What is the best treatment approach for a 70-year-old woman with a burning foot sensation, suspected to be due to neuropathy?

Treatment for Burning Foot Sensation in a 70-Year-Old Woman

For a 70-year-old woman with burning foot sensation likely due to neuropathy, first-line treatment should include gabapentinoids (pregabalin or gabapentin) or serotonin-norepinephrine reuptake inhibitors, with pregabalin being the preferred initial medication due to its FDA approval for neuropathic pain.

Initial Assessment and Diagnosis

• Evaluate for underlying causes of neuropathy including diabetes, vitamin B12 deficiency, renal disease, chronic inflammatory demyelinating neuropathy, inherited neuropathies, and vasculitis 1
• Perform a comprehensive foot examination including inspection of the skin, assessment of foot deformities, neurological assessment (10-g monofilament testing with at least one additional assessment: pinprick, temperature, or vibration), and vascular assessment 1
• Assess for loss of protective sensation (LOPS) using the 10-g monofilament test along with at least one other assessment (pinprick, temperature or vibration sensation using a 128-Hz tuning fork, or ankle reflexes) 1
• Screen for peripheral arterial disease (PAD) through history of claudication and assessment of pedal pulses 1

Pharmacological Treatment Options

First-Line Medications

• Gabapentinoids:

  • Pregabalin (75-300 mg every 12 hours) - FDA approved for diabetic peripheral neuropathy 1, 2
  • Gabapentin (starting at 300 mg at bedtime, up to 2400 mg daily divided into 3 doses) 1, 3

• Serotonin-norepinephrine reuptake inhibitors (SNRIs):

  • Duloxetine - FDA approved for diabetic neuropathic pain 1
  • Venlafaxine (up to 75 mg daily) 1

Second-Line Medications

• Tricyclic antidepressants (TCAs):

  • Amitriptyline - effective for neuropathic pain but may have anticholinergic side effects that limit use in older adults 1
  • Consider lower starting doses and more gradual titration in elderly patients 1

• Sodium channel blockers:

  • Options include carbamazepine, oxcarbazepine, lamotrigine, lacosamide, and valproic acid 1
  • Consider for patients who don't respond to first-line treatments 1

Topical Treatments

• Capsaicin:

  • Available as cream/lotion (0.025% to 0.075%) applied 3-4 times daily for 6 weeks 1
  • Capsaicin patches (0.025%) can be applied for 30 minutes, repeated every 3 months 1
  • May cause initial stinging and burning sensations 1

• Other topical options:

  • Lidocaine 5% patches for localized pain 1
  • Compounded formulations containing amitriptyline, ketamine, clonidine, gabapentin, and/or lidocaine 1
  • Diclofenac 1% gel or topicals containing camphor or menthol 1

Special Considerations for Elderly Patients

• Pregabalin is substantially excreted by the kidney, requiring dose adjustment in elderly patients with renal impairment 2
• TCAs may have dose-limiting anticholinergic side effects that restrict use in individuals ≥65 years 1
• Gabapentin shows a larger treatment effect in patients 75 years and older, but requires dose adjustment based on renal function 3
• Monitor for adverse effects such as dizziness, vision changes, balance disorders, and confusion, which are more frequent in patients over 65 years 2

Non-Pharmacological Approaches

• Evaluate for and address any foot deformities or increased plantar pressures 1
• Consider well-fitted walking shoes or athletic shoes that cushion the feet and redistribute pressure 1
• For patients with bony deformities, recommend extra wide or deep shoes 1
• Provide education on proper foot care, including nail and skin care 1
• Encourage daily foot monitoring, especially in patients with sensory loss 1

Treatment Algorithm

1. Start with first-line therapy:

   • Begin with pregabalin 75 mg twice daily, titrating up to 300 mg twice daily as needed and tolerated 1
   • OR gabapentin 300 mg at bedtime, gradually increasing to effective dose 1

2. If inadequate response after 4-6 weeks:

   • Switch to alternative first-line agent (SNRI if gabapentinoid was first choice) 1
   • OR consider combination therapy 1

3. If still inadequate response:

   • Add or switch to second-line agent (TCA or sodium channel blocker) 1
   • Consider topical treatments as adjuncts 1

4. For refractory cases:

   • Consider pain specialty consultation 1
   • Evaluate for recalcitrant pain syndrome and consider referral to pain rehabilitation center 1

Monitoring and Follow-up

• Reassess pain control and medication side effects regularly 1
• For patients with sensory loss or prior ulceration, inspect feet at every visit 1
• Monitor for development of foot ulcers or other complications 1
• Adjust medication doses based on renal function, especially in elderly patients 2, 3

Remember that while symptomatic treatment is important for quality of life, identifying and addressing any underlying cause of neuropathy is equally crucial for comprehensive management 1.