Cerebral Palsy

Cerebral palsy (CP) refers to a group of conditions resulting in motor impairment affecting tone and posture and limiting physical activity. Cerebral palsy is the most common cause of childhood disability. It is caused by a nonprogressive CNS injury to the fetal or infant brain. It is classified according to muscle tone, its distribution, and the presumed time of injury (spastic diplegia is the most common), and it is present in around 3 per 1,000 live births. Diagnosis is made by a detailed history and physical exam with an MRI scan confirming CNS insult. Interventions are multidisciplinary and prognosis depends on the degree of disability.

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Overview

Definition

Cerebral palsy (CP) is a syndrome of permanent motor impairment (posture and movement) that results from nonprogressive lesions to the developing brain.

Epidemiology

  • 2.0–3.5 per 1,000 live births
  • Boy-to-girl ratio of 1.4:1
  • Prenatal events cause the majority of cases.
  • Prevalence is inversely proportional to gestational age and birth weight:
    • Prevalence is higher in preterm children.
    • Infants < 28 weeks at highest risk
    • Infants < 1,500 grams have 5%–15% risk.
  • The most common form is spastic diplegia (35%), a form of paralysis that affects symmetrical body parts (i.e., both legs or both arms).
  • Risk factors for CP:
    • Prematurity
    • Placental abnormalities
    • Major and minor birth defects
    • Meconium aspiration
    • Emergency cesarean section
    • Birth asphyxia
    • Neonatal seizures
    • Respiratory distress syndrome
    • Intrauterine and neonatal infections
    • Multiple-gestation births (twins, triplets, etc.)
    • Intrauterine growth restriction/low birth weight
    • Maternal substance abuse
    • Preeclampsia
    • Perinatal hypoglycemia
    • Genetic susceptibility

Etiology

  • CNS injury of many types can lead to CP.
  • CP is nonprogressive.
  • Can occur in any of the following developmental periods:
    • Prenatal:
      • Congenital brain malformations
      • Intrauterine infections
      • Intrauterine stroke
      • Chromosomal abnormalities
    • Perinatal:
      • Hypoxic-ischemic insults
      • CNS infections
      • Stroke
      • Kernicterus
    • Postnatal: 
      • Head trauma
      • CNS infections
      • Stroke
      • Anoxic insults
      • May be accompanied by:
        • Sensory, cognitive, communication, and behavioral disturbances
        • Epilepsy
        • Musculoskeletal impairment

Classification

  • According to muscle tone:
    • Spastic (hypertonic)
    • Flaccid (hypotonic)
    • Ataxic
    • Dystonic (athetoid)
    • Mixed
  • According to distribution:
    • Diplegia (paralysis of both legs or both arms)
    • Hemiplegia (1 side of the body is affected)
    • Quadriplegia (all extremities are affected)
  • According to presumed time of injury:
    • Prepartum
    • Intrapartum
    • Postneonatal

Pathophysiology

The ultimate cause of CP is injury to a child’s CNS during its embryological or perinatal development. The pathophysiology of this insult varies based on its etiology.

Table: CP subtypes, etiologies, and MRI findings
CP subtype Etiologies MRI findings
Hemiplegia (25%)
  • Thrombophilic disorders
  • Infection
  • Genetic/developmental
  • Periventricular hemorrhagic infarction
  • Stroke: in utero or neonatal
  • Focal infarct or cortical, subcortical damage
  • Cortical malformations
Spastic quadriplegia (20%)
  • Ischemia, infection
  • Endocrine/metabolic, genetic/developmental
  • Periventricular leukomalacia
  • Multicystic encephalomalacia
  • Cortical malformations
Spastic diplegia (35%)
  • Prematurity
  • Ischemia
  • Infection
  • Endocrine/metabolic (e.g., thyroid)
  • Periventricular leukomalacia
  • Periventricular cysts or scars in white matter, ventricles enlarged, squared-off posterior ventricles
Extrapyramidal (athetoid, dyskinetic) (15%)
  • Asphyxia
  • Kernicterus
  • Mitochondrial
  • Genetic/metabolic
  • Asphyxia: symmetric scars in putamen and thalamus
  • Kernicterus: scars in globus pallidus, hippocampus
  • Mitochondrial: scarring of globus pallidus, caudate, putamen, brainstem
  • No lesions: dopa-responsive dystonia

Clinical Presentation

History

  • Perinatal:
    • Preterm birth 
    • Low birth weight
    • Complications during pregnancy
    • Infections or exposure to infections during pregnancy
  • Developmental/cognitive:
    • Cognitive impairment (seen in approximately 50%): degree of disability correlates with severity of motor handicap
    • Developmental delay: delay in gross motor milestones (most commonly, not sitting up by 8 months, not walking by 16 months)
    • Behavioral abnormalities: 
      • Excessive irritability or docility
      • Autism spectrum disorder
      • Obsessive compulsive behavior 
      • ADHD
  • Neurological:
    • Disability is static (progressive CNS lesions must be excluded).
    • Visual and/or hearing impairment
    • 35% have a visual problem.
    • Delay in disappearance of primitive reflexes
    • Epilepsy
    • Chronic pain
    • Sleep dysfunction 
  • Pulmonary:
    • Frequent lung infections (aspiration pneumonia)
    • Restrictive lung disease due to poor tone and scoliosis
  • Gastrointestinal:
    • Feeding intolerance (often leads to failure to grow)
    • Chronic constipation
    • Gastroesophageal reflux
  • Urological: 
    • Voiding difficulty due to spasticity or hypotonia of bladder muscles
    • Frequent urinary tract infections (UTIs)
  • Orthopedic:
    • Frequent fractures due to osteopenia
    • Contractures
    • Dislocations
    • Hip dysplasia 

Physical examination

Neurological:

  • Spasticity (scissoring of the legs)
  • Ataxia
  • Dystonia
  • Choreoathetosis (movement disorder causing involuntary twitching or writhing)
  • Diplegic gait in cases with a diplegic distribution
  • Early sign of spastic diplegia, dragging legs when crawling (e.g., “commando crawl”)
  • Decreased spontaneous movements on the affected side
  • Feet in a position of equinovarus:
    • Also known as clubfoot
    • Hindfoot in varus, a forefoot that is adducted, and an ankle in equinus
Photograph of a child with spastic diplegia

Photograph of a child with spastic diplegia:
Notice the scissoring of the legs, a key finding in the spastic diplegic form of cerebral palsy (CP).

Image: “Practical diagnosis- the use of symptoms in the diagnosis of disease (1899) (14785191513)” by H.A. Hare. License: Public Domain, cropped and edited by Lecturio.

Diagnosis

  • History and clinical findings are sufficient for initial diagnosis.
  • Further investigation to define subtype/severity and comorbid conditions:
    • MRI to determine:
      • Location and extent of structural lesions/congenital malformations
      • Presence of spinal cord pathology 
    • Hearing and visual function
    • Genetic evaluation in patients with: 
      • Congenital malformations (chromosomes)
      • Suspected metabolic disorders (e.g., amino acids, organic acids, magnetic resonance (MR) spectroscopy)
Different types of structural brain abnormalities in cerebral palsy

Different types of structural brain abnormalities in cerebral palsy (CP):
All images are axial T2-weighted MRI scans. Each image is subtitled by its presumed etiology and timing during gestation.
A: a child with lissencephaly showing cortical thickening and agyria
B: a child with congenital cytomegalovirus infection showing an overfolded cortex (polymicrogyria), thin white matter, and dilated lateral ventricles
C: an ex-premature child showing cystic white matter injury (arrows) consistent with periventricular leukomalacia
D: a child who suffered a hemorrhagic stroke in the newborn period. There is cortical and white matter loss in the right frontal and parietal lobes (arrowheads) consistent with previous ischemia.

Image: “Examples of different types of structural brain abnormalities in cerebral palsy” by Boyd, R.N., et al. License: CC BY 2.0
Table: Gross motor function classification system (GMFCS)
GMFCS level Characteristics
I
  • Is able to walk over more challenging terrain, and climb stairs without using hands for support
  • Is able to run and jump
  • Speed, balance, and coordination may be decreased
II
  • Is able to climb stairs using railing
  • Difficulty navigating challenging terrain (e.g., uneven surfaces, inclines, and crowds)
  • Is mostly unable to run or jump
III
  • Has physical impairments limiting purposeful movement
  • Struggles to maintain fixed head and neck position even only against gravity
  • Is impaired in all areas of motor function
  • Cannot sit or stand independently, even with adaptive equipment
  • Walks with powered mobility aids only
IV
  • Cannot walk even with assistive devices
  • Requires wheelchairs for ambulation, may control power wheelchair
  • Can perform standing transfers, with or without assistance
V
  • Is able to walk with assistive mobility on flat surfaces both indoors and outdoors
  • May be able to climb stairs using a railing
  • May ambulate with manual wheelchair, but requires help over long distances or uneven surfaces

Management

There is no curative treatment at this time. Management focuses on improving symptoms and increasing function while addressing comorbidities. Early multidisciplinary intervention improves patient outcomes.

  • Physical and occupational therapy: 
    • Stretching exercises as early as possible (contracture prevention)
    • Adaptive equipment (e.g., walkers, poles)
    • Individualized evaluation/intervention for educational needs
  • Medical therapy:
    • Aimed at the treatment of:
      • Pain
      • Seizures
      • Spasticity
      • Sialorrhea
      • Behavioral disorders
    • Valium (diazepam) and other benzodiazepines 
    • Dantrolene
    • Baclofen
    • Anticholinergics (e.g., atropine)
    • Botulinum toxin (Botox) injections in spastic areas
  • Surgical therapy:
    • In cases of marked spasticity
    • Surgical soft-tissue procedures (e.g., tenotomy, the surgical cutting of a tendon)
  • Prevention:
    • Proper prenatal care and screening 
    • Administration of magnesium sulfate in cases of preterm labor before 32 weeks’ gestation
    • Genetic counseling for future offspring in select situations
  • Prognosis:
    • Dependent on the degree of motor, cognitive, and sensory deficit
    • Most patients survive into adulthood.
    • Life expectancy has improved significantly in the last 10–20 years.
    • Most common cause of early death is a respiratory failure as a result of aspiration pneumonia.

Clinical Relevance

The following conditions are etiological and/or risk factors for CP:

  • Neonatal respiratory distress syndrome: a syndrome of respiratory distress caused by lack of pulmonary surfactant in the preterm infant. The syndrome is a known risk factor for the development of intraventricular hemorrhage and periventricular leukomalacia, lesions frequently associated with CP.
  • Preterm delivery: delivery of the fetus before the pregnancy reaches 37 weeks’ gestation. Etiology of preterm delivery is multifactorial, including maternal and fetal factors, some of which are treatable/preventable, while others are not. Preterm birth has been identified as a major risk factor for the development of CP.
  • Gestational infections (chorioamnionitis, congenital TORCH infections): chorioamnionitis (the inflammation of the chorion and amnios) and fetal infection by TORCH (Toxoplasmosis, Other agents, Rubella, Cytomegalovirus, and Herpes simplex) microorganisms are well-known risk factors for CP. Infection can cause direct CNS injury or complications with the delivery/perinatal course, or induce premature labor.
  • Meningitis: an inflammation of the meninges, usually caused by an infectious pathogen. Cerebral palsy is among the neurological sequelae that can develop in children under 5 of age who undergo the CNS inflammation seen in meningitis.
  • Hyperbilirubinemia: elevated bilirubin levels during the neonatal period (first 28 days of life). Hyperbilirubinemia and its neurological complications (bilirubin-induced neurological dysfunction (BIND)) are risk factors for the development of CP.
  • Preeclampsia: a gestational disorder featuring the elevation of maternal blood pressure above 140/90 mm Hg, seen in association with proteinuria. Preeclampsia can lead to early delivery and has a strong association with CP.
  • Stroke: broadly understood as a hemorrhagic or ischemic abnormality in blood flow to brain tissue. A stroke can cause CP if it occurs in the prenatal or postnatal periods.

References

  1. Colver, A, & Pharoah, POD. (2014). Cerebral palsy. The Lancet. 383(9924), 1240–1249. https://doi.org/10.1016/S0140-6736(13)61835-8
  2. Johnston, MV. (2020). Encephalopathies. In Kliegman R.M., et al. (Eds.), Nelson textbook of pediatrics. pp. 3168–3186.e1 https://www.clinicalkey.com/#!/content/3-s2.0-B9780323529501006167
  3. Yin, R, Reddihough, D, Ditchfield, M, & Collins, K. (2000). Magnetic resonance imaging findings in cerebral palsy. Journal of Paediatrics and Child Health. 36(2), 139–144. https://doi.org/10.1046/j.1440-1754.2000.00484.x
  4. Thygesen, SK, Olsen, M, Østergaard, JR, & Sørensen, HT. (2016). Respiratory distress syndrome in moderately late and late preterm infants and risk of cerebral palsy: A population-based cohort study. BMJ Open. 6(10), e011643. https://doi.org/10.1136/bmjopen-2016-011643
  5. Demeši Drljan, Č, et al. (2016). Cerebral palsy in preterm infants. Vojnosanitetski Pregled. 73(4), 343–348. https://doi.org/10.2298/VSP140321019D
  6. Wu, YW, et al. (2015). Risk for cerebral palsy in infants with total serum bilirubin levels at or above the exchange transfusion threshold: A population-based study. JAMA pediatrics. 169(3), 239–246. https://doi.org/10.1001/jamapediatrics.2014.3036
  7. Hanna, JN, & Wild, BE. (1991). Bacterial meningitis in children under five years of age in Western Australia. The Medical Journal of Australia, 155(3), 160–164. https://pubmed.ncbi.nlm.nih.gov/1875809/
  8. Strand, KM, et al. (2013). Mediators of the association between pre-eclampsia and cerebral palsy: A population-based cohort study. BMJ (Clinical Research Ed.). 347, f4089. https://doi.org/10.1136/bmj.f4089
  9. Hadjipanayis, A, Hadjichristodoulou, C, & Youroukos, S. (1997). Epilepsy in patients with cerebral palsy. Developmental Medicine and Child Neurology. 39(10), 659–663. https://doi.org/10.1111/j.1469-8749.1997.tb07359.x
  10. Oskoui, M, et al. (2013). An update on the prevalence of cerebral palsy: a systematic review and meta-analysis. Dev Med Child Neurol. 55(6), 509–519. https://pubmed.ncbi.nlm.nih.gov/23346889/
  11. Van Eyk, CL, et al. (2018). The emerging genetic landscape of cerebral palsy. Handb Clin Neurol. 147, 331–342. https://pubmed.ncbi.nlm.nih.gov/29325622/
  12. McMichael, G, et al. (2015). Whole-exome sequencing points to considerable genetic heterogeneity of cerebral palsy. Mol Psychiatry. 20(2), 176–182. https://pubmed.ncbi.nlm.nih.gov/25666757/
  13. MacLennan, AH, et al. (2015). Cerebral palsy: Causes, pathways, and the role of genetic variants. Am J Obstet Gynecol. 213(6), 779–788. https://pubmed.ncbi.nlm.nih.gov/26003063/
  14. Nelson, KB. (2008). Causative factors in cerebral palsy. 51(4), 749–762. https://pubmed.ncbi.nlm.nih.gov/18981800/
  15. Morris, C, et al. (2007). The definition and classification of cerebral palsy. Dev Med Child Neurol. 49(s109), 1–44. https://pubmed.ncbi.nlm.nih.gov/17371509/

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