One of the most commonly used diagnostic tests for multiple sclerosis includes the spinal tap. If your physician recommends other tests or procedures to help understand the underlying cause of your condition, you will receive specific instructions at that time.
- What is a Lumbar Puncture?
- Why do I need one?
- How do I prepare?
- What happens on the day of my appointment?
- What happens after my procedure?
- Do I need additional help?
A lumbar puncture is a procedure used to collect cerebral spinal fluid (CSF) for analysis. Cerebral spinal fluid is a clear fluid that circulates in the space surrounding the spine and brain. It acts like a cushion protecting the brain and spine from injury. During the procedure, a hollow needle, or cannula, is used to penetrate the spinal canal at the level of the third-to-fourth or fourth-to-fifth lumbar vertebra. CSF is then drawn through the needle.
A lumbar puncture is most commonly performed to measure the pressure within the cerebrospinal fluid (CSF) and to collect a sample for further testing. The CSF can be evaluated for color, blood cells, bacteria, malignant cells, glucose, protein and many other chemical changes. The results of the evaluation can be used to diagnose some neurological disorders. Lumbar punctures can also be used to decrease spinal fluid pressure in patients with normal pressure hydrocephalus and benign intracranial hypertension. Lumbar punctures can also be used as an access method for spinal anesthesia, introduction of radio opaque contrast (as used in myelograms), corticosteroids, antibiotics, and chemotherapeutic agents.
Preparing for your lumbar puncture is easy. Your doctor will probably order several blood tests to be sure that you don’t have any unusual bleeding or clotting. If you take a blood thinner, make sure you ask your doctor when you should stop this medication. If you take Ibuprofen or aspirin frequently, you should stop taking them a few days before your spinal tap.
You should plan to spend at least three hours at the hospital on the day of your procedure. Although the actual spinal tap takes only a few minutes, numbing and cleaning the area and preparation can take about 30 minutes. You will want to wear loose fitting clothing to increase your comfort following your procedure.
You will also need to lie flat following the spinal tap for a minimum of one hour to promote clotting at the site of the puncture.
We ask that you arrive as scheduled at the Neurology/Neurosurgery reception desk located on the fifth floor of the Johns Hopkins Outpatient Center. Family members may be allowed to accompany you to the procedure area and join you following the procedure.
If you get lost, or are running late, please call the reception desk at 410.955.7642 for help.
Before the procedure, you will be asked to empty your bladder. You will remove your outer pants only and put on a hospital gown. A healthcare worker will help position you on an exam table so that your back is facing the doctor. Some doctors prefer to have their patients sit on the exam table and hunch your back over a bedside table or pillow. Either way will allow the spaces of the back bones to stretch open for the very small spinal needle to fit in between the bony area. You will be draped and prepped with an antiseptic cleansing solution like iodine. This solution will feel cold. The doctor will use a very small needle to numb the area. You may feel some stinging for a brief time during this process.
Once the area is numb, the doctor will place the needle below the spinal cord level but into the spinal canal. Since the spinal cord ends approximately at the navel, risk of injury to the actual spinal cord is very minimal. Most people report feeling only pressure during this part of the procedure, not pain. Rarely, patients may feel a mild nerve shock as the needle brushes some of the nerve endings. If this does occur the needle can be moved to reduce discomfort. The entire procedure usually takes 15-20 minutes.
Generally three-to-four small vials of fluid are removed.
Once the needle is removed, a Band-Aid is placed over the hole in your skin. You will be asked to remain flat on the exam table for a minimum of one hour to promote closing of the inner hole. To promote cerebral spinal fluid production, you will be encouraged to drink fluid while you recover. We recommend drinking extra fluids for the next two-to-three days. Although this will certainly result in additional trips to the bathroom, it may reduce the likelihood of headaches.
A headache following spinal tap occurs in five-twenty percent of patients. It typically comes on upon standing and is relieved by lying down. You should lie flat on your back or stomach (but not your side) for as long as you can the first 24 hours after the procedure or if you have a headache. Also, to minimize complications, it is recommended that patients avoid bending and heavy lifting for two-to-three days following the procedure. Even lifting a small child following this procedure can cause the clot formation to become dislodged. Your physician will tell you when it is safe to return to work. Most people can generally return to work in one-to-two days.
Some post-LP headaches do not resolve with fluids and bed rest. If this happens, a blood patch can be performed to relieve your symptoms. Rarely, the lumbar puncture/spinal tap can cause infection. You should monitor yourself closely for three-to-five days for signs of infection, including: fever/ temperature over 101, drainage or redness at the site, severe stiff neck, persistent head pain that is not affected by acetaminophen (Tylenol), nausea or vomiting.