“Electrophysiology is getting simpler and more likely to be available in the primary practitioner’s office,” Dr. Arezzo says. “There is a handheld device that is available now. Sensory evaluations are also going to become more practical, more computerized, and simpler to do.”
Another approach is quantitative sensory testing, which measures and evaluates responses to stimuli such as hot and cold, vibration, and pain. Computerized analysis and standardized threshold levels have made these tests much more useful, and people with diabetes are more and more likely to see them in their physicians’ offices.
There are shortcomings to sensory testing, and so researchers continue to look for more sensitive and definitive measures of nerve function. For instance, electrophysiological exams assess myelinated fibers (nerves within a sheath), but it may be that neuropathy is evident first in small, unmyelinated nerve fibers, such as certain nerves that feed the blood vessels in the skin.
“These smaller fibers escape the attention of a standard electrophysiological test,” says Aaron I. Vinik, MD, PhD, Director of the Diabetes Research Institute of the Strelitz Diabetes Institutes at Eastern Virginia Medical School in Norfolk, Virginia. “Diminished blood flow in the skin, which is regulated by these small, unmyelinated nerve fibers, is one of the earliest abnormalities you can detect in diabetes.”
There are several means of measuring the status of these nerves, including laser Doppler measurement of blood flow. “It’s going to take a long while before this becomes standardized and can be used in clinical practice,” Dr. Vinik says, “but it’s easy to perform, it’s not invasive, and it can be done in a doctor’s office in 10 or 15 minutes.”
Other, more esoteric, measurement methods used by researchers to evaluate nerves include microdialysis and iontophoresis, but Dr. Vinik believes they will remain research tools only. However, he predicts that another technique called a skin punch biopsy will eventually become commonly used. According to Dr. Vinik, “The appearance of the small nerve fibers in the skin can tell you more about them than anything else, and skin punch biopsy is being used in research settings to actually see them. It could eventually be done in the office in less than five minutes with a little local anesthesia, and you could actually count the number of nerve fibers.”
Active participation is foremost
Diabetes care is a team effort, and in the prevention of foot disease, the individual with diabetes who is educated and aware is the most effective member of the team.
“The more you know, the better,” Dr. Perry says. “Here in Maine, we’ve documented a 51% increase in the utilization of podiatrists after a patient goes to Ambulatory Diabetes Education classes. Some studies have found a 63% improvement in amputation avoidance when the patient sees a professional for foot care, so the potential benefit of education to patients is tremendous.
“There is a tremendous amount of denial about foot problems, especially in men over 50. They’re afraid of what it means, that if they report a problem they’re going to lose their foot. Some of that is, frankly, justified, because the surgical approach — amputation — is still the first resort of many medical professionals. But amputation is not inevitable. Our first goal is to save the foot.”
The science of wound care has improved greatly in the past few years, along with the science of prevention. Ulcers that once were certain to lead to amputation can now be healed, and there are many simple, noninvasive ways to prevent ulcers in the first place.
“We have a lot of tools at our disposal,” Dr. Perry says. “The right shoes, inserts, physical therapy, and stretching, for instance. We might be able to recommend prophylactic surgery to straighten a contracted toe that would otherwise be at risk, or lower limb bypass surgery to improve blood flow. We know a lot more about wound care today, and there are new medications that actually help regrow skin to cover wounds.”