NEWS: Brain Imaging Studies Investigate Pain Reduction By Hypnosis

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University of Iowa News Release

March 14, 2005

Brain Imaging Studies Investigate Pain Reduction By Hypnosis

Although hypnosis has been shown to reduce pain perception, it is not

clear how the technique works. Identifying a sound, scientific

explanation for hypnosis' effect might increase acceptance and use of

this safe pain-reduction option in clinical settings.

Researchers at the University of Iowa Roy J. and Lucille A. Carver

College of Medicine and the Technical University of Aachen, Germany,

used functional magnetic resonance imaging (fMRI) to find out if

hypnosis alters brain activity in a way that might explain pain

reduction. The results are reported in the November-December 2004 issue

of Regional Anesthesia and Pain Medicine.

The researchers found that volunteers under hypnosis experienced

significant pain reduction in response to painful heat. They also had a

distinctly different pattern of brain activity compared to when they

were not hypnotized and experienced the painful heat. The changes in

brain activity suggest that hypnosis somehow blocks the pain signal

from getting to the parts of the brain that perceive pain.

" The major finding from our study, which used fMRI for the first time

to investigate brain activity under hypnosis for pain suppression, is

that we see reduced activity in areas of the pain network and increased

activity in other areas of the brain under hypnosis, " said Sebastian

Schulz-Stubner, M.D., Ph.D., UI assistant professor (clinical) of

anesthesia and first author of the study. " The increased activity might

be specific for hypnosis or might be non-specific, but it definitely

does something to reduce the pain signal input into the cortical

structure. "

The pain network functions like a relay system with an input pain

signal from a peripheral nerve going to the spinal cord where the

information is processed and passed on to the brain stem. From there

the signal goes to the mid-brain region and finally into the cortical

brain region that deals with conscious perception of external stimuli

like pain.

Processing of the pain signal through the lower parts of the pain

network looked the same in the brain images for both hypnotized and

non-hypnotized trials, but activity in the top level of the network,

which would be responsible for " feeling " the pain, was reduced under

hypnosis.

Initially, 12 volunteers at the Technical University of Aachen had a

heating device placed on their skin to determine the temperature that

each volunteer considered painful (8 out of 10 on a 0 to 10 pain

scale). The volunteers were then split into two groups. One group was

hypnotized, placed in the fMRI machine and their brain activity scanned

while the painful thermal stimuli was applied. Then the hypnotic state

was broken and a second fMRI scan was performed without hypnosis while

the same painful heat was again applied to the volunteer's skin. The

second group underwent their first fMRI scan without hypnosis followed

by a second scan under hypnosis.

Hypnosis was successful in reducing pain perception for all 12

participants. Hypnotized volunteers reported either no pain or

significantly reduced pain (less than 3 on the 0-10 pain scale) in

response to the painful heat.

Under hypnosis, fMRI showed that brain activity was reduced in areas of

the pain network, including the primary sensory cortex, which is

responsible for pain perception.

The imaging studies also showed increased activation in two other brain

structures -- the left anterior cingulate cortex and the basal ganglia.

The researchers speculate that increased activity in these two regions

may be part of an inhibition pathway that blocks the pain signal from

reaching the higher cortical structures responsible for pain

perception. However, Schulz-Stubner noted that more detailed fMRI

images are needed to definitively identify the exact areas involved in

hypnosis-induced pain reduction, and he hoped that the newer generation

of fMRI machines would be capable of providing more answers.

" Imaging studies like this one improve our understanding of what might

be going on and help researchers ask even more specific questions aimed

at identifying the underlying mechanism, " Schulz-Stubner said. " It is

one piece of the puzzle that moves us a little closer to a final answer

for how hypnosis really works.

" More practically, for clinical use, it helps to dispel prejudice about

hypnosis as a technique to manage pain because we can show an

objective, measurable change in brain activity linked to a reduced

perception of pain, " he added.

In addition to Schulz-Stubner, the research team included Timo Krings,

M.D., Ingo Meister, M.D., Stefen Rex, M.D., Armin Thron, M.D., Ph.D.

and Rolf Rossaint, M.D., Ph.D., from the Technical University of

Aachen, Germany.

University of Iowa Health Care describes the partnership between the UI

Roy J. and Lucille A. Carver College of Medicine and UI Hospitals and

Clinics and the patient care, medical education and research programs

and services they provide. Visit UI Health Care online at

www.uihealthcare.com.

http://www.uiowa.edu/%7Eournews/2005/march/031405hypnosis.html