[Editor's note: This article is from 2007. Some newer treatments and current statistics are not included here. See further information on BrainWeb]
sections include: classifying cerebral palsy, causes of cerebral palsy, diagnosis, treatment, future challenges
Cerebral palsy (CP) is the term for a group of lifelong neurological disorders of varying severity that alter body tone and impair movement.
CP results from genetic or acquired medical conditions affecting brain formation and development, rather than from conditions primarily affecting nerves or muscles themselves. These conditions, most of which begin before labor, disrupt developing networks of neurons (brain cells) that control movement, and the myelinated fibers (brain white matter) that connect them to the spinal cord. In most cases, affected individuals have primary limitations in mobility and hand use, but they may have or develop associated problems with speech; seizures; eye movements; swallowing; bone, muscle, or joint structure; and cognitive processing. People with CP may have normal intelligence despite their speech-generating problems, and many overcome their physical disabilities and live fulfilling lives.
Symptoms may appear soon after birth or during early childhood. Infants with markedly increased or decreased body tone, or difficulty with head control, are at increased risk. Other early signs of concern include delays in rolling, sitting, crawling, standing; and becoming right-handed or left-handed before twelve months of age. However, children with specific genetic disorders may develop signs of cerebral palsy later in infancy or early childhood. For example, children with a condition called glutaric aciduria, a metabolic disorder, develop normally until an acute metabolic stress such as a viral illness leads to a sudden, dramatic loss of motor function and the subsequent finding of cerebral palsy. It is important to recognize that the manifestations of CP may change and that the symptoms sometimes progress over time. For example, infants who are hypotonic (floppy) in the first one to two years of life may develop hypertonia (stiffness) later in childhood. Adults may develop signs of spinal cord injury with loss of extremity function as a result of repeated, long-standing abnormal body movements. These changes highlight the need for lifelong care by experienced professionals.
Classifying Cerebral Palsy
In determining the type of CP and specifics of rehabilitation, medical and rehabilitative specialists look for particular neurological signs and assess limb involvement and severity of functional impairment. Depending on the neurological findings, CP may be classified as spastic, extrapyramidal, or mixed. In spastic cerebral palsy, motor pathways descending from the brain to the spinal cord send abnormal signals, resulting in increased muscle tone. This produces a resistance to movement similar to the feeling of opening a pocketknife. Functional impairment is generally greater in the legs than in the arms. Because of the abnormal pull of muscles around joints, deformities of joint (orthopedic), including hip dislocation, scoliosis (curvature of the spine), and deformities of the foot, ankle, and arm, may develop.
Extrapyramidal (also called dyskinetic) forms of CP involve increased or reduced body movements in association with muscular rigidity or hypotonia. The term extrapyramidal (meaning outside the pyramidal tract) refers to abnormalities in brain areas including the basal ganglia, thalamus, and cerebellum, which regulate motor function. This is distinct from the pyramidal motor pathways directing movement, which are made up of large myelinated bundles of white-matter fibers that may be affected in spastic CP. In extrapyramidal CP, the arms are usually more affected than the legs, with less risk for orthopedic deformities. Movement abnormalities may include chorea (dancelike movements of the hands), athetosis (slow, writhing movements of the extremities), and dystonia (fixed, twisted postures). It is important to note that while speaking may be impaired, understanding of language may be normal in extrapyramidal CP.
Other terms also help carefully define the disorder for purposes of planning care and treatment. Affected individuals may be described as having diplegia, quadriplegia, or hemiplegia. Diplegia refers to the greatest involvement being that of the lower extremities; quadriplegia describes four-limb involvement; and hemiplegia refers to the involvement of one side of the body. Rehabilitation therapists may also classify cerebral palsy according to the ability to walk, or “ambulate.” For example, in some people ambulation is limited to the home or rehabilitation facility, while others may freely move in a community setting. This description is further refined by the nature of any assistive devices required (for example, cane, walker, or wheelchair).
In most individuals with CP, structural brain abnormalities are seen using magnetic resonance imaging (MRI) or computed tomography (CT). White-matter pathways from the cortex to various brain structures and the spinal cord are vulnerable in premature infants (24 to 34 weeks) who later develop spastic forms of cerebral palsy. This can be seen by MRI as periventricular leukomalacia (PVL), the term used to describe this white-matter injury. As the fetus approaches term, vulnerability shifts from white matter to neurons in the motor cerebral cortex and basal ganglia, with the common clinical presentation of extrapyramidal CP. For example, acute perinatal injury often has a characteristic imaging pattern of abnormal signaling in the basal ganglia (putamen) and thalamus.
Causes of Cerebral Palsy
The cause of CP has been controversial for more than a century. Sir William Little, an orthopedic surgeon in Great Britain in the mid-1800s, attributed CP to problems with birth. Alternatively, Sigmund Freud, who spent the early part of his career as a neurologist, favored a prenatal origin for the disorder. Sir William Osler, the noted Johns Hopkins physician, contributed a book on CP at the turn of the century, highlighting the role of infection. The National Collaborative Perinatal Project, which was sponsored by the National Institutes of Health (NIH) and studied more than 54,000 mothers and their infants born between 1959 and 1966, provided the most comprehensive information about the causes of CP. The study found that most CP is caused by prematurity, infection, genetic syndromes, and developmental brain malformations. Fewer than 20 percent of cases are thought to result from trauma or lack of oxygen associated with labor and delivery.
Disorders involving energy production may affect the brain at birth or during infancy. Many of these disorders, including kernicterus (yellow jaundice) and pyruvate dehydrogenase deficiency (mitrochondrial disorder), target specific regions in the basal ganglia and also lead to extrapyramidal CP. Genetically based developmental brain malformations can cause CP as well—for example, lissencephaly, an abnormality in brain cell migration that leads to a smooth brain surface, or holoprosencephaly (where the front part of the brain doesn’t divide into two halves, which should occur at two to four weeks gestation). It is important to identify children whose CP has a genetic cause because some have medically treatable disorders. Furthermore, some of these disorders have specific recurrence risks for future pregnancies, which is important information for families.
History and neurological examination remain key components to diagnosis. A medical specialist will review the family history for possible relevant genetic disorders and will observe the infant or child’s movement and motor abilities, such as rolling, sitting, crawling, and standing. Once the child is comfortable, a detailed neurological examination will be conducted to determine what type of CP is present, which is of great benefit in determining medical therapies, including drug therapy and surgical interventions.
When CP is suspected, a brain scan should be obtained. Depending on the situation, this may be an ultrasound scan of the head, a CT scan, or an MRI. Of the three, MRI often provides the most useful information. The changing vulnerability of different parts of the brain to insults occurring during early development results in distinct imaging patterns. For example, there are often relatively specific findings for spastic and extrapyramidal types of CP. A careful interpretation of each scan is important for diagnosis and treatment, as well as establishing the recurrence risk for future pregnancies.
Like the progress in understanding the causes of CP, advances in medical care offer improved treatment options. Most medium-to-large medical centers in countries around the world have experienced clinicians, including neurodevelopmental pediatricians, neurologists, orthopedists, physiatrists, nurse-practitioners, nurses, and therapists, to help individuals with CP and their families. These professionals are trained to select and carry out optimal therapies at the appropriate time in the child’s, adolescent’s, or adult’s life. Modern rehabilitation offers a wide range of effective treatment approaches. The overall purpose is to improve motor abilities, develop communication and independence skills, and address any associated problems. Physical, occupational, and speech therapies are the mainstays of treatment, serving to promote development and foster independence.
When spasticity affects motor development, oral drugs including baclofen and valium are often used, with injections of botulinum toxin (Botox) into specific muscles as required. These treatments are used to decrease spasticity and improve motor abilities. For more severe degrees of spasticity, procedures called selective dorsal rhizotomy and intrathecal baclofen have been effective. Selective dorsal rhizotomy involves cutting a small number of nerves at the base of the spinal cord that affect foot and leg movements. Cutting these nerves diminishes spasticity and may improve mobility. In intrathecal baclofen, a pump placed under the skin in the abdomen delivers a continuous dose of baclofen to the spinal cord through a catheter. This treatment is often very effective in reducing spasticity and at times improving functional abilities.
If skeletal deformities progress to the point at which either function or the activities of daily living (for example, dressing or bathing) are significantly affected, orthopedic surgery is often required. Frequently soft tissue procedures are performed first, where tendons are lengthened, or contracted muscles cut, for example, to reduce toe walking or decrease hip dislocation. If the deformities continue, surgery on affected bones may be required. It has not yet been clearly established that drug therapy, rhizotomy, or intrathecal baclofen reduces the need for orthopedic surgery.
Extrapyramidal forms of CP with disorders of movement may respond to one or more oral medications, with some types also responding to intrathecal baclofen. Another type of surgery, stereotactic neurosurgery, is more frequently being considered in highly specialized medical centers for those for whom more conventional therapies have not worked. In stereotactic surgery, lesions or fine electric wires are strategically placed in the thalamus or basal ganglia to decrease unwanted movements. Long-term studies of this surgery are currently not available.
Affected people and their families often consider alternative therapies when conventional ones fail to achieve desired effects. Acupuncture, energy therapy, massage therapy, water therapy, and horseback riding have all been reported to be of benefit. Recently, therapy by means of high-oxygen environments, termed hyperbaric oxygen therapy, has been employed for a wide range of medical conditions, but there is little evidence that it is successful. To date, theoretical concerns that high oxygen could cause oxidative damage to developing brain pathways have not been substantiated.
In summary, CP is a chronic disease that affected individuals and their families need to learn to manage. Federal law, contemporary medical practice, and parental input have combined to improve medical and rehabilitative care for affected children, adolescents, and adults with CP. However, families still face financial barriers in gaining access to equipment, therapies, transportation, and housing that would serve them best. The psychological challenges of raising children with disabilities, as well as the problems faced by the individuals affected, can be daunting. Furthermore, adults with CP still face obstacles with respect to the workplace, housing, medical care, and opportunities for social interaction.
Recent advances in diagnosis and management are cause for optimism. A number of techniques are being developed to more accurately image the brain, and promising therapeutic strategies are being developed, including intrathecal drug administration and stereotactic neurosurgery. For parents of a child with cerebral palsy, early identification and intervention services provide parents with the guidance and encouragement needed to optimize their child’s potential and to intervene in medically treatable disorders. These advances will lead to further improvements in care and lifestyle.
The wide range of conventional and alternative therapies available serves to point out the need for improved classification and more objective measurements of outcome. Using these tools, careful studies can then be done so that the best form of rehabilitation is selected for each person with CP. It is encouraging that researchers around the world are currently addressing these challenges.
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