Acupuncture: Pinpointing pain relief

Thousands of Filipinos attain pain relief through acupuncture each year and many, these days, seek the treatment at their doctor’s suggestion. Mainstream medical interest in acupuncture has grown as the studies pile up: A US National Institutes of Health statement, published in 1997, concluded that the procedure appeared most promising in treating nausea, then pain. Yet, despite this growing Western faith in the ancient Chinese practice, scientists and doctors understand remarkably little, in modern medical terms, about how the procedure works to provide lasting pain relief.

In recent years, scientists have begun studying the body’s biological responses to the treatment in hopes of shedding light on how a handful of needles can perform as well as, or better than, Western medicine’s strongest pain-killing drugs. They have come up with an array of theories to explain the technique’s effectiveness, some of them accepted, others too new to assess. "We’re still in the early stages of understanding how it works," says Dr. Ka-Kit Hui, founder and director of the Center for East-West Medicine at UCLA. Already, he adds, studies on the topic are raising interesting questions about the body’s physical and emotional responses to pain — and might someday force Western medicine to reassess its understanding of the sensation of pain.

Philosophical Approach

In traditional Chinese medicine terms, good health depends upon two things: an unobstructed flow through the body of energy, or qi, along 12 major channels, or meridians, and a balance between two life forces — cool, passive yin and warm, active yang. Illness or pain occurs when the flow of qi is blocked, or when one life force dominates the other.

Acupuncture is thought to act on meridians. In the form of the treatment most widely practiced, hair-thin needles are inserted into the skin at specific points along the meridians to redirect or unblock stagnant qi. Other types of acupuncture treatment apply pressure, smoldering herbs, or electrical currents at these points. These so-called acupoints correspond, in traditional theory at least, to different organs or systems in the body.

For example, inserting a needle at a point inside the forearm known as P6 is intended to treat nausea; needling Liv3, on top of the foot, is meant to help with motor function. Studies suggest that inserting needles into acupoints does affect the body, and in potential meaningful ways. In a study of 37 subjects published in 2005 in the journal Neuroscience Letters, inserting a needle into acupoint L14 on the hand — traditionally used to treat pain — was shown to deactivate parts of the brain that are involved in processing pain.

Indeed, a decade of acupuncture imaging research has shown that "people who get better with acupuncture have clear changes in their brain function," says Dr. John Farrar, a pain researcher at the University of Pennsylvania School of Medicine. Changes are seen in the thalamus, a brain region that processes information from the senses, including touch and also pain. Acupuncture also affects activity in the region called the cingulate gyrus as well as other brain structures that make up the limbic system, which processes the range of human emotions and memory.

Hormone release could be key to such brain changes. Thirty years ago, about the same time acupuncture started to pique the interest of the Western world, Chinese medical researchers began studying it in animals. They showed — and subsequently Western researchers confirmed — that acupuncture increased the body’s production of its own natural pain killers, known as endogenous opioids, or endorphins. People experienced no relief from acupuncture if they were first injected with a drug that blocked the opioids’ activity.

But some medical acupuncture researchers maintain that this can’t be the whole picture. Most crucially, they say, endorphins alone cannot explain why individual acupuncture points or meridians would correspond to particular functions or parts of the body – if, indeed, they do.

The Meridian Theory

For thousands of years, acupuncture has been based on the premise that specific points along the meridians correspond to specific organs, such as the liver, and functions, such as motor control. From the 1970s through the 1990s, the relationship between the acupoints and their related organs was a key focus of acupuncture research. Some early studies supported the idea that the links were real. But such studies are hard to perform objectively, and scientists aren’t sure what to make of them. Recently, focus has shifted to the unique physical properties of acupoints and meridians without attempts to link them to specific organs or functions.

The meridians depicted in Chinese medical charts have no obvious anatomical basis — though diagrams of them do bring the nervous system to mind. Meridians and acupoints might also correspond to areas of the body with physiologically distinct properties. In a study published in the scientific journal Anatomical Record in 2002, Dr. Helene Langevin of the University of Vermont College of Medicine showed that about 80 percent of the acupoints on the arm correspond to areas of connective tissue between muscles.

These might be why practitioners and patients alike often notice a distinct feeling when an acupuncture needle is inserted into the skin, says Dr. Langevin. Patients sometimes describe the feeling, called de qi in Chinese, as a pressure, a nick, something akin to a mosquito bite. Dr. Langevin is now examining what implications this might have for how acupuncture sends messages to the brain. She has published data showing that when needles are inserted into acupoints, the underlying connective tissue winds around the needle "like spaghetti around a fork," she says. This doesn’t happen when a needle goes into a non-acupoint area. Dr. Langevin has also shown that the winding action causes the cells in the area to change shape, a process she theorizes might signal the central nervous system.

Other older studies conducted and published in Asia and Europe during the 1970s and 1980s produced evidence suggesting that acupoints might be areas of very low electrical resistance, might be slightly more sensitive to touch, or might lie near major nerve pathways. But scientists don’t know the significance of these characteristics.

Controversy Continues

In fact, not all scientists are believers of the so-called "point specificity" of acupuncture. They note that many studies have shown that simply inserting needles in the skin can relieve pain — regardless of whether the needles are placed at random or in places defined by traditional Chinese medicine. For example, in studies comparing real, sham, and no acupuncture for osteoarthritis of the knee, real and sham acupunctures both offered more relief than no acupuncture at all — suggesting that acupuncture might be effective regardless of needle placement. This raises an important question for acupuncture researchers. Does something highly location-specific occur at the point of needle insertion, or does simply inserting a needle, no matter where, trigger a set of pathways that enable patients to "turn on" their brains’ own healing capacity?

Dr. Zang-Hee Cho of the University of California at Irvine, for one, has found in recent studies that inserting needles in real and sham sites produces similar changes in parts of the brain perceiving pain. In simplified terms, he thinks that inserting a needle at almost any point on the body triggers a series of biochemical messages between the brain’s hypothalamus and the hormone-producing pituitary and adrenal glands. The signals tell the body to alter its production of, for example, certain stress hormones and immune molecules that help the body cope with stressors — such as bacteria, viruses, emotional trauma or pain.

As acupuncture research evolves, scientists acknowledge that there might be other effects of the therapy that have little to do with slipping needles into the skin. For instance, skeptics have long held that acupuncture helps heal through the power of the mind: that patients feel better because they think they are receiving an effective treatment. The placebo effect, as it is called, can be powerful.

But for patients convinced of acupuncture’s effectiveness, it might be of little importance whether it’s the needles themselves or other aspects of the treatment that produce its desired effects. What is important is that acupuncture is able to provide them the necessary relief from pain and suffering, and improve the quality of their lives.