“Pocket filaments” and specifications for the semmes-weinstein monofilaments

T he value of Semmes-Weinstein monofilaments (S-W monofilaments) for testing and monitoring touch sensibility is being increasingly recognized. The test can successfully map out otherwise undetectable nerve distribution areas with diminished function, can demonstrate pathologic changes not always detected by other forms of testing, and can be predictive of what a patient can and cannot "feel." It can demonstrate changes in nerve status that can be correlated with treatment, and has been shown to have instrument reliability if calibrated correctly. Despite these numerous advantages, the traditional filament kit in its present form is cumbersome to carry, time-consuming to use, and expensive. Although in recent years its manufacture has undergone improvements, reports regarding difficulties in obtaining testing kits continue, particularly from outside the U.S. The expense makes even a mini-kit of five filaments prohibitive for the third world. The small market for the instrument in the past has been one reason for its limited availability and high manufacturing cost. This paper explores some recent information that has surfaced regarding the test, clarifies some physical characteristics of the material used in its manufacture, and suggests ways the instrument can be improved to be more useful and cost effective in this age of cost containment and need for validation of clinical instruments used in objective clinical tests.