Lumbar puncture and myelogram

Your brain and spinal cord float in a clear liquid called cerebrospinal fluid, or CSF. It is held inside a thin sac. In the lower back, below where the spinal cord ends, the sac contains only fluid and fine nerve roots. A thin needle placed there can safely collect fluid or deliver medicine. This is a lumbar puncture, also called a spinal tap.

Many spinal taps are done at the bedside by feel. We use live X-ray, called fluoroscopy, to guide the needle between the bones of the spine. This helps when the spine is hard to feel, such as with arthritis, scoliosis, past back surgery, a larger body size, or an earlier tap that did not work.

On the X-ray, the bones of the lower spine look like a stack of blocks. We aim the needle into the small gap between two of them, and a drop of clear fluid at the needle hub tells us we are in the right place.

Most people only need numbing medicine in the skin. If you are very anxious, ask us about a mild calming medicine. See before your procedure.

1. 1
   Positioning

   You lie on your stomach on the X-ray table, often with a pillow under your belly to open the spaces between the bones. Sometimes we have you lie on your side.

2. 2
   Numbing

   We clean your lower back and inject numbing medicine into the skin. This stings for a few seconds.

3. 3
   Placing the needle

   Guided by X-ray, we pass a thin needle between two bones into the fluid sac. You may feel pressure. A brief zing down one leg can happen if the needle touches a nerve root, and it passes quickly.

4. 4
   Collecting fluid or giving dye

   We may measure the pressure, then let the fluid drip slowly into tubes, or inject dye for a myelogram. The needle comes out and a small bandage goes on.

The procedure itself usually takes 20 to 45 minutes. After a myelogram, you go to the CT scanner for pictures, which takes about 15 minutes more.

1. First hour
   Rest in the recovery area. After a myelogram, keep your head raised at least 30 degrees.
2. Rest of the day
   Take it easy at home. Drink plenty of fluids. Caffeine, such as coffee, can help prevent a headache.
3. First 24 hours
   No heavy lifting, hard exercise or bending. After a myelogram, keep your head raised and avoid lying flat for several hours.
4. Next day
   Most people return to normal activities, including work and driving. You can remove the bandage and shower.

Mild soreness at the needle site for a day or two is common and usually eases with acetaminophen (Tylenol). Your test results go to the doctor who ordered them. Some results come back in a day, while others, such as cultures or special proteins, can take one to several weeks.

The most common side effect is a post-dural puncture headache. It happens when fluid slowly leaks through the tiny hole in the sac. The headache is much worse when you sit or stand, and better within minutes of lying flat. It may come with neck stiffness, nausea or ringing in the ears. It usually starts within 1 to 3 days.

This headache happens in roughly 1 in 10 people. It is less common with the thin, blunt-tipped needles we prefer, and more common in younger people and women. Most such headaches go away on their own within a week with rest, fluids, caffeine and simple pain medicine.

If the headache is severe or lasts more than a day or two, an epidural blood patch usually fixes it. We draw a small amount of your own blood from your arm, about 15 to 20 mL, and inject it into the space just outside the sac, near where the tap was done. The blood forms a seal over the leak. Many people feel better within minutes to hours, and most have lasting relief after one patch.

Most of my patients are surprised by how quick and tolerable a guided spinal tap is. The part I spend the most time on is the headache, because I want you to recognize it. If your head pounds when you stand and eases when you lie down, call me. A blood patch is a small procedure, and I would much rather do it than have you suffer at home for a week.

Fabio Komlos, MD, interventional radiologist · About Dr. Fabio Komlos