What are the causes of descending paralysis in pediatric patients?

Causes of Descending Paralysis in Children

Primary Cause: Botulism

Botulism is the classic and most critical cause of descending paralysis in children, characterized by acute onset of bilateral cranial nerve palsies that progress downward to respiratory, extremity, and axial muscles over hours to days. 1, 2

Key Clinical Features of Botulism

• Afebrile presentation (<100.4°F) is nearly universal (99% of cases), which immediately distinguishes it from infectious causes 1
• Descending pattern: Begins with cranial nerves (blurred vision, diplopia, ptosis, dysphagia, dysphonia), then progresses to trunk and limbs 1, 2, 3
• Symmetric neurologic deficits affecting proximal before distal muscles, with preserved consciousness throughout 2
• Unreactive or dilated pupils occur in 25% of confirmed cases—a distinguishing feature from other paralytic conditions 2
• Gastrointestinal symptoms (nausea, vomiting) occur in 50% of foodborne cases 2

Exposure History to Elicit

• Consumption of home-canned foods, honey (in infants), or improperly preserved foods 3
• Recent wounds that could harbor Clostridium botulinum spores 3

Critical Management

• Immediate consultation with CDC botulism clinical service and administration of botulinum antitoxin as soon as diagnosis is suspected 2
• Monitor for respiratory failure from pharyngeal collapse even before diaphragmatic weakness develops 2

Other Important Causes

Guillain-Barré Syndrome (GBS)

While GBS classically presents with ascending paralysis, it is the most common cause of acquired paralysis in children in countries where polio has been eliminated and can rarely present with descending features 4, 5:

• Symmetric weakness with diminished or absent reflexes 4
• Severe pain is common and may delay diagnosis 4
• Albuminocytological dissociation on CSF analysis (elevated protein, normal cell count) 6
• Preceded by infection (especially Campylobacter jejuni) 1-4 weeks prior 4
• Progressive phase peaks in 7-14 days 4

Key Distinguishing Feature: GBS typically shows ascending pattern, absent reflexes throughout, and CSF protein elevation—whereas botulism shows descending pattern, may have unreactive pupils, and normal CSF 1, 6, 4

Poliomyelitis

In areas where polio remains endemic or in unvaccinated children 7:

• Asymmetric spinal paralysis, more severe proximally than distally 7
• Rapid progression to maximum paralysis within 2-4 days 7
• Fever and muscle pain during progression 7
• Absent or diminished deep tendon reflexes 7
• Bulbar paralysis affecting respiration and swallowing 7
• Preceded by nonspecific febrile illness 7

Acute Flaccid Myelitis (AFM)

A polio-like condition mainly affecting young children 8:

• Acute onset limb weakness with low muscle tone 8
• Often difficult to differentiate from other AFP causes at onset 8
• May be confused with transverse myelitis or GBS 8

Diagnostic Approach Algorithm

1. Assess fever status: Afebrile strongly suggests botulism 1
2. Determine pattern of weakness:
   • Descending (cranial nerves → trunk → limbs) = botulism 1, 2
   • Ascending = GBS (most common) 4
   • Asymmetric = consider polio 7
3. Examine pupils: Unreactive/dilated pupils point to botulism 2
4. Check reflexes: Preserved early in botulism; absent throughout in GBS 1, 4
5. Assess consciousness: Preserved in botulism; altered suggests alternative diagnosis 1, 2
6. Obtain exposure history: Food sources, wounds, vaccination status, recent infections 1, 2, 4

Critical Pitfalls to Avoid

• Do not assume altered mental status excludes botulism—consciousness is typically preserved, and altered status may indicate concurrent respiratory failure 2
• Do not delay botulinum antitoxin while awaiting laboratory confirmation, as toxin assays take days to result 9
• Consider botulism when GBS is suspected, as these are the most common misdiagnoses of each other 2, 6
• Do not administer plasma exchange if botulism is possible, as it may remove administered antitoxin 6
• Perform thorough serial neurologic examinations including pupillary responses, pattern of weakness progression, and cranial nerve function to distinguish these conditions 2