Acupuncture Causes Brain Changes in Patients With Hand Pain

Laird Harrison

May 28, 2015

PALM SPRINGS, California — Acupuncture appears to thicken the cortex of patients with idiopathic hand pain while alleviating their pain, a new study suggests.

The finding provides new evidence for a condition resembling carpal tunnel syndrome but with a different cause, said first author, Norman Kettner, DC, chair of radiology at Logan University in Chesterfield, Missouri.

"This needs further investigation," he told Medscape Medical News.

Dr Kettner presented the finding here at the American Pain Society (APS) 54th Annual Scientific Meeting.

Typical symptoms of carpal tunnel syndrome include pain and paresthesia over median-nerve innervated regions of the hand. But while conduction is decreased in the median nerves of some of these patients, it is normal in others.

To understand the differences in these two groups, Dr Kettner and his colleagues assigned 15 patients with idiopathic hand pain and 21 patients with carpal tunnel syndrome to 16 acupuncture treatments over the course of 8 weeks.

The carpal tunnel syndrome group averaged 49.2 years of age, while the idiopathic hand pain group averaged 38.5 years of age.

Acupuncture consisted of electrical stimulation at 2 Hz in points PC7 and TW5, with manual acupuncture at three additional points among HT3, PC3, SI4, LI5, LI10, and LU5 chosen by practitioners on the basis of their diagnoses.

The researchers measured the patients' nerve latency and velocity using electrophysiologic testing. They used MRI to measure cortical thickness.

At baseline, median nerve conduction latency was significantly higher for the carpal tunnel group, and median nerve conduction velocity was significantly lower than in the idiopathic pain group and a control group of 13 healthy people.

Differences in ulnar nerve conduction latency and velocity did not significantly differ among the groups.

Also at baseline, average cortical thickness in the bilateral insula was greater in the idiopathic hand pain group than in the carpal tunnel group.

The nerve conduction measurements did not change significantly after acupuncture treatment.

On the other hand, cortical thickness increased in the left S1, right posterior cingulate cortex/precuneus, and bilateral insula after acupuncture in the idiopathic hand treatment group but not in the carpal tunnel group.

Meanwhile, scores on the Boston Carpal Tunnel Syndrome Questionnaire (BCTSQ) improved for both the idiopathic hand pain and the carpal tunnel syndrome groups. The improvements were statistically significant at the conclusion of the acupuncture treatment and 3 months later (P < .05).

While the idiopathic pain group improved more on the BCTSQ than the carpal tunnel group, this difference was not statistically significant.

Table. Changes in the Boston Carpal Tunnel Syndrome Questionnaire

Treatment Interval Idiopathic Hand Pain (n = 15) Carpal Tunnel Syndrome (n = 21)
Baseline 2.7 2.8
Postacupuncture 1.9 2.1
3-month follow-up 1.7 2.2

 

In the patients with idiopathic hand pain, the greater the increase in insula thickness, the greater the reduction in symptom severity.

"This will help characterize a subset of carpal tunnel patients," said Dr Kettner. "One weakness of pain medicine is the failure to subtype patients."

One could conclude from this study that carpal tunnel syndrome has a strong peripheral nerve component that affects brain functioning, while idiopathic hand pain does not, said Roger B. Fillingim, PhD, director of the Pain Research & Intervention Center of Excellence at the University of Florida in Gainesville.

"It is a small, short-term study, so we don't want to jump to conclusions," he told Medscape Medical News.

One question the study does not address is whether other types of treatment, such as exercise or transcutaneous electrical nerve stimulation, would have similar effects as acupuncture, he pointed out.

The study was funded by the National Center for Complementary and Alternative Medicine (since renamed the National Center for Complementary and Integrative Health). Dr Kettner and Dr Fillingim have disclosed no relevant financial relationships.

American Pain Society (APS) 34th Annual Scientific Meeting. Abstract 536. Presented May 14, 2015.

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