NEW YORK (Reuters Health) - An X-ray-guided spinal tap — a procedure in which a small needle is inserted into the patient’s lower spine to retrieve cerebrospinal fluid — carries higher risks for infants and the elderly, a new study shows.
Researchers at Wake Forest University School of Medicine in Winston-Salem, North Carolina, found that spinal tap procedures fail more than half of the time in young infants and, therefore, should be used sparingly, if at all, in this age group, they conclude.
They also found that the X-ray-guided form of spinal tap, called fluoroscopy-guided lumbar puncture, doubles the risk of bleeding in people older than 80 years compared to younger people. The risk of bleeding caused by the procedure, they found, can be reduced by doing the puncture at the middle of the lower back rather than at the lowest levels of the spine.
Spinal tap procedures are often used to diagnose patients who have sudden severe headache, possible meningitis infection or cancers around the brain. In up to a quarter of procedures, placement of the needle causes some bleeding into the cerebrospinal fluid, which makes it more difficult to arrive at a diagnosis because it is hard to determine if the blood is a symptom of the condition or a result of the lumbar puncture.
In their study, Dr. Annette J. Johnson and colleagues reviewed more than 750 patients ranging in age from less than 1 year to 90 years old who had fluoroscopy-guided lumbar puncture.
They found that the procedure failed in about 60 percent of the cases that involved very young patients and needle insertion caused bleeding into the cerebrospinal fluid in about 25 percent of the infant cases.
For patients older than age 80, the researchers found that such bleeding occurred in about 26 percent of cases — twice the rate seen in younger patients.
Regardless of age, lumbar punctures in the lower part of the low-back were twice as likely to result in bleeding as were those in the middle low-back.
The study appears in the latest issue of the American Journal of Neuroradiology.
“Lumbar punctures,” Johnson said in a prepared statement, “will very likely continue to be a common medical procedure. The findings of this study should help ordering physicians decide how best to order this test and should help radiologist physicians choose at which levels to perform the procedure.”
SOURCE: American Journal of Neuroradiology, March 2009.