Betsy Miller
A report from the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics concludes that most instances of cerebral palsy originate from prenatal causes, rather than lack of oxygen (hypoxia) during labor and delivery. The task force that prepared the report studied infants who were term or near term at birth (34 weeks or more).
Babies with cerebral palsy usually have symptoms of neonatal encephalopathy (any defect of the function or structure of the brain) at birth poor muscle tone, breathing problems or seizures. Not all babies with neonatal encephalopathy have neurological problems. However, children who have cerebral palsy caused by lack of oxygen to the brain during labor and delivery must also have neonatal encephalopathy.
Understanding Cerebral Palsy
Cerebral palsy is a developmental disability that causes uncontrollable movement and posture. Symptoms typically appear within the first few years of life and do not get progressively worse over time. Cerebral palsy is not caused by problems with muscles or nerves. The motor areas in the brain are damaged or do not develop correctly. Children with cerebral palsy may also have other neurological problems such as epilepsy, mental impairments, growth problems, vision or hearing problems.
There is a wide range of symptoms among individuals who have cerebral palsy. Children with mild cases may have difficulty with fine motor coordination and be somewhat awkward. In other cases all limbs may be severely affected. According to the United Cerebral Palsy Association, over 500,000 Americans have cerebral palsy. There are four types of cerebral palsy spastic, dyskinetic, ataxic, and mixed.
• Spastic: This type affects 70 to 80% of cerebral palsy patients. The muscles controlled by the damaged motor centers in the brain are stiff and permanently contracted. The parts of the body affected by this condition vary from person to person. Most commonly the legs are affected. Some people may also have tremors, which cause shaking on one side of the body.
• Dyskinetic: In dyskinetic cerebral palsy there are slow, writhing movements. About 10 to 20% of patients have this type. The hands, feet, arms or legs may be affected. In some cases muscles of the face and tongue are affected.
• Ataxic: This type of cerebral palsy is rare and affects the sense of balance and depth perception. Only 5 to 10% of people with cerebral palsy have it. People with this condition may have difficulty walking or making exact movements. They may also have intention tremor, which causes them to tremble when they make a voluntary movement.
• Mixed: It is common for people to have a combination of types. The most common combination is spastic with dyskinetic movements.
Spastic cerebral palsy, especially when mixed with a movement disorder, is the only type that can be caused by a lack of oxygen during labor and delivery. Dyskinetic and ataxic cerebral palsy usually have a genetic cause.
Results of the Study
In the past, cerebral palsy has been widely believed to be caused by lack of oxygen to the brain during labor and delivery. Studies have shown that less than one-quarter of infants with neonatal encephalopathy had insufficient oxygen (hypoxia) during labor. The vast majority of cases originated from problems such as infections, clotting disorders, or a combination of factors that impact the baby's developing brain before birth. A prenatal problem was the main reason in 69% of neonatal encephalopathy cases and contributory in another 25%. In the remaining cases, 4% had evidence only of hypoxia, and 2% had no known risk factors.
The overall incidence of HIE (encephalopathy only due to lack of oxygen during labor or delivery) without prenatal causes is estimated to be 1.6 per 10,000. This figure does not include cases of encephalopathy resulting from prenatal strokes, infection, cerebral malformation, or genetic disorders.
"By helping to understand the causes of neonatal encephalopathy and cerebral palsy, our efforts may lead to clinical interventions that will reduce the rates of these serious pathologies," said Gary D.V. Hankins, MD, the chair of the ACOG task force.
The report, Neonatal Encephalopathy and Cerebral Palsy: Defining the Pathogenesis and Pathophysiology, has been endorsed by numerous governmental and professional organizations, including the National Institute of Child Health and Human Development of the National Institutes of Health, the Centers for Disease Control and Prevention, the March of Dimes Birth Defects Foundation, and the Society for Maternal and Fetal Medicine.
Prenatal Problems
Some prenatal conditions have the potential to damage the motor centers of the baby's developing brain, resulting in cerebral palsy and/or other neurological problems. Infections during pregnancy such as rubella (German measles) and toxoplasmosis are two examples.
Clotting disorders in the mother or baby or strokes may cause bleeding in the brain that damages the motor centers. Rh incompatibility is a blood disorder in which the mother's immune system attacks the baby's blood cells. This results in a form of jaundice in the newborn. Newborns with severe, untreated jaundice may develop brain damage.
Asphyxia During Labor and Delivery
Asphyxia is a lack of oxygen due to breathing problems or a poor oxygen supply. A baby's blood is able to compensate for low levels of oxygen and asphyxia, which are common during labor and delivery.
Previously, researchers attributed most cases of cerebral palsy to asphyxia or birth complications if they could not identify another cause. It has since been determined that large numbers of babies with asphyxia do not have disorders, and only a small number have encephalopathy soon after birth.
When asphyxia is prolonged, the oxygen supply to the baby is severely lowered for long periods. The child may develop a type of brain damage called hypoxic-ischemic encephalopathy (HIE). This condition may result in death or cerebral palsy, often accompanied by seizures.
Resources
For more information about cerebral palsy, contact the National Institute of Neurological Disorders and Stroke (NINDS). This organization is part of the National Institute of Health (NIH). For health or medical questions and general information:
NIH Neurological Institute
P.O. Box 5801
Bethesda, MD 20824
Voice: 800-352-9424
TTY (for people using adaptive equipment): 301-468-5981
www.ninds.nih.gov
Their publication, Cerebral Palsy: Hope Through Research, is available at their website www.ninds.nih.gov/health_and_medical/pubs/cerebral_palsyhtr.htm.
For information about the report, Neonatal Encephalopathy and Cerebral Palsy: Defining the Pathogenesis and Pathophysiology , contact:
The American College of Obstetricians and Gynecologists
409 12th St. S.W., PO Box 96920
Washington, D.C. 20090-6920
www.acog.org
The National Institute of Child Health and Human Development of the National Institutes of Health offers a clearinghouse for questions about health:
Telephone: 800-370-2943
www.nichd.nih.gov/
The March of Dimes Birth Defects Foundation also provides information to the public.
March of Dimes
Resource Center
1275 Mamoroneck Avenue
White Plains, NY 10605
888-MODIMES
www.modimes.org
www.nacersano.org
Betsy Miller is a freelance technical writer and editor living in the San Francisco Bay Area
May not be reproduced in any format without written permission.
