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Large Volume Lumbar Puncture
A large volume lumbar puncture is a special kind of lumbar puncture (spinal tap) specifically intended to remove 30 to 40 ml of cerebrospinal fluid (CSF) to both assess and temporarily relieve symptoms of hydrocephalus.
Why It Is Performed
When a large volume lumbar puncture is used to assess normal pressure hydrocephalus, your doctor will assess your gait and balance both before and after the procedure to see if removal of CSF results in a significant improvement. These tests will help guide treatment decisions.
Some patients with hydrocephalus have a dramatic improvement after a single lumbar puncture. Other people who show no significant improvement from a single tap do show a benefit with extended CSF drainage, during which 300 to 400 ml of fluid is gradually drained over a four- to five-day stay in the hospital. Extended CSF drainage, because it is more sensitive, identifies more individuals who will ultimately benefit from a shunt.
Learn more: Read our Lumbar Puncture (LP) for NPH patient information handout.
Preparing for a Large Volume Lumbar Puncture
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
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 one to seven days before a 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 325mg). Please discuss alternatives to these medications with your healthcare provider before stopping them.
Large Volume Lumbar Puncture: 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.
- 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 and collects about 30 to 40 ml of the fluid.
- The practitioner removes the needle, cleans the area and bandages the needle site. You will be asked to lie down for 30 to 60 minutes after the test.
Large Volume Lumbar Puncture: What It Is Like
Holding the proper position may be uncomfortable, but it is extremely important to stay still to avoid moving the needle.
The anesthetic will sting or burn when first injected. You might feel a 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 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.
Headache After Lumbar Puncture
Sometimes after a lumbar puncture some CSF leaks out of the area, resulting in a headache. The typical post lumbar puncture headache goes away after the person lies down for five to 15 minutes, and gets worse during standing or sitting. For most people, the headache resolves within one to three days.
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 immediately.
Epidural Blood Patch
In most cases, a CSF leak will seal itself and the headache will resolve. But if CSF continues to leak and cause debilitating headaches, the best treatment is an epidural blood patch.
This procedure involves 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.