Bilateral Foot Burning Sensation in Dengue NS1 Positive Patient
The bilateral foot burning sensation in your dengue patient is most likely a peripheral neuropathy related to dengue infection, which can manifest as mononeuritis multiplex, multifocal motor neuropathy, or hypokalemia-induced neuromuscular weakness—check serum potassium immediately and correct if low, as this resolves symptoms within 24 hours in most cases.
Likely Causes and Diagnostic Approach
The burning sensation represents a neurological complication of dengue, which occurs more commonly than previously recognized. Based on the evidence, you need to differentiate between three main etiologies:
1. Hypokalemia-Induced Neuropathy (Most Common and Reversible)
- Check serum potassium urgently 1
- In a study of 12 dengue patients with acute neuromuscular weakness, 10 had hypokalemia as the cause
- Motor weakness typically develops on days 2-4 of illness 1
- Recovery occurs within 24 hours of potassium correction 1
- Also check CPK and liver enzymes (SGOT), as these are often elevated
2. Direct Neurological Complications
Dengue can cause various neuropathies through direct neuroinvasion, immune-mediated mechanisms, or systemic complications 2:
- Mononeuritis multiplex: Can present with foot symptoms and diplopia 3
- Multifocal motor neuropathy (MMN): Typically occurs 5 days post-infection with asymmetric motor weakness 4
- Guillain-Barré syndrome: Post-infectious complication 1, 2
3. Myositis
- Check CPK levels (can be markedly elevated, >5000 IU in myositis cases) 1
- Associated with muscle pain and weakness
Immediate Management Algorithm
Step 1: Laboratory Evaluation
- Serum potassium (STAT)
- Complete blood count (expect thrombocytopenia)
- CPK, SGOT, liver and kidney function
- Consider nerve conduction studies if weakness persists beyond potassium correction
Step 2: Potassium Correction
- If hypokalemic: Aggressive potassium replacement
- Expect rapid improvement (within 24 hours) if this is the cause 1
Step 3: Supportive Dengue Management
- Judicious fluid resuscitation with crystalloids during the critical phase 5
- Monitor for warning signs: abdominal pain, persistent vomiting, bleeding, plasma leakage
- Do NOT give prophylactic platelet transfusion 5
- Watch for severe dengue complications (shock, severe bleeding, organ failure)
Step 4: If Symptoms Persist After Potassium Correction
- Perform nerve conduction velocity and electromyography 1
- Consider post-infectious immune-mediated neuropathy
- IVIG therapy may be indicated for MMN or Guillain-Barré syndrome 4
Critical Pitfalls to Avoid
- Don't assume all neurological symptoms are "just dengue"—hypokalemia is a treatable cause that requires immediate correction 1
- Don't delay potassium testing—this is the most rapidly reversible cause
- Neurological manifestations can be the presenting symptom of dengue, not just a late complication 3
- The timing matters: symptoms during acute phase (days 2-4) suggest hypokalemia or direct viral effects, while symptoms 5-10 days post-infection suggest post-infectious immune complications 4, 1
Prognosis
- Hypokalemia-related symptoms: Excellent prognosis with 24-hour recovery 1
- Mononeuritis multiplex: Near-complete resolution within 2 weeks with supportive care 3
- MMN with IVIG: Good response to treatment 4
Age Considerations
If your patient is ≥60 years old, monitor more closely for memory loss and movement disorders, as older adults have significantly higher odds of these complications (aOR 6.38 for movement disorders) 6.
The key is immediate potassium assessment and correction, as this single intervention resolves the majority of dengue-associated neuromuscular weakness cases within 24 hours 1.