How should I evaluate and manage a child with acute flaccid paralysis?

Approach to Acute Flaccid Paralysis in Children

Immediately assess and stabilize respiratory and bulbar function, as respiratory failure is the leading cause of mortality in children with acute flaccid paralysis, then systematically differentiate between anterior horn cell disease (particularly acute flaccid myelitis), Guillain-Barré syndrome, and other causes through targeted clinical examination and urgent MRI spine. 1

Immediate Stabilization Priorities

The first actions must focus on life-threatening complications, as early respiratory failure determines survival:

• Assess respiratory muscle strength through respiratory rate, work of breathing (accessory muscle use, nasal flaring, paradoxical breathing), and serial objective measurements including spirometry, EtCO2 monitoring, or blood gas analysis 2
• Evaluate bulbar function for dysphagia, dysarthria, nasal voice, drooling, impaired gag reflex, and swallowing ability to determine aspiration risk 2
• Monitor cardiovascular stability with continuous cardiac rhythm monitoring and frequent blood pressure measurements 2
• Establish intravenous access immediately in any child with progressive weakness or respiratory compromise 2

Critical pitfall: Facial paralysis can produce a placid expression that obscures respiratory distress, and diaphragmatic paralysis causes paradoxical abdominal movement (abdomen moves inward during inspiration), potentially masking severe respiratory insufficiency 2

Focused Clinical Assessment

Key Historical Features

• Onset timing and progression: Symptoms developing acutely (<72 hours) suggest different etiologies than subacute progression over days 3, 1
• Prodromal illness: Fever or respiratory symptoms preceding weakness by days strongly suggests acute flaccid myelitis (AFM), particularly during late summer/early fall outbreaks 4, 5
• Pattern of weakness: Asymmetric limb weakness favors AFM, while ascending symmetric weakness suggests Guillain-Barré syndrome 6, 4
• Associated symptoms: Severe pain at onset, sensory changes, or bladder/bowel dysfunction help differentiate causes 1, 6

Critical Physical Examination Findings

• Tongue fasciculations: This is a red flag for lower motor neuron disorders (particularly spinal muscular atrophy or motor neuron disease) and requires immediate pediatric neurology referral 7
• Muscle tone and deep tendon reflexes: Hypotonia with absent reflexes characterizes anterior horn cell disease (AFM, polio-like illness), while preserved or hyperactive reflexes suggest spinal cord pathology 7, 1
• Cranial nerve involvement: Facial weakness, extraocular movement abnormalities, or bulbar dysfunction indicate brainstem involvement 4
• Sensory examination: Preserved sensation with pure motor weakness suggests anterior horn cell disease, while sensory loss indicates peripheral nerve or spinal cord involvement 1, 6

Diagnostic Algorithm

Urgent Imaging (Within Hours)

Obtain MRI spine with and without contrast immediately when spinal cord involvement is suspected, as compressive or traumatic lesions require emergency neurosurgical intervention 1

For suspected AFM: MRI spine demonstrates characteristic longitudinally extensive T2 hyperintensity predominantly affecting gray matter (anterior horn cells) spanning multiple spinal segments 6, 4, 5

For alternative diagnoses:

• Transverse myelitis shows central cord involvement with both gray and white matter signal abnormality 6
• Guillain-Barré syndrome typically has normal spinal imaging or only nerve root enhancement 6

Laboratory Investigations

• Cerebrospinal fluid analysis: Pleocytosis (elevated white blood cells) with normal to mildly elevated protein suggests AFM, while elevated protein with minimal cells (albuminocytologic dissociation) indicates Guillain-Barré syndrome 6, 4, 5
• Viral studies: Send respiratory specimens and stool for enterovirus PCR and culture, particularly enterovirus D68 during outbreak periods 4, 5
• Creatine kinase: Elevated levels suggest muscle destruction rather than neurogenic weakness 7
• Electrophysiological studies: Nerve conduction studies and electromyography help localize the lesion (anterior horn cell vs. peripheral nerve vs. neuromuscular junction) 7, 1

Differential Diagnosis Framework

Acute Flaccid Myelitis (AFM)

• Peak age: Young children (median 5 years) 4, 5
• Seasonality: Biennial outbreaks in late summer/early fall 4
• Presentation: Asymmetric limb weakness, often with respiratory/bulbar involvement, following viral prodrome 4, 5
• MRI: Gray matter predominant spinal cord lesions 6, 4

Guillain-Barré Syndrome

• Presentation: Ascending symmetric weakness with areflexia 6
• CSF: Albuminocytologic dissociation 6
• MRI: Normal spine or nerve root enhancement 6

Transverse Myelitis

• Presentation: Sensory level, bladder/bowel dysfunction, symmetric weakness 6
• MRI: Central cord involvement with both gray and white matter abnormality 6

Botulism

• Presentation: Descending paralysis, dilated pupils, constipation, dry mouth 2
• Management: Requires botulinum antitoxin within 24-48 hours of symptom onset 2

Treatment Approach

Supportive Care (All Patients)

• Respiratory support: Institute mechanical ventilation for respiratory failure; AFM patients may require prolonged ventilation (weeks to months) 2, 4, 5
• Bulbar dysfunction management: NPO status with nasogastric or gastrostomy feeding if swallowing is unsafe 2
• Monitor for complications: Urinary retention, constipation/ileus, DVT prophylaxis for immobilized patients 2

Specific Therapies

For suspected AFM: No proven effective treatment exists, but consider:

• Intravenous immunoglobulin (IVIG) or corticosteroids (evidence limited) 4, 5
• Early neurology consultation for potential investigational therapies 5

For Guillain-Barré syndrome: IVIG or plasmapheresis initiated early improves outcomes 1

For botulism: Administer botulinum antitoxin (BAT) within 24-48 hours; delays beyond 48 hours reduce efficacy 2

Early Rehabilitation

Initiate immediately upon stabilization:

• Physical therapy for hypotonia and gross motor deficits 7
• Occupational therapy for fine motor skills and sensory integration 7
• Speech and language evaluation for oral-motor dysfunction 7

Critical consideration: AFM patients typically have substantial residual disability requiring long-term, specialized rehabilitation 5

Mandatory Specialist Referrals

• Immediate pediatric neurology consultation for all cases of acute flaccid paralysis 7, 1
• Ophthalmology referral if facial weakness prevents eye closure (risk of corneal exposure) 3
• Neurosurgery consultation if imaging reveals compressive spinal lesions 1
• Genetics referral if tongue fasciculations, family history, or syndromic features suggest inherited neuromuscular disease 7, 3

Monitoring and Follow-up

• Serial neurological examinations: Frequency based on progression rate; very frequent for rapidly progressive cases 2
• Respiratory monitoring: Continuous for patients with bulbar/respiratory symptoms not yet requiring intubation 2
• Long-term surveillance: Regular assessment for disease progression, loss of motor milestones (suggesting neurodegenerative process), feeding difficulties, and growth parameters 7