Common Questions about CP
Page 7 of 7
Cerebral palsy is not one disease with a
single cause, like chicken pox or measles. It is a group of disorders that are
related but have different causes. When physicians try to uncover the cause of
cerebral palsy in an individual child, they look at the form of cerebral palsy,
the mother's and child's medical history, and onset of the disorder.
About 10 to 20 percent of children who have cerebral palsy acquire the disorder
after birth. Acquired cerebral palsy results from brain damage in the first few
months or years of life and often follows brain infections, such as bacterial
meningitis or viral encephalitis, or results from head injury--most often from a
motor vehicle accident, a fall, or child abuse.
Congenital cerebral palsy, on the other hand, is present at birth, although it
may not be detected for several months. In most cases, the cause of congenital
cerebral palsy in unknown. Thanks to research, however, scientists have
pinpointed some specific events during pregnancy or around the time of birth
that can damage motor centers in the developing brain. Some of these causes of
congenital cerebral palsy include
What Are The Risk Factors?
Research scientists have examined thousands of expectant mothers, followed them through childbirth, and monitored their children's early neurological development. As a result, they have uncovered certain characteristics, called risk factors, that increase the possibility that a child will later be diagnosed with cerebral palsy.
Infections during pregnancy. German measles, or rubella, is caused by a virus that can infect pregnant women and, therefore, the fetus in the uterus, to cause damage to the developing nervous system. Other infections that can cause brain injury in the developing fetus include cytomegalovirus and toxoplasmosis.
Jaundice in the infant. Bile pigments, compounds that are normally found in small amounts in the blood stream, are produced when blood cells are destroyed. When many blood cells are destroyed in a short time, as in the condition called Rh incompatibility, the yellow-colored pigments can build up and cause jaundice. Severe, untreated jaundice can damage brain cells.Perinatal asphyxia. During labor and delivery, a shortage of oxygen in the blood, reduced brain blood flow, or both can impair the supply of oxygen to the newborn's brain, causing the condition known as perinatal asphyxia. When asphyxia is severe enough to put the newborn at risk for a long-term brain damage, it immediately causes problems with brain functions (as in moderate to severe hypoxic-ischemic encephalopathy). Asphyxia this severe is very uncommon, is always linked to dysfunction of other body organs, and is often accompanied by seizures.
Rh incompatibility. In this blood condition, the mother's body produces immune cells called antibodies that destroy the fetus's blood cells, leading to a form of jaundice in the newborn.
Stroke/interacranial hemorrhage. Bleeding in the brain (intracranial hemorrhage) has several causes--including broken blood vessels in the brain, clogged blood vessels, or abnormal blood cells--and is one form of stroke. Newborn respiratory distress, a breathing disorder that is particularly common in premature infants, is one cause. Although strokes are better known for their effects on older adults, they can also occur in the fetus during pregnancy or the newborn around the time of birth, damaging brain tissue and causing neurological problems. Ongoing research is testing potential treatments that may one day help prevent stroke in fetuses and newborns.
Breech presentation. Babies with cerebral palsy are more likely to present feet first, instead of head first, at the beginning of labor.
Complicated labor and delivery. Vascular or respiratory problems of the baby during labor and delivery may sometimes be the first sign that a baby has suffered brain damage or that a baby's brain has not developed normally during the pregnancy. Such complications can cause permanent brain damage.
Inborn malformations outside the nervous system. Babies with physical birth defects--including faulty formation of the spinal bones, hernia (a protrusion of organs through an abnormal opening inside the body) in the groin area, or an abnormally small jaw bone--are at an increased risk for cerebral palsy.
Low Apgar score. The Apgar score (named for anesthesiologist Virginia Apgar) is a numbered rating that reflects a newborn's condition. To determine an Apgar score, doctors periodically check the baby's heart rate, breathing, muscle tone, reflexes, and skin color in the first minutes after birth. They then assign points; the higher the score, the more normal the baby's condition. A low score at 10-20 minutes after delivery is often considered an important sign of potential problems.
Low birthweight and premature birth. The risk of cerebral palsy is higher among babies who weigh less than 2500 grams (5 lbs., 7 1/2 oz.) at birth and among babies who are born less than 37 weeks into pregnancy. This risk increases as birth weight falls.
Multiple births. Twins, triplets, and other multiple births are linked to an increased risk of cerebral palsy.
Nervous system malformations. Some babies born with cerebral palsy have visible signs of nervous system malformation, such as an abnormally small head (microcephaly). This suggests that problems occurred in the development of the nervous system while the baby was in the womb.
Maternal bleeding or severe proteinuria late in pregnancy. Vaginal bleeding during the sixth to ninth months of pregnancy and severe proteinuria (the presence of excess proteins in the urine) are linked to a higher risk of having a baby with cerebral palsy.
Maternal hyperthyroidism, mental retardation, or seizures. Mothers with any of these conditions are slightly more likely to have a child with cerebral palsy.
Seizures in the newborn. An infant who has seizures faces a higher risk of being diagnosed, later in childhood, with cerebral palsy.
Knowing these warning signs helps doctors keep a close eye on children who face a higher risk for long-term problems in the nervous system. However, parents should not become too alarmed if their child has one or more of these factors. Most such children do not have and do not develop cerebral palsy.
In addition, it is always good to work toward a healthy pregnancy through regular prenatal care and good nutrition and by eliminating smoking, alcohol consumption, and drug abuse. Despite the best efforts of parents and physicians, however, children will still be born with cerebral palsy. Since in most cases the cause of cerebral palsy is unknown, little can currently be done to prevent it. As investigators learn more about the cause of cerebral palsy through basic and clinical research, doctors and parents will be better equipped to help prevent this disorder.
In the past, physicians and scientists attributed most cases of cerebral palsy to asphyxia or other complications during birth if they could not identify another cause. However, extensive research by the National Institute of Neurological Disorders and Stroke (NINDS) scientists and others has shown that very few babies who experience asphyxia during birth develop encephalopathy after birth. Research also shows that most babies who experience asphyxia do not grow up to have cerebral palsy or other neurological disorders. In fact, current evidence suggests that cerebral palsy is associated with asphyxia and other birth complications in no more than 10 percent of cases other factors.
What Are The Early Signs Of Cerebral Palsy?
Early signs of cerebral palsy usually appear before 3 years of age, and parents
are often the first to suspect that their infant is not developing motor skills
normally. Infants with cerebral palsy are frequently slow to reach developmental
milestones, such as learning to roll over, sit, crawl, or walk. This is
sometimes called developmental delay.
Some affected children have abnormal muscle tone. Decreased muscle tone is
called hypotonia; the baby may seem flaccid and relaxed, even floppy. Increased
muscle tone is called hypertonia, and the baby may seem stiff or rigid. In some
cases, the baby has an early period of hypotonia that progresses to hypertonia
after the first 2 to 3 months of life. Affected children may also have unusual
posture or favor one side of their body.
Parents who are concerned about their baby's development for any reason should
contact their physician, who can help distinguish normal variation in
development from a developmental disorder.
How Is Cerebral Palsy Diagnosed?
Doctors diagnose cerebral palsy by testing an infant's motor skills and looking
carefully at the infant's medical history. In addition to checking for those
symptoms described above--slow development, abnormal muscle tone, and unusual
posture--a physician also tests the infant's reflexes and looks for early
development of hand preference.
Reflexes are the movements that the body makes automatically in response to a
specific cue. For example, if a newborn baby is held on its back and tilted so
the legs are above its head, the baby will automatically extend its arms in a
gesture, called the Moro reflex, that looks like an embrace. Babies normally
lose this reflex after they reach 6 months, but those with cerebral palsy may
retain it for abnormally long periods. This is just one of several reflexes that
a physician can check.
Doctors can also look for hand preference--a tendency to use either the right or
left hand more often. When the doctor holds an object in front and to the side
of the infant, an infant with hand preference will use the favored hand to reach
for the object, even when it is held closer to the opposite hand. But infants
with spastic hemiplegia, in particular, may develop a preference much earlier,
since the hand on the unaffected side of their body is stronger and more useful.
The next step in diagnosing cerebral palsy is to rule out other disorders that
can cause movement problems. Most important, doctors must determine that the
child's condition is not getting worse. Although its symptoms may change over
time, cerebral palsy by definition is not progressive. If a child is
continuously losing motor skills, the problem is probably due to other
causes--including genetic diseases, muscle diseases, disorders of metabolism, or
tumors in the nervous system. The child's medical history, special diagnostic
tests, and, in some cases, repeated check-ups can help confirm that other
disorders are not the cause.
The doctor may also order specialized tests to learn more about the possible
cause of cerebral palsy. One such test is computed tomography, or CT, a
sophisticated imaging technique that uses x-rays and a computer to create an
anatomical picture of the brain's tissues and structures. A CT scan may reveal
brain areas that are underdeveloped, abnormal cysts (sacs that are often filled
with liquid) in the brain, or other physical problems. With the information from
CT scans, doctors may be better equipped to judge the long-term outlook for an
affected child.
Magnetic resonance imaging, or MRI, is a relatively new brain imaging technique
that is rapidly gaining widespread use for identifying brain disorders. This
technique uses a magnetic field and radio waves, rather than x-rays. MRI gives
better pictures of structures or abnormal areas located near bone than CT.
A third test that can expose problems in brain tissues is ultrasonography. This
technique bounces sound waves off the brain and uses the pattern of echoes to
form a picture, or sonogram, of its structures. Ultrasonography can be used in
infants before the bones of the skull harden and close. Although it is less
precise than CT and MRI scanning, this technique can detect cysts and structures
in the brain, is less expensive, and does not require long periods of
immobility.
Finally, physicians may want to look for other conditions that are linked to
cerebral palsy, including seizure disorders, mental impairment, and vision or
hearing problems.
When the doctor suspects a seizure disorder, an electroencephalogram, or EEG,
may be ordered. An EEG uses special patches called electrodes placed on the
scalp to record the natural electrical currents inside the brain. This recording
can help the doctor see telltale patterns in the brain's electrical activity
that suggests a seizure disorder.
Intelligence tests are often used to determine if a child with cerebral palsy is
mentally impaired. Sometimes, however, a child's intelligence may be
underestimated because problems with movement, sensation, or speech due to
cerebral palsy make it difficult for him or her to perform well on these tests.
If problems with vision are suspected, the doctor may refer the patient to an
ophthalmologist for examination; if hearing impairment seems likely, an
otologist may be called in.
Identifying these accompanying conditions is important and is becoming more
accurate as ongoing research yields advances that make diagnosis easier. Many of
these conditions can then be addressed through specific treatments, improving
the long-term outlook for those with cerebral palsy.
Source: "Cerebral Palsy: Hope Through
Research," Brochure, National Institute of Neurological Disorders and
Stroke, NIH Publication No. 93-159, September 1993.
RETURN TO: Types of CP (1)
|
 |