Health post: Diagnosing HAVS

While I was still in Malmö, I visited the Medeon Science Park there, a life-sciences park and incubator. I met with Ulf at VibroSense, one of Medeon’s member companies. VibroSense has developed a method and technology to diagnose hand-arm vibration syndrome, or HAVS, a lack of sensitivity to vibrations often caused by working too much with vibrating power tools. I tested the method out myself and learned about how the company came to be.

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Entrance to the Medeon Science Park, south of central Malmö.

VibroSense began when a professor, Göran Lundborg, was working on hand surgery in the 1980s. He was receiving patients that had numbness and tickling in their fingers, and yet no diagnostic tools could identify their problem. Decades of research revealed that all these patients had been over-exposed to tools like lawn mowers and high speed drills, which had damaged the mechanoreceptors and nerves in the hand.

So, how to test someone’s sensitivity to vibrations, or lack thereof? This is when Professor Lundborg realized that sensitivity to vibrations in the hand could be similar to sensitivity to vibrations in the eardrum; therefore, he focused on creating a method based on a hearing test. Rather than test someone’s ability to hear quieter and quieter phrases, he could test someone’s ability to feel milder and milder vibrations.

The VibroSense company was established in 2005 in response to the EU issuing “a directive saying that the companies that had…workers exposed to vibrations should offer them health screening and health tests and so on, and work actively to stop the injuries caused by vibrations. That directive was also transferred into Swedish law.” However, this directive had a smaller effect than VibroSense expected. Now, in 2016, they are a company of 10 people. In Sweden, 400,000 people (about 4% of the population) are diagnosed with HAVS. Ulf says that “HAVS is a big thing, but kept under the carpet.” To say that no one should use vibrating tools for extended periods of time would bring down industries that rely on workers using such tools in factories, for example, and workers trained to use such tools might not have the option to take long breaks or switch professions.

VibroSense’s product, as I said, is a diagnostic tool that assesses someone’s sensitivity to vibrations, much like a hearing test. There is a physical part, the vibrometer, with a vibrating peg that you touch and a button you depress while feeling a vibration. It’s transportable, non-invasive, pain-free, and takes about four minutes to test one finger. It’s standardized with repeatable results. At the start of the test, the peg vibrates at 8 Hz (8 times per second) and increases throughout the test up to 500 Hz (500 times per second). Much like a hearing test, the higher frequencies are more difficult to sense.

Performing the test produces a vibrogram, which is the non-physical aspect of the test. The vibrogram is a graph showing the results of your test, comparing your sensitivity to the “normal, healthy range” for someone your age. (VibroSense has performed many trials with non-HAVS people to determine this range).

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A vibrogram taken from VibroSense’s website. The pink bars show the normal range. This patient has severe HAVS, as their specific results fall far below the pink bars at several frequencies (indicating a lack of sensitivity). (www.vibrosense.eu)

Ideally, anyone working with vibrating tools should be screened by a vibrometer annually, before they realize any numbness. HAVS is preventable, but irreversible. As Ulf described, the physical process of sensing vibrations is “an integrated method.” Mechanoreceptors deep in the fingers communicate to sensory nerves in a fiber that then travels up to the brain. “So if you have a problem anywhere along this line, you don’t feel anything.” Many groups of people are susceptible to vibration-induced neuropathies, including “construction workers, car mechanics, [people in the] engineering industry or manufacturing plants, lumberjacks, road workers, slaughterhouse workers, park workers, dentists, dental hygienists and technicians.” Of course, HAVS was less of a problem before power saws and drills. Now, the only way to deal with it is to stop using such tools completely.

Today, there is a new purpose for VibroSense’s work: diagnosing diabetes in addition to HAVS. Diabetes patients also have sensitivity problems, especially in their feet. If left untreated, such neuropathies and circulation problems can lead to persistent ulcers and even foot amputations. VibroSense recently realized that they could use their method to find neuropathies in diabetic feet earlier rather than later, and they are developing a version of their technology that works for feet rather than hands.

I took the test myself, and while I attempted to take it honestly, I started to question myself as the vibrations became fainter and fainter. I worry that I was causing false positives, pressing the button because I knew a vibration should be there even if I couldn’t feel it (or did I feel it? Or was that the last vibration? and so on). My vibrogram result revealed that I was slightly more sensitive than average, especially at one frequency. No HAVS, though!

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Here is VibroSense’s product, the vibrometer. The patient lies their right hand on the pad of the blue part with their index finger resting on the small peg by the whole. Holding the red button in your other hand, you keep the button pressed while you feel a vibration.

 

I think the diagnostic area of medical device development is tough because you have to encourage people to get screened and tested even when they experience no symptoms. I’m not sure if that can be achieved simply by having an attitude that regular check-ups are important or even through industry-specific directives, which hasn’t seemed to quell the HAVS issue in the last ten years. Diabetes might be different, however. Ulf said that people with Type 1 diabetes seem to be good at self-monitoring (since they have to be and since they are responsible for their own treatment), and everyone in Sweden with diabetes is registered and followed in a special database.

Still, I think that VibroSense’s work is really exciting, especially in terms of the implications for diabetes patients. VibroSense is currently testing their prototype for a foot vibrometer on non-diabetic healthy volunteers, and once they begin testing it on diabetic patients, they hope to prove its capability as a diagnostic tool. Ulf described this process a bit, saying that they can only develop the product if they can prove its results. “We have to prove the method and we have to get key opinion leaders within the research community or [doctors in the health community] to recognize that this is something that gives proven results. Also then we have to get financed,” partially or even mostly by the government due to its control of the health care system.

I also asked Ulf about the general health attitude in Sweden. He replied, “Health is important. Swedes are quite physically active, they care about what they eat, how much they exercise and so on…I think we have a pretty healthy lifestyle.” At the same time, Sweden suffers from the worst habits health-wise as the rest of “all the Western countries,” says Ulf, “eating too much, lack of exercise,” and smoking, especially the teenagers. As in the US, there is a wide range depending on who you talk to and what their background is, especially with socioeconomic factors.

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