In the Semmes-Weinstein microfilament test, what does the inability to feel a filament with a 10-gram bending force indicate?

• A. Preserved protective sensation
• B. Loss of protective sensation
• C. Normal sensory function
• D. Foot ulcer risk assessment

Answer: (B)

The Semmes-Weinstein microfilament test is a crucial tool used to assess sensory perception in patients, particularly in the context of diabetic foot assessments. The inability to feel a filament that exerts a 10-gram bending force indicates a loss of protective sensation.

When a patient cannot detect this level of pressure, it suggests that their sensory receptors are not functioning properly, particularly in the dermal and subdermal layers where the microfilament applies pressure. Protective sensation is essential as it allows individuals to detect potentially harmful stimuli, such as excessive pressure or injury to the skin. Without this awareness, there is a high risk of unnoticed injuries or wounds, which can lead to complications such as infections or ulcers, especially in patients with diabetes or neuropathy.

The other options would imply different underlying conditions. For instance, preserved protective sensation would indicate functioning sensory nerves, which is not the case here. Normal sensory function suggests that the individual can adequately feel and respond to various stimuli, and foot ulcer risk assessment tends to be broader, involving more than just the determination of sensation through the microfilament test. Thus, loss of protective sensation is the most accurate interpretation of an inability to feel the 10-gram filament.