Spinal Tap Medical Procedures

A spinal tap, also called a lumbar puncture, is used to obtain a sample of cerebrospinal fluid from the area around the spinal cord. The procedure is also used to measure the pressure of the cerebrospinal fluid. Analysis of the fluid is helpful in diagnosing infections and nervous-system diseases.

• A spinal tap is used to withdraw fluid from around the spinal cord for testing.

Significance

• Evaluating cerebrospinal fluid can help your doctor make a diagnosis regarding your condition. A white-blood-cell count is obtained from the sample and glucose and protein levels are determined. The fluid is also examined for the presence of bacteria, fungi and abnormal cells. The spinal tap procedure is used to test for such diseases and conditions as meningitis, spinal cord tumors, multiple sclerosis, tuberculosis, stroke and Guillain-Barre syndrome. In addition to detecting diseases, a spinal tap procedure can be used to deliver spinal anesthesia, inject medication or dye for a test or relieve excess pressure in the head.

Identification

• Cerebrospinal fluid is normally clear. Red or bloody fluid can indicate bleeding in the brain or spinal cord or an obstructed spinal cord. Cloudy fluid may indicate an infection, while brown, yellow or orange fluid can indicate previous bleeding or increased protein in the sample, according to the MedLinePlus website.

Proper Position

• Before the spinal-tap procedure begins, you will be asked to lie on your side with your knees bent close to your chin or sit on an examination table with your head and upper spine bent forward. These positions curve the back and widen the spaces between the vertebrae, allowing for accurate placement of the needle used in the procedure.

The Procedure

• An anesthetic will be injected into your spine before the procedure to minimize pain. When your back is numb, your doctor will insert a hollow spinal needle between two vertebrae and penetrate the spinal canal to withdraw cerebrospinal fluid. In some cases, your doctor may use an X-ray machine to help place the needle in your spine. The area will be cleaned and bandaged after the needle is removed. Your doctor may ask you to lie on your stomach or back for an hour or two after the spinal tap is completed to reduce the chance that you will get a headache.

Complications

• Possible complications after a spinal tap may include an allergic reaction to the anesthetic, a headache, bleeding in the spinal canal or an infection from the insertion of the needle. If you take blood thinning medication, you should tell your doctor before the procedure, as people who take blood thinners may experience an increased risk of bleeding. Spinal-cord nerve damage can occur if you do not remain perfectly still during the procedure.