Variability of Diagnosis of Cerebral Palsy of Preemies
Diagnosis of cerebral palsy varies widely over time and among practitioners.
Back when I was writing the first edition of The Premature Baby Book (early 1980s), Cerebral Palsy (CP) was a term that was broadly used to refer to neurologically based motor problems in which the injury occurred in the prenatal or perinatal period. Now it is defined very strictly so that some preemies who seem to have neurologically-based movement disorders are not being classified as having CP.
For example, in a recent study of 425 very low birth weight children in Wisconsin, only 12.6% of the children had a CP diagnosis at age 5. However, 29.4% (nearly one-third!) scored more than 2 standard deviations below the mean in tests of mobility. When someone scores this low on an IQ test it is called retardation and is considered to be a serious handicap.
Usually preemies with motor problems who do not have a CP diagnosis are said to be "developmentally delayed," but by age five, a delay of this magnitude looks like a permanent problem. (Palta M et al. Functional assessment of a multicenter very low-birth-weight cohort at age 5 years. Archives of Pediatric and Adolescent Medicine Jan, 2000; 154 : 23-30)
There has been recent criticism of the use of the strict definitions of CP in follow-up studies, because a lot of kids with obviously serious motor problems are not included. Last month, the EPICure study from the UK and Ireland was published in The New England Journal of Medicine. The study included all children born from March through December of 1995 who were below the gestational age of 26 weeks. The 283 children were evaluated at 30 months. Overall, half the children had a disability at this point with 18% having cerebral palsy. However a number of other children had serious motor disability that failed to meet the CP definition. Here is what the authors wrote about it: "Cerebral palsy is often chosen as an index of long-term outcome by which changes in neonatal and perinatal care can be measured, because the clinical syndromes are often recognizable by two years of age. However, as a means of identifying disability, this method would lead to an underestimation of motor disability in the children in our study: of 67 children with abnormal motor function, only 50 (75%) had a recognizable pattern of cerebral palsy." (Wood N et al. Neurologic and Developmental disability after extremely preterm birth. New England Journal of Medicine August 10, 2000: 343 : 378-384.)
As part of an international follow-up study of school age preemies, I have been in meetings where we all looked at videotapes of the movement patterns of various prematurely born children. In reaction to one child's video (a child whose CP looked less serious than my son's, BTW), one physician member of a world renowned follow-up team remarked that this was obviously "disabling cerebral palsy," while a member of another even more famous follow-up team asked in astonishment: "You mean you call *that* cerebral palsy?!? [This child wouldn't even have been given a CP diagnosis in their study.]
So CP diagnosis, even with new standards and definitions, is highly subjective.
I think the lesson here is that the words "cerebral palsy" don't necessarily tell how a child is actually functioning, and that is the most important consideration. Motor disorders in preemies seem to exist on a spectrum, and only some of this spectrum is currently characterized as CP. And there are a lot of behavioral and perceptual, and cognitive issues related to neurologically-based motor problems whether these motor problems are referred to as CP or not. Cortical vision problems (which my son also has, along with his "mild" CP) are often part of the pattern. Even with very mild motor problems, preemies tend to have a constellation of behavioral, cognitive and perceptual issues that are also seen in kids with diagnosed CP.