Lumbar puncture (LP), or spinal tap, is a procedure by which cerebrospinal fluid (CSF) is removed so that it can be analyzed for abnormalities commonly seen in MS. CSF is a fluid that bathes and cushions the brain and the spinal cord. It is removed during LP with a spinal needle inserted into the lower spine, between the 3rd and 4th or the 4th and 5th lumbar vertebrae.
What can I expect when I undergo a lumbar puncture?
Lumbar puncture can be done in your neurologist’s office in about 30 minutes, however you will need to lie absolutely flat and still for at least an hour afterwards. During the procedure, you will be asked to lie on your side with your knees drawn up to your chest, exposing your back and spine. A local anesthetic is injected into your back near the site of the LP. After the area is numb, a small hollow needle called a spinal needle is inserted into an area of the spine below the lowest tip of your spinal cord typically between the 3rd and 4th or the 4th and 5th lumbar vertebrae. After needle insertion, a small amount of CSF (1 to 2 tablespoons) is withdrawn which can take anywhere from 2 to 5 minutes. The doctor may measure the amount of pressure in the CSF using a special device called a manometer.
After removal of the needle, the doctor will apply pressure to the site of the puncture and have you lie absolutely still on your back for at least an hour or longer. It is very important to lie still after the procedure to help prevent the development of a spinal headache which can occur if CSF leaks from the site of the puncture. The spinal headache is a common side effect of LP that affects 10%-40% of patients. If you do experience headache or nausea after your LP, it should resolve with rest. If the spinal headache persists for more than 24 hours, you need to go back to your neurologist’s office to receive a blood patch, which involves the injection of a small amount of blood into the space of the original puncture in order to provide a blood clot to seal the spinal fluid from leaking. It is also important to get plenty of fluids before and after the LP, as well as limit physical activity for at least 24 hours following the procedure.
What does CSF look like and what will my doctor be looking for?
CSF is colorless and clear, containing very few red and white blood cells. It will be tested for the presence of certain cells and proteins, including oligoclonal bands (O-bands), which indicate the kind of abnormal immune response seen in MS. The CSF chemical analysis will also test for other diseases which might cause MS-like symptoms.
Is there risk for any serious complications with lumbar puncture?
As with any invasive medical procedure, a risk for complications with LP exists, however serious complications are extremely rare. Trauma to the spinal nerve root may result in loss of sensation, weakness, or pain. If the spinal needle comes in contact with the spinal nerve root, an abnormal sensation or pain in the legs may occur. If this happens, don’t worry, it’s harmless and will resolve when the procedure is completed. Epidural bleeding is another rare complication of lumbar puncture.