- Associated Conditions
- Life Expectancy
Facts you should know about cerebral palsy
- Cerebral palsy (CP) is an abnormality of motor function, the ability to move and control movements.
- Cerebral palsy is acquired at an early age, usually less than a year of age.
- Cerebral palsy is due to a brain abnormality that does not progress in severity.
- The causes of cerebral palsy include prematurity, genetic disorders, strokes, and infection of the brain.
- Taking certain precautions during the pregnancy might decrease the risk of cerebral palsy.
- Asphyxia, the lack of oxygen to the brain, at birth is not as common a cause of cerebral palsy as had been thought.
- There are different types of cerebral palsy based on symptoms -- spastic, hypotonic, choreoathetoid, and mixed types.
- The best approach for diagnosis, treatment, and management is through and interdisciplinary team.
- Cerebral palsy may be associated with many other medical conditions, including mental retardation or seizures. Many of these conditions can be treated with improved quality of life.
- Many children with cerebral palsy have a normal intellect and have no seizures.
- Treatment of cerebral palsy is for the symptoms only; there are few treatments for the underlying causes.
- There are many alternative medicines promoted for the treatment of cerebral palsy that have never been proven to be helpful. Families and advocates of persons with cerebral palsy should be aware of the lack of scientific basis for these treatments.
What is cerebral palsy?
Cerebral palsy (CP) is an abnormality of motor function (as opposed to mental function) and postural tone that is acquired at an early age, even before birth. Signs and symptoms of cerebral palsy usually show in the first year of life.
This abnormality in the motor system is the result of brain lesions that are nonprogressive. The motor system of the body provides the ability to move and control movements. A brain lesion is any abnormality of brain structure or function. "Nonprogressive" means that the lesion does not produce ongoing degeneration of the brain. It is also implied that the brain lesion is the result of a one-time brain injury, that will not occur again. Whatever the brain damage that occurred at the time of the injury is the extent of damage for the rest of the child's life.
Cerebral palsy affects approximately one to three out of every thousand children born. However, it is much higher in infants born with very low weight and in premature infants.
Interestingly, new treatment methods that resulted in an increased survival rate of low-birth weight and premature infants actually resulted in an overall increase in the number of children with cerebral palsy. The new technologies, however, did not change the rate of cerebral palsy in children born full term and with normal weight.
What are causes of cerebral palsy?
In full-term infants the cause of cerebral palsy is usually prenatal and not related to events at time of delivery; in most instances it is related to events that happened during the pregnancy while the fetus is developing inside the mother's womb.
Premature birth is a risk factor for cerebral palsy. The premature brain is at a high risk of bleeding, and when severe enough, it can result in cerebral palsy. Children that are born prematurely can also develop serious respiratory distress due to immature and poorly developed lungs. This can lead to periods of decreased oxygen delivered to the brain that might result in cerebral palsy. A poorly understood brain process observed in some premature infants is called periventricular leukomalacia. This is a disorder in which holes form in the white matter of the premature infant's brain. The white matter is necessary for the normal processing of signals that are transmitted throughout the brain, and from the brain to the rest of the body.
White matter abnormalities are observed in many cases of cerebral palsy. Nevertheless, it is important to recognize that the vast majority of premature infants, even those born very prematurely, do not suffer from cerebral palsy. There have been many advances in the field of neonatology (the care and study of problems affecting newborn infants) that have enhanced the survival of very premature infants.
Even though it is widely believed that the most common cause of cerebral palsy is a lack of oxygen to the brain during delivery (birth asphyxia), it is actually a very rare cause of cerebral palsy. When cerebral palsy is the result of birth asphyxia, the infant almost always suffers severe neonatal encephalopathy with symptoms during the first few days of life. These symptoms include:
- feeding and respiratory problems,
- lethargy, and
- coma depending on the severity.
In rare instances, obstetrical accidents during particularly difficult deliveries can cause brain damage and result in cerebral palsy. Conversely, it is very unlikely that cerebral palsy symptoms would develop after a few years of age as a result of obstetrical complications.
Child abuse during infancy can cause significant brain damage which, in turn, can lead to cerebral palsy. This abuse often takes the form of severe shaking from a frustrated parent or caregiver, causing hemorrhage in or just outside the brain. To further compound the problem, many children with developmental abnormalities are at risk for being abused. Thus, a child with cerebral palsy may be made significantly worse or even killed by a single incident of abuse.
Despite the diversity of causes of cerebral palsy, many cases remain without a defined cause. However, the enhanced ability to see the brain structure with magnetic resonance imaging (MRI) and CT scans as well as improved diagnostic capabilities for genetic disorders has made the number of such cases much lower.
What are symptoms and signs of cerebral palsy?
The predominant symptoms and signs of cerebral palsy are related to motor difficulties, which are the consequence of the brain damage. The extension and severity of the brain lesion is the leading factor in the magnitude of the motor deficit. Many of the symptoms observed in these children are related to the primary problem that is impaired motor functions. For example, developmental motor delay, gait disorders, poor fine and gross motor coordination, swallowing disorders, or speech delay are all the result of the basic motor disorder. The way they present varies from child to child. For that reason, it is difficult to describe a clinical picture that will satisfy every child with cerebral palsy. The clinical presentation, even though with many common features, is very much unique for a particular child. In addition, the comorbid conditions add more to the uniqueness of the presentation of the child with cerebral palsy. For example, some children may be blind, while others may have normal vision; or some children may have severe cognitive delay while others may have normal or near normal cognitive level.
What are the types of cerebral palsy?
Based upon the form of motor impairment, cerebral palsy can be divided into types:
- spastic cerebral palsy,
- dyskinetic cerebral palsy (according to the predominant symptoms dyskinetic CP may be either dystonic or choreoathetotic), which includes ataxic cerebral palsy, and
- hypotonic cerebral palsy.
These categories are not rigid, and the majority of patients most probably have a mixture of them.
What is spastic cerebral palsy?
Spastic cerebral palsy refers to a condition in which the muscle tone is increased, causing a rigid posture in one or more extremities (arm(s) or leg(s)). This rigidity can be overcome with some force, ultimately giving way completely and suddenly -- very much like the familiar jackknife (or clasp knife). The spasticity leads to a limitation of use of the involved extremity, largely due to the inability to coordinate movements. Often the spasticity occurs on one side of the body (hemiparesis), but it can also affect the four limbs (quadriparesis) or be limited to both legs (spastic diplegia). When the condition occurs in both legs, the individual often has a scissoring posture, in which the legs are extended (straightened) and crossed.
Spasticity is often the result of damage to the white matter of the brain, but it can also be due to damage of gray matter.
The degree of spasticity can vary, ranging from mild to severe. Children who are mildly affected may experience few limitations of their function while severely affected children may have little to no meaningful use of the affected limb(s). Spasticity, if not properly treated, can result in contractures, which are permanent limitations in the ability of joint movement. Contractures can be greatly limiting in the care of children with cerebral palsy. Spasticity can also be quite painful, requiring medication to relax the muscle tone.
The same fundamental processes that influence spasticity of the limbs can also result in abnormalities of movement and muscle tone in other body systems. In the muscles of the head and face, for example, cerebral palsy can greatly limit the coordination and production of speech, even when the child is perfectly capable of understanding speech. There can also be limitations of chewing, swallowing, and facial and eye movements. These symptoms can be particularly troubling for afflicted children and their families.
Many patients with spastic cerebral palsy cannot control their output of urine. This inability is not necessarily due to problems in thinking but is caused by heightened reflexes of the bladder. When the bladder fills in these children, it is just like tapping on it with a reflex hammer, thus making it contract more vigorously than normal and causing a spilling of urine. This incontinence can be quite embarrassing, especially in a cognitively intact child.
What is dyskinetic cerebral palsy?
What is ataxic cerebral palsy?
Ataxic CP is a rare form of CP. It is a dyskinetic form of CP; that is, abnormal movements are present. In these children there is a marked loss of orderly muscular coordination so that movements are performed with abnormal force, rhythm, and accuracy. The fine motor coordination is much affected, as well as the gait.
What is dystonic cerebral palsy?
Dystonic CP is characterized by predominance of slow movements with muscle rigidity and persistent abnormal postures that relax after seconds or minutes. The frequency of these abnormal involuntary movements is less than in the choreoathetotic form. Usually the muscle tone is increased.
What is choreoathetoid cerebral palsy?
Choreoathetoid (sometimes referred as athetoid) cerebral palsy is associated with abnormal, uncontrollable, writhing movements of the arms and/or legs. Different from spastic cerebral palsy, persons with choreoathetoid cerebral palsy have variable muscle tone often with decreased muscle tone (hypotonia). Contractures of extremities are less common. The abnormal movements are activated by stress, as well as by normal emotional reactions such as laughing. Any attempt to do voluntary movements, for example extending the arm in an attempt to reach an object, might result in many involuntary movements in arms, legs, trunk, and even the face. There are different types of abnormal movements. Two of the most common are choreoathetotic movement disorder with rapid, irregular, unpredictable contractions of individual or small muscles groups and dystonia with a persistent but not permanent, abnormal posture of some body parts (arms, legs, trunk) due to abnormal muscle contractions. The dystonic disorder also affects the muscles for facial expression, swallowing, deglutition, and speech, resulting in severe functional deficiencies.
These movements can be quite debilitating and greatly limit the child's ability to perform many motor tasks. Furthermore, the movements are akin to constant exercise, thereby causing the affected child to metabolize a huge number of calories. Choreoathetoid cerebral palsy is often associated with damage to specialized brain structures that are involved in movement control -- the basal ganglia. Like spastic cerebral palsy, the degree of symptom severity often varies, from mild to severely affected.
What is hypotonic cerebral palsy?
Hypotonia is diminished muscle tone. The infant or child with hypotonic cerebral palsy appears floppy -- like a rag doll. In early infancy, hypotonia can be easily seen by the inability of the infant to gain any head control when pulled by the arms to a sitting position (this symptom is often referred to as head lag). Children with severe hypotonia may have the most difficulty of all children with cerebral palsy in attaining motor skill milestones and normal cognitive development.
Hypotonic cerebral palsy is often the result of severe brain damage or malformations. It is believed that hypotonic cerebral palsy is the result of an injury or malformation at an earlier brain developmental stage than that which causes spastic or choreoathetoid cerebral palsy.
Hypotonia in infancy is a common finding in many neurological conditions, ranging from very mild abnormalities to severe or even fatal neurodegenerative or muscle disorders. It is important to note that many children with spastic cerebral palsy go through a short stage of being somewhat hypotonic in early life, before presenting the full syndrome.
What is mixed cerebral palsy?
Many (possibly most) children with cerebral palsy have multiple symptoms with combinations of the various forms of cerebral palsy. For example, children with spastic cerebral palsy often continue to have a head lag, which is representative of hypotonia. Children with choreoathetoid or hypotonic cerebral palsy often have increased deep tendon reflexes, which are suggestive of some spasticity. Children with bilateral spastic cerebral palsy may also have dystonic movements in the limbs affected. The different types of cerebral palsy described above are rarely seen as pure clinical forms, more often the child with cerebral palsy has a mixture of signs or symptoms. Nevertheless, in clinical practice the type of cerebral palsy is defined on the basis of the predominant manifestations.
What other conditions are associated with cerebral palsy?
Since cerebral palsy is indicative of damage to or malformation of the brain, it stands to reason that other symptoms that are associated with brain dysfunction can be present in children afflicted with cerebral palsy. In fact, other disorders, besides the motor dysfunctions already described, are almost always seen in these patients. Some of them such as poor speech, swallowing disorders, drooling, and poor fine or gross motor coordination are the result of the motor disorder affecting specific muscles involved in those functions. Other conditions are the results of simultaneous injuries in areas of the brain besides the motor areas.
Cognitive disabilities, sometimes referred to as developmental delay, are often associated with cerebral palsy. Up to half of patients with cerebral palsy have cognitive disabilities. However, many of these children can be educated and lead productive lives. It is also just as important to note that many children with severe motor impairment due to cerebral palsy, as is the case with many children with the choreoathetotic or the diplegic form of cerebral palsy, are only mildly or not at all intellectually impaired.
Virtually all testing of a young child's cognitive development involves some sort of motor activity on the part of the child. If a child is capable of complex thoughts, but incapable of motor activity, the observer will not be able to detect his or her mental aptitude. Therefore, one must be very careful in assigning labels to patients with cerebral palsy. Certain features, however, are more likely to be associated with significant cognitive disabilities in the patient with cerebral palsy. These include extensive damage occurring on both sides of the brain, children with spastic quadriplegia, microcephaly (small head size), a documented genetic disorder, and a documented prenatal infection.
Seizures are a common finding in patients with cerebral palsy. Perhaps a third of all cerebral palsy patients have seizures. Seizures are caused by abnormal electrical activity of the neurons in the brain. The damaged or malformed brain is more prone to seizures. Moreover, cognitive disability is frequently associated with epileptic seizures.
The symptoms of seizures can vary depending on where in the brain they originate. Generalized seizures engage the entire cerebral cortex at once, while partial seizures only involve part of the cerebral cortex. Often, generalized seizures begin as partial seizures but spread throughout the brain rapidly. Generalized seizures may take the form of true convulsions ("grand mal"), in which the entire body jerks in a rhythmic fashion, or the form of absences ("petit mal"), which interrupt the patient's activities for a brief period, but does not cause a fall.
Other forms of generalized seizures can occur in the cerebral palsy patient. Atonic seizures cause the patient to slump suddenly to the ground or forward in their chair, resembling a marionette in which the puppeteer suddenly cut the strings. Tonic seizures are just the opposite and cause the entire body to suddenly stiffen. Both tonic and atonic seizures can result in drop attacks in which the patient falls to the ground, often resulting in injury.
Partial seizures may involve the jerking of the arm and leg on the same side of the body. Alternatively, they may be associated with strange sensory phenomena, such as flashing lights, or emotions, such as fear, depending on where in the brain the seizure occurs.
Vision deficiencies are frequently seen. Some of them, for example, strabismus ("lazy eyes") can be corrected by surgical procedures in the muscles of the eyes. Some can be corrected with eye glasses (that may be difficult to implement in non-cooperative children). In other children, the visual deficiencies are the result of brain injuries to the areas of the brain that are associated with vision, rendering the child blind ("cortical blindness") even if the eyes themselves are perfectly normal. At the present time, there is no treatment to improve this condition.
Children with cerebral palsy can have speech disorders of many types. Some, like poor word pronunciation (dysarthria), are the result of impairment of the peripheral mechanism of speech (poor lips, tongue, or palate coordination). In another circumstance, there is brain injury in the gray matter of the brain that controls the central mechanism of speech (aphasia).
It is difficult for children with cerebral palsy to gain weight and they frequently have delayed growth. This is the result of several factors including feeding disorders, gastroesophageal reflux, and in some instances, for example, children with choreoathetotic disorders, excessive caloric consumption. On the other, hand obesity could be a problem in those children with cerebral palsy that have limited mobility.
How is a child evaluated for cerebral palsy?
Most of the information leading to the diagnosis of cerebral palsy is generally obtained from a thorough medical history and examination. The most critical tasks of the health care professional are to identify potentially treatable causes of a child's impairment. The health care professional evaluating the child with possible cerebral palsy should be experienced in neurological examination and assessment of impaired children and well-versed in the potential causes of cerebral palsy. Often, but not necessarily, this practitioner should be a pediatric neurologist. Once the examination is complete, depending on the findings, the practitioner may order laboratory tests to help in the assessment.
There is no single test to diagnose cerebral palsy. But since cerebral palsy is the result of multiple different causes, the tests performed are used to identify specific causes when possible. Other tests will be performed to assess the condition of the child (nutritional status for example) or to assess other concomitant conditions that the child might have.
Blood and urine tests may be used to identify some of the more common inborn errors of metabolism. Blood tests may also be used for chromosomal or other genetic studies. Brain imaging studies can also be used to detect structural changes in the brain. The most sensitive brain imaging study is the MRI examination. Nuclear medicine neuroimaging studies such as SPECT or PET have no place in the initial evaluation of a child with cerebral palsy, but may prove very useful in the assessment of selected candidates.
Despite all of these tests, it may not be possible to answer some of the burning questions in the mind of a parent of a neurologically impaired infant, such as "Why does my child have cerebral palsy?" or "Will my child be normal?" This is particularly true if a specific diagnosis is not reached and the child is under one year of age. Some severely impaired young infants can grow up to be independent, productive members of society, while other children, seemingly less impaired, may require care throughout their lives.
Once the diagnostic evaluation is complete, further testing may be needed in order to define the specific needs of any individual child. For example, if seizures are present or suspected, an EEG (electroencephalogram) is performed. However, this test is not needed if there are no signs of epilepsy.
What are treatment options for cerebral palsy?
Most of the causes of cerebral palsy do not have specific, curative treatments. However, children with cerebral palsy present many medical problems that can be treated or prevented. The initial stage of treatment involves an interdisciplinary team, consisting of a pediatrician, preferable one with experience in neurodevelopmental disorders, a neurologist (or other neurological practitioner), a mental health practitioner, an orthopedic surgeon, a physical therapist, a speech therapist, and an occupational therapist. Each member of the team has important, independent contributions to make in the care of the affected child.
- The physical therapist evaluates muscle tone, strength, and gait (walking).
- The occupational therapist reviews the child's ability to perform tasks of self-help and care -- from feeding to manual dexterity.
- The speech therapist evaluates the child's ability to speak and understand speech.
Most children with neurological impairment have significant emotional distress and also require therapy from a mental health practitioner.
Virtually all states have federally-mandated programs for the assessment and treatment of children with cerebral palsy and other developmental conditions. In many states, these programs are termed "Regional Centers" and can be found in local phone books. Also Children's Hospitals usually have special clinics with experience with children with cerebral palsy. Furthermore, when a child reaches the age of 3 years, the school district may become formally involved in the review of at-risk children. These programs protect children up to the age of 21 years.
At the present time, there is a vacuum in the provision of medical care for adults (young and old) with cerebral palsy living in the community settings. There are a limited number of services in adult hospitals geared to the treatment of adults with cerebral palsy or developmental disabilities.
What are specific treatment plans for cerebral palsy?
After the initial evaluation, specific treatment plans are outlined for each child:
If the child has seizures, the treatment is based on the type and frequency of the seizures. Complete seizure control can often be achieved using a single medication, but some children with cerebral palsy have particularly difficult-to-control seizures. Medication can have side effects affecting the brain, ranging from sedation to hyperactivity. They can also affect liver function, white and red blood cells, and bone metabolism. Side effects are usually not harmful and resolve when the offending medication is discontinued. The goal of the treating physician should be for the child to become seizure free with few or no side effects. It must be noted that it is of no benefit to the child to be seizure-free but significantly impaired by medication side effects.
Medications for spasticity: The treatment of spasticity can involve multiple health professionals. Treatments involve the use of medications and surgical procedures to decrease the spasticity, facilitate movement, and prevent contractions. Among the most common medications are dantrolene sodium (Dantrium) and diazepam (Valium). Diazepam is both a muscle relaxant and a sedative. Baclofen (Lioresal) can be taken by mouth or infused continuously with an implanted pump (intrathecal infusion) directly in the cerebrospinal fluid (the liquid that bathe the spinal cord and the brain). This treatment might be specifically useful for patients with spasticity in the lower legs. The most common complications with these medications are drowsiness, sleepiness, and some degree of weakness. The sedative side effects of such medications often limit their usefulness. In the case of the baclofen pump, the most common complication seen in a small number of patients is the infection of the catheter. Additionally, a muscle relaxing agent called botulinum toxin can be injected into tight muscles to relax them. When used prudently, this procedure may prevent surgical intervention.
Surgery for spasticity: In the case of severe muscle spasticity, surgery may be a valuable option. Tendon release procedures, usually performed by an orthopedic surgeon, allow improved range of motion in some cases. Such procedures are usually performed on the muscles of the calf or inner thigh. A less commonly used procedure, is the dorsal rhizotomy. During this operation, the surgeon cuts some of the nerve roots that send sensory information from the muscles to the spinal cord and brain. This procedure relieves some of the spasticity and thereby helps the child walk with a more normal gait. Most neurosurgeons performing dorsal rhizotomies very carefully select only those patients whom they feel may be helped by the surgery. From time to time, other surgical interventions are required in children with cerebral palsy. In very rare cases of choreoathetoid cerebral palsy, in which the writhing movements severely limit the ability of the child to function, highly selective neurosurgical techniques can curtail these movements without significantly harming other functions.
Other surgical procedures
Ophthalmologists (eye specialists) can help strabismus by operating on the muscles that control the movement of the eye or to correct some other complications such as cataracts.
Neurosurgeons can treat intractable seizure control. Operations such as callosotomy, hemispherectomy, and focal resections of areas of abnormal brain tissue responsible for the seizures, might be indicated in some cases. An alternative procedure for the treatment of epilepsy is the vagal nerve stimulation, an implantable device, that can be useful in selected patients with difficult to control seizures.
Scoliosis, or curvature of the spine, is often the result of severe hypotonia. This condition can create discomfort for the patient and difficulty for caregivers in performing the activities of daily living. Furthermore, severe scoliosis may actually restrict a patient's ability to breathe. Several surgical procedures are available in specialized centers for the correction of scoliosis.
The treatment of spasticity can involve multiple allied health care professionals. Physical and occupational therapists play an important role.
Physical therapy: The extent of physical therapy depends on the degree of spasticity, hypotonia, and motor impairment. The main therapeutic effect of physical therapy is maintaining range of motion at the joints, thereby preventing contractures. Some scientists and therapists feel that physical therapy actually helps maintain the connections in the brain, although this is controversial. Other skills, such as improved gait, stance, and balance can be helped by physical therapy. A strong, proactive physical therapy program greatly aids in the life of a child with cerebral palsy.
Occupational therapy: Occupational therapy assists children with the skills needed for day-to-day life in school and at home, including eating, writing, and work skills. In early infancy, occupational therapists can provide assistance in feeding a child with a poor or uncoordinated sucking response.
Speech therapy: Speech and language pathologists are involved with the development and improvement of speech production. Using different techniques, the speech pathologist helps to improve the quality and the quantity of the speech production. The role of these specialists is not limited to speech production alone, but they also teach the patients other communication techniques (sign language, use of communication boards) to facilitate the communication abilities.
Medical care of children with cerebral palsy is often seriously hampered by the inability of the child to communicate his or her needs and sensations. Relatively common childhood illnesses in children with cerebral palsy, such as ear infections, urinary tract infections, and appendicitis, which are easily treatable in most children, may prove to be life-threatening due to delayed recognition on the part of caregivers and physicians. Each child with cerebral palsy should have a primary care professional that is experienced with the special medical needs of affected children.
Because physicians have offered limited hope in curing cerebral palsy, many families have turned to alternative methods in the treatment of their children. Such therapies may include diets, herbal remedies, aromas, play with animals, and hyperbaric oxygen. The scientific evidence supporting the use of diets is inadequate. Some of them such as hyperbaric oxygen therapy, which is delivered in specialized centers, can be quite expensive and has not been scientifically proven to help children with cerebral palsy. Other remedies must be investigated on a case-by-case basis. Hopefully, the family of the affected child will be able to approach their physician regarding these alternative treatments.
What is the long-term outlook for patients with cerebral palsy?
The answer is complex. Since cerebral palsy is actually a set of symptoms associated with a variety of causes, potential treatments will have to be diverse. Many scientists are now focusing on recent discoveries that suggest we will be able to replace lost or damaged brain cells. While such therapies are not yet available, it is likely that real clinical trials will begin in the next 5 to 10 years.
The more we know about the causes of cerebral palsy, the more we can do to prevent it. For example, the use of folic acid in sexually active women may prevent central nervous system malformations that might lead to cerebral palsy. Avoiding the use of certain drugs during the pregnancy whether legal, such as prescribed medications, alcohol or tobacco, or illegal such as cocaine and crack, will also decrease the changes of cerebral palsy in a child.
It cannot be overemphasized that the most important person in the lives of children with cerebral palsy is their caregiver. The caregiver, whether a parent or other person, must be able to recognize a child's needs and provide for him or her in a loving, positive environment. Because of the difficulty that many children with cerebral palsy have in expressing their needs, they are at great risk for unintentional and intentional neglect as well as overt child abuse. Often, the care of children with cerebral palsy can be quite taxing emotionally and financially on the family. The appropriate care for children with cerebral palsy, therefore, must take into account mental health and financial support for families and caregivers. Many state-run programs provide out-of-home schooling as well as respite care for the caregivers, but these services often fall short of what is truly needed. Health care professionals can very simply improve the lives of their patients by taking some extra time to listen to the concerns and hopes of the caregivers and provide thoughtful answers to their questions.
We must recognize that many, and possibly most, children with cerebral palsy can lead full, meaningful, and happy lives. The team of parents, caregivers, and health practitioners has the responsibility to help the child with cerebral palsy achieve this goal.
Brain and Nervous System Resources
Health Solutions From Our Sponsors
"Clinical features and classification of cerebral palsy." UpToDate.com.