Cerebral palsy is an umbrella-like term used to describe a group of chronic disorders impairing control of movement that appear in the first few years of life and generally do not worsen over time. The term cerebral refers to the brain's two halves, or hemispheres, and palsy describes any disorder that impairs control of body movement. Thus, these disorders are not caused by problems in the muscles or nerves. Instead, faulty development or damage to motor areas in the brain disrupts the brain's ability to adequately control movement and posture.
Symptoms of cerebral palsy lie along a spectrum of varying severity. An individual with cerebral palsy may have difficulty with fine motor tasks, such as writing or cutting with scissors; experience trouble with maintaining balance and walking; or be affected by involuntary movements, such as uncontrollable writhing motion of the hands or drooling. The symptoms differ from one person to the next, and may even change over time in the individual. Some people with cerebral palsy are also affected by other medical disorders, including seizures or mental impairment. Contrary to common belief, however, cerebral palsy does not always cause profound handicap. While a child with severe cerebral palsy might be unable to walk and need extensive, lifelong care, a child with mild cerebral palsy might only be slightly awkward and require no special assistance. Cerebral palsy is not contagious nor is it usually inherited from one generation to the next. At this time, it cannot be cured, although scientific research continues to yield improved treatments and methods of prevention.
How Many People Have This Disorder?
The United Cerebral Palsy Associations estimate that more than 500,000 Americans have cerebral palsy. Despite advances in preventing and treating certain causes of cerebral palsy, the number of children and adults it affects has remained essentially unchanged or perhaps risen slightly over the past 30 years. This is partly because more critically premature and frail infants are surviving through improved intensive care. Unfortunately, many of these infants have developmental problems of the nervous system or suffer neurological damage. Research is under way to improve care for these infants, as in ongoing studies of technology to alleviate troubled breathing and trials of drugs to prevent bleeding in the brain before or soon after birth.
What Are the Different Forms?
Spastic diplegia, the disorder first described by Dr. Little in the 1860s, is only one of several disorders called cerebral palsy. Today doctors classify cerebral palsy into four broad categories -- spastic, athetoid, ataxic, and mixed forms -- according to the type of movement disturbance.
Spastic cerebral palsy. In this form of cerebral palsy, which affects 70 to 80 percent of patients, the muscles are stiffly and permanently contracted. Doctors will often describe which type of spastic cerebral palsy a patient has based on which limbs are affected. The names given to these types combine a Latin description of affected limbs with the term plegia or paresis, meaning paralyzed or weak. The four commonly diagnosed types of spastic cerebral palsy are illustrated in the figure.
When both legs are affected by spasticity, they may turn in and cross at the knees. As these individuals walk, their legs move awkwardly and stiffly and nearly touch at the knees. This causes a characteristic walking rhythm, known as the scissors gait.
Individuals with spastic hemiparesis may also experience hemiparetic tremors, in which uncontrollable shaking affects the limbs on one side of the body. If these tremors are severe, they can seriously impair movement.
Athetoid, or dyskinetic, cerebral palsy. This form of cerebral palsy is characterized by uncontrolled, slow, writhing movements. These abnormal movements usually affect the hands, feet, arms, or legs and, in some cases, the muscles of the face and tongue, causing grimacing or drooling. The movements often increase during periods of emotional stress and disappear during sleep. Patients may also have problems coordinating the muscle movements needed for speech, a condition known as dysarthria. Athetoid cerebral palsy affects about 10 to 20 percent of patients.
Ataxic cerebral palsy. This rare form affects the sense of balance and depth perception. Affected persons often have poor coordination; walk unsteadily with a wide-based gait, placing their feet unusually far apart; and experience difficulty when attempting quick or precise movements, such as writing or buttoning a shirt. They may also have intention tremor. In this form of tremor, beginning a voluntary movement, such as reaching for a book, causes a trembling that affects the body part being used and that worsens as the individual gets nearer to the desired object. The ataxic form affects an estimated 5 to 10 percent of cerebral palsy patients.
Mixed forms. It is common for patients to have symptoms of more than one of the previous three forms. The most common mixed form includes spasticity and athetoid movements but other combinations are also possible.
What Other Medical Disorders Are Associated With Cerebral Palsy?
Many individuals who have cerebral palsy have no associated medical disorders. However, disorders that involve the brain and impair its motor function can also cause seizures and impair an individual's intellectual development, attentiveness to the outside world, activity and behavior, and vision and hearing. Medical disorders associated with cerebral palsy include:
Mental impairment. About one-third of children who have cerebral palsy are mildly intellectually impaired, one-third are moderately or severely impaired, and the remaining third are intellectually normal. Mental impairment is even more common among children with spastic quadriplegia.
Seizures or epilepsy. As many as half of all children with cerebral palsy have seizures. During a seizure, the normal, orderly pattern of electrical activity in the brain is disrupted by uncontrolled bursts of electricity. When seizures recur without a direct trigger, such as fever, the condition is called epilepsy. In the person who has cerebral palsy and epilepsy, this disruption may be spread throughout the brain and cause varied symptoms all over the body -- as in tonic-clonic seizures -- or may be confined to just one part of the brain and cause more specific symptoms -- as in partial seizures.
Tonic-clonic seizures generally cause patients to cry out and are followed by loss of consciousness, twitching of both legs and arms, convulsive body movements, and loss of bladder control.
Partial seizures are classified as simple or complex. In simple partial seizures, the individual has localized symptoms, such as muscle twitches, chewing movements, and numbness or tingling. In complex partial seizures, the individual may hallucinate, stagger, perform automatic and purposeless movements, or experience impaired consciousness or confusion.
Growth problems. A syndrome called failure to thrive is common in children with moderate-to-severe cerebral palsy, especially those with spastic quadriparesis. Failure to thrive is a general term physicians use to describe children who seem to lag behind in growth and development despite having enough food. In babies, this lag usually takes the form of too little weight gain; in young children, it can appear as abnormal shortness; in teenagers, it may appear as a combination of shortness and lack of sexual development. Failure to thrive probably has several causes, including, in particular, poor nutrition and damage to the brain centers controlling growth and development. In addition, the muscles and limbs affected by cerebral palsy tend to be smaller than normal. This is especially noticeable in some patients with spastic hemiplegia, because limbs on the affected side of the body may not grow as quickly or as large as those on the more normal side. This condition usually affects the hand and foot most severely. Since the involved foot in hemiplegia is often smaller than the unaffected foot even among patients who walk, this size difference is probably not due to lack of use. Scientists believe the problem is more likely to result from disruption of the complex process responsible for normal body growth.
Impaired vision or hearing. A large number of children with cerebral palsy have strabismus, a condition in which the eyes are not aligned because of differences in the left and right eye muscles. In an adult, this condition causes double vision. In children, however, the brain often adapts to the condition by ignoring signals from one of the misaligned eyes. Untreated, this can lead to very poor vision in one eye and can interfere with certain visual skills, such as judging distance. In some cases, physicians may recommend surgery to correct strabismus. Children with hemiparesis may have hemianopia, which is defective vision or blindness that impairs the normal field of vision of one eye. For example, when hemianopia affects the right eye, a child looking straight ahead might have perfect vision except on the far right. In homonymous hemianopia, the impairment affects the same part of the visual field of both eyes. Impaired hearing is also more frequent among those with cerebral palsy than in the general population.
Abnormal sensation and perception. Some children with cerebral palsy have impaired ability to feel simple sensations like touch and pain. They may also have stereognosia, or difficulty perceiving and identifying objects using the sense of touch. A child with stereognosia, for example, would have trouble identifying a hard ball, sponge, or other object placed in his hand without looking at the object.
What Causes Cerebral Palsy?
Cerebral palsy is not one disease with a single cause, like chicken pox or measles. It is a group of disorders with similar problems in control of movement, but probably with 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.
In the United States, about 10 to 20 percent of children who have cerebral palsy acquire the disorder after birth. (The figures are higher in underdeveloped countries.) Acquired cerebral palsy results from brain damage in the first few months or years of life and can follow 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 months. In most cases, the cause of congenital cerebral palsy is 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:
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 NINDS scientists and others has shown that very few babies who experience asphyxia during birth develop encephalopathy soon after birth. Research also shows that a large proportion of babies who experience asphyxia do not grow up to have cerebral palsy or other neurological disorders. Birth complications including asphyxia are now estimated to account for about 6 percent of congenital cerebral palsy cases.
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:
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.
Can Cerebral Palsy Be Prevented?
Several of the causes of cerebral palsy that have been identified through research are preventable or treatable:
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 causes of cerebral palsy through basic and clinical research, doctors and parents will be better equipped to help prevent this disorder.
What Are the Early Signs?
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, smile, 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 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. During the first 12 months of life, babies do not usually show hand preference. 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 more likely springs from elsewhere -- 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 at fault.
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 suggest 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.
How is Cerebral Palsy Managed?
Cerebral palsy can not be cured, but treatment can often improve a child's capabilities. In fact, progress due to medical research now means that many patients can enjoy near-normal lives if their neurological problems are properly managed. There is no standard therapy that works for all patients. Instead, the physician must work with a team of health care professionals first to identify a child's unique needs and impairments and then to create an individual treatment plan that addresses them.
Some approaches that can be included in this plan are drugs to control seizures and muscle spasms, special braces to compensate for muscle imbalance, surgery, mechanical aids to help overcome impairments, counseling for emotional and psychological needs, and physical, occupational, speech, and behavioral therapy. In general, the earlier treatment begins, the better chance a child has of overcoming developmental disabilities or learning new ways to accomplish difficult tasks.
The members of the treatment team for a child with cerebral palsy should be knowledgeable professionals with a wide range of specialties. A typical treatment team might include:
Individuals who have cerebral palsy and their family or caregivers are also key members of the treatment team, and they should be intimately involved in all steps of planning, making decisions, and applying treatments. Studies have shown that family support and personal determination are two of the most important predictors of which individuals who have cerebral palsy will achieve long-term goals.
Too often, however, physicians and parents may focus primarily on an individual symptom -- especially the inability to walk. While mastering specific skills is an important focus of treatment on a day-to-day basis, the ultimate goal is to help individuals grow to adulthood and have maximum independence in society. In the words of one physician, "After all, the real point of walking is to get from point A to point B. Even if a child needs a wheelchair, what's important is that they're able to achieve this goal."
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Last Updated: July 1, 2001