Peripheral neuropathy, a common complication of diabetes, causes sensory loss in the arms and legs. Such sensory loss in the feet increases the patient’s risk of developing foot ulcers that could ultimately lead to amputation.Usually, sensory loss is diagnosed by an examiner touching different areas of the patient’s foot with a pin. Unfortunately, this technique isn’t reliable. An examiner may not exert the same amount of pressure on each area, and some examiners are more heavy-handed than others. In fact, the same examiner may be heavy-handed one day and have a lighter touch the next, making comparisons difficult.

Filament testing with a monofilament device alleviates these problems. The device places exactly 10 grams of force on a small area of the skin . To assess sensory loss in the feet, an examiner uses the device at 10 sites on each foot.

The test result is normal if the patient feels the filament in all 10 spots on each foot. The result is abnormal if she doesn’t feel it in one or more spots.

Filament testing can be used to monitor the progression of a patient’s sensory loss and to help in tailoring an ulcer prevention program for her.

Nursing Considerations

Have the patient lie down on the examination table and instruct her to say yes each time she feels the filament.

Have her keep her eyes closed to avoid an invalid response. After the test, develop an ulcer prevention program for your patient .