What is the appropriate management for a 5‑year‑old girl who had a viral fever 7 days ago and now presents with severe bilateral lower‑extremity pain, inability to walk due to pain, and unilateral facial palsy?

Immediate Management: Supportive Care for Post-Viral Myositis with Concurrent Bell's Palsy

This 5-year-old girl most likely has benign acute childhood myositis (BACM) following her viral illness, combined with Bell's palsy, and should be managed with supportive care including hydration, pain control with ibuprofen or paracetamol, and observation—with steroids being optional for the facial palsy given the lack of strong evidence in children.

Clinical Diagnosis

This presentation is classic for two distinct post-viral complications occurring simultaneously:

Post-Viral Myositis (Bilateral Lower Limb Pain)

• The bilateral lower extremity pain with inability to walk occurring 7 days after viral fever is pathognomonic for BACM 1, 2, 3
• This condition typically presents at the early convalescent phase of viral illness, most commonly influenza A or B 2, 3
• Key diagnostic features include:
  • Bilateral calf pain and tenderness
  • Difficulty or inability to walk
  • Self-limited course with resolution within 1 week 3

Unilateral Facial Palsy (Bell's Palsy)

• The facial palsy represents a separate post-viral complication
• Children have better spontaneous recovery rates than adults 4

Immediate Diagnostic Workup

Check creatine phosphokinase (CPK) levels immediately to confirm myositis and assess severity:

• Expect markedly elevated CPK (can be >8000 U/L) 2
• Also check AST, renal function, and urinalysis for myoglobin 1
• Consider influenza testing if still within appropriate window 2, 3

Common pitfall: Normal CPK does not rule out post-streptococcal myositis, but in the context of recent viral illness (not bacterial), elevated CPK is expected 5.

Management Algorithm

For the Myositis (Primary Concern):

1. Hydration: Admit for IV hydration if CPK is markedly elevated or if oral intake is poor 1

   • Monitor renal function to prevent rhabdomyolysis complications
   • Most cases resolve within 24-48 hours 1

2. Pain Management:

   • Ibuprofen or paracetamol for pain control 6
   • Pain typically rated 4-6/10 in these cases

3. Observation:

   • Monitor CPK levels—expect normalization within 24 hours 1
   • Reassess ambulation status
   • Discharge when pain improves and CPK normalizes

4. No antiviral therapy needed at this stage (7 days post-viral illness) 7

For the Bell's Palsy:

The evidence for steroid use in children with Bell's palsy is weak and inconclusive 4. The guideline explicitly states that children show higher rates of spontaneous recovery than adults, and no controlled trials support routine steroid use in pediatric Bell's palsy 4.

However, you may offer oral corticosteroids (e.g., prednisolone 1-2 mg/kg/day for 5-7 days) with extensive caregiver counseling about:

• Uncertain benefit in children
• Generally favorable benefit-harm ratio
• High spontaneous recovery rates without treatment 4

Do not prescribe antiviral therapy alone for Bell's palsy—this is a strong recommendation against monotherapy 4. If you choose steroids, you may optionally add antivirals (valacyclovir or famciclovir) within 72 hours of facial palsy onset, though evidence shows only potential small benefit 4.

Key Clinical Pitfalls to Avoid

• Do not pursue extensive neuromuscular workup for the leg pain—BACM is self-limited and requires only supportive care 3, 7
• Do not delay hydration if CPK is markedly elevated—rhabdomyolysis prevention is critical 1
• Do not assume the facial palsy requires aggressive treatment—spontaneous recovery in children is excellent 4
• Reassure parents extensively that both conditions are self-limited with excellent prognosis 3, 7

Expected Timeline

• Myositis: Complete resolution within 1 week, often within 24-48 hours 1, 3
• Bell's palsy: Spontaneous recovery expected over weeks to months, with children having better outcomes than adults 4