Normal pressure hydrocephalus can cause trouble walking, memory changes and bladder accidents, symptoms that are easy to blame on aging. The lumbar tap test helps answer an important question: will removing extra spinal fluid make you better?
A lumbar tap test, also called a high-volume lumbar puncture, removes a larger-than-usual amount of spinal fluid through a thin needle in the lower back, usually about 30 to 50 milliliters (2 to 3 tablespoons). Your walking, and sometimes your thinking, is tested before and after to see whether removing fluid helps.
For some patients, a lumbar drain trial is used instead: a small tube drains fluid slowly over two to three days in the hospital.
The test is used for patients with suspected normal pressure hydrocephalus (NPH). If your walking clearly improves after fluid is removed, there is a good chance you will benefit from a VP shunt, a permanent drain that does the same thing long-term. Dr. Grunch uses the results, along with your MRI or CT, to decide whether a shunt is likely to help.
First, your walking is tested, for example by timing how long it takes to walk a set distance and turn around, and counting your steps. Then you lie on your side or sit leaning forward while the skin is numbed and a thin needle is placed in your lower back. Fluid is drained slowly for several minutes. Your walking is tested again, often 30 minutes to a few hours later.
Rest and drink plenty of fluids for the rest of the day. Pay attention to how you walk and think over the next one to two days, because improvement sometimes shows up later, and tell the office what you and your family notice. Call if you have a headache that is much worse when you sit or stand, a fever or a stiff neck. Dr. Grunch or one of her physician assistants will review the results and talk with you about whether a shunt is a good option.
The lumbar tap test is a low-risk test. The most common side effect is a headache from the needle site, which usually improves with rest and fluids. Infection and bleeding are rare.
It is a spinal tap that removes a larger amount of spinal fluid, with walking tests before and after, to see whether you might improve with a shunt for normal pressure hydrocephalus.
It does not always rule out NPH. Dr. Grunch may recommend a longer lumbar drain trial, or look at other possible causes of your symptoms.
Some people walk better within hours. Others notice changes over the next day or two, which is why your observations at home matter.
If Dr. Grunch has ordered a lumbar tap test for you and you have questions, call 470-293-9800 or contact us. You can also ask general questions any time through our “Ask Us Anything” chat. For questions about scheduling, cost or arrival time for the test itself, call the imaging center where it is booked.
Related: All imaging and diagnostic tests · Normal pressure hydrocephalus · VP shunt
This information is for educational purposes only and is not medical advice. It does not replace individualized care from a licensed physician. Please talk to your provider about your symptoms and follow the instructions from your imaging center.
