Neuropathy is one of the most common risk factors for lower extremity complications in our diabetic patients. With sensory neuropathy the patient has a loss of protective sensation that leads to a decrease in the ability for our diabetic patient to sense pain and temperature changes. This loss of protective sensation puts the patient at an increased risk for plantar foot injury. Unfortunately the patient may not feel the injury until significant complications have occurred.
The American Diabetes Association set up guidelines for us as healthcare professionals, these guidelines recommend screening in diabetic patients for neuropathy to check for loss of protective sensation on an annual basis, one way this can be done by doing the Semmes Weinstein Monofilament test. If the patient is found to have decreased sensation and is found to be at high risk the monofilament test should then be done quarterly.
The Semmes Weinstein 10g Monofilament is a test that checks for protective sensation in the diabetic foot. It uses a 5.07 monofilament that exerts 10 grams of force when bowed into a C-shape against the skin for one second. We don’t apply the filament directly to the ulcer site, callous, scar or necrotic tissue. Ask the patient to close their eyes during the exam and tell them to reply “yes” when the monofilament is felt, repeat without touching skin occasionally to be sure of patients response. Be sure to use random order on successive tests.
Areas to be tested include the dorsal midfoot, plantar aspect of the foot including pulp (fleshy mass on the distal plantar aspect) of the first, third, and fifth digits, the first, third and fifth metatarsal heads, the medial and lateral midfoot and at the calcaneus. Record the results on the screening form, noting a “+” for sensation felt and a “-” for no sensation felt. The patient is said to have an “insensate foot” if they fail on retesting at just one or more sites on either foot.
Those patients who cannot feel the application of the monofilament to designated sites on the plantar surface of their feet have lost their “protective sensation”. Without this protective sensation the diabetic is now at increased for injury or ulceration. Neuropathy is usually noted in the first and third toes and then progresses to the first and third metatarsal heads.
Injury is much more likely to occur in the diabetic insensate foot at these areas and interventions must be implemented to protect the diabetic foot that is at risk for ulceration. Patient education and good “shoe fit assessment” will be part of our plan of care to protect the diabetic neuropathic patients foot.