Summary

Cerebral palsy (CP), defined as a nonprogressive disorder of posture or movement due to a lesion in the developing brain, occurs annually in about 10 000 infants born in the U.S.[1] To help pediatricians assess a child with this common disorder, this review will highlight the latest findings on pathogenesis of CP, summarize the new recommendations for diagnostic testing, and discuss the prognostic implications of various types of brain injury responsible for CP.

Educational objectives

At the conclusion of this activity, participants will be able to:

• Describe the underlying causes of cerebral palsy
• Direct the initial assessment of a child with cerebral palsy
• Recognize when a referral to a pediatric neurologist is required in the evaluation and management of a child with cerebral palsy

CME credit

This is an article from The Child's Doctor, Fall 2004 issue. You may take the quiz for learning purposes, but credits are no longer valid.

Author disclosures

Dr. Epstein has no industry relationship to disclose and does not refer to products that are still investigational or not labeled for the use in discussion.

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Diagnosis

CP is usually recognized early in life when a child fails to reach motor milestones at the appropriate chronological age. Diagnosis is based on detailed history and physical examination, including a neurological evaluation.

Since CP is distinguished from degenerative brain disorders, medical history must establish that the child is not losing previously acquired function. However, some neurological disorders, due to slow progression of symptoms, may initially be mistaken for CP (eg, dopa-responsive dystonia, hereditary spastic paraplegia, ataxia telangiectasia). These conditions may be suggested by unusual complaints, a history of progressing deficits, characteristic abnormalities on neuroimaging studies, or a family history of childhood neurologic disorder with associated CP.

During examination, pediatricians should check developmental reflexes, muscle tone, deep tendon reflexes, and plantar responses. Attention should be paid to reflexes that are retained for abnormally long periods, which is common for children with CP. The Moro reflex, for example, tends to be seen beyond the usual 6 months in children with CP. However, children with CP may develop hand preference much earlier than usual (age 3).

It is also useful to classify the clinical type of CP, since this has implications regarding etiology and associated conditions, as discussed in more detail below. In one study, 44% of the CP population were spastic diplegic, 33% spastic hemiplegic, and 6% spastic quadriplegic. Even less common presentations include ataxic and dyskinetic CP. [2]

Etiology

The brain abnormality resulting in CP may have been caused by various antenatal, perinatal and postnatal events. In the past, the most common cause of CP in the term or near term infant was thought to be intrapartum hypoxic-ischemic injury, often called perinatal asphyxia. It is now known that hypoxia-ischemia is not the only cause of neonatal encephalopathy, and that CP is rarely caused by hypoxia-ischemia. Epidemiological studies have established that antenatal factors account for as much as 70% of acute neonatal encephalopathy. [3]

Furthermore, not all cases of neonatal encephalopathy result in CP. Mild encephalopathy is invariably associated with favorable prognosis, and normal outcome is seen in about 75%-80% infants with moderate encephalopathy. [4] All infants with severe encephalopathy stringently defined have a poor outcome. [4]

According to the essential criteria developed by the American College of Obstetricians and Gynecologists, [3] in order to attribute CP to intrapartum hypoxia, the child born at 34 or more weeks of gestation must have had the clinical signs of severe or moderate neonatal encephalopathy, defined as seizures, abnormal tone, poor feeding, and a depressed level of consciousness within the first 24 hours of life. Computed tomography (CT) scan and electroencephalogram (EEG) if obtained will be abnormal. In addition, evidence of a metabolic acidosis in fetal umbilical cord arterial blood obtained at delivery (pH< 7and base deficit >/ = 12 mmol/L) is needed, as well as exclusion of other identifiable etiologies such as trauma, coagulation disorders, infectious conditions, or genetic disorders. Finally, the only forms of CP attributable to acute hypoxic intrapartum events are spastic quadriplegic and, less commonly, the dyskinetic type.

Spastic quadriplegia, however, may result from causes other than intrapartum hypoxia. Also, purely dyskinetic or ataxic CP, especially with an associated learning difficulty, commonly has a genetic etiology and is rarely caused by intrapartum or peripartum asphyxia.

Spastic hemiplegia and spastic diplegia are almost always due to antepartum events, the latter occurring almost exclusively in preterm babies. [5] Generally, infants born very prematurely or with low birth weight are at higher risk for CP, compared to term or near-term infants.

CP with antenatal origins is often due to infections during pregnancy (eg, rubella, cytomegalovirus, toxoplasmosis), stroke, toxemia, or placental abruption. [6] Other antenatal factors associated with CP include intrauterine growth restrictions, multiple pregnancies, coagulation disorders, antepartum bleeding, congenital or genetic anomalies, and infertility treatments. [3] In addition to hypoxic-ischemic encephalopathy, other causes of CP with perinatal onset include kernicterus and trauma. [6] Postnatal causes of CP include brain infections (eg, bacterial meningitis, viral encephalitis), progressive hydrocephalus, or brain injury from car accidents, falls, or child abuse. [6]

Diagnostic testing

The role of diagnostic testing is to clarify the etiology and suggest the prognosis based on the type and severity of confirmed brain injury. In the recently published guidelines from the American Academy of Neurology and the Child Neurology Society, [6] neuroimaging is recommended as the initial diagnostic study in children with CP. (See images 1-4 below for examples of neuroimaging studies used as diagnostic tools in CP evaluation.) The guidelines do not recommend routine use of metabolic and genetic testing, coagulation studies, or EEG. However, since 70% of children with CP have associated conditions, [1] early screening is advised for potential cognitive delay, vision and hearing impairments, speech and language disorders, and swallowing disorders.

* Note that for all images the left side of the brain appears on the right side of the image.

Image 1: MRI axial T2 sequence of a 14-month-old girl with a right hemiparesis. There is an abnormal hyperintense signal in the white matter of the right hemisphere indicating an old (antepartum) infarct.

Image 2: MRI axial T1 sequence of a 14-month-old boy with microcephaly and delayed motor development. The MRI demonstrates enlarged ventricles and a large porencephalic cyst in the left frontal lobe with a thin rim of residual cortex. There is also thickened and simplified cortex (pachygyria) in the right frontal lobe.

Image 3: CT scan of an 18-month-old girl born prematurely who sustained an intraventricular hemorrhage. She has a left hemiparesis and a mild degree of spastic diparesis. The CT scan demonstrates enlargement of the right lateral ventricle.

Image 4: CT scan of a 5-month-old boy with a severe spastic quadriparesis and acquired microcephaly associated with an intrapartum hypoxic-ischemic injury. The scan shows marked diffuse atrophy and encephalomalacia with secondary enlargement of the ventricles and sulci.

MRI or CT

The AAN/CNS review of research concluded that magnetic resonance imaging (MRI) is preferable to CT, since MRI was abnormal in 89% of children with CP, compared to 77% of cases with abnormal CT findings. MRI also is more sensitive than CT in detecting periventricular leukomalacia, other perinatally acquired lesions, and subtle congenital anomalies of brain development, and is more useful in determining whether the brain injury was antenatal, perinatal, or postnatal. Periventricular white matter damage (eg, periventricular leukomalacia) is frequently found in children with CP who were preterm births. A child with CP who was a preterm birth and suffered severe cerebral hypoperfusion during early fetal life, however, will usually have injury that is mostly in the deep gray matter and brain stem nuclei. In term births, severe reduction to cerebral blood flow more commonly causes injury to subcortical white matter and cerebral cortex. [7]

Genetic and metabolic testing

Since the introduction of neuroimaging, congenital brain malformations have been discovered in some children with CP (12% on MRI and 7% on CT). [6] These malformations include lissencephaly, schizencephaly, and pachygyria, which have been associated with specific genetic disorders (eg, lissencephaly/Miller-Dieker syndrome/ chromosome 17p13.3, Zellweger syndrome). Also, some metabolic disorders may appear as CP. These disorders include glutaric aciduria (type 1), Lesch-Nyhan syndrome, 3­-methylglutaconic aciduria, pyruvate dehydrogenase deficiency, and female carriers of ornithine transcarbamylase deficiency. If a brain malformation is found in a child with CP, or if neuroimaging does not show a specific structural abnormality, genetic or metabolic testing is warranted.

Coagulopathies

Diagnostic testing for coagulation disorders should be considered only in children with spastic hemiplegic CP, since neuroimaging shows high incidence of unexplained cerebral infarction in these children. Coagulation disorders may include Factor V Leiden deficiency, the presence of anticardiolipin or antiphospholipid antibodies, and Protein C or S deficiency.

Epilepsy and EEG

Although epilepsy accompanies cerebral palsy in 45% of cases, [6] routine EEG is not useful during initial evaluation, since it does not help to determine the etiology of CP. An EEG is recommended only when epileptic features are present. Epilepsy is seen more often in children with spastic quadriplegia or hemiplegia, compared to children with other types of CP.

Children with CP and epilepsy are classified as having symptomatic epilepsy. Children with epilepsy associated with CP are more likely to have neonatal seizures and seizures within the first year of life, status epilepticus, and a need for polytherapy. These children are more likely to have partial seizures and are less likely to become seizure free. In children with CP and epilepsy, favorable factors associated with a seizure-free period of 1 year or more include normal intelligence, single seizure type, monotherapy, and spastic diplegia. [8]

Screening for other associated conditions

Screening for conditions commonly found in children with CP must be included in the initial evaluation. Cognitive delay occurs in 52% of children with CP, and it is more likely to be present if neuroimaging studies are abnormal than if they are normal or have minor abnormalities. [9] Also, type and etiology of CP are associated with specific disorders. For example, mental impairment tends be more severe in children with spastic quadriplegia than in children with spastic hemiplegia or diplegia. Visual problems, found in 28% of cases, are more likely in children whose CP was caused by periventricular leukomalacia. [6] Hearing impairment occurs in 12% of children with CP, and is more frequent when CP is related to very low birth weight, kernicterus, neonatal meningitis, or severe hypoxic-ischemic insults. [6]

Prognostic implications of neuroimaging findings

Neuroimaging is helpful in determining prognosis. Outcomes are less favorable in children with bilateral injury involving cortical and subcortical structures usually associated with a spastic quadriparetic type of CP. Neuroimaging findings of atrophy, abnormal gray matter configuration, and marked leukomalacia usually imply severe impairment. [10]

In very premature infants, selective vulnerability of the periventricular white matter to ischemic injury produces diplegic CP with greater motor deficit in the lower extremities compared to the upper extremities. In term infants, white matter lesions with internal capsule involvement are associated with abnormal motor outcome, whereas moderate white matter changes with normal internal capsule are correlated with normal motor function. [11]

Extensive bilateral cerebral and basal ganglia lesions, associated with spastic quadriplegia and the most adverse outcome, commonly signal epilepsy and severe cognitive, motor, visual and auditory impairments. [11] Mild basal ganglia lesions, however, are found in dyskinetic type of CP and indicate minor neuro-motor abnormalities and sometimes normal cognitive development. [11]

Children with focal ischemic injury (stroke) limited to 1 hemisphere will usually have a residual hemiparesis, but are likely to have normal or nearly normal cognitive function. The MRI will show loss of brain parenchyma and compensatory increase in the size of the ventricles and subarachnoid spaces on the involved side. Partial seizures with or without secondary generalization are also common with this type of injury.

Although neuroimaging studies help to assess prognosis for a child's CP, more substantial prognostic information must be derived by considering imaging data in combination with clinical evaluation.

Pediatric neurology consultation

In evaluation and management of a child with cerebral palsy, consultation with a pediatric neurologist should be considered when there are questions about accuracy of the diagnosis, to determine the underlying cause, or if there are unusual clinical features to suggest that the child may have a progressive rather than a static condition. A pediatric neurologist may also help to inform parents about initial evaluation, interpretation of neuroimaging studies, and prognosis. Severe cases can be referred to a pediatric neurologist for regular evaluations on annual or semiannual basis, and for coordination of therapy with physical, occupational and speech therapists, and with orthopedic specialists. Finally, a referral is needed when there are associated neurological problems, in particular seizures, which may be difficult to control.

Conclusion

CP is common and will be seen in most pediatric practices. There are multiple causes of CP and the pediatrician should not assume that minor events in the intrapartum period are responsible without careful consideration of the criteria for neonatal encephalopathy and a thorough investigation for other causes. There are medical-legal implications to casual comments or written notes regarding the etiology of CP even if these are not well founded. Neuroimaging, in particular MRI, is the most useful diagnostic tool for children with CP. Neurological consultation is most often justified to help establish the type of cerebral palsy and to discuss prognosis with the child's parents.

REFERENCES

[1.] Boyle CA, Yeargin-Allsopp M, Doernberg NS, et al. Prevalence of selected developmental disabilities in children 3-10 years of age: the Metropolitan Atlanta Developmental Disabilities Surveillance. MMWR 1996;45:1-14.

[2.] Hagberg B, Hagberg G, Beckung E, et al. Changing panorama of cerebral palsy in Sweden. VIII. Prevalence and origin in the birth year period 1991-94. Acta Paediatr 2001;90:271-277.

[3.] American College of Obstetricians and Gynecologists Task Force on Neonatal Encephalopathy and Cerebral Palsy. Neonatal Encephalopathy and Cerebral Palsy: Defining the Pathogenesis and Pathophysiology. Washington, DC: ACOG; 2003.

[4.] Volpe JJ. Neurology of the Inborn. 4th ed. Philadelphia, PA: WB Saunders; 2001.

[5.] Nelson KB, Grether JK. Potentially asphyxiating conditions and spastic cerebral palsy in infants of normal birth weight. Am J Obstet Gynecol 1998;179:507-513.

[6.] Ashwal S, Russman BS, Blasco PA, et al. Practice Parameter: Diagnostic assessment of the child with cerebral palsy: Report of the Quality Standards Subcommittee of the American Academy of Neurology and the Practice Committee of the Child Neurology Society. Neurology 2004;62(6):851-863.

[7.] Barkovich AJ, Hallam D. Neuroimaging in perinatal hypoxic ischemic injury. Ment Retard Dev Disabil Res Rev 1997;3:28-41.

[8.] Wallace SJ. Epilepsy in cerebral palsy. Dev Med Child Neurol 2001;43:713-717.

[ 9.] Schouman-Claeys E, Picard A, Lalande G, et al. Contribution of computed tomography in the aetiology and prognosis of cerebral palsy in children. Br J Radiol 1989;62:248-252.

[10.] Yokochi K, Hosoe A, Shimabukuro S, et al. Gross motor patterns in children with cerebral palsy and spastic diplegia. Pediatr Neurol 1990;6:245.

[11.] Mercuri E, Barnett AL. Neonatal brain MRI and motor outcome in school age children with neonatal encephalopathy: A review of personal experience. Neural Plasticity 2003;10(1-2):51-57.