Surgery – Diagnostic testing – Touch or pain response of skin
Reexamination Certificate
1996-09-24
2001-05-22
O'Connor, Cary (Department: 3736)
Surgery
Diagnostic testing
Touch or pain response of skin
Reexamination Certificate
active
06234976
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device used by health care providers for detecting patients' loss of protective sensation. More particularly, it relates to an improved monofilament-type device used for this purpose.
BACKGROUND OF THE INVENTION
Protective sensation, or ability to feel pain, is a warning system that enables an individual to avoid injury and that alerts the individual when injury does occur. Certain neurological and other medical examinations require the detection of impaired or lost sensitivity. Such detection is particularly important for patients with certain diseases or disabilities. For example, nearly half of all diabetes patients in the United States develop diabetic neuropathy, a complication that suppresses a patient's ability to feel pain. Diabetic peripheral neuropathy is characterized by loss of protective sensation, which may be manifested as analgesia (absence of pain or touch sensitivity), hyposthesia (reduced sensitivity), weakness, or autonomic changes. Loss of protective sensation is that degree of sensory loss that permits cutaneous injury to occur without being perceived by the patient as painful.
When due to neuropathy, loss of protective sensation is a major permissive factor in the pathogenesis of foot injury, and often leads to ulceration, infection, and, potentially, amputation. These problems are significant: Approximately 15% of diabetes patients sustain foot or leg ulcers, and may reacquire them in the absence of preventive and protective intervention. In addition, diabetic foot ulcers account for more than 20% of total hospital days for patients with diabetes, and they are the leading cause of hospital admissions for diabetic patients. Approximately 50% of all nontraumatic amputations in the United States are caused by complications from diabetes.
Routine testing for loss of protective sensation is critical, particularly for atrisk patients, such as those with diabetes. Prior art devices, however, are cumbersome and relatively expensive, and thus hinder such routine testing. For example, the device disclosed by Low et. al, U.S. Pat. No. 3,662,744, issued May 16, 1972, telescopically extends and retracts a monofilament. This device requires the health care practitioner to turn a knob to extend the monofilament each time the device is used, to ensure the proper length of monofilament is extended from the device, and to turn the knob to retract the monofilament when done. Because the length of monofilament extended from the device is variable, the health care practitioner has difficulty knowing how much force is being exerted by the monofilament on the patient. The device also has many moving parts, and thus is relatively costly to manufacture.
The Semmes-Weinstein esthesiometer, which currently is in widespread use, also has disadvantages. The Semmes-Weinstein device consists of a monofilament that is permanently attached at a 90 degree angle to the end of a plastic rod. The monofilament is always exposed, and thus is prone to damage. To compensate, the device generally is kept in a protective case in a drawer. The result is that the device is often not conveniently accessible to the health care provider, and thus is not used on a consistent basis.
There is an unmet need for a device for evaluating protective sensation that is convenient to carry and easy to operate and clean, thereby enabling health care practitioners to evaluate routinely whether their patents have lost protective sensation. Such a device preferably also will be inexpensive, small, and lightweight.
SUMMARY OF THE INVENTION
The present invention relates to a device that tests for loss of protective sensation. The device has a probe, preferably a monofilament, with a stimulating tip at one end. The other end of the probe is attached to a pivoting head, which itself is mounted toward the end of a handle member. When the head is pivoted into its open position, the probe extends outwardly (and, preferably, generally perpendicularly) from the handle member. In this position the device is operational. When the head is rotated into the closed position, the probe is moved into a protective channel in the handle member. A pocket clip is provided to assist in making the device easy to carry.
A primary object of the present invention is to provide a device for testing for loss of protective sensation that is easily opened for operation and closed for storage. A further object of the present invention is to ensure that the probe is protected when the device is in the closed position. Another object of the present invention is to provide a testing device that is small, light, and easy to carry. Still another object of the present invention is that the device be inexpensive and simple to manufacture. It is yet another object of the present invention that the device be easy to clean, and thus reusable.
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Products for a More Productive Workplace; North Coast Industrial Health & Safety Catalog, p. 22; Summer 1994.
Sidney Weinstein, PhD; Fifty Years of Somatosensory Research: From the Semmes-Weinstein Monofilaments to the Weinstein Enhanced Sensory Test; Journal of Hand Therapy, Published by Hanley & Belfus, Inc.; Jan.-Mar. 1993.
Marsha Spivak, B.S., R.N.; Weinstein Enhanced Sensory Test & Peripheral Neuropathy; The WEST Advantage: Greater Sensitivity to Neuropathy, Copyright 1994 Connecticut Bioinstruments Inc.
WEST Nerve Testers, Quantitative Sensory Testing Brochure; Connecticut Bioinstruments Inc., 39-B Mill Plain Road, Danbury, Connecticut 06811.
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Curative Health Services, Inc.
Dorsey & Whitney LLP
O'Connor Cary
Wingood Pamela
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