Medicine Information

Lumbar Puncture: This (Really) Is Spinal Tap


I couldn't resist the title's corny riff on the name of the rock band and their movie, but the kind of spinal tap featured in this article was a spinal tap before Spinal Tap was Spinal Tap. (Does that make any sense?)

Known more formally as a lumbar puncture, this kind of spinal tap is a valuable medical test with an interesting history. In 1891 Heinrich Quincke, of Kiel, Germany, introduced this procedure as we know it today. His original intent was to help babies suffering from hydrocephalus (water on the brain) by draining away excess fluid, but from the outset he was also interested in lumbar puncture's use as a diagnostic tool.

To understand the usefulness of this test and why you might someday need to have one, a little background is helpful. The brain and spinal cord are wrapped in a membrane called the meninges. Within the meninges, a watery fluid called the cerebrospinal fluid (CSF) bathes the inside and outside of the brain and the outside of the spinal cord. Within the brain's fluid chambers (ventricles), the body perpetually manufactures new CSF from constituents of the bloodstream. Once the CSF has percolated through openings to get outside the brain, it is reabsorbed and recycled into the bloodstream. The entire volume of CSF-about 150 milliliters or five ounces-is made and reabsorbed several times per day.

Dr. Quincke understood that analyzing the CSF's makeup could be useful in diagnosing infections and other diseases affecting the central nervous system (brain plus spinal cord). Measuring the CSF's protein and glucose (sugar) content along with inspecting a sample of CSF under a microscope to count red and white blood-corpuscles soon became standard practices.

The premier use of lumbar puncture in both Quincke's time and ours has been to diagnose meningitis. The suffix "-itis" signifies inflammation, so meningitis means inflammation of the meninges. Most, but not all, instances of meningitis are due to infections, but the kinds of infections seen have evolved over the years. In Quincke's lifetime tuberculosis and syphilis germs were common causes of meningitis, but presently, in developed countries these are uncommon. Nowadays, the usual causes of meningitis are other bacteria, viruses or even funguses. In cases of suspected infection, CSF protein, glucose and blood-corpuscle measurements are supplemented by other tests on the fluid that can track down the specific, infecting organisms.

Another important use of lumbar puncture is to diagnose subarachnoid hemorrhage, an abrupt, devastating, and potentially lethal bleed into the CSF space caused by rupture of an aneurysm or other abnormal blood vessel. In suspected cases-classically presenting with "the worst headache of my life"-a computed tomographic (CT) scan is usually performed first. While very sensitive in detecting subarachnoid hemorrhages, CT scans can still miss cases. So if the doctor is still suspicious that a bleed occurred, the next step is to do a lumbar puncture which is 100% sensitive in detecting this condition. That is, it never misses.

Lumbar puncture with CSF analysis can also help in the diagnosis of multiple sclerosis, a disease in which the patient's own immune system attacks the central nervous system. In this condition the immune reaction produces abnormal proteins that can be detected and measured in the CSF.

How is the test performed? Well, the first step, of course, is the informed consent process in which your doctor explains the risks and benefits of the test and you sign a permission form. In this author's opinion, lumbar puncture is the most benign test for which written permission is traditionally required and is less risky than some other procedures-like drawing blood from a high-pressure artery-for which written permission is traditionally omitted.

The next step is to lie on your side on a bed or procedure table with your knees tucked up to your chest. The skin of your lower back is painted with an iodine-based solution to produce a sterile field. If you have an allergy to iodine, an alcohol-based solution is substituted. The surrounding area is then covered with sterile paper or cloth. The skin and the tissue beneath the skin are then numbed with local anesthetic, and then everything is ready to insert the spinal needle.

The reason the lower back (lumbar spine) is chosen is because here the sac of meninges can be entered without risk of poking a hole in the spinal cord. This is because the spinal cord ends several inches higher within the spinal canal. The composition of the CSF is nearly the same throughout its system. Thus, CSF from the lumbar region is as good for diagnosis as from anywhere else, yet safer to obtain.

Once the spinal needle enters the lumbar sac of fluid, correct positioning of the needle is confirmed by the emergence of clear, colorless drops of fluid from the back of the needle. (When a similar procedure is performed for the purpose of epidural anesthesia, the tip of the needle stops just short of entering the meninges, and the drug is infused outside the sac.) A thin plastic tube is then attached to the back of the needle so the CSF's pressure can be measured. Subsequently, CSF is allowed to drip into each of several sealable test-tubes suitable for sending to the laboratory.

Once adequate fluid has been obtained, the needle is withdrawn and the small puncture site in the skin is covered with an adhesive bandage. Typically, there are no more than a few drops of blood-loss from this test.

How about risks? Fortunately, they are minimal. As with any other test in which a needle is inserted somewhere that Mother Nature never intended, bleeding is a possibility. Luckily, there are no major blood-vessels in the vicinity, so even an off-course needle is unlikely to cause trouble. Theoretically, a needle-insertion could also bring germs into the body and cause infection, but this almost never occurs because the needle is sterile and because the lumbar region had been surgically prepped.

About one-in-five patients experiences a headache from the procedure. When a spinal-tap headache occurs, it always has the following characteristics: it is present while the patient is sitting or standing, and is promptly relieved by lying down. Spinal-tap headaches are due to persistent leaking of CSF through the hole that the needle made in the meninges. (The leaking occurs within the spinal column and doesn't leave the body.) Until the hole seals up again and the full volume of CSF is restored, the CSF cannot provide its usual cushioning effect with changes in head position, and a headache ensues. In such cases the patient remains horizontal until the leak has sealed over.

Reviewing a list of potential complications can have a discouraging effect on people who need a test. But it is reassuring to know that millions of people have had Dr. Quincke's test since he devised it over a century ago. If the test caused unforeseen problems, they should have turned up by now.

(C) 2005 by Gary Cordingley

Gary Cordingley, MD, PhD, is a clinical neurologist, teacher and researcher who works in Athens, Ohio. For more health-related articles, see his website at: http://www.cordingleyneurology.com


MORE RESOURCES:
This RSS feed URL is deprecated, please update. New URLs can be found in the footers at https://news.google.com/news


Financial Times

Scientists develop electronic 'smart skin' for sports and medicine
Financial Times
Electronic “smart skin” devices are being developed to monitor the biochemistry of sweating sports players, the health of stroke patients and the heartbeat of sick babies, researchers told the American Association for the Advancement of Science meeting ...
Japanese researchers develop ultrathin, highly elastic skin displayEurekAlert

all 19 news articles »


KFDI

Flus, cold and cavities: How cold medicine can affect your kids teeth
KFDI
INDIANAPOLIS -- During this cold and flu season, dentists want you to take extra steps when giving cold and cough medicine to your children. Dentists at Indiana University Health report many of the liquid medications are chock full of sugars, which end ...

and more »


Standard Speaker

New medicine effective in fighting high cholesterol
Standard Speaker
The new drug is expensive, about $14,000 a year before insurance for the twice-monthly self-injected medicine. Blum said insurance companies typically will cover the drug for patients who can't reach their cholesterol goals with the highest tolerated ...

and more »


Forbes

Is Gaming Technology 'Medicine's New Frontier?'
Forbes
The Internet is rife with articles about the potentially harmful effects of gaming. Psychologists and parents have been debating the pros and cons of the issue for decades now—namely whether video games promote violence, social isolation and obesity ...



Stuff.co.nz

Popular Arthrem medicine linked with potential harm to liver
Stuff.co.nz
Medsafe is advising members of the public taking the dietary supplement Arthrem of a potential risk of harm to the liver. A widely used supplement to relieve joint pain could harm the liver - and some users have needed hospital care, Medsafe warns ...
Warning of potential harm to liver associated with the natural medicine ArthremNew Zealand Doctor Online

all 6 news articles »


HuffPost South Africa

Local Black Women Breaking Down Barriers In Medicine
HuffPost South Africa
From the youngest black female hospital CEO to the country's first black female neurosurgeon — young women in medicine are trailblazing. These mbokodos, all in their thirties, are as inspirational as they are aspirational. And today we're celebrating ...



Tri-City Herald

Medicine engineered specifically for you? That's PNNL's goal
Tri-City Herald
How disease develops and how it responds to treatment can be as different as people themselves. That knowledge is inspiring a new medical discipline, precision medicine, that relies heavily on the type of scientific expertise and resources found at ...



Front Page Africa

Why Is Liberian Health System Struggling With Modern Day Medicine?
Front Page Africa
Corruptions which includes, misappropriate used of funds, irrational used of resources and the failure of auditor to report the actual case if there is any because they negotiate with said administrator/s for little of nothing leaving the majority with ...

and more »


Healthcare IT News (blog)

Penn Medicine CISO: 3 Strategies every security team should have
Healthcare IT News (blog)
After all the cybersecurity threats and events in the last 12 months, infosec teams should focus on these priorities as the craft strategies into the future. By Dan Costantino. February 19, 2018. 09:08 AM. Share. cybersecurity threats. The information ...



Catholic San Francisco

'SLOW MEDICINE'
Catholic San Francisco
Sweet, now an associate clinical professor of medicine at UC San Francisco, decided to write a book “and capture what I learned so other people could experience what I experienced.” Five years later, in 2012, she published “God's Hotel: A Doctor, a ...


Google News

home | site map | Dr. Thad Thomas
© 2006