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Diabetes

Pearls of Wisdom: Screening for Diabetic Peripheral Neuropathy

A 62-year-old man with a 14-year history of type 2 diabetes comes to your office for routine check-up of his glycated hemoglobin, blood pressure, and lipid levels.

During his visit, he reports a new set of symptoms, including tingling, pain, and numbness in his feet. These symptoms flare at night. You immediately suspect diabetic peripheral neuropathy (DPN).

What is the best screening tool to identify DPN? 

A. Biothesiomety
B. Pedal skin temperature
C. Monofiilament testing
D. Tuning fork

 

What is the correct answer?
(Answer and discussion on next page)

Louis Kuritzky, MD, has been involved in medical education since the 1970s. Drawing upon years of clinical experience, he has crafted each year for almost 3 decades a collection of items that are often underappreciated by clinicians, yet important for patients. His “Pearls of Wisdom” as we like to call them, have been shared with primary care physicians annually in an educational presentation entitled 5TIWIKLY (“5 Things I Wish I Knew Last Year”…. or the grammatically correct, “5 Things I Wish I’d Known Last Year”).

Now, for the first time, Dr Kuritzky is sharing with the Consultant360 audience. Sign up today to receive new advice each week.
 

Answer: Tuning fork

The American Diabetes Association recently conducted a telephone survey of patients with type 2 diabetes (T2DM) to gauge the level of awareness of and instances of diagnosis in cases of diabetic peripheral neuropathy (DPN).

The results of the survey suggested that a shocking minority of patients were familiar with DPN, and the majority of patients with typical diagnostic symptoms of DPN had not been diagnosed.1
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My Own Clinic

I was immediately prompted to address the next several T2DM patients visiting my own clinic about DPN. Within just a few days, I met several patients with DPN—none of whom had been diagnosed.

When the first patient I queried gave answers that were indicative of typical DPN, I asked him why he hadn’t previously told me about his symptoms that had been persistent for over a year. He simply responded that, “nobody ever asked me about my feet before today.”

Diabetes is a busy disorder; we have to worry about glucose and lipid levels, blood pressure, kidney disease, eye disease, neuropathy, diet, exercise, and weight control, to name a few comorbidities, and it’s easy to push some questions to the back burner. But, it’s important to note that the complexity of the diagnosis should not be the reason we fail to screen for DPN.

The Research

Even though most of us were trained to use monofilament as the best screening test, a recent study suggests otherwise.1

To test the predictive value of several DPN scoring systems, researchers tested 3 matched groups (n=69): diabetes with neuropathic foot ulcers, diabetic without known DPN or ulcers, and nondiabetics.1

Diagnosing DPN: Study Design1

The Results

Even though each of the scoring systems performed well, the overall best predictive value was found with the 128-Hz tuning fork, which outperformed even the more traditional monofilament screen. A bonus: The tuning fork is remarkably inexpensive (generally <$20), and has great longevity.

To test using the tuning fork:

  1. Stimulate the tuning fork to vibrate and apply it to your own wrist, to show the patient your intended move.
  2. Apply the tuning fork to the patient’s wrist, so that they can learn to identify the vibratory sensation. Although it is unlikely, some patients with diabetes may have upper extremity neuropathy. In these instances, apply the tuning fork to the forehead, chin, or anyplace where they can appreciate the vibratory sensation.
  3. Apply the vibrating tuning fork to the metatarsophalangeal (MTP) of the great toe.
  4. Ask the patient if he feels the vibration.
  5. Then ask the patient to tell you when the vibration ceases.
  6. Apply the tuning fork to your wrist immediately after the sensation ceases in the patient’s foot.
  7. There are 3 classifications of nerve function:
    1. Normal: The patient reports vibration has ceased and you are also unable to feel further vibration.
    2. Impaired: The patient reports vibration has ceased but you still feel the vibration.
    3. Absent: The patient has identified the vibration at another body site, but does not detect it at the MTP.

What’s the “Take Home”?

DPN is the most common factor leading to limb loss in diabetes, and early identification may provide an opportunity to slow progression of DPN and treat its symptoms. The tuning fork appears to have the best predictive value in screening for DPN.

Reference: 

1. Meijer  JWG, Smit AJ, Lefrandt JD, et al. Back to basics in dianosing diabetic polyneuropathy with the tuning fork. Diabetes Care. 2005;28(9):2201-2205.