During a diabetic foot exam, how is protective pain sensation tested?

• A. Use a safety pin and a softer object, with the patient eyes closed, to identify sharp versus dull touch.
• B. Tuning fork vibration testing.
• C. Temperature discrimination with hot/cold objects.
• D. Light touch with a cotton ball.

Answer: (A)

Protective pain sensation is about detecting potentially injurious stimuli to prevent injury to the foot. To test it, you use a sharp stimulus (like a safety pin) and a softer object to compare sharp versus dull sensations, with the patient’s eyes closed so visual cues don’t help. If the patient can consistently identify the sharp stimulus as painful and distinguish it from dull touch, protective pain sensation is intact. If they can’t tell the difference, they’re at higher risk for unnoticed injuries and ulcers.

This approach specifically targets nociception, the nerve fibers that carry pain signals. Other tests shown—tuning fork for vibration, temperature discrimination, and light touch with a cotton ball—assess different sensory modalities (large-fiber vibration, small-fiber temperature, and light touch, respectively) and don’t measure protective pain in the same direct way.