Current And Emerging Tools For Assessing Diabetic Peripheral Neuropathy
- Volume 23 - Issue 5 - May 2010
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The simplest and likely most frequently utilized instrument for assessing neuropathy is the Semmes-Weinstein (SW) monofilament. Lee and colleagues attempted to determine the reliability of the SW monofilament in patients with diabetes.20 They applied the monofilament to the 10 recommended sites and found the sensitivity and specificity of the plantar metatarsal region to be 93 percent and 100 percent respectively. Other studies have confirmed their conclusion that the device is a sensitive, specific and inexpensive screening tool for identifying diabetic peripheral neuropathy.21,22
A critique of this instrument is its fairly limited scope. It is unable to quantify or stage a level of neuropathy, and also does not provide any information about the motor and autonomic components of the disease process.
One should fully assess motor neuropathy and autonomic neuropathy during an examination, but this can represent a challenging problem when attempting to have objective and reproducible results.
One means for attempting to quantify all components of diabetic peripheral neuropathy is the Michigan neuropathy screening instrument (MNSI). This consists of a history portion that the patient completes and a physical exam portion that the healthcare professional completes. The patient portion consists of 15 questions such as “Are your legs and/or feet numb?” and “Are you able to sense your feet when you walk?” The exam portion looks at such factors as appearance (deformities, calluses, etc.), ulceration, ankle reflexes, vibration perception at the hallux and monofilament detection.23,24
This simple screening test encompasses all sensory, motor and autonomic components of neuropathy, and allows for a quantitative and objective measurement. The developers of the instrument have found it to be sensitive and reproducible for screening and diagnosis.
Moghtaderi and co-workers assessed the validity of the MNSI and aimed to determine the diagnostic performance of the test characteristics for the diagnosis of peripheral neuropathy.25 This study found that the accuracy of the MNSI made it a useful screening test for diabetic neuropathy. In deciding which patients one should refer to a neurologist or for electrophysiological studies, the authors specifically suggested a cutoff score of “2” during the physical examination portion for diagnosis and referral.
Large prospective clinical studies, such as the Diabetes Control and Complications Trial and United Kingdom Prospective Diabetic Study, have shown tight glucose control and euglycemia prevent the onset or slow the progression of diabetic neuropathy. Unfortunately, we usually deal with patients whose hyperglycemia has already caused significant damage to the peripheral nervous system.
It is important for clinicians to appreciate the full breadth of diabetic peripheral neuropathy, specifically how the motor and autonomic components contribute to the pathogenesis in addition to the sensory dysfunction. It is also important that we are consistent, objective and reliable with respect to our clinical examination of these patients. The Michigan neuropathy screening instrument provides a simple means to accomplish this task that may help improve your overall evaluation and treatment of patients with diabetes.
Dr. Piemontese is a resident with the Temple University Hospital Podiatric Surgical Residency Program at Temple University Hospital in Philadelphia.
Dr. Meyr is an Assistant Professor in the Department of Podiatric Surgery at the Temple University School of Podiatric Medicine in Philadelphia.
Dr. Steinberg is an Assistant Professor in the Department of Plastic Surgery at the Georgetown University School of Medicine in Washington, D.C. Dr. Steinberg is a Fellow of the American College of Foot and Ankle Surgeons.