Neurologists order spinal tap to diagnose illnesses that may be affecting a patient’s brain, spinal cord, or nervous system.
Spinal tap, also called lumbar puncture, is a medical procedure in which a medical provider inserts a long hollow needle into the patient’s lower back (lumbar region) between two lumbar bones to collect a sample of cerebrospinal fluid. The cerebrospinal fluid (CSF) surrounds the brain and the spinal cord, and the results from CSF analysis can point to possible infections or diseases.
Spinal tap is also used to test the pressure of the CSF which might have been altered by certain conditions such as the presence of large tumors.
Another application of spinal tap is injecting anesthesia to block pain in the lower half of the body. For example, the technique is used for epidural administration to block pain during childbirth.
Diseases diagnosed by spinal tap
Your doctor may order spinal tap to diagnose conditions such as bleeding in the brain, inflammation in the brain tissue or spinal cord, infection in the brain (meningitis), cancers such as leukemia and cancers of the brain or spinal cord, autoimmune conditions such as multiple sclerosis, Alzheimer’s disease, and dementia.
Information from CSF analysis is highly valuable in hard-to-diagnose conditions such as neurosyphilis and neurological Lyme disease.
Spinal tap for neurosyphilis.
Syphilis is a sexually transmitted disease (STD) that is contracted by having sexual contact with someone who has syphilis. Syphilis is also transmitted from pregnant women to their babies in the womb. The bacterium that causes syphilis spreads through the body and causes many widespread symptoms that may not appear related to an STD. In neurosyphilis, the syphilis infection spreads to the brain and the spinal cord causing neurological problems such as headaches, problems with walking and balance, vertigo, personality changes, and dementia.
CSF samples can help diagnose neurosyphilis. The white blood cell (WBC) count of 20 cells/µL or greater, or a reactive CSF Venereal Disease Research Laboratory (VDRL) test result indicates neurosyphilis.
Spinal tap for neurological Lyme
Lyme disease occurs because of getting bit by an infected tick that carries the pathogen that causes Lyme disease in humans. While early Lyme disease is easier to diagnose, especially when the patient has the characteristic rash (erythema migrans) around the bite location, late Lyme disease can be notoriously hard to diagnose. Late Lyme disease or persistent post-treatment Lyme disease can cause a variety of neurological symptoms such as headaches, hallucinations, depression, and depersonalization. CSF samples are often used to diagnose neurological Lyme by testing for antibodies the body makes against the pathogen that causes Lyme disease.