Migraine Test: Lumbar Puncture Or Spinal Tap
Question: What can I expect from a Lumbar Puncture or Spinal Tap test for my Migraine disease?
Headache and Migraine specialists often order several specific tests when they suspect their patient might suffer Migraine or other headache disorder. Most of the time, the physician isn’t actually looking for something ominous however. Migraine is considered a diagnosis of exclusion. Click here for more information on Migraine testing.
Lumbar Puncture Overview
A lumbar puncture (LP) is also known by the term Spinal Tap. This test is often performed when the physician needs to rule out other more serious conditions or comorbidities which may be present in patients who show certain symptoms or suffer chronic or intractable Migraine or headache. In some patients, the test itself may serve as treatment for increased CSF pressure and the headaches that result.
A needle is inserted into the space between the spinal cord and the dura that encases the spinal cord to draw out some of the cerebral spinal fluid (CSF) that surrounds both the brain and spinal cord.
When the needle punctures the dura, a pressure reading is taken. When the test is finished, another pressure reading is also noted.
Once the fluid has been drawn into a syringe it may be visualized and tested in the laboratory.
LP is a fairly simple, straightforward test that is often done in a doctor’s office or an emergency department or outpatient setting.
What Happens During An LP?
The patient will be taken to a room and asked to dress in a gown with the ties/snaps to the back. Undergarments may or may not be allowed, but details about them will be given by a nurse or assistant who gives you instructions before the procedure. Socks are usually okay to keep on, but you may have to ask about them before gowning up.
Some physicians allow a friend or family member to remain present in the room and by the head or upper body to help the patient through the procedure, but you may ask if you are concerned.
The physician performing the LP will enter the room with one or more assistants. They will introduce themselves and the doctor will explain the procedure to the patient. If the patient is not comfortable with the description, or feels that the description has not given them all the information they need to feel comfortable, this is the time to start a dialog with the doctor. Continue asking questions until you are comfortable about the process and what to expect.
The patient will be asked to sign paperwork that gives the doctor consent to do the procedure.
The doctor or assistants may ask you some questions, such as where your pain is on the pain scale, or about your current medications etc.
A special small metal table and tray will contain a number of instruments that have been autoclaved and made sterile, wrapped in a bundle. Some of the items necessary for the test are new and will be sealed inside their wrappers, laid out in a specific order. These instruments and items will be unwrapped as needed before and during the procedure. When the doctor needs them he/she will often ask an assistant, so expect an ongoing dialog between them during the procedure. Not all the instruments present will always be used during the procedure.
The patient will usually be asked to lie slightly curled up their side on the table, chin to chest, knees to chest, spine facing the physician. An alternative position is sitting, slightly bent forward, chin to chest.
The gown will be opened enough to reveal the area of the lower back where the procedure will take place, and a surgical solution such as Betadine will be applied liberally in a circular motion over a wide area to ensure sterility, and the patient is draped with a sterile surgical cloth.
As the Betadine or other surgical prep is used on the patient, the physician should be explaining what they will be doing. If they don’t explain what they are doing and you would be more comfortable with the play by play action, let your doctor know. Most are happy to talk their patients through the procedure. Other patients don’t want the doctor to tell them anything.
The doctor will palpate (feel) for the spot he wants to work with. He is looking for the space between the bony vertebrae at the level of L3/L4 (middle lumbar spine in the lower back) where the needle will pass most easily. In an adult, the spinal cord actually ends at about L2. He/she may mark that spot with a pen as well as orient the spot to the rest of the nearby anatomy.
After a verbal warning, the patient will receive a series of small injections to numb the external area where the puncture will occur. First a tiny needle numbs the skin followed by a slightly larger needle (which the patient often never feels) that numbs the tissue below the skin. To make this less painful, a special cream that numbs the area slightly before the injection can be used, as can an ice bag, but is not usually necessary. The injection may feel something like a small bee sting. If the injection is too painful, it is okay to ask for the doctor to inject the medicine slower which will often produce less of a sting. The doctor will wait a short period of time for the medicine to sufficiently numb the area where the LP will occur. During this time a special sterile kit is opened and prepared.
The doctor will check to be sure you are sufficiently numb then will adjust your position to maximize the ability to get between the vertebrae easily. Throughout the procedure, you may be asked to make very minor adjustments to your position. Once in the correct position, you will need to hold that position carefully.
The doctor will use a small gauge needle to slowly enter the space between the vertebrae and into the dural sac. He/she will record the pressure of your spinal fluid when he enters this space. The instrument used is called a Manometer and the reading is called the Opening Pressure. Someone will be on hand to record this and other pertinent information such as the appearance of the fluid and other notations.
A small amount of fluid is removed and put into special tubes to be tested in the lab. You’ll want to ask your doctor which tests you will have, but some of the tests done routinely on Migraine patients include:
- CSF pressure check
- Examination for presence of blood, infection, discolored fluid etc
- Lyme Disease
- Bacteria, fungus count and culture
- Cell count with differential
- Glucose, protein, MS chemistry
- Additional testing may be ordered
When your doctor has removed as much of the CSF as necessary, a last pressure reading is recorded and is called the Closing Pressure.
When the doctor is ready, the needle is removed, the area wiped with Betadine or similar solution. The Betadine (a non-staining iodine solution) may be washed off, but the patient usually has to request this. Patients with thyroid dysfunction are often encouraged to ask for the removal of an iodine solution from their skin because it can affect their comorbid medical conditions. They may also ask ahead for a non iodine based solution to be used instead.
A bandage may be placed over the puncture site, and the patient is encouraged to roll on their back and to make themself comfortable and rest. The patient re-dresses and is allowed to go home. Although reasonable activities are usually fine, your doctor will advise you what he/she wants you to avoid doing for the next day or so. It is the wise patient who spends the next 24 hrs taking it easy, staying clear of anything that causes the patient to strain. This includes bending over, exercising, lifting, straining to have a bowel movement, laughing, sneezing , coughing or sexual activity.
Test results will usually be completed in a relatively short period of time. The pressure readings will be evident immediately upon the LP procedure. Other tests may take additional time, especially if they need to be sent off to another lab for evaluation. Ask your doctor when you should expect results to be in, as well as a written list of the tests that have been requested. If you want someone else to have or pick up these results for you, ask to sign the required paperwork before you leave so you’re not slowed down by HIPAA regulations later. Remind your doctor that you will want a paper copy of these results when they come in.
- If papilledema is present in the eye or the physician suspects intracranial hypertension, it is important for a CT scan to be done before the LP procedure.
- If the room is excessively cool or warm, mention it when you enter the room and ask for accommodations which might include adjusting the room’s temperature or giving you a warming blanket to snuggle up in.
- Friends and family often make a nice diversion, making the procedure easier on the patient.
- Relaxation during the procedure is important and will make the experience much easier. Do whatever is necessary to relax yourself, including requesting medicine that may help to relax you before the procedure. Although the procedure is easy and medication is rarely necessary, it is important for some patients who may suffer anxiety or are afraid. If you prefer to do the procedure lying down to make you more relaxed, be sure to talk to your physician about that too.
- Ask your physician for the smallest gauge needle they feel comfortable using. This is usually a 20 – 23 gauge needle. The higher the number, the smaller the needle. The smaller the needle the more difficult it is for the physician, but the less chance of a CSF leak.
- It is important that the puncture site seals itself well before the patient exerts pressure by sitting up, standing, straining, etc. Most often the puncture seals just fine after a few minutes to 2 hours and the patient is allowed to dress and go home. Sometimes the puncture fails to seal appropriately and an additional procedure called a Blood Patch may be necessary to seal the hole and replace missing CSF, eliminating an additional problem called a Spinal Headache or Intracranial Hypotension. A blood patch takes additional personnel and equipment however, so patients with an unexpected leak often must schedule an appointment elsewhere for the procedure. A CSF leak will result in severe postural headache which, combined with severe Migraine or other headache disorder may be too much for the patient to tolerate long enough to schedule a blood patch procedure to be done later. Often the delay involves days or even weeks. It is for this reason that I encourage patients in chronic pain to speak with their physician before the procedure and ask for a preventive blood patch to be done at the time of the LP. Average patients do not usually find this necessary, however we are not average patients and are already dealing with sometimes disabling head pain.