What is the likely cause and appropriate management for sharp foot pain, particularly in the heel and toes, in a patient with a history of cardiovascular disease and multiple medications?

Evaluation and Management of Sharp Foot Pain in a Patient with Cardiovascular Disease

Based on the patient's symptoms of sharp pain in the heel and toes, the most likely diagnosis is peripheral neuropathy secondary to cardiovascular disease, which requires prompt evaluation with foot radiographs and referral to a podiatric specialist for comprehensive management.

Clinical Assessment of the Patient's Foot Pain

The patient presents with sharp pain in both feet that started one month ago, with different patterns in each foot:

• Left foot: Sharp pain in the toes when walking
• Right foot: Sharp pain in the heel, described as "walking over glass"

These symptoms strongly suggest peripheral neuropathy, which is a common complication in patients with cardiovascular disease 1. The patient's medication list reveals multiple cardiovascular medications, indicating significant cardiovascular disease:

• Ranolazine (Ranexa)
• Clopidogrel (Plavix)
• Nitroglycerin (Nitrostat)
• Isosorbide mononitrate (Imdur)
• Aspirin
• Atorvastatin (Lipitor)
• Amlodipine (Norvasc)
• Furosemide (Lasix)
• Metoprolol
• Losartan (Cozaar)

Additionally, the patient is taking metformin, suggesting diabetes, which further increases the risk of peripheral neuropathy.

Diagnostic Approach

Step 1: Initial Imaging

• Radiography of both feet should be performed as the first imaging study 1. This will help identify structural abnormalities and rule out fractures or other bone pathologies.

Step 2: Clinical Examination

Perform a focused neurological examination of the feet, including:

• Assessment of pinprick sensation
• Vibration testing using a 128-Hz tuning fork
• Light touch perception using a 10-g monofilament
• Ankle reflexes 1

Step 3: Vascular Assessment

• Check pedal pulses to assess for peripheral arterial disease (PAD)
• Consider ankle-brachial index (ABI) measurement if pulses are diminished 1

Management Plan

1. Immediate Pain Management:

   • Consider a trial of gabapentin or pregabalin for neuropathic pain
   • Avoid NSAIDs due to the patient's cardiovascular disease

2. Referral to Podiatric Specialist:

   • The patient should be referred to a foot care specialist for ongoing preventive care and surveillance 1
   • This is particularly important given the patient's cardiovascular risk factors

3. Preventive Foot Care Education:

   • Provide comprehensive foot self-care education 1
   • Daily foot inspection
   • Proper footwear selection
   • Avoiding walking barefoot

4. Therapeutic Footwear:

   • Recommend appropriate therapeutic footwear to reduce pressure on painful areas 1
   • Consider custom orthotics if standard footwear is insufficient

5. Regular Follow-up:

   • Schedule comprehensive foot evaluations at least annually 1
   • Examine feet at every visit

Differential Diagnosis

1. Neurologic Heel Pain:

   • Peripheral neuropathy (most likely given cardiovascular history and diabetes)
   • Nerve entrapment syndromes
   • Radiculopathy from lumbar spine pathology 1

2. Plantar Fasciitis:

   • Typically causes pain with first steps in the morning
   • Pain usually improves with activity 1

3. Achilles Tendonitis/Bursitis:

   • Usually presents with posterior heel pain
   • Often aggravated by pressure from shoes 1

4. Stress Fracture:

   • Pain on compression of the calcaneus
   • Often preceded by increased walking activity 1

Important Considerations and Pitfalls

• Cardiovascular Medication Effects: Some medications may contribute to neuropathic symptoms; review medication list carefully
• Diabetes Management: Ensure optimal glycemic control as poor control worsens neuropathy 1
• Avoid Corticosteroid Injections: In patients with suspected neuropathy, injections may mask symptoms and lead to further tissue damage
• Don't Delay Referral: Early intervention by a foot care specialist can prevent progression to ulceration and amputation 1
• Consider Vascular Etiology: The patient's extensive cardiovascular disease may be contributing to ischemic pain that mimics neuropathy

The sharp, glass-like pain described by the patient is highly characteristic of neuropathic pain, which requires different management approaches than mechanical or inflammatory foot conditions. Given the patient's cardiovascular disease and likely diabetes, prompt attention to these symptoms is essential to prevent serious complications such as foot ulcers or amputation.