What Happens at the Spot Where the Needle Goes In

What people who ask me about acupuncture want to know is usually one thing. At the spot the needle goes into, what actually happens.

It is a good question. And there is an answer, to a degree. Let me go through it today.

There is a substance released at the tip of the needle

In 2010 there was an interesting experiment. Researchers needled mice and drew off the tissue fluid at the spot the needle entered in real time to measure what was in it.

While the needle was in and being stimulated, a substance called adenosine rose sharply at that spot. More than twenty times baseline. Adenosine is something our body makes anyway, and it binds to receptors that act to damp down pain signals.

Here the study went one step further. They gave the same needling to mice that lack the receptor that receives adenosine. The pain-relieving effect did not appear. Which means it was not a phenomenon that happened to be observed alongside — that substance was actually doing work at that spot.

And two years later the same group confirmed it in people. They needled 13 people and measured the tissue fluid at the spot; adenosine went up there too, and it stayed up for a while after the stimulation ended.

What is interesting is what comes next. Off the spot, that rise did not appear. Which means where you put it made a difference in the measurement.

The tissue at the spot the needle sits in

There is another branch of research. The sensation transmitted to the fingertips from the spot the needle has entered — something Korean medicine has talked about for a long time. This research looked at what it actually is.

While the needle is in the tissue, the connective tissue around it engages with the needle. In people, the force needed to withdraw the needle changed. In a study measuring 60 people, that force rose by up to 167%. Meaning connective tissue winds onto the needle the way thread winds onto a spool. In animals, on top of this, a change in the volume of the tissue beneath the skin was confirmed as well. Not because muscle contracts, but because the connective tissue itself responds.

In a study dissecting and examining a human arm, about 80% of the sites known as acupuncture points lay along planes of connective tissue running between or through muscles. It is the result of a single dissection, so it needs more work, but I find this study interesting because it is a point where the sensation at the fingertips and anatomy meet.

When connective tissue is pulled, the cells at that spot actually respond. Fibroblasts in the tissue were observed spreading out broadly and extending processes. But how that carries through to a therapeutic effect — that route is still a hypothesis.

I would add that the strength and manner of stimulation differ according to the purpose. It is not that stronger is better. If the stimulation is excessive, the pain and the burden at that spot can rise along with it, so I use only as much as is needed.

What about in patients

If there is a mechanism, there ought to be results too.

There is a large study that gathered and analysed, at the level of the individual person, the data of people who received acupuncture for chronic pain. Thirty-nine trials from several countries, data from more than 20,000 people. The result was that those who received acupuncture had clearly less pain than those who did not, and that most of the difference was still there a year later.

There are not many treatments with data accumulated on this scale. I take it as it is, neither inflating it nor playing it down.

The needle is one axis among several

Acupuncture is one axis among several. For someone whose pain has gone on a long time, I look first at why that spot keeps hurting. (If treating the painful spot doesn't cure it · What changes once pain passes three months)

Try to explain everything with acupuncture alone, and from that point the explanation starts to strain.

That said, if after an injury you have lost strength or lost sensation, or if the pain gets bad enough to wake you at night — tests come first. It is safer to keep to that order.

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At the spot where a needle goes in, something actually happens. A substance is released, the tissue responds, and it has been measured in people too. Where you put it made a difference in the measurement — which means that old business of finding the spot was not wasted work.

Acupuncture is a treatment that can be explained by naming compounds and receptors. Since the 21st century began those routes have been uncovered one by one, and I study them and set them down here.

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References

• Adenosine rises locally with acupuncture stimulation, and without its receptor the analgesia disappears — Nature Neuroscience, 2010
• A study confirming the same phenomenon in humans — The Journal of Pain, 2012
• An analysis pooling data from 39 chronic pain trials and 20,827 people — The Journal of Pain, 2018

Written by Dr. Heo Ji-young (PhD in Korean Medicine Pathology, Kyung Hee University · former Research Professor of Herbology, Kyung Hee University)