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I'm going to see a physical therapist for a Semmes-Weinstein monofilament test. What is this?

The Semmes-Weinstein monofilament test measures the sensitivity of your nerves. It's used to assess loss of sensory function when a nerve is damaged or injured. It's commonly used with carpal tunnel syndrome (CTS). A monofilament is a thin piece of wire. It's touched to the patient's fingertip until it bends. Without looking, the patient is asked to say when he or she feels the pressure. The therapist starts out with the thinnest monofilament possible and gives the pressure three times. If the patient doesn't feel anything, the next size monofilament is tried. This is repeated with larger monofilaments until the patient reports the sensation. Normal light touch is felt when using a monofilament between 1.65 and 2.83. The sense of light touch is mildly lost when it takes a monofilament size between 3.22 and 3.61 to be felt. Monofilament testing can be used to find a loss of protective sensation and loss of deep pressure. Of course, someone with no feeling will not feel the pressure of any size monofilament.

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