Also called: Cerebrospinal Fluid Test, CFS Test, Cerebrospinal Fluid Exam, Lumbar Puncture, CFS Exam, Spinal Puncture
A spinal tap is a procedure in which a long needle is inserted into the spinal canal in the lower back to collect cerebrospinal fluid (CSF) for laboratory analysis. This clear, watery fluid circulates around the brain and spinal cord and is tested for:
- Protein. High levels of protein may be antibodies that indicate an infection or another condition.
- White blood cells. High levels of white blood cells may indicate infection.
- Glucose (blood sugar). Low levels of glucose may indicate infection.
Also known as a lumbar puncture, a spinal tap can be an outpatient procedure. However, the patient typically has to remain in the hospital for several hours afterward for monitoring. Although a spinal tap is not generally painful, it can cause discomfort. Children in particular may find the procedure to be uncomfortable and may have to be gently restrained during the test.
A spinal tap may not be recommended for certain patients, such as obese individuals, those who have had back surgery and pregnant women.
Spinal taps may be used to test for neurologic conditions including:
- Infections such as meningitis and encephalitis
- Bleeding around the brain (subarachnoid hemorrhage)
- Headaches caused by spinal fluid pressure that is too high or too low
- Cancers that affect the brain and spinal cord
- Movement disorders such as dystonia
About spinal taps
A spinal tap, also called a lumbar puncture, removes a tiny amount of cerebrospinal fluid (CSF) for laboratory analysis. CSF is the clear, watery fluid that surrounds the brain and spinal cord. Spinal taps can be used to detect or treat various neurological disorders, and are also used to measure CSF pressure. Although a spinal tap is not generally painful, it can cause discomfort.
CSF forms in areas of the brain called ventricles and flows down into the area around the spinal cord. It is usually clear and contains small amounts of proteins and glucose (blood sugar). Its main function is to cushion and protect the brain and spinal cord by maintaining uniform pressure within the skull and spine.
Conditions related to neurology that may be diagnosed or treated with a spinal tap include:
- Viral or bacterial infections of the brain and spinal cord. These may include Lyme disease, encephalitis, meningitis, polio and neurosyphilis. Infections also can cause neurological symptoms and conditions such as apraxia, seizures, dementia, myoclonus and peripheral neuropathy.
- Headaches caused by spinal fluid pressure that is too high or too low.
- Bleeding around the brain (subarachnoid hemorrhage) and in the central nervous system.
- Central nervous system disorders characterized by tissue destruction, such as multiple sclerosis or various other nerve diseases. In addition, researchers have recently found that reduced concentrations in CSF of certain amyloid beta proteins may be an early indication of Alzheimer’s disease.
- Guillain-Barré syndrome. Disorder in which the body’s immune system attacks part of the peripheral nervous system.
- Hydrocephalus. An abnormal accumulation of CSF within the skull, often referred to as “water on the brain.”
- Movement disorders such as dystonia.
- Myositis. Neuromuscular swelling of the muscles sometimes brought on by injury, infection or medicines.
- An obstruction in CSF circulation.
- Cancers that affect the brain and spinal cord. These include leukemia, lymphoma and retinoblastoma.
Spinal taps are used to administer spinal anesthetic for some kinds of surgery. They are also sometimes used to administer chemotherapy medications designed to treat or prevent brain and central nervous system cancers. In this procedure, known as intrathecal chemotherapy, the drug is injected directly into the CSF and flows freely to the brain and spinal cord.