CSF for Analysis

Specimen Required

CSF

Fasting Required

Purpose of the Test

To diagnose a disease or condition affecting the central nervous system (CNS) such as bleeding within the brain or skull, cancer, autoimmune disorder or infection

When this test is required

CSF analysis may be requested when a doctor suspects that a patient has a condition or disease involving their CNS. A patient’s medical history may prompt the request for CSF analysis. It may be requested when a patient has suffered trauma to the brain or spinal cord, has been diagnosed with cancer that may have spread (metastatic) or has signs or symptoms suggestive of a condition involving their CNS. The signs and symptoms of CNS 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 CNS bleeding or infection or may be slow to develop, indicating a chronic disease such as cancer or multiple sclerosis.Depending on a patient’s history, doctors may request CSF analysis when some combination of the following signs and symptoms appear: changes in mental status and consciousness confusion, hallucinations or seizures muscle weakness or lethargy, fatigue nausea (feeling sick) flu-like symptoms that intensify over a few hours to a few days fever or rash sudden, severe or persistent headache or a stiff neck sensitivity to light numbness or tremor dizziness difficulties with speech difficulty walking, lack of coordination mood swings, depression infants may be 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 the Test Detects

Cerebrospinal fluid (CSF) is a clear watery liquid filtrate that is formed by the choroid plexus, a special tissue that has many blood vessels and lines the small spaces or chambers (ventricles) in the brain. CSF flows around the brain and spinal cord, surrounding and protecting them. CSF is continually produced, circulated, and then absorbed into the blood system. About 500 mL is produced each day. This rate of production means…Cerebrospinal fluid (CSF) is a clear watery liquid filtrate that is formed by the choroid plexus, a special tissue that has many blood vessels and lines the small spaces or chambers (ventricles) in the brain. CSF flows around the brain and spinal cord, surrounding and protecting them. CSF is continually produced, circulated, and then absorbed into the blood system. About 500 mL is produced each day. This rate of production means that all of the CSF is replaced every few hours. A protective blood-brain barrier separates the brain from circulating blood and regulates the distribution of substances between the blood and the CSF. The barrier helps keep large molecules, toxins, and most blood cells away from the brain. Any condition that disrupts this protective barrier may result in a change in the normal level or type of constituents of CSF. Because CSF surrounds the brain and spinal cord, testing a sample of CSF can be very valuable in diagnosing a variety of diseases affecting the central nervous system (CNS). Although a sample of CSF may be more difficult to obtain than, for example, urine or blood, the results may reveal more directly the cause of brain-related symptoms. For example, infections and inflammation in the meninges (called meningitis) or the brain (called encephalitis) can disrupt the blood-brain barrier and allow white and red blood cells and increased amounts of protein into the CSF. Meningitis and encephalitis can also lead to the production of antibodies. Immune diseases that affect the CNS, such as Guillain-Barré Syndrome, and multiple sclerosis can also produce antibodies that can be found in the CSF. Cancers such as leukaemia can lead to an increase in CSF white blood cells (WBCs), and cancerous tumours can result in the presence of abnormal cells. These changes from normal CSF constituents make the examination of cerebrospinal fluid valuable as a diagnostic tool. CSF analysis usually involves an initial basic set of tests performed when CSF analysis is requested:CSF colour, clarity and pressure during collection CSF protein CSF glucose CSF cell count and differential If infection is suspected, CSF gram stain and culture A wide variety of other tests may be requested as follow-up depending on the results of the first set of tests. The specific tests that are requested may also depend on the signs and symptoms of the patient and the disease the doctor suspects is the cause. Each of these tests can be grouped according to the type of examination that is performed:Physical characteristics —includes measurement of the pressure during sample collection and the appearance of the CSF. Chemical tests —this group refers to those tests that detect or measure the chemical substances found in spinal fluid. CSF is basically an ultafiltrate of the blood (all of the large molecules such as proteins are left in the blood and do not normally pass across into the CSF), so it can also be affected by what is going on in the blood. Normally, certain constituents of CSF such as protein and glucose are a percentage of blood levels, so CSF levels are often evaluated in relation to blood levels. Microscopic examination (Cell count and differential) any cells that may be present are counted and identified by cell type under a microscope. Infectious disease tests —numerous tests can be performed to detect and identify microorganisms if an infection is suspected. For detailed explanations of various type of examinations, please see Details on CSF Tests below. See MoreSee Less

Preparation for the Test

No specific preparation. It will be necessary to lie still in a curled-up foetal position during the test and to lie quietly for a time period after the collection.

Sample Requirements

A sample of cerebrospinal fluid (CSF) is collected by a doctor from the lower back using a procedure called a lumbar puncture or spinal tap. Often, three or more separate tubes of CSF are collected, and multiple tests may be run on the different samples.

Additional Notes

Multiple tubes of CSF are often collected during a lumbar puncture to ensure the quality of samples for testing.Meningitis due to infective causes is a medical emergency. Your doctor must rapidly distinguish between this and other causes. Because prompt treatment is crucial, your doctor may start you on a broad-spectrum antibiotic before the diagnosis has been definitely determined. To help diagnose your illness your doctor may want to know what recent illnesses and vaccinations you may have had, what symptoms you are experiencing, whether you have been in contact with any ill people, and what places you have recently travelled to.

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