Why would a neurologist order a spinal tap?

March 25, 2024
Avatar for Jyoti KinghornJyoti Kinghorn
Spinal tap can help diagnose neurosyphilis and neurological Lyme

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.


Spinal tap

What happens during the procedure

Before beginning, the medical provider performing the spinal tap generally speaks to the patient about the procedure and what to expect during it. To begin the procedure, the providers help the patient get into a position that makes the lumbar region accessible. These include lying on a side and pulling the knees to the chest, and sitting and leaning forward. The providers clean the area and numb it with a local anesthetic which may have a burning sensation. After the anesthetic has taken effect, the patient will not feel pain though they may feel pressure. The provider then inserts a long, thin, and hollow needle and moves it into the target area for CSF collection.

How to prepare for the spinal tap

While no special preparation is required, patients should stop taking blood-thinning medications such as Aspirin, Ibuprofen, warfarin, and Plavix a week before the procedure. Any new medication even if it is an over-the-counter drug needs to be approved by the healthcare provider before taking in the week before the procedure. Patients should bring with them any X-rays, MRI scans, or CT scans of their brain or spine to the hospital.

Safety and after-effects of the spinal tap technique

Spinal tap is generally a safe technique that helps physicians diagnose a patient’s symptoms. The technique however has some risks and in some cases has aftereffects such as headache and back pain.

How to care for yourself after spinal tap

You will need a responsible adult to drive you home after the procedure. Carefully follow the discharge instructions. It is recommended to drink extra fluids and avoid beverages such as alcohol and caffeine. You should get plenty of sleep and avoid strenuous exercise for the following 24-48 hours. If you have fever or chills after the procedure, back pain, abnormal sensation in the legs or difficulty moving them, severe headache, or discharge from the puncture site, contact your medical provider.

The information provided in our blog posts is for informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this blog.

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