WEST-foot™
Answers to your questions about Quantitative Sensory Testing with the WEST-foot™
Connecticut Bioinstruments, Inc.
39B Mill Plain Rd, Danbury, CT 06811
800-336-1935
fax 203-744-74881. What is the WEST-foot™ ?
The WEST-foot™ is a patented (U.S. Patents 5,316,011 and 5,381,806) nerve tester used to evaluate tactile sensation. Because tactile sensation reflects neural integrity and vascular insufficiency, pathologies can be detected and graded with the WEST. Five calibrated nylon filaments deliver specified forces to the skin. The minimal force that is detected determines the extent of pathology present, based upon expected values (norms). Each "shirt-pocket portable" instrument comes with a manual, testing forms, and a protective carrying case.
2. Why Perform Quantitative Sensory Testing with the WEST?
The primary reason for routinely conducting quantitative sensory testing is to reduce risk. Neuropathic tissue is at risk for ulceration. Patients with certain diseases, such as diabetes, are at high risk for lower extremity amputation because the disease compromises sensory capabilities. When a patient has lost sufficient feeling --loss of protective sensation-- there is a greater probability of ulceration, and too often amputation is necessary to save the patient. It is estimated that most of the 54,000 cases of lower extremity amputation each year could be prevented with routine quantitative sensory testing.
3. How do I use the WEST in my practice?
Efforts supported by government agencies and educational institutions such as LEAP (Lower Extremity Amputation Prevention) are focusing on primary care physicians to perform sensory testing. As part of a routine examination, all patients at risk should be subjected to sensory screening. If sensation is found to be compromised, follow-up visits with more comprehensive multiple-site evaluations should be conducted. Ulcer-preventative measures (e.g., pressure-reducing orthopedic footwear) must be considered.
4. What do researchers say about the WEST?
Dr. C. Everett Koop recommended the WEST to the World Health Organization in his May 1995 letter. He cited the WEST's calibration, reduced fragility, and less painful and more consistent stimulation as improvements over prior methods. Dr. Koop also indicated that anything less low-tech than the WEST will not get the job done.
Research conducted by Dr. Sir S. Weinstein, the inventor of the predecessor of the WEST, indicated that the WEST produces more consistent and reliable stimulation. He concluded by stating that "the WEST is the superior instrument for measuring impairments in peripheral nerve function." J. Bell-Krotoski, et al. stated that it is essential that sensory testing instruments be calibrated for applied force. The WEST is currently the only manually applied instrument that ensures that the forces applied to the skin are within a specified calibration range.
In a recent article published in the Canadian Journal of Plastic Surgery, (Vol.3, #1) Dr. M.M. Al-Qattan compared the Semmes-Weinstein to the WEST in the clinical setting, measuring how often the instruments were used, the duration of testing, and filament slippage rates. The WEST was found to be superior on all measures. Al-Qattan concluded that the "WEST has several advantages.... "
5. How is the WEST (tm) different from other evaluation methods?
Several evaluation methods are currently available. Computer controlled devices costing thousands of dollars may offer automated data handling. However, no device provides better assessment of tactile sensation. In fact, the expensive devices may be more cumbersome to use in practice since a computer restricts portability.
Pulse measures only determine general circulation and cannot determine site specific vascular insufficiencies. The validity and reliability of vibration tests are affected by extraneous factors, including application force and composition of underlying substrates.
Similarly, the validity and reliability of two-point discrimination tests are compromised by the inconsistency inherent in the method of application. Cheap "screening" filaments can suffer from inaccuracy due to lack of calibration. Additionally, simple single filament screeners cannot be used to grade or track pathologies. They only can be used to determine if "something is wrong."
"Improvised" techniques (using pins, pencils, paper clips, etc.) have been proven to be both inaccurate and potentially risky. These "improvised" methods should never be used.
The WEST provides the best overall solution to the problem of quick and accurate sensory evaluation.
Return to Main Page, Wound Care Institute Newsletter, Fall 1996
