What is the definition, diagnostic criteria, etiologies, and types of cerebral palsy in children?

Cerebral Palsy in Children: Definition, Diagnostic Criteria, Etiologies, and Types

Definition

Cerebral palsy is defined as "a group of permanent disorders of the development of movement and posture, causing activity limitation, that are attributed to non-progressive disturbances that occurred in the developing fetal or infant brain." 1, 2

• CP is the most common physical disability in childhood, with a prevalence of 2 to 3 cases per 1000 births 1
• The condition is characterized by permanent and nonprogressive clinical course, though clinical manifestations emerge and evolve during the first 2 years of life 1
• Activity limitations result from altered brain development affecting muscle tone, posture, and movement 1

Diagnostic Criteria

Diagnosis is clinical, based on a combination of medical history, neurological signs, standardized assessments, and neuroimaging showing congruent abnormal findings indicative of cerebral palsy. 1, 2

Before 5 Months Corrected Age (Most Predictive Tools):

• Term-age MRI (86-89% sensitivity) 1, 2
• Prechtl Qualitative Assessment of General Movements (98% sensitivity) 1, 2
• Hammersmith Infant Neurological Examination (90% sensitivity) 1, 2

After 5 Months Corrected Age (Most Predictive Tools):

• MRI (86-89% sensitivity) where safe and feasible 1, 2
• Hammersmith Infant Neurological Examination (90% sensitivity) 1, 2
• Developmental Assessment of Young Children (83% C index) 1

Key Diagnostic Features:

• Alterations in muscle tone, posture, and/or movement noted in the first years of life 1
• Nonprogressive clinical course (any acute deterioration requires urgent evaluation for alternative diagnoses) 2, 3
• Diagnosis typically occurs between 12 and 24 months of age, though earlier detection is increasingly possible 1

Red Flags Suggesting Alternative Diagnosis:

• Loss of motor milestones (suggests neurodegenerative process) 2
• Respiratory insufficiency with generalized weakness 2
• Motor delays present only during minor acute illness 2

Etiologies

The underlying cause of CP is uncertain in most cases, though genetic factors, prenatal complications, and perinatal events all contribute. 1, 2

Genetic Factors:

• Recent evidence demonstrates 14% of cases have a genetic component 2
• Rare genomic variants including copy number variants (CNVs) identified in 10-31% of cases 1
• Pathogenic or likely pathogenic single-nucleotide variants (SNVs) found in 7-55% of cases through exome sequencing 1
• Exome sequencing has a diagnostic yield of 31.1% overall, with 34.8% in pediatric populations 1

Prenatal Risk Factors:

• Maternal thyroid disease and preeclampsia 2
• Maternal infections 2
• Intrauterine growth restriction 2
• Multiple gestation 2
• History of stillbirths or miscarriages 2
• Low socioeconomic status 2
• Assisted reproduction 2
• Abnormal genetic copy number variations 2

Perinatal Risk Factors:

• Prematurity (prevalence 70 times higher in infants <1500g compared to >2500g) 1, 2
• Low birth weight 1
• Birth complications 1
• Birth asphyxia accounts for less than 10% of CP cases, contrary to historical belief 1

Postnatal Risk Factors:

• Infections occurring in early infancy 2
• Trauma 2
• Stroke 2
• Hypoxic events 2

Neuroimaging Patterns (Most Predictive for CP):

• White matter injury including cystic periventricular leukomalacia or periventricular hemorrhagic infarctions (56%) 2
• Cortical and deep gray matter lesions including basal ganglia/thalamus lesions, watershed injury, multicystic encephalomalacia, or stroke (18%) 2
• Brain maldevelopments including lissencephaly, pachygyria, cortical dysplasia, polymicrogyria, or schizencephaly (9%) 2

Types of Cerebral Palsy

CP is classified by motor type and topographical distribution, with spasticity being the most common form (85-91% of cases). 1, 2, 4

Classification by Motor Type:

1. Spastic CP (85-91% of cases):

• Characterized by increased muscle tone and velocity-dependent resistance to passive movement 1, 2, 4
• Most common motor type 1, 2

2. Dyskinetic CP (4-7% of cases):

• Includes dystonia and athetosis 1, 2, 4
• Usually affects all four limbs 1

3. Ataxic CP (4-6% of cases):

• Characterized by coordination and balance difficulties 1, 2, 4
• Usually affects all four limbs 1

4. Hypotonic CP (2% of cases):

• Not classified in all countries 1, 2, 4
• Usually affects all four limbs 1

Classification by Topographical Distribution (for Spastic CP):

1. Unilateral/Hemiplegia (38% of spastic cases):

• One side of the body affected 1, 2, 4, 3

2. Bilateral Diplegia (37% of spastic cases):

• Lower limbs affected more than upper limbs 1, 2, 4, 3

3. Quadriplegia (24% of spastic cases):

• All four limbs and trunk affected 1, 2, 4, 3

Important Clinical Considerations:

• Motor types and topography may emerge and change during the first 2 years of life 1, 4
• Approximately half of infants have their Gross Motor Function Classification System (GMFCS) level reclassified during early development 4
• The absence of spasticity does not exclude cerebral palsy, as some children have dyskinetic or ataxic forms without spasticity 3

Common Comorbidities

CP frequently coexists with multiple disabling conditions that significantly impact quality of life and require systematic screening. 1, 2, 4, 3

• Chronic pain (75%) 1, 2, 4, 3
• Intellectual disability (27-49%) 1, 2, 4, 3
• Epilepsy (35-38%) 1, 2, 4, 3
• Speech disorders (33-82%) 1
• Musculoskeletal problems including hip displacement (28%) 1, 2, 4, 3
• Behavioral disorders (26%) 1, 2
• Sleep disorders (23%) 1, 2
• Functional blindness (11%) 1, 2, 3
• Hearing impairment (4%) 1, 2, 3
• Autism spectrum disorder (3-9%) 1

Prognosis

In high-income countries, 2 in 3 individuals with CP will walk, 3 in 4 will talk, and 1 in 2 will have normal intelligence. 1, 2, 4

Critical Management Principles:

• Early diagnosis and prompt referral to diagnostic-specific intervention is essential to optimize infant motor and cognitive plasticity, prevent secondary complications, and enhance caregiver well-being 1, 2, 4, 3
• Early intervention should begin as soon as CP is suspected rather than waiting for definitive diagnosis 2
• Delaying diagnosis can be harmful to parent and caregiver well-being, potentially leading to depression and lasting anger 2