While relaxing on the chaise longue outdoors, I noticed a tickling sensation. An ant had climbed up the chair and was scuttling about on my leg in the usual erratic fashion. I noted that I could feel the ant as it traversed my knee, but not as it explored my foot and toes. Doubtless, my peripheral nerves are aging.
This finding has implications for the care of patients with diabetes and others with peripheral neuropathy. A worker ant weighs between 1 and 5 mg,1 making the pressure on the skin about 0.5 mg per ant leg, which provides a possible threshold for tactile sensation. Why waste time with tiresome pinprick and nylon-filament tests? We need only have an annual Internists' and Diabetic Patients' Picnic on the hospital lawn. Each patient, wearing shorts, would relax on a towel, and the attending physician would apply some ants2 or simply wait for ants to start their explorations, perhaps encouraging their peregrinations with a sheet of paper from the patient's chart. The patient would report the level at which the tickling became impalpable. A 5-ant test could be quickly accomplished and the results averaged by the time the barbecue was ready.
A word of warning: hornets are sometimes attracted to picnic crumbs, watermelon rinds, the rims of beverage glasses and, in my experience, the acetone scent of freshly applied nail polish, which in any case should not be applied to the toenails during the ant explorations.
Footnotes
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Note: There are apparently no ants in Antarctica, Iceland, Greenland or Polynesia east of Tonga, nor are they found on a few remote islands in the Indian Ocean. However, it would be difficult to hold outdoor picnics in icy latitudes, and Polynesian diabetologists doubtless have access to tiny land crabs, etc.