Can normal tone and absence of spasticity rule out cerebral palsy (Cerebral Palsy)?

Normal Tone and Spasticity Cannot Rule Out Cerebral Palsy

The absence of spasticity and normal tone cannot rule out cerebral palsy, as motor types and topography of cerebral palsy may emerge and change during the first 2 years of life. 1

Understanding Motor Presentations in Cerebral Palsy

• The onset of spasticity may occur after age 1 year; therefore, the absence of early detectable spasticity does not mean that the infant does not have spastic cerebral palsy 1
• Cerebral palsy can be difficult to accurately classify early, but clinical signs exist that can help with identification 1
• Infants may have more than one motor disorder because spasticity and dystonia often coexist 1
• As the infant's voluntary activity levels increase, some symptoms may resolve (e.g., nonuse of a limb), while other symptoms may worsen (e.g., increased involuntary dystonic posturing in response to voluntary movement) 1

Diagnostic Challenges in Early Cerebral Palsy

• Without a laboratory biomarker, an early diagnosis is not always clinically clear-cut because of the possibility of false positives and false negatives 1
• False negatives can occur for several reasons:
  • There is a latency between the initial brain lesion and the later onset of clinical neurological signs (e.g., exaggerated spasticity or dystonia from voluntary movement) 1
  • Approximately 10% of cerebral palsy cases have normal neuroimaging 1
  • Half of cerebral palsy cases have a seemingly uneventful pregnancy and birth 1
  • One-third have the mildest form (GMFCS I) and may initially achieve all of their motor milestones on time, offering false reassurance about their motor development 1

Recommended Diagnostic Approach

• Early diagnosis begins with a medical history and involves using neuroimaging, standardized neurological, and standardized motor assessments that indicate congruent abnormal findings indicative of cerebral palsy 1
• When cerebral palsy is suspected but cannot be made with certainty, use the interim clinical diagnosis of "high risk of cerebral palsy" until a diagnosis is confirmed 1
• To assign the interim diagnosis of high risk of cerebral palsy, the infant must have motor dysfunction (essential criterion) and at least one of two additional criteria (abnormal neuroimaging or clinical history indicating risk for cerebral palsy) 1

Motor Assessment and Classification

• In infants younger than 2 years, motor severity is difficult to accurately predict because:
  • Almost half of all infants younger than 2 years have their Gross Motor Function Classification System (GMFCS) reclassified 1
  • Little natural history data exist about infants with cerebral palsy (e.g., the onset of spasticity, dyskinesia, or contractures) 1
  • Motor skills are developing 1
  • The presence or absence of hypertonia changes and evolves 1
  • There is rapid brain growth and use-dependent reorganization in response to caregiving and therapy 1

Standardized Assessment Tools

• For early detection before 5 months' corrected age, the most predictive tools are:
  • Term-age magnetic resonance imaging (86%-89% sensitivity) 1
  • The Prechtl Qualitative Assessment of General Movements (98% sensitivity) 1
  • The Hammersmith Infant Neurological Examination (90% sensitivity) 1
• After 5 months' corrected age, the most predictive tools are:
  • Magnetic resonance imaging (86%-89% sensitivity) 1
  • The Hammersmith Infant Neurological Examination (90% sensitivity) 1
  • The Developmental Assessment of Young Children (83% C index) 1

Clinical Implications and Monitoring

• When an infant is perceived to be at risk of cerebral palsy, they should be referred for cerebral palsy-specific early intervention with regular medical, neurological, and developmental monitoring 1
• In milder presentations, especially unilateral cerebral palsy, it is possible for an infant to score within the normal range on a standardized motor assessment while still displaying abnormal movements 1
• Assessments should be carried out by a professional skilled at determining atypical movement from variation in typical movement 1
• Prognosis of motor severity predictions should be made cautiously in infants younger than 2 years and always involve the use of standardized tools 1

Important Considerations

• In high-income countries, population data indicate that 2 in 3 individuals with cerebral palsy will walk, 3 in 4 will talk, and 1 in 2 will have normal intelligence 1
• Eighty-six percent of parents of a child with cerebral palsy suspect it before the clinical diagnosis is made 1
• Population data indicate that seeking to avoid false-positive results by delaying diagnosis is harmful to parent and caregiver well-being 1