What Causes Cerebral Palsy?

We do not know the cause of most cases of cerebral palsy. That is, we are unable
to determine what caused cerebral palsy in most children who have congenital
CP. We do know that the child who is at highest risk for developing CP is the
premature, very small baby who does not cry in the first five minutes after
delivery, who needs to be on a ventilator for over four weeks, and who has
bleeding in his brain.

Babies who have congenital malformations in systems
such as the heart, kidneys, or spine are also more likely to develop CP, probably
because they also have malformations in the brain. Seizures in a newborn also
increase the risk of CP. There is no combination of factors which always results
in an abnormally functioning individual. That is, even the small premature
infant has a better than 90 percent chance of not having cerebral palsy. There
are a surprising number of babies who have very stormy courses in the newborn
period and go on to do very well. In contrast, some infants who have rather
benign beginnings are eventually found to have severe mental retardation or
learning disabilities.

Many children with cerebral palsy have a congenital malformation of the brain,
meaning that the malformation existed at birth and was not caused by factors
occurring during the birthing process. Not all of these malformations can be
seen by the physician, even with today’s most sophisticated scans, but when
CP is recognized in a newborn, a congenital malformation is suspected. When
a diagnosis of CP is made, the mother and father often feel guilty and wonder
what they did to cause their child to have this disorder. While it is certainly
true that good prenatal care is an essential part of preventing congenital
problems, it must be stated that congenital problems, or “birth defects,” often
occur even when the mother has strictly followed her physician’s advice in
caring for herself and the developing infant.

Though the causes of “birth defects” are usually unknown, we do know that
the developing brain can be affected by several factors. When the fetus is exposed
to certain chemicals or infections through the expectant mother, for example.
The developing brain can be injured if the expectant mother suffers severe physical
trauma, the fetal brain can be injured, too, but this is rare. Finally, prematurity
and a low birth weight have been shown to be related to an increased incidence
of specific disorders. Many chemicals are known to adversely affect the developing
brain, alcohol being the most commonly used.

The term Fetal Alcohol Syndrome describes the long-term, multi-system effect
of alcohol on a child whose mother abused alcohol during the pregnancy. When
a fetus is exposed to large amounts of alcohol, several body systems, including
the neurological system will almost certainly suffer damage. Cigarette smoking
by the mother has been shown to decrease birth weight, and low birth weight
is associated with several disorders, including cerebral palsy. Severe malnutrition
in the mother can adversely affect brain growth in the fetus, and it, too, can
result in a low birth weight. The use of cocaine or crack by the expectant mother
is associated with blood vessel complications, and these complications affect
many organs as well as the central nervous system.

Cocaine use is increasing and thus becoming more prevalent as cause of brain
damage in infants. Most infants whose mothers used cocaine during pregnancy
develop mental retardation rather than cerebral palsy, however. Infections such
as rubella (German measles), toxoplasmosis, and cytomegalovirus (CMV), ( if
a woman has them during pregnancy), also may injure the brain of the fetus.
Rubella can be prevented by immunization, prior to becoming pregnant, and the
chances of becoming infected with toxoplasmosis can be minimized by not handling
the feces of cats and by avoiding raw or uncooked meat.

Congenital infection with human immunodeficiency virus (HIV, the virus that
causes AIDS) also causes brain damage in children, though it usually causes
mental retardation rather than CP. It is likely that many other infections in
the expectant mother injure the developing fetus, but they are not recognized
as causative factors because the woman who has the infection either does not
recognize the symptoms of infection or is symptom-free. Premature infants are
at a much higher risk for developing cerebral palsy than full-term babies, and
the risk increases as the birth weight decreases. Between 5 and 8 percent of
infants weighing less than 1500 grams (3 pounds) at birth develop cerebral palsy,
and infants weighing less than 1500 grams are 25 times more likely to develop
cerebral palsy than infants who are born at full term weighing more than 2500

Many premature infants suffer bleeding within the brain, called intraventricular
hemorrhages, intracranial hemorrhages. Again, the highest frequency of hemorrhages
is found in the babies with the lowest weight: the problem is rare in babies
who weigh more than 2000 grams (4 pounds). This bleeding may damage the part
of the brain that controls motor function and thereby lead to cerebral palsy.
If the hemorrhage results in destruction of normal brain tissue (a condition
called periventricular leukomalacia) and small cysts around the ventricles and
in the motor region of the brain, then that infant is more likely to have CP
than an infant with hemorrhages alone. Does prematurity “cause” cerebral palsy,
or do some infants who are born prematurely have abnormal brains from the beginning,
leading to their premature births? We do not know the answer to this question.

There are no specific events that, if they occur during pregnancy, delivery,
or infancy, will always occurring at birth or right after birth). This is apparently
why the incidence of CP in undeveloped and poverty stricken areas of the world,
where infant mortality is very high, is the same as in northern Europe, where
infant mortality is the lowest. It also explains why modern obstetrical care,
including monitoring and a high rate of Cesarian section, has lowered infant
mortality rates but not the incidence of cerebral palsy. One large study, for
example, has shown that more than 60 percent of all pregnancies have at least
one complication, and that most of these complications cause no problems. For
instance, 25 percent of all newborns have the umbilical cord wrapped around
their neck, and 16 percent passed meconium (had the first bowel movement) at
the time of birth.

These “birth events” and the development of CP have only a small correlation.
In other words, the chances of a child developing CP were nearly the same whether
the child was born with a cord wrapped around her neck or not. On the other
hand, newborns in this study who had very low Apgar scores (less than 3 at 20
minutes) had a risk 250 times greater than infants with normal Apgar scores
of developing cerebral palsy. An Apgar score at this level suggests that the
infant suffered severe asphyxia (lack of sufficient oxygen to the brain) during
birth. Half of the infants who suffered severe asphyxia during birth did not
develop cerebral palsy, however. When CP is diagnosed in childhood, it is often
discovered that the child suffered asphyxia at birth, but the asphyxia is usually
considered the symptom of an otherwise sick baby with a neurological problem,
and not the primary cause of CP. In two different large studies, only about
9 percent of children with CP were thought to have CP directly and exclusively
related to asphyxia at delivery. Ninety-one percent of the babies had other
inherent causes which led to prematurity or perinatal or neonatal problems (problems
In the nineteenth century, Dr. William John Little described cerebral palsy
and stated that the condition was due to birth injury in most cases. Cerebral
palsy is also known as Little’s disease and static encephalopathy, but the term
cerebral palsy is most widely used.

Dr. Sigmund Freud (who was a prominent neurologist before he founded the field
of psychiatry) also investigated the causes of cerebral palsy. Freud thought
that the condition was due to something which occurred before the child’s birth.
He argued that the problems seen at birth were often due to an abnormality present
in the baby before birth, rather than being caused by the birthing process.
This view of Freud’s was greatly ignored in the first half of this century,
but recent research has lent support to the idea that cerebral palsy is more
often a result of a congenital abnormality than to an injury sustained at birth.
Nevertheless, the birthing process can be traumatic for the infant, and injuries
occurring during birth do sometimes cause cerebral palsy. Modern prenatal care
and improved obstetric care have significantly reduced the incidence of birth
injury, but it is unlikely that it will ever be completely eliminated.

During infancy and early childhood, the child is completely dependent on others
for his or her safety and protection. Protecting the child from injury is one
of the most important responsibilities of the child’s caregivers. One such
injury is asphyxia, which can damage the brain in a variety of ways, and is
the number one cause of CP in this age group. The three most common causes
of asphyxia in the young child are: choking on foreign objects such as toys
and pieces of food (including peanuts, popcorn, and hot dogs); poisoning; and
near drowning. The brain may also be damaged when it is physically traumatized
as a result of a blow to the head. A child who falls or is involved in a motor
vehicle accident or is the victim of physical abuse may suffer irreparable
injury to the brain. One form of child abuse is the shaken baby syndrome, in
which the caretaker is trying to quiet the baby by shaking too vigorously,
causing the brain to strike repeatedly against the skull under high pressure.

Severe infections, especially meningitis or encephalitis, can also lead to
brain damage in this age group. Meningitis is inflammation of the meninges (
the covering of the brain and the spinal cord), usually caused by a bacterial
infection, and encephalitis is brain inflammation which may be caused by bacterial
or viral infections. Either of these infections can cause disabilities ranging
from hearing loss to CP to severe retardation.


Children with disabilities have many problems in common, especially problems
involving interactions with family members and society at large. The physical
and medical problems of children with disabilities vary widely, however. Some
of the problems caused by various disorders resemble those affecting children
with cerebral palsy, but on closer inspection the medical issues turn out to
be quite distinct. Children with spinal cord dysfunction, for example, face
medical problems such as insensate skin and bowel and bladder dysfunction, which
differ markedly from the medical problems faced by children with cerebral palsy.
Spinal cord dysfunction may be a result of spinal cord injury, spina bifida
(meningomyelocele), or a congenital spinal cord malformation. Another large
group of children who at time may look similar to those with cerebral palsy
are children with temporary motor problems resulting from closed head injuries,
seizures, drug overdoses, or some brain tumors. The medical issues for this
group of children are also different from the medical issues for children with
cerebral palsy, because these injuries can occur at any age

and the severity of the problems caused by these injuries changes over time.
We can also say that disorders that are primarily of muscle, nerve, and bone
are not cerebral palsy by definition. Such conditions include muscular dystrophy,
peripheral neuropathies such as Charcot-Marie- Tooth disease, and osteogenesis
imperfecta. All of these conditions are associated with specific medical problems.
Children with progressive neurologic disorders (including Rett’s syndrome, leukodystrophy,
and Tay-Sach’s disease) also have medical needs which are different from those
of children with cerebral palsy.

Some children with chromosomal anomalies (for example, trisomy 13 and 18)
or congenital disorders (hereditary spastic paraplegia, for example) may appear
similar to children with cerebral palsy; others, such as children with Down’s
syndrome, appear very different from children with cerebral palsy. Children
with these disorders have some problems in common with children who have cerebral
palsy; they also have problems that are unique for children with that specific

Many of the normal developmental milestones, such as reaching for toys (3-4
months), sitting (6-7 months), and walking (10-14 months), are based on motor
function. A physician may suspect cerebral palsy in a child whose development
of these skills is delayed. In making a diagnosis of cerebral palsy, the physician
takes into account the delay in developmental milestones as well as physical
findings that might include abnormal muscle tone, abnormal movements, abnormal
reflexes and persistent infantile reflexes. Making a definite diagnosis of
cerebral palsy is not always easy, especially before the child’s first birthday.
In fact, diagnosing cerebral palsy usually involves a period of waiting for
the definite and permanent appearance of specific motor problems.

Most children with cerebral palsy can be diagnosed by the age of 18 months,
but eighteen months is a long time for parents to wait for a diagnosis, and
this is understandably a difficult period for them. Making a diagnosis of cerebral
palsy is also difficult when, for example, a two-year- old has suffered a head
injury. The child may immediately appear to be severely injured, and three months
after the injury he may have symptoms that are typical of a child with cerebral
palsy. But one year after the injury such a child may be completely normal.
This child does not have cerebral palsy. Although he has a scar on his brain,
the scar is not permanently impairing his motor activities. After injury, waiting
and observing are necessary before the diagnosis can be made.

As noted above, in making a diagnosis of cerebral palsy the most meaningful
aspect of the examination is the physical evidence of abnormal motor function.
A diagnosis of cerebral palsy cannot be made on the basis of an x-ray or blood
test, though the physician may order such tests to exclude other neurologic
diseases (such as those mentioned above). Blood tests and chromosome analysis
are helpful in diagnosing hereditary conditions that may influence the parents’
future child-bearing decisions. When the tests indicate that a child’s condition
is something other than cerebral palsy and that the condition is inherited,
family members will benefit from genetic counselling. Cerebral palsy is not
a hereditary condition, however, and these tests will neither establish nor
rule out a diagnosis of CP.

Magnetic resonance imaging (MRI) and Computed Tomography (CT) scans are often
ordered when the physician suspects that the child has cerebral palsy. These
tests may provide evidence of hydrocephalus (an abnormal accumulation of fluid
in the cerebral ventricles), and they may be used to exclude other causes of
motor problems. These scans do not prove whether a child has a cerebral palsy;
nor do they predict how a specific child will function as she grows. Thus, children
with normal scans may have severe cerebral palsy, and children with clearly
abnormal scans occasionally appear totally normal or have only mild physical
evidence of cerebral palsy. As a group, though, children with cerebral palsy
do have brain scars, cysts, and other changes which show up on scans more frequently
than in normal children. Therefore, when a scar is seen on a CT scan of the
brain of a child whose physical examination suggests he may have cerebral palsy,
the scar is one more piece of evidence indicating that the child is likely to
have motor problems in the future.

Cerebral palsy may be classified by the type of movement problem (such as spastic
or athetoid cerebral palsy) or by the body parts involved (hemiplegia, diplegia,
and quadriplegia). Spasticity refers to the inability of a muscle to relax,
while athetosis refers to an inability to control the movement of a muscle.
Infants who at first are hypotonic wherein they are very floppy may later develop
spasticity. Hemiplegia is cerebral palsy that involves one arm and one leg
on the same side of the body, whereas with diplegia the primary involvement
is both legs. Quadriplegia refers to a pattern involving all four extremities
as well as trunk and neck muscles. Another frequently used classification is
ataxia, which refers to balance and coordination problems. The motor disability
of a child with CP varies greatly from one child to another; thus generalizations
about children with cerebral palsy can only have meaning within the context
of the subgroups described above. For this reason, subgroups will be used in
this book whenever treatment and outcome expectations are discussed. Most professionals
who care for children with cerebral palsy understand these diagnoses and use
them to communicate about a child’s condition.

As noted above, a useful method for making subdivisions is determined by which
parts of the body are involved. Although almost all children with cerebral palsy
can be classified as having hemiplegia, diplegia, or quadriplegia, there are
significant overlaps which have led to the use of additional terms, some of
which are very confusing. To avoid confusion, most of the discussion in his
book will be limited to the use of these three terms. Occasionally such terms
as paraplegia, double hemiplegia, triplegia, and pentaplegia may occasionally
be encountered by the reader; these classifications are also based on the parts
of the body involved. The dominant type of movement or muscle coordination problem
is the other method by which children are subdivided and classified to assist
in communicating about the problems of cerebral palsy. The component which seems
to be causing the most problem is often used as the categorizing term. For example,
the child with spastic diplegia has mostly spastic muscle problems, and most
of the involvement is in the legs, but the child may also have a smaller component
of athetosis and balance problems.

The child with athetoid quadriplegia, on the other hand, would have involvement
of both arms and legs, primarily with athetoid muscle problems, but such a child
often has some ataxia and spasticity as well. Generally a child with quadriplegia
is a child who is not walking independently. The reader may be familiar with
other terms used to define specific problems of movement or muscle function
terms such as: dystonia, tremor, ballismus, and rigidity. The words severe,
moderate, and mild are also often used in combination with both anatomic and
motor function classification terms (severe spastic diplegia, for example),
but these qualifying words do not have any specific meaning. They are subjective
words and their meaning varies depending on the person who is using them.


Cerebral palsy is the term used to describe the motor impairment resulting from
brain damage in the young child regardless of the cause of the damage or its
effect on the child. Impairment is the correct term to use to define a deviation
from normal, such as not being able to make a muscle move or not being able
to control an unwanted movement. Disability is the term used to define a restriction
in the ability to perform a normal activity of daily living which someone of
the same age is able to perform. For example, a three year old child who is
not able to walk has a disability because normal three year old can walk independently.

Handicap is the term used to describe a child or adult who, because of the
disability, is unable to achieve the normal role in society commensurate with
his age and socio-cultural milieu. As an example, a sixteen-year- old who is
unable to prepare his own meal or care for his own toileting or hygiene needs
is handicapped. On the other hand, a sixteen-year- old who can walk only with
the assistance of crutches but who attends a regular school and is fully independent
in activities of daily living is disabled but not handicapped. All disabled
people are impaired, and all handicapped people are disabled, but a person can
be impaired and not necessarily be disabled, and a person can be disabled without
being handicapped. In the past there has been a disturbing lack of awareness
and sensitivity, both among the general public and in literature, with respect
to the words used when people with disabilities are discussed. But an increasing
amount of attention is being paid to such language in our society along with
issues for education, employment, and public access for disabled individuals.

Certainly, the use of obviously pejorative expressions has always been inappropriate,
and the formerly accepted practice of referring individuals by their disability
(“the epileptic,” “the spastic,” “the retarded child”) is no longer acceptable.
While it may take years for our language to catch up with our changing views,
the current acceptable terminology stresses the individual person and then mentions
the disability that person has, therefore, we refer to a girl with spastic diplegia
or a boy with mental retardation. Clearly, this language acknowledges that there
is much more to this individual than his or her disability. Other terms that
have recently come into use represent an even more enlightened view. For example,
the child who is mentally challenged, rather than the child who is mentally
retarded. In this book, we have chosen to use language that reflects the appropriate
current societal goal of employing respectful terminology and that also reflects
our concern with presenting information in a way that can be understood by the
general reader. We fully realize that there may be newer, even better terms
to use, but we will not use them when there is a significant risk of introducing
confusion into our discussion.

The first questions usually asked by parents after they are told their child
has cerebral palsy are “What will my child be like?” and “Will he walk?” Predicting
what a young child with cerebral palsy will be like or what he will or will
not do (called the prognosis) is very difficult. Any predictions for an infant
under six months of age are little better than guesses, and even for children
younger than one year it is often very difficult to predict the pattern of
involvement. By the time the child is two years old, however, the physician
can determine whether the child has hemiplegia, diplegia, or quadriplegia.
Based on this involvement pattern, some predictions can be made. It is worth
saying again that children with cerebral palsy do not stop doing activities
once they have begun to do them.

Such a loss of skills, called regression, is not characteristic of cerebral
palsy. If regression occurs, it is necessary to look for a different cause of
the child’s problems. In order for a child to be able to walk, some major events
in motor control have to occur. A child must be able to hold up his head before
he can sit up on his own, and he must be able to sit independently before he
can walk on his own. It is generally assumed that if a child is not sitting
up by himself by age 4 or walking by age 8, he will never be an independent
walker. But a child who starts to walk at age 3 will certainly continue to walk
and will be walking when he is 13 years old unless he has a disorder other than

It is even more difficult to make early predictions of speaking ability or
mental ability than it is to predict motor function. Here, too, evaluation is
much more reliable after age 2, although a motor disability can make the evaluation
of intellectual function quite difficult. Sometimes “motor-free” tests which
can assess intellectual ability without, the person being tested, needing to
use his hands are administered by psychologists who have expertise in their
use. Overall, the intellectual ability of the person, far more than their physical
disability, will determine the person’s prognosis. In other words, mental retardation
is far more likely than cerebral palsy to impair a child’s ability to function.

Parents are naturally concerned when their newborn child has problems, and physicians
need to evaluate the child’s condition and prognosis as well as they can. For
example, evidence of a bleed in the child’s brain should be discussed with
parents, although the outcome of such a bleed cannot be predicted. As we’ve
discussed, the diagnosis of cerebral palsy cannot be made at birth and, most
assuredly, the extent and severity of involvement that an individual child
might eventually have is impossible to assess at birth. Many neonatologists,
aware of the interaction that generally occurs between the newborn and parents,
avoid discussing the child’s problems in detail because they want to permit
this interaction to take place.

The presumption of a bleak future for a child sometimes causes parents to
withdraw from the child and this can have a significant negative effect on the
child. Physicians usually communicate their concerns in terms of the child’s
symptoms, such as muscle problems, and prepare parents for the possibility of
neurologic damage. Clearly, it is part of the physician’s role to inform parents,
but the variability of outcome makes it virtually impossible for the physician
to predict the future, and so the physician must weigh the need to inform (and
the imprecision of information) against the need for the parents to have hope
for, and to become close to their child.

Many times when a child is a few years old and severely disabled, parents begin
to wonder whether treatment should have been less aggressive than it was. Given
the tremendous uncertainties in outcome, physicians and parents usually choose
to treat newborns and preserve life with the hope that the outcome will be
a good one. There are clearly exceptions, such as when the baby has a known
chromosomal defect (such as trisomy 18), where the poor prognosis is known
and where very aggressive treatment may not be used. However, in the majority
of cases the information regarding ultimate outcome is not available, and families
and physicians do the best they can with he limited information they have.
Often the prognosis is based on information from studies of a large number
of babies with a similar birth weight. The chance of an individual baby having
cerebral palsy or mental retardation(expressed as a percentage) is derived
from these studies. Nevertheless, it is impossible to know whether an individual
infant will fit into the 70-90 percent group that has a good outcome or the
10-30 percent group with a poor outcome.

The role of the physician is to gather as much information about the child’s
condition as possible and to convey this information to families along with
the best information available about chances for outcome. The role of the family
is to help in the decision-making process when there are decisions to be made
about further aggressive treatment, though ultimately it is the physician’s
responsibility to decide what should or should not be done. Most physicians
will take into consideration a family’s wishes, but physicians cannot give up
their legal and moral obligation to do what is best for their patient, nor can
a physician withhold treatment without the family’s permission. The problem
is trying to figure out what is best. At the time the decisions must be made
it is often very difficult to know what will ultimately be best. A decision
to treat aggressively usually involves the use of sophisticated equipment, although
availability of such technology does not mean that it must always be used, and
there are clearly times when it is more humane to withhold or withdraw aggressive
treatment. These are never easy decisions to make. Clergy, social workers, ethicist,
and other health care workers who have come to know the patient and family often
help in making a decision about what is best.

When it comes to expectations and questions of what the future holds for the
child with CP, it is important to maintain a combination of optimism and realism,
just as one would with any child. Suppose, for example, that the parent of
a non-disabled three year old has hopes and expectations that the child will
go to college and law school, enter politics, and eventually become President
of the United States. Some of these expectations are realistic and are likely
to be met, while others are extremely unlikely to occur to the point of being
clearly unrealistic. Regardless of these realistic and not realistic expectations,
however, the parent needs to care for the child as a three year old and not
as a college student or as a politician. It is equally important for the parent
of a child with cerebral palsy to understand the child’s present and future

That parent’s expectations are also probably a combination of realistic and
unrealistic goals for the child, but in time, with professional help, the parent
will develop a set of mostly realistic goals and it is to these goals that the
parent, child, and professional will dedicate their effort. Occasionally, difficulties
in communication arise when the parents, educators, and medical care providers
discuss present abilities. As stated in the Preface, a significant goal of this
book is to., improve this communication so that parents, educators, and medical
care providers can communicate their impressions to each other regarding a specific
child and in this way help the child function at his or her maximum ability.
An attempt to define future expectations is usually most important in the teenage
years and beyond, when function is better defined and the future looks more
clear to everyone involved.


Children with cerebral palsy have many problems, not all of them related to
the brain injury. Most of these complications are nevertheless neurological.
They include epilepsy, mental retardation, learning disabilities, and attention
deficit-hyperactivity disorder. These problems are discussed in chapter 3, as
are problems that occur less commonly, such as swallowing problems in children
with spastic quadriplegia. In the next chapter, we look at normal pediatric
development, to establish a basis with which to compare the development and
behavior of a child with cerebral palsy.

Children with cerebral palsy may also develop hip subluxation or have problems
with the gait.