Topic: Peripheral Neuropathy
Subject: Medicine
A 68-year-old male presents to your department complaining of a very horrible sensation in his legs that started out 4 weeks ago as pins and needles tickling him but now has progressed and feels like being stabbed in his feet. He has started to use a walker because he feels that when he walks it feels like stepping on eggshells. The pain has not been responsive to acetaminophen and ibuprofen. The patients past medical history is significant for diabetes type II treated with metformin and glimepiride. The patient has not been very compliant with medications, especially metformin because he feels it causes him an upset stomach. His most recent HbA1C level was 9.8%. He also has hypercholesterolemia treated with lovastatin and hypertension treated with Lisinopril and amlodipine. His vital signs are temperature 37.4°C, BP is 125/70 mmHg, pulse 85/min, and respirations 15/min. The dorsalis pedis and posterior tibial pulses are +2 bilaterally. No distal muscles weakness or atrophy is observed. Manual esthesiometer with monofilaments is used and reveals decreased sensation from the midfoot distally on both feet. There is no evidence of erythema, edema, or any wounds on either foot. He has tenderness to light touch on both feet. Labs reveal normal Vitamin B12 and thyroid function.
Which of the following would be the most appropriate treatment for this patients pain?

This patient presents with complaints of dysesthesias and given his history of uncontrolled diabetes mellitus, this is concerning for diabetic neuropathic pain. Dysesthesias are unpleasant sensations that are often described as electric shock, pins and needles, or feelings as though one is walking on broken glass with barefoot. Diabetic neuropathy is present in at least 50% of diabetes patients and while its primary symptoms are unpleasant, the secondary complications such as falls, foot ulcers, arrhythmias, and ileus are even more serious.
To confirm this diagnosis, it is important to do physical examination in patients who present with its common symptoms, as signs are better predictors of polyneuropathy than symptoms. Moreover, electrodiagnostic studies further increase the accuracy of diagnosis as sensitive, specific and validated measures of the presence of polyneuropathy.
Management of diabetic neuropathy obviously includes endeavors to control blood glucose, but this would not be sufficient for immediate relief of pain in the patient. For neuropathic pain management available oral agents include antidepressants and anticonvulsant drugs. Pregabalin (choice C) has been found to have the same efficacy and safety in older patients and results are comparable to those observed in younger patients with neuropathic pain.
> Daily metformin (choice A) would gradually decrease HbA1C over a period of several months and greatly improve the patients overall condition, but his pain needs immediate attention.
> Metoclopramide (choice B) is used in the treatment of diabetic gastroparesis but it would not be the best choice for treating neuropathic pain.
> Alpha lipoic acid (choice D) has been studied as treatment option for diabetic neuropathy but there have been insufficient evidence to support or refute the usefulness of this drug in the treatment of neuropathic pain.
> Amitriptylline (choice E) is useful as analgesic for neuropathic pain but its benefits in elderly are limited by the increased adverse effects reported in these patients. Generally, tricyclic antidepressants should be avoided in patients who are > 65.
Key point:
The most commonly used oral agents for diabetic neuropathic pain are antidepressants and anticonvulsants. Pregabalin has the same efficacy and safety in older patients and results are comparable to those observed in younger patients with neuropathic pain.