cerebral palsy - ?· cerebral palsy lawrence t.taft, md* tobeclassified ascerebral palsy (cp),...

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FOCUS QUESTIONS1. In reaching a diagnosis, how

would you differentiate among

diplegic, hemiplegic, quadriplegic,and athetoid cerebra] palsy?

2. What are the most common causesof each of the four types of cere-

bral palsy?3. What risk factors are associated

with cerebral palsy?

4. What disabilities are most likely tobe associated with cerebral palsy,

and how are they managed?

*professor of Pediatrics, University of

Medicine & Dentistmy of New Jersey, RobertWood Johnson Medical School, New

Brunswick, NJ.

Pediatrics in Review Vol. 16 No. / / November 1995 411

ARTICLE

Cerebral PalsyLawrence T. Taft, MD*

To be classified as cerebral palsy(CP), there must be difficulty in neu-romotor control, a nonprogressivebrain lesion, and an injury to thebrain that occurred before it wasfully mature. The term cerebralpalsy should be used only if a staticencephalopathy exists. If there is anyquestion that a progressive centralnervous system disorder exists, theterm cerebral palsy should not beused diagnostically until the status of

the lesion is clarified.Although the primary abnormality

must be a motor deficit, often thereare many associated symptoms ofcerebral dysfunction present.

Incidence and Prevalence

The prevalence of CP has changedvery little over the past 40 years, inspite of many technological advances

that have decreased mortality in com-promised preterm and full-term in-fants. The prevalence rate has been

estimated to be between 2 and 5 per1000 live births. At 12 months of

age, the prevalence rate was esti-mated to be 5.2 per 1000, but at7 years of age, the rate was estimatedto be 2 per 1000 live births. Thisindicates that many children whoshowed signs or experienced symp-toms suggesting a motor disorder didnot have CP on follow-up.

The past 3 decades have seen anincreased survival rate of very small

preterm infants, resulting in a changein the percentage rates of the differ-ent clinical types of motor disabilitiesamong patients classified as having

CP. Because preterm infants are sus-ceptible to developing a spastic diple-gia, this type of disability now is themost common. Of children whose CPis identified at 7 years of age, onethird have a spastic diplegia.

There is a definite correlation be-

tween birthweight and/or gestational

age and the incidence of CP.

Etiology

The insult to the brain may occurprenatally, perinatally, or postnatally.

Until recently it was believed thathypoxic/ischemic incidents occurringpennatally caused the majority of CPcases. However, a collaborative pen-natal project started in 1960 that fol-lowed 454 000 pregnant women andthe outcome of their offspring re-vealed that adverse prenatal factorsmay be the primary culprits. An ab-normal fetal brain on fetal environ-

ment may make the infant more vul-nerable for being born prematurelyor, if born full-term, may place him

on hen at risk for cardiorespinatoryproblems in the neonatal period.

In more than 50% of the patientswho have CP, an etiology may not be

evident, even after having obtained acomprehensive history for knownhigh-risk factors and a genetic his-

tory; having performed a completephysical and neurological examina-

tions; and having evaluated meta-bolic, chromosomal, and neunoimag-ing studies. Although prematurity is

the most common antecedent of CP,

the majority of infants who developthis disorder have had full gestationalterms. This paradox is explained bythere being seven to ten times more

full-term than preterm babies born.The lower the birthweight, the

higher the incidence of CP. However,even for very low-birthweight infants(

NEUROLOGYCerebral Palsy #{149}

TABLE 1. Timing of Pathogenetic Periods in Cerebral Palsy*

TERM BIRThS PRETERM BIRTHS

N=457(%) N=224(%)

Obvious prenatal cause or risk 24 6

factor

Combined prenatal and perinatal 20 23

factors

Purely peninatal factors 19 51

No identifiable risk factors 30 17

Obvious postnatal cause 8 2

*Adapfed from Hagberg B and Hagberg (3 (210, pp 116-134)

4/2 Pediatrics in Review Vol. /6 No. / / November 1995

Classification

Classification of the cerebral palsiesstill is based on the type of motor

disorder, not on etiology or pathol-ogy. Although the available neuro-imaging techniques may help in de-

fining the anatomic deficit better,they still will not reveal any pathol-ogy in the majority of children whohave CP. The clinical classification isbased on the extremities involved, the

type of tone abnormalities, and thecharacteristics of the involuntarymovements. One problem in using

the type of motor dysfunction forclinical classification is that the neu-rologic picture may change as theinfant grows older. Therefore, theexact type of motor deficit may notbe clarified until 2 to 3 years of age.

An added difficulty is that 20% to30% of infants who appear to fit thecriteria for the diagnosis of CP at1 year of age will not show any man-ifestations of a motor deficit by7 years of age. Pediatricians must becautious in prognosticating whetheran infant will or will not have CP orin offering a judgment as to futurecognitive abilities.

Clinical Characteristics

Table 2 offers a clinical classificationof cerebral palsy. Spastic diplegiaencompasses the largest number of

CP patients. In the past decade, thenumber of patients who have spasticdiplegia have, relatively speaking,increased in numbers, concomitant

with the increased survival rates ofpreterm infants.

Because the insults to the brain

that produce CP often result in dif-

fuse pathology, the mixed types ofCP are not uncommon. Those clini-cians who appraise movement disor-dens carefully find that more than10% are of the mixed variety. Priorto the use of immunoglobulins toprevent blood incompatibility from

developing in pregnant women, bil-irubin encephalopathy with resultingkernicterus and athetosis occurred ata higher percentage than shown inTable 2. Now the most commoncause of the athetoid-dystonic type ofCP is hypoxic-ischemic injury to thebasic ganglia.

Ataxic-spastic CP and spastic CPfrequently have similar antecedents.Hydrocephalus often is present inataxic-spastic disorders. Genetic fac-tors have been implicated in the pureataxic CP. Also, it is necessary to beaware that when ataxia is the primarymotor disorder, one should not imme-diately conclude that the diagnosis isCP. Ataxia is a relatively uncommontype of CP, but it is not uncommonas a manifestation of a progressive

neurometabolic encephalopathy. Thechild who has nonprogressive ataxicCP frequently is mentally retarded.

Many children who have insults totheir motor systems at birth will showtransient hypotonia that develops into

increased tone of the spastic or rigidtype. A few will remain hypotonicthroughout life. These children who

have atonic CP have severe motorand intellectual disabilities.

Clinical Approach toDiagnosis

Any infant whose motor developmenthas been delayed must be considered

suspect for having CP. Diagnosis isvery difficult before 6 months of age,

primarily because abnormalities in

tone or reflexes or involuntary move-

ments rarely manifest during early

infancy. The primary reason for thisis that much of the movement ob-served in infants younger than a few

months of age is of reflex origin and

not under voluntary motor cortical

control. It is only with maturation ofthe cortex that the clinical picture of

CP emerges more clearly. There of-ten is additional diagnostic uncer-

tainty after an acute peninatal insultto the brain. Tone and reflex abnor-

malities may be noted immediatelyand falsely indicate permanent dam-

age to the central nervous systemmotor system. However, the tone

and reflex changes may prove to betransient phenomena; after 2 to

12 months, these signs of CP

disappear.

Delay in achieving motor mile-

stones at an appropriate age is com-mon for children who are retarded

but who do not have CP. Adding to

the diagnostic dilemma is that manyof these children present with hypo-

tonia. One should be much more

highly suspicious of the presence ofCP if there is a motor delay but evi-

dence of normal cognitive develop-ment. However, that is not to say that

children who have CP cannot be re-

tarded; more than 50% of them are.When assessing a child who has a

motor delay, it is necessary to decidewhere the pathology exists anatomi-

cally: centrally (eg, brain) or peniph-erally (eg, spinal cord, anterior horn

cell, peripheral nerve, myoneuraljunction, or muscle). If the brain is

the site of the pathology. the child isconsidered to have CP.

It also is important to determine ifthe motor delay is a manifestation ofa progressive central nervous systemdisorder. Clues to a progressive dis-order are: I) regression; 2) normaldevelopment for a period of time,then a slowing; 3) consanguinity;

4) congenital skeletal anomalies suchas pes cavus or scoliosis; and 5) neu-rocutaneous stigmata. In certain pro-gressive diseases, the evidence ofregression may not occur until verylate in the course; at the early onsetof the disorder, only a delay inachievement of motor milestones

TABLE 2. Clinical Classification of Cerebral Palsy

TYPE FREQUENCY %

Spastic 70-80Hemiparesis (monoparesis)*Diplegia

Quadriparesis (double hemiplegia)