Recent figures suggest that the rate of babies born with cerebral palsy steady for the last 60 years may be falling.
Cerebral palsy is a nonprogressive disorder of movement or posture. Since 1997, its severity has been measured by a technique which allows thorough classification. Diagnosis now includes problems with movement, sensation, cognition, communication, perception, behavior and seizures. There is no known cure but occupational and speech therapy are often beneficial. Surgery can be used to loosen tight muscles and release fixed joints.
In developed countries, the rate of cerebral palsy is about 2 to 2.5 per 1,000 live births. The United Cerebral Palsy (UCP) Foundation estimates that nearly 800,000 children and adults in the United States are living with cerebral palsy. About 10,000 babies are born with cerebral palsy each year. The condition is 20 to 80 times more common among infants born weighing less than 3.3 pounds (1,500 grams) known as very low birth weight (VLBW). Improved care in neonatal intensive care units has led to higher survival rates for these babies, many of whom have brain damage or defects to the nervous system.
A team led by Dr. Mary Jane Platt of Liverpool University, UK recently investigated changes in cerebral palsy rates. They looked at data recorded at 16 European cerebral palsy centers from 1980 to 1996, all using a standard definition. Information was available on the children up to the age of 4 years.
The team found that the rate of cerebral palsy in very low birth weight infants those weighing less than 3.3 pounds (1,500 grams) and those born at less than 32 weeks’ gestation dropped significantly, from six percent of live births in 1980 to four percent in 1996. This was in spite of an increase in VLBW babies, a drop in infant deaths, and a rise in multiple births.
However, the drop occurred mainly in infants between 2.2 and 3.3 pounds (1,000 and 1,499 grams). Lighter babies only began to show a slight fall in cerebral palsy risk towards the end of the time period studied.
In the Jan.6, 2007 edition of The Lancet, the team noted that the decline was due to a drop in bilateral spastic cerebral palsy, generally the most severe type, and was probably due to improved care at and around the time of birth. Dr. Platt said that VLBW babies “now have a better chance of survival than previously, and more importantly, a better chance of survival without severe neurological impairment, which demonstrates that improvement in neonatal care has not resulted in increased survival at the cost of substantial morbidity.”
In a commentary, experts from Case Western Reserve University in Cleveland, Ohio said the findings are consistent with their research on infants weighing less than 2.2 pounds (less than 1,000 grams) born between 2000 and 2002. But they added that “despite the encouraging decrease in the prevalence of cerebral palsy there is no cause for complacency. Cerebral palsy is associated with major disabilities.”
In the current study, many of the children were unable to walk or had “severe mental retardation” (i.e., IQ less than 50). “Therefore every effort needs to be invested in the prevention of preterm birth and its associated brain injury,” they concluded.
Other research teams in the UK, Denmark and Sweden have found evidence that the cerebral palsy rate among VLBW infants has begun to fall, but studies from centers in Australia and Emory University, Atlanta have not shown a fall.
Sarah Winter, M.D., and colleagues at Emory looked at the rate of cerebral palsy in Atlanta from 1975 to 1991. They found a “modest increase” from 1.7 to 2.0 per 1,000 babies who survived for at least a year.
“This trend was primarily attributable to a slight increase in cerebral palsy in infants of normal birth weight,” they explain. “No change was seen in low birth weight and very low birth weight infants.”
So what can be done to reduce cerebral palsy rates in the future? Not a great deal, says Steven L. Clark, M.D. of the University of Utah.
After investigating possible links to fetal heart rate monitoring and cesarean deliveries, he concludes: “Except in rare instances, cerebral palsy is a developmental event that is unpreventable given our current state of technology.”
Platt M. J. et al. Trends in cerebral palsy among infants of very low birthweight (more than 3.3 pounds) or born prematurely (less than 32 weeks) in 16 European centres: a database study. The Lancet, Vol. 369, January 6, 2007, pp. 43-50.
Hack M. and Costello D. W. Decrease in frequency of cerebral palsy in preterm infants. The Lancet, Vol. 369, January 6, 2007, pp. 7-8.
Winter S. et al. Trends in the prevalence of cerebral palsy in a population-based study. Pediatrics, Vol. 110, December 6, 2002, pp. 1220-25.
Clark S. L. and Hankins G. D. V. Temporal and demographic trends in cerebral palsy Fact and fiction. American Journal of Obstetrics and Gynecology, Vol. 188, March 2003, pp.628-33.