At the very least sensibility testing needs to be repeatable with accurate instruments. Most hand-held instruments apply a too gross (large and unrepeatable) stimulus relative to the sensitive detection of sensory end-organ receptors in the skin.

The monofilament instruments are hand-held in application but DO have control on their force of application by bending at a specific force of application, and have been found to be highly repeatable in test stimulus within a very small standard deviation (sd). Data has been accruing from standard use of this test in clinical subjects over the last 30 years.

But for data to be valid and compared with other data, the test instrument has to be correctly calibrated.

For data to be valid, the test instrument has to be consistent with that used in normative studies.

For determined levels of interpretation to be valid, instruments have to be correctly calibrated, and tests made in a protocol consistent with that used in normative studies.

Diminution in sensibility usually occurs before diminution of motor (muscle) function in peripheral nerves becoming impaired, thus monitoring of sensibility with accurate tests serves as a sensitive monitor and indicator of peripheral nerve status, and direction of change in nerve function with repair, or treatment intervention.

References