteristics and appearance of CSF
chemical tests on substances found in your spinal fluid or comparisons to levels of similar substances found in your blood
cell counts and typing of any cells found in your CSF
identification of any microorganisms that could cause infectious diseases
CSF is in direct contact with your brain and spine. So CSF analysis is more effective than a blood test for understanding CNS symptoms. However, it’s more difficult to obtain a spinal fluid sample than a blood sample. Entering the spinal canal with a needle requires expert knowledge of the spine’s anatomy and a clear understanding of any underlying brain or spinal conditions that might increase the risk of complications from the procedure.

How CSF samples are taken
A lumbar puncture generally takes less than 30 minutes. It’s performed by a doctor who is specially trained to collect CSF.

CSF is usually taken from your lower back area, or the lumbar spine. It’s very important to remain completely still during the procedure. This way you avoid incorrect needle placement or trauma to your spine.

You may be seated and asked to lean over so that your spine is curled forward. Or your doctor may have you may lie on your side with your spine curved and your knees drawn up to the chest. Curving your spine makes a space between your bones in the lower back.

Once you’re in position, your back is cleaned with a sterile solution. Iodine is often used for cleaning. A sterile area is maintained throughout the procedure. This reduces the risk of infection.

A numbing cream or spray is applied to your skin. Your doctor then injects anesthetic. Once the site is fully numb, your doctor inserts a thin spinal needle between two vertebrae. A special type of X-ray called fluoroscopy is sometimes used to guide the needle.

First, the pressure inside the skull is measured using a manometer. Both high and low CSF pressure can be signs of certain conditions.

Fluid samples are then taken through the needle. When fluid collection is complete, the needle is removed. The puncture site is cleaned again. A bandage is applied.

You’ll be asked to remain lying down for about one hour. This reduces the risk of a headache, which is a common side effect of the procedure.

Related procedures
Sometimes a person can’t have a lumbar puncture because of a back deformity, infection, or possible brain herniation. In these cases, a more invasive CSF collection method that requires hospitalization might be used, such as one of the following:

During a ventricular puncture, your doctor drills a hole into your skull and inserts a needle directly into one of the ventricles of your brain.
During a cisternal puncture, your doctor inserts a needle into the back of your skull.
A ventricular shunt or drain can collect CSF from a tube that your doctor places in your brain. This is done to release high fluid pressure.
CSF collection is often combined with other procedures. For example, dye might be inserted into your CSF for a myelogram. This is an X-ray or CT scan of your brain and spine.

Risks of lumbar puncture
This test requires a signed release that states you understand the risks of the procedure.

Primary risks associated with lumbar puncture include:

bleeding from the puncture site into the spinal fluid, which is called a traumatic tap
discomfort during and after the procedure
an allergic reaction to the anesthetic
an infection at the puncture site
a headache after the test
People who take blood thinners have a heightened risk of bleeding. Lumbar puncture is extremely dangerous for people who have clotting problems such as a low platelet count, which is called thrombocytopenia.

There are serious additional risks if you have a brain mass, tumor, or abscess. These conditions put pressure on your brain stem. A lumbar puncture could then cause brain herniation to occur. This can result in brain damage or even death.

Brain herniation is a shifting of structures of the brain. It’s usually accompanied by high intracranial pressure. The condition eventually cuts off blood supply to your brain. This causes irreparable damage. The test won’t be done if a brain mass is suspected.

Cisternal and ventricular puncture methods carry additional risks. These risks include:

damage to your spinal cord or brain
bleeding within your brain
disturbance of the blood-brain barrier
Why the test is ordered
CSF analysis may be ordered if you’ve had CNS trauma. It may also be used if you have cancer and your doctor wants to see if the cancer has spread to the CNS.

In addition, CSF analysis may be ordered if you have one or more of the following symptoms:

severe, unremitting headache
stiff neck
hallucinations, confusion, or dementia
flu-like symptoms that persist or intensify
fatigue, lethargy, or muscle weakness
changes in consciousness
severe nausea
fever or rash
light sensitivity
numbness or tremor
speaking difficulties
trouble walking or poor coordination
severe mood swings
intractable clinical depression
Diseases detected by CSF analysis
CSF analysis can accurately distinguish between a wide range of CNS diseases that can otherwise be difficult to diagnose. Conditions found by CSF analysis include:

Infectious diseases
Viruses, bacteria, fungi, and parasites can all infect the CNS. Certain infections can be found by CSF analysis. Common CNS infections include:

fungal infections
West Nile virus
eastern equine encephalitis virus (EEEV)
Intracranial bleeding can be detected by CSF analysis. However, isolating the exact cause of bleeding may require additional scans or tests. Common causes include high blood pressure, stroke, or an aneurysm.

Immune response disorders
CSF analysis can detect immune response disorders. The immune system can cause damage to the CNS through inflammation, destruction of the myelin sheath around the nerves, and antibody production.

Common diseases of this type include:

Guillain-Barré syndrome
multiple sclerosis
CSF analysis can detect primary tumors in the brain or spine. It can also detect metastatic cancers that have spread to your CNS from other body parts.

CSF analysis and multiple sclerosis
CSF analysis may also be used to help diagnose multiple sclerosis (MS). MS is a chronic condition in which your immune system destroys the protective covering of your nerves, which is called myelin. People with MS may have a variety of symptoms that are constant or come and go. They include numbness or pain in their arms and legs, vision problems, and trouble walking.

CSF analysis may be done to rule out other medical conditions that have symptoms similar to MS. The fluid may also show signs that your immune system isn’t functioning normally. This can include high levels of IgG (a type of antibody) and the presence of certain proteins that form when myelin breaks down. About 85 to 90 percent of people with MS have these abnormalities in their cerebral spinal fluid.

Some types of MS progress quickly and can be life-threatening within weeks or months. Looking at the proteins in CSF may enable doctors to develop “keys” called biomarkers. Biomarkers can help identify the type of MS you have earlier and more easily. Early diagnosis could allow you to get treatment that could extend your life if you have a form of MS that’s rapidly progressing.

Lab testing and analysis of CSF
The following are often measured in CSF analysis:

white blood cell count
red blood cell count
glucose, or blood sugar
lactate dehydrogenase, which is a blood enzyme
antigens, or harmful substances produced by invading microorganisms
total proteins
oligoclonal bands, which are specific proteins
cancer cells
viral DNA
antibodies against viruses
Interpreting your test results
Normal results mean that nothing abnormal was found in the spinal fluid. All measured levels of CSF components were found to be within normal range.

Abnormal results may be caused by one of the following:

a tumor
metastatic cancer
encephalitis, which is an inflammation of the brain
an infection
Reye’s syndrome, which is a rare, often fatal disease affecting children that’s associated with viral infections and aspirin ingestion
meningitis, which you can get from fungi, tuberculosis, viruses, or bacteria
viruses such as West Nile or Eastern equine
Guillain-Barré syndrome, which is an autoimmune condition that causes paralysis and occurs after viral exposure
sarcoidosis, which is a granulomatous condition of unknown cause affecting many organs (primarily the lungs, joints, and skin)
neurosyphilis, which happens when an infection with syphilis involves your brain
multiple sclerosis, which is an autoimmune disorder that affects your brain and spinal cord
Following up after a CSF analysis
Your follow-up and outlook will depend on what caused your CNS test to be abnormal. Further testing will most likely be required in order to get a definitive diagnosis. Treatment and outcomes will vary.

Meningitis caused by a bacterial or parasitic infection is a medical emergency. Symptoms are similar to viral meningitis. However, viral meningitis is less life-threatening.

People with bacterial meningitis may receive broad-spectrum antibiotics until the cause of the infection is determined. Prompt treatment is essential to save your life. It can also prevent permanent CNS damage.