MKSAP quiz: Burning pain in feet
This month's quiz asks readers to evaluate a 55-year-old man with type 2 diabetes and burning pain in both feet.
A 55-year-old man is evaluated for burning pain in both feet. Medical history is significant for type 2 diabetes mellitus, which was diagnosed 10 years ago. His only medication is metformin.
On physical examination, vital signs are normal. Deep tendon ankle reflexes are absent. He has decreased sensation to monofilament and pinprick bilaterally on the plantar surfaces. The remainder of the examination is normal.
A serum vitamin B12 level is normal. Hemoglobin A1c is 8.5%.
In addition to optimizing glucose control, which of the following is the most appropriate management?
A. Electrodiagnostic testing
B. Heavy metal screening
C. Neurologic evaluation
D. Pregabalin
E. Topiramate
MKSAP Answer and Critique
The correct answer is D. Pregabalin. This item is available to MKSAP 19 subscribers as item 8 in Extension Set 2 of the Endocrinology and Metabolism section. More information about MKSAP is online.
The most appropriate management for this patient with diabetes mellitus and classic distal symmetric polyneuropathy (DSPN) symptoms is adding pregabalin (Option D). DSPN is the most common type of diabetic neuropathy and results in damage to small and large peripheral nerve fibers. Symptoms may include pain, burning, tingling, and poor balance. DSPN is a clinical diagnosis in patients with diabetes who have a classic presentation, including distal ("stocking and glove") symptoms and symmetric distal sensory loss, as seen in this patient. Clinical examination may reveal length-dependent loss of light touch, pinprick, and vibration sensations and loss of ankle reflexes. Additional evaluation is not usually needed in patients with diabetes who present with classic symptoms and signs and do not have potential alternative clinical causes of neuropathy. The American Diabetes Association recommends gabapentinoids, serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressants, and certain sodium channel blockers (e.g., oxcarbazepine, valproic acid, lamotrigine, lacosamide) as first-line pharmacologic therapies for neuropathic pain in diabetes. This patient has classic symptoms of DSPN and should receive treatment to control his symptoms.
Electrodiagnostic testing or neurologic evaluation are generally unnecessary and should only be considered for patients whose symptoms and signs are not classic for DSPN (Option A, Option C). Rapid symptom onset, asymmetric presentation, or motor-predominant symptoms are uncharacteristic DSPN findings in a patient with diabetes mellitus and should prompt consideration of further testing, such as additional laboratory investigations, electrodiagnostic testing, and/or neurologic evaluation.
Heavy metal screening is unnecessary in this patient with diabetes, classic symptoms of DSPN, and a clinical history that does not suggest heavy metal exposure (Option B). Although heavy metal toxicity may also induce axonal neuropathy, testing for heavy metals is only indicated in the presence of a suggestive exposure history or if evaluation and testing have excluded more common causes of axonal neuropathies.
Although gabapentinoid antiepileptic drugs have an essential role in managing DSPN, topiramate is not effective and is not recommended by the American Diabetes Association or the American Academy of Neurology to treat diabetic neuropathy (Option E).
Key Points
- The American Diabetes Association recommends gabapentinoids, serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressants, and certain sodium channel blockers as initial therapy for neuropathic pain in patients with diabetes mellitus.
- Additional evaluation is not usually needed in patients with diabetes who present with classic symptoms and signs and do not have potential alternative clinical causes of neuropathy.