What is the cause and treatment for swollen and tender toes with a burning sensation, considering potential underlying conditions like diabetes, vascular disease, or gout?

Swollen and Tender Toes with Burning Sensation

If you have diabetes with neuropathy, you must immediately suspect active Charcot neuro-osteoarthropathy and immobilize the foot urgently—do not wait for imaging, as untreated Charcot leads to fractures, deformity, ulceration, and amputation. 1, 2

Immediate Life-Threatening Conditions to Rule Out First

Active Charcot Neuro-Osteoarthropathy (If Diabetic)

• Check for diabetes with neuropathy presenting as red, warm, swollen toes—this is Charcot until proven otherwise. 1, 2
• Measure skin temperature difference between feet using infrared thermometry; a difference ≥2°C strongly suggests active Charcot. 1, 3
• Apply total contact cast or knee-high immobilization device immediately while awaiting imaging—delaying immobilization is the most critical pitfall. 1, 2
• Pain may be minimal or absent due to neuropathy, so never assume absence of pain rules out serious pathology. 3
• Order MRI if plain radiographs are normal but clinical suspicion remains high, as early Charcot may not show fractures initially. 1, 2

Diabetic Foot Infection

• Diagnose infection clinically if purulent discharge is present OR at least 2 cardinal signs of inflammation: erythema, warmth, swelling/induration, tenderness/pain. 2
• Probe the wound with a sterile blunt metal instrument—if bone is palpable (feels stony), osteomyelitis is highly likely. 2
• Obtain tissue specimens (not swabs) from debrided wound base for culture before starting antibiotics. 2
• Start empiric oral antibiotics targeting Staphylococcus aureus and Streptococcus for mild superficial infections. 2, 1
• For deep infections with systemic signs, initiate parenteral broad-spectrum antibiotics covering gram-positive, gram-negative, and anaerobic bacteria. 2

Peripheral Artery Disease Assessment

• Palpate foot pulses—if absent or diminished, measure ankle-brachial index (ABI <0.9 indicates PAD). 2
• If toe pressure <30 mmHg or transcutaneous oxygen pressure (TcPO2) <25 mmHg, consider urgent vascular imaging and revascularization. 2
• For non-healing ulcers with ankle pressure <50 mmHg or ABI <0.5, obtain urgent vascular imaging. 2

Differential Diagnosis Based on Clinical Pattern

Burning Pain Without Ulceration

Small-Fiber Neuropathy (Most Common)

• Presents as burning pain in feet, typically in middle-aged and older adults. 4
• Caused by diabetes (most common), HIV, genetic abnormalities, drug toxicity, or autoimmune diseases—but often idiopathic. 4, 5
• Physical examination shows paucity of objective signs despite distressing subjective symptoms. 5
• Standard electrophysiologic tests do not detect small-fiber dysfunction. 4
• Treatment focuses on symptomatic management of neuropathic pain with gabapentin, pregabalin, or duloxetine. 4

Erythromelalgia

• Episodes of severe burning pain in distal limbs with striking redness and warmth, precipitated by heat or activity. 6
• Symptoms terminated only by cooling the affected part. 6
• Primary form is hereditary; secondary form occurs with thrombocythemia, collagen-vascular diseases, diabetes, or peripheral neuropathy. 6
• Aspirin is effective for thrombocythemia-associated cases, but most cases are treatment-resistant. 6

Swelling with Redness and Warmth

Venous Eczema (If Bilateral Lower Legs)

• Associated with chronic venous insufficiency, varicose veins, or leg swelling history. 3
• Look for hemosiderin staining (brown discoloration), dry scaly skin, or lipodermatosclerosis. 3
• Apply hydrocortisone cream 3-4 times daily for inflammation and itching—do NOT prescribe antibiotics, as this is the most common error. 3
• Elevate legs when sitting or lying down; use compression therapy if no arterial insufficiency. 3

Gout (If Single Toe, Especially Great Toe)

• Acute onset of severe pain, swelling, erythema, and warmth in single toe. 7
• Diagnose with joint aspiration showing monosodium urate crystals. 7
• Treat acute attack with NSAIDs, colchicine, or corticosteroids. 7

Diagnostic Workup Algorithm

1. Document diabetes status, glycemic control (HbA1c), smoking history, and prior foot complications. 1
2. Perform monofilament testing to assess for loss of protective sensation. 2
3. Obtain plain radiographs of the foot first to evaluate for fracture, bone destruction, or gas in soft tissues. 1, 2
4. Order MRI if plain films are normal but clinical suspicion remains high for Charcot, osteomyelitis, or deep soft tissue infection. 1, 2
5. Measure ABI, toe pressures, or TcPO2 if pulses are diminished or ulcer is present. 2

Treatment Based on Final Diagnosis

If Charcot Confirmed

• Apply total contact cast (gold standard) or knee-high removable walking device rendered irremovable. 1, 2
• Continue immobilization until bone marrow edema resolves on MRI and temperature difference normalizes. 2

If Infection Present

• Debride all necrotic tissue and surrounding callus. 2
• Oral antibiotics for 1-2 weeks for superficial soft-tissue infection; 2-4 weeks for deeper infections. 2
• Parenteral antibiotics for 2-4 weeks if bone or joint involvement. 2

If Ischemia Present

• Revascularization aim is to restore direct flow to at least one foot artery, preferably the artery supplying the wound region. 2
• Both endovascular techniques and bypass surgery should be available. 2

Offloading for Any Ulcer

• Non-removable knee-high offloading device (total contact cast or removable walker rendered irremovable) is the preferred treatment for plantar ulcers. 2
• Instruct patient to limit standing and walking; use crutches if necessary. 2

Critical Pitfalls to Avoid

• Never delay immobilization while waiting for imaging in diabetic patients with neuropathy and swollen, warm toes. 1, 3
• Do not prescribe antibiotics for venous eczema—this leads to unnecessary antibiotic exposure and resistance. 3
• Do not assume absence of pain rules out serious pathology in diabetic patients with neuropathy. 3
• Do not use footbaths for wound care, as they induce skin maceration. 2
• Avoid too rapid reduction in HbA1c (>3% drop in short period), as this can cause treatment-induced neuropathy flare-up. 2

Multidisciplinary Referral Indications

• Immediate referral to diabetic foot care team (podiatry, infectious disease, vascular surgery, orthopedics) if diabetic with suspected Charcot, deep infection, or ischemia. 1, 2
• Vascular surgery consultation if toe pressure <30 mmHg, TcPO2 <25 mmHg, or ulcer not healing after 6 weeks despite optimal management. 2

Follow-Up Monitoring

• Reassess patients with infection at 48-72 hours for clinical improvement; if no improvement, reconsider diagnosis and check culture results. 1
• Monitor inflammatory markers to determine when infection has resolved and antibiotics can be discontinued. 1
• For Charcot, continue immobilization until temperature difference normalizes and MRI shows resolution of bone marrow edema. 2