When you’re being evaluated for some nerve disorders and diseases, you may need a spinal tap or lumbar puncture. This procedure involves inserting a needle into the spinal canal, located low in the back, to collect and look at fluid surrounding the brain and spinal cord.
A spinal tap can help diagnose serious conditions like meningitis, as well as disorders of the central nervous system like multiple sclerosis and some forms of cancer.
The most common risks associated with spinal tap include headache, back discomfort and bleeding at the puncture site. A spinal tap usually is completed as an outpatient procedure with a local anesthetic used to numb the puncture site before the needle is inserted. The procedure is completed in less than an hour, and you will need to avoid strenuous activities for the remainder of the day. Nonprescription pain-relieving medication can help reduce back pain or headache.
Your spinal fluid sample will be sent to a laboratory for analysis where it will be checked for:
- Appearance – A cloudy appearance may be a sign of infection or inflammatory condition.
- White blood cells – Increased numbers may indicate infection.
- Protein and Sugar (Glucose) – Elevated protein and sugar levels may also indicate infection or another condition.
- Microorganisms – The presence of microorganisms such as viruses, bacteria or fungi may indicate an infection.
- Cancer Cells – Abnormal cells in spinal fluid may indicate certain types of cancer.
Lab results are used along with other tests to determine a possible diagnosis.