What is pseudoparalysis in a child?

Pseudoparalysis in a Child

Pseudoparalysis in a child is the apparent inability or refusal to move a limb due to pain, not true neurological paralysis, most commonly caused by painful conditions such as congenital syphilis (Pseudoparalysis of Parrot), osteomyelitis, septic arthritis, fractures, or scurvy. 1, 2, 3

Clinical Definition and Key Features

Pseudoparalysis refers to decreased or absent spontaneous movement of a limb that mimics true paralysis but is actually caused by pain rather than neurological dysfunction. 1 The child typically:

• Shows obvious discomfort with passive movement of the affected limb 1
• Demonstrates decreased spontaneous movement but maintains intact neurological function 1
• May have subtle swelling or tenderness of the affected area 1
• Presents with fussiness or irritability, particularly when the limb is manipulated 1

Critical Differential Diagnoses

Congenital Syphilis (Pseudoparalysis of Parrot)

This is a re-emerging cause that emergency physicians must recognize given the growing burden of syphilis infection. 1 Key features include:

• Typically presents in infants 2-3 months of age 1, 3
• Caused by painful syphilitic periostitis affecting long bones 1
• Associated laboratory findings: anemia, transaminitis, elevated inflammatory markers 1
• Radiographic findings show periosteal thickening of affected limbs 3
• Can occur even with negative maternal serology during first trimester 3

Scurvy

An often-forgotten diagnosis that can present dramatically. 2 Characteristics include:

• Can present as acute-onset pseudoparalysis without other obvious signs, even in older children 2
• May be misdiagnosed as acute paralytic poliomyelitis when fever and respiratory infection are present 2
• Shows swelling, thickening, and tenderness of affected bones on examination 2
• X-ray reveals characteristic features of scurvy 2
• Dramatic response to parenteral vitamin C therapy within two weeks confirms diagnosis 2

Other Important Causes

• Osteomyelitis: Infection of bone causing severe pain with movement 1
• Septic arthritis: Joint infection limiting active range of motion
• Fractures: Including non-accidental trauma, which must always be considered 1
• Soft tissue injuries: Cellulitis or abscess causing pain-limited movement

Diagnostic Approach

Initial Clinical Assessment

When evaluating a child with apparent limb paralysis:

1. Assess for pain response: Observe for discomfort with passive movement, which distinguishes pseudoparalysis from true neurological paralysis 1
2. Examine for subtle physical findings: Look for edema, warmth, erythema, or tenderness of the affected limb 1
3. Evaluate neurological function: True paralysis will have absent reflexes and sensory changes, while pseudoparalysis maintains intact neurology 1

Imaging and Laboratory Workup

• Plain radiographs: First-line imaging to exclude fractures, periostitis, or bone lesions 1, 2, 3
• Laboratory studies when infection suspected: Complete blood count, inflammatory markers (ESR, CRP), liver function tests 1
• Syphilis serologies: Essential when congenital syphilis is considered, particularly in young infants with periosteal changes 1, 3
• Vitamin C levels: When scurvy is suspected based on dietary history and radiographic findings 2

Critical Pitfalls to Avoid

Do not assume acute paralytic poliomyelitis or other neurological conditions without first excluding painful musculoskeletal causes. 2 The presence of fever, respiratory infection, and muscle weakness can mislead clinicians toward neurological diagnoses when the true cause is nutritional or infectious. 2

Do not overlook congenital syphilis in the differential diagnosis of infant limb immobility. 1, 3 This diagnosis is re-emerging and can occur even when maternal screening was negative during early pregnancy, emphasizing the need for high clinical suspicion. 3

Always consider non-accidental trauma when evaluating decreased limb movement in infants, but recognize that normal plain films do not exclude serious pathology such as congenital syphilis. 1

Distinguishing from Cerebral Palsy

Unlike cerebral palsy, which involves permanent motor dysfunction from non-progressive brain disturbances 4, 5, pseudoparalysis:

• Has acute or subacute onset rather than gradual recognition of developmental delay 4
• Is caused by pain, not neurological impairment 1
• Resolves completely with treatment of the underlying cause 1, 2
• Does not show the motor quality abnormalities seen in cerebral palsy (such as absent fidgety movements or abnormal tone patterns) 4