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Lumbar Puncture for Pseudotumor Cerebri (PTC)
Lumbar puncture (also known as a spinal tap) is a procedure to drain the cerebrospinal fluid that surrounds the brain and spinal cord. Cerebrospinal fluid (also known as CSF) acts like a cushion, protecting the brain and spine from injury. The test is also used to measure pressure in the cerebrospinal fluid.
Preparing for a Lumbar Puncture to Treat PTC
Certain tests are necessary before a lumbar puncture to reduce risks. These include:
- A brain CT or MRI to help rule out a brain tumor and ensure there is no obstruction to CSF flow.
- Blood studies to ensure you don't have a bleeding disorder
- A neurologic examination by your physician to ensure a lumbar puncture is safe for you.
Medications and Lumbar Puncture
Before your lumbar puncture, it is essential to tell your doctor about all medications you take. Some of them, individually or in combination, may affect your safety or the performance of the procedure, especially use of blood thinners. These include:
- Clopidogrel (Plavix®)
- Ticlopidine (Ticlid®)
- Prasugrel (Effient®)
- Warfarin (Coumadin®)
- Enoxaparin (Lovenox®)
- Dalteparin (Fragmin®)
- Tinzaparin (Innohep®)
- Dabigatran (Pradaxa®)
- Rivoroxaban (Xarelto®)
- Apixaban (Eliquis®)
- Edoxaban (Savaysa®)
Other heparin derivatives may need to be stopped anywhere from 1 to 7 days before your lumbar puncture. Also let your doctor know if you take high doses of garlic, over-the-counter pain medications like ibuprofen (Advil®), naproxen (Aleve®) or high doses of aspirin (greater than 325 mg). Please discuss alternatives to these medications with your healthcare provider before stopping them.
Lumbar Puncture for PTC: What Happens
During the procedure you will lie on your side, with your knees pulled up toward your chest and your chin tucked downward. Sometimes the health care practitioner will have you seated but bent over. You will need to be repositioned once the needle is in place to ensure accurate measurement of the fluid pressure.
For the most accurate reading of the spinal fluid pressure you should be on your side, with your hips and knees in a straight line and your head in a neutral position, looking straight forward.
- After your back is cleaned with an antiseptic solution, the practitioner will inject a local numbing medicine (anesthetic) into your lower spine.
- When the area is numb, the practitioner inserts the spinal needle, usually into the lower back area.
- Once the needle is properly positioned, the practitioner measures the pressure of your CSF. If the pressure is high, CSF will be drained until a normal pressure is recorded. The CSF is also sent for laboratory analysis.
- The practitioner removes the needle, cleans the area and bandages the needle site. You will be asked to lie down for a short time after the test.
Lumbar Puncture for PTC: What It Is Like
The entire procedure usually takes about 30 to 60 minutes, but may take longer. Holding the proper position may be uncomfortable, but it is extremely important to stay still to avoid moving the needle so the doctor can get an accurate measurement of your CSF pressure.
The anesthetic will sting or burn when first injected. You might feel a hard pressure sensation when the needle is inserted and some people experience a brief pain when the needle goes through the tissue surrounding the spinal cord. This pain should stop in a few seconds. Overall, discomfort is minimal to moderate.
What if my results are normal?
The cerebrospinal fluid pressure varies throughout the day and night. The lumbar puncture provides only a spot measurement of the pressure. If your providers have a high suspicion of elevated pressures, you may need continuous cerebrospinal fluid pressure monitoring over 24 to 48 hours, which involves placing a lumbar catheter and recording pressures over an extended period of time.
What if the lumbar puncture is not successful?
Undergoing a successful lumbar puncture may be challenging for some people. In these situations, the procedure may be done with the assistance of x-ray guidance (fluoroscopy). People who sometimes experience difficulty in getting a lumbar puncture include:
- Those who have had back surgery
- Those with an abnormal back shape such as scoliosis (curvature of the spine)
- Those who are very obese
What are the risks associated with a lumbar puncture?
Risks of lumbar puncture include:
- Headache after the test: About 20 percent of people undergoing lumbar puncture will experience one
- Hypersensitivity (allergic) reaction to the anesthetic
- Discomfort during the test
- Infection, such as meningitis (less than one percent)
- Back pain and leg pain
- Temporary hearing loss or dizziness (less than one percent)
- Bleeding (a risk for individuals who take blood thinners)
- A mass in the brain such as a tumor or abscess may cause brain herniation, which can result in brain damage or death. Lumbar puncture will not be performed if an exam or test reveals signs of a brain mass.
What about headache after lumbar puncture?
Sometimes after a lumbar puncture some CSF leaks out of the area, resulting in a headache. It is routine to have patients lie down for 30-60 minutes after the procedure, however, studies have shown no difference in the prevalence of headaches with rest periods after a lumbar puncture.
The typical post lumbar puncture headache goes away after you lie down for five to 15 minutes, and gets worse while you are standing or sitting. For most people, the headache resolves within one to three days. Newer lumbar puncture needles are smaller, which reduces the risk of headache.
Pain relievers such as acetaminophen or ibuprofen can help you manage symptoms, and some people find drinking caffeinated fluids like tea or coffee helpful.
If the headache is severe or doesn't improve with time, contact your physician. If you have a fever, stiff neck, nausea or vomiting you should contact your physician and go to the emergency room right away.
Epidural Blood Patch
In most cases, a CSF leak will seal itself and the headache will resolve. But in about 3 out of 10 people undergoing a lumbar puncture, the CSF continues to leak and cause debilitating headaches.
If this happens, the best treatment is an epidural blood patch, which involves a doctor injecting about 10 to 20 ml of your own blood into the spinal area to seal the leak. It may take about 24 to 48 hours to schedule this procedure, so those who cannot tolerate any delay may need to go to the emergency room to have an epidural blood patch done.