Case Study 2: My Feet Are Numb

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Headshot of Dawn Elise DeWitt, MD, MSc, CMedEd, MACP, FRACP, FRCP-London · Senior Associate Dean, Collaboration for InterProfessional Health Education Research & Scholarship (CIPHERS)
Dawn Elise DeWitt
MD, MSc, CMedEd, MACP, FRACP, FRCP-London · Senior Associate Dean, Collaboration for InterProfessional Health Education Research & Scholarship (CIPHERS)
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Case study 2: Manu—My feet are numb

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A 65-year-old man sees you to discuss progressive numbness and tingling in his feet. He first noticed the numbness a few months ago, but at that time it was only in his toes. The patient says he thought it was just the cold winter weather making his feet less sensitive. However, when the numbness began to spread into his feet and he started to feel tingling, he realized something was wrong. He has no chronic medical conditions, apart from “some high blood sugar” on a blood draw last year.

question

Which of the following is the most likely complication of this patient’s neurologic condition?

While it is not unlikely that this patient may experience falls or require an amputation in the future as a result of his diabetic neuropathy, the more pressing immediate concern is the development of foot ulcers. Diabetic neuropathy can lead to a “stocking and glove”–pattern of sensory loss, involving the distal extremities. While people tend to notice wounds on their hands, it can be less apparent when they arise on the feet and due to this patient’s sensory loss, an ulcer may not be felt. If such a wound were to spread into the bone, an amputation may eventually become necessary. Charcot foot (diabetic neuropathic arthropathy) is a late complication of neuropathy with structural changes to the foot from ligamentous laxity and small (intrinsic) muscle weakness with resulting changes in bony alignment in the foot. Patients can have collapse of their plantar arch and may develop hammer or claw toes as well from denervation and “dropping” of the metatarsal heads. “Charcot foot” may present with a swollen, warm foot and be mistaken for cellulitis, DVT, or gout.

Diabetic polyneuropathy

  • Three main pathologic alterations to normal nerve function:
    • Inflammation.
    • Oxidative stress.
    • Mitochondrial dysfunction.
  • Free radical formation is generally considered the most significant contributor to axonal degeneration and segmental demyelination.
  • Risk factors:
    • Age (older >> younger).
    • Male gender.
    • Longer duration of diabetes.
    • Poor blood sugar control.
    • Concurrent obesity.
  • Distal symmetric polyneuropathy “stocking and glove” distribution (affects the longest nerves first hands and feet; begins distal and moves in proximal direction).
  • Pain, numbness, pins and needles sensation (paresthesias).
    • Note: Patients can have paresthesias first that then go away as the neuropathy progresses to numbness, leading the patient to think they are better. (Dr. DeWitt)
    • May have secondary balance issues.
  • Unrecognized foot wounds/ulcers = major complication.
  • Blood glucose control.
  • In-office diabetic foot exams (with monofilament for “protective sensation” screen)—at least every 6 months.
  • Regular self foot exams need to monitor closely for unnoticed wounds.
  • Wound care as needed. 
  • Pain management (SNRIs, TCAs, Gabalins; capsaicin may be useful but isn’t well tolerated).

Image credits

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