I use palpation as one of my primary diagnostic tools. My years of experience give me confidence that I’m picking up relevant signals from a patient’s bodily tissues. But I always wonder how scientific research judges if the information I’m picking up with my fingertips is accurate, reliable, and meaningful.
Back in 1988 this question was addressed in a research paper published in the Medical Journal of Australia. Practitioners scored a perfect 15 out of 15 attempts to detect jammed joints in the neck, strongly supporting the accuracy of diagnosis by palpation.
These results sound almost too good to be true. And, in fact, since 1988, other researchers have tried to replicate and extend these findings, and have generated a steady stream of negative results. The standard conclusion is that manual diagnosis isn’t very accurate.
However, a 2010 article in Anesthesia and Analgesia presents a more nuanced picture. Instead of using hands-on palpation to diagnose problems of the neck joints, the researchers used a quantifiable method: Pressure Pain Threshold (PPT) measurements.
With Pressure Pain Threshold measurements, you probe into the spinal tissues with controlled amounts of pressure, and notice how much pressure it takes to cause pain. The researchers compared the pain threshold on the right side of the neck to the left, for example, or the PPT at one spinal level to the PPT above or below. Zones where it took a lighter amount of pressure to cause pain were identified as spinal problem areas.
If the researchers looked at situations in which only a small difference in pain threshold existed between one side and another (or one level and another) they were able to detect a lot of neck problems. But there were also many false positives. On the other hand, if they looked at only those situations in which a large PPT difference existed, they missed a lot of neck problems. Though when a large discrepancy did exist between one side and the other, they were strongly confident that a true problem had been detected. In other words, there were a lot of false negatives.
This article pinpoints one of the challenges of using manual diagnosis: if you press hard enough, you can cause tenderness almost anywhere.
In the real world, an astute practitioner can work around this issue by using varying amounts of pressure – screening first for potential problem areas, but then back-tracking to make sure the potential problem areas truly stand out from the background.
There’s an additional strategy I use in manual diagnosis. The initial evaluation by palpation is only the first half of arriving at the diagnosis. The second half is monitoring the results of treatment. If I work on an area of the spine and a patient feels better, I’m highly confident my diagnosis is accurate. The initial trial of treatment is woven into the diagnostic process.