Phantom limb syndrome is an eerie condition, in which amputees have the physically painful sensation that their missing limbs are still present. Now, a small new study has shown that people can twist those ghostly limbs in anatomically impossible ways, while still feeling that the limb is real and present. In essence, each amputee’s brain reshaped his understanding of where his body was. The findings show that the brain can alter how we perceive our bodies all by itself, without input from our senses [Reuters].
Researchers had patients with “vivid phantoms” try to move their wrists in a physically impossible way—a 360 degree spin of the wrist around the long axis of the forearm—and found that 4 of the 7 patients could move their wrists this way. Some patients that were able to move their wrists later reported that their phantom hands were now more difficult to move from side to side because of changes in their phantom arms’ shapes.
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With a little deception and an fMRI machine, scientists have traced the placebo effect to the spinal cord, according to new research published in the journal Science. The placebo effect, of course, is the well-known phenomenon in which patients who think they are getting medical treatment report that they feel better, even when they get only a sugar pill or other fake therapy [Los Angeles Times]. To test the limits of the placebo effect, researchers applied an anesthetic “lidocaine” cream to one arm, and a “control” cream to the other, making sure to tell the subjects which cream was which. The researchers applied a hot stimulus for 20 seconds to the skin where the each cream was applied. Participants said the “lidocaine” cream reduced pain by an average of 26 percent.
This would all be fairly straightforward had the researchers not been lying to their test subjects. You see, neither cream had active ingredients. They also primed a response by turning down the painful heat for the painkiller cream in a first test run, and so tricked volunteers into thinking that the cream would work the next time. But actual tests with an MRI scanner on involved the same level of heat for both creams. Volunteers nonetheless reported less pain with the painkiller cream [Popular Science].
The fMRI data backed up the participants’ pain perception. Normally when a person experiences pain, the dorsal horn area of the spinal cord near the lower neck will appear to be on fire with activity, but the fMRI scans showed nerve activity was reduced significantly when subjects believed they were getting the anesthetic [Reuters]. The researchers say this indicates that “psychological factors” can have an effect on pain outside of the brain. They hope to develop new treatments that can exploit the placebo effect’s painkiller effect.
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80beats: 50% of U.S. Doctors Secretly Dose Their Patients—With the Placebo Effect
80beats: Fake Surgery Eases Spinal Pain as Well as the “Real” Thing
80beats: When Surgery Is Over, Anesthetics Actually Increase Pain
Image: flickr / fbaett
An increasingly common surgical procedure for repairing spinal fractures might not be all it’s cracked up to be–in fact, the surgery had the same effect on patient’s pain as a placebo, two studies report in the New England Journal of Medicine.
The technique, called vertebroplasty, involves injecting medical cement into a fractured spine bone to strengthen it. More than 38,000 such procedures are done in the United States every year and the number has been [increasing] rapidly, nearly doubling from 2001 to 2005 [Reuters]. But the new studies showed that the procedure alleviated pain about the same amount as a placebo “surgery,” in which the physicians tapped on the spine and piped in the smell of cement to make groggy volunteer subjects believe they were receiving the real thing.
Researchers found that 36 volunteers who received sham surgery did just as well as 35 who got the real operation. A separate test, of 131 people at 11 medical centers, … also found that sham surgery produced a comparable degree of pain reduction and movement [Reuters].
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