Effectiveness of Semmes-Weinstein monofilament examination for diabetic peripheral neuropathy screening

To evaluate the effectiveness of the Semmes-Weinstein monofilament examination (SWME) for diabetic peripheral neuropathy (DPN) screening at an outpatient clinic.

Eighty-two type 2 diabetic outpatients were questioned about 13 subjective symptoms and tested for deep reflexes. They were examined using two types of quantitative sensory testing: SWME (using 4.31/2 g and 5.07/10 g monofilaments) and vibration testing (using the C-64 quantitative tuning fork). The patients were diagnosed with DPN when two of the following three criteria from both legs were met: (1) the presence of either pain, numbness, or paraesthesia; (2) a diminished or absent ankle reflex; or (3) a scale below 4 for their vibration perception thresholds (VPT).

The most common subjective symptoms were muscle cramps and numbness in the extremities. SWME 4.31/2 g at the great toe or the plantar aspect of the fifth metatarsal was the most useful diagnostic test for DPN, providing 60.0% sensitivity and 73.8% specificity. SWME 4.31/2 g was correlated with lower limb VPT (P=.029) and three subjective symptoms including fainting. SWME 5.07/10 g was correlated with lower limb VPT (P=.011), the ankle reflex (P=.013), the knee reflex (P=.031), and two subjective symptoms. However, the sensitivity to diagnose DPN was low (30.0%).

The abnormalities indicated by SWME correlated well with those identified by lower limb VPT. Moreover, SWME 4.31/2 g correlated with fainting, suggesting that it could detect abnormalities in the small fibers. Considering the minimal time for this examination, SWME 4.31/2 g is a useful examination in an outpatient setting along with lower limb VPT and ankle reflex testing.