LEARNING PROBLEMS AND THE CENTRAL NERVOUS SYSTEM IN CHILDREN WITH SPINA BIFIDA

BY DR. JACK FLETCHER, Professor of Pediatrics at The University of Texas-Houston Health Science Center.

    Spina bifida meningomyelocele is the most common severely disabling birth defects in North America. Children born with spina bifida meningomyelocele have a well known spine malformation that is responsible for the identification as a child with spina bifida at birth. The spine malformation is associated with a variety of problems, including difficulties with ambulation, bladder problems, and other factors that often lead to physical disability. However, what is often not recognized is that children with spina bifida meningomyelocele usually have characteristic malformations of the brain that result not only in hydrocephalus, but in longer term learning difficulties that interfere with school functioning and behavioral adaptation.

    Most children with spina bifida meningomyelocele have a malformation of the hindbrain and cerebellum called Arnold-Chiari II malformation. This malformation usually obstructs the flow of cerebrospinal fluid (CSF), leading to progressive hydrocephalus that requires shunting in 80-90% of children with spina bifida meningomyelocele. They cerebellum is responsible for fine motor functions and is also a gateway for a variety of cognitive skills that involve attention, planning, and the learning procedures. It is less well-known that many children with spina bifida meningomyelocele have other congenital brain abnormalities. The most common involves the corpus callosum. The corpus callosum is a fiber pathway that connects the two cerebral hemispheres. In many children with spina bifida meningomyelocele, parts of the corpus callosum may be missing, which is termed "partial agenesis". Since the corpus callosum is the major fiber pathway that connects the two cerebral hemispheres, children with corpus callosum anomalies may have reduced communication between the two cerebral hemispheres. Research completed by our group has shown that the development of the corpus callosum is clearly related to the problems with spatial and motor skills that characterize many children with spina bifida meningomyelocele.

    The hydrocephalus that many children with spina bifida develop also has significant effects on the brain. When significant hydrocephalus occurs, white matter fibers such as the corpus callosum are often stretched. Common in children with hydrocephalus is selective thinning of posterior brain regions associated with the development of spatial skills.

    These central nervous system changes in children with spina bifida meningomyelocele are associated with problems in development of cognitive and motor skills, and behavioral difficulties that reflect the effects of these cognitive problems. Despite the extent to which the central nervous system is altered in children with spina bifida meningomyelocele, few children with spina bifida meningomyelocele are mentally deficient. Moreover, few children can be characterized simply as slow learners: the child with spina bifida meningomyelocele typically has strengths and weaknesses (or as some parents would say, valleys and mountains!) in their learning profiles.

    Learning deficiencies that characterize many children with spina bifida meningomyelocele include deficiencies in non-verbal skills, including motor, perceptual-motor, and visual-spatial skills. Many children with spina bifida meningomyelocele have a particular type of learning disability called a "non-verbal" learning disability. Non-verbal learning disabilities are associated with social problems, particularly as the child enters adolescence. This problems is a result of the interaction of the cognitive difficulties and the types of response that many children with spina bifida meningomyelocele receive from the environment. As adolescents, some children with spina bifida meningomyelocele may become more lethargic and somewhat depressive, showing tendencies towards social isolation.

    Non-verbal learning disabilities often include problems with math. Indeed, the most common academic deficit characterizing children with spina bifida meningomyelocele is a problem with any form of math. As adults, many individuals with spina bifida meningomyelocele and other problems that lead to early hydrocephalus show profound problems with mathematics that are quite handicapping to them as adults. In contrast, reading problems are less apparent. In particular, word recognition and spelling skills are often well developed. Problems with reading comphrension are more likely, but not as common as problems with math and writing.

    Children with spina bifida meningomyelocele use and understand single words with some skill. They often have large vocabularies and seem highly fluent to the external observer. However, many children with spina bifida meningomyelocele have problems formulating language at the level of both text and discourse. What this means is that in expressing an idea or in comprehending reading material, many children with spina bifida meningomyelocele have difficulty either organizing verbal output, or understanding large amounts of text.

    Many children with spina bifida meningomyelocele have difficulties with memory and attention. These problems are not well understood, but often manifested in difficulties with attention span, attention shifting, and controlling the focus of attention. This is a cognitive problem than can be manifested in the child's behavior. In many children with spina bifida meningomyelocele this problem reflects a reduction in the level of arousal and alertness. It is not the same type of attention problem observed in hyperactive/impulsive children, and children with spina bifida meningomyelocele very rarely show this type of attentional disorder. The attentional problems that characterize many children with spina bifida meningomyelocele tend to be under identified and under treated. These behaviors, along with the manifestations of reduced arousal are often interpreted as passivity, lack of interest in learning, and poor motivation by many individuals in school settings. In fact, these problems are often manifestations of cognitive difficulties that are secondary to the underlying neurological disorder.

    It is important for parents and advocacy groups to help schools begin to recognize the characteristic learning deficits apparent in many children with spina bifida meningomyelocele. One of the most important changes that should occur for these children is to ensure that the neurological component of their disability is recognized as part of their handicapping condition. One of procedures that we commonly follow is to change the handicapping condition to include provisions in special education legislation that are specific for children with underlying neurological disorder. For example, in addition to orthopedically handicapped, we ask that the child also be qualified for special education as a child with "Other Health Impairment", which includes children with neurological disorders. It is important to emphasize that the learning deficits are products of the central nervous system components of spina bifida meningomyelocele, and not just behavioral difficulties that reflect poor motivation and lack of interest in learning. Programming appropriate for children with non-verbal learning disabilities is available, but these programs are presently not easily translated into academic solutions. In addition, children with spina bifida meningomyelocele may not always show a non-verbal learning disability, and may have other learning difficulties with language formulation, reading comphrension, attention, and problem solving do not characterize every child, and may be present or absent to varying degrees within an individual child. Parents can be effective advocates for their child. With any child with a disability, it is important for parents to be informed about their child, to advocate for their child, and for professionals to provide parents with as much usable information as possible.

    It is our hope that  better understanding of children with spina bifida meningomyelocele will lead to the development of systematic programs for these children that will impact on their early development and school functioning. The National Institute of Child Health and Human Development (NICHHD) awarded researchers a $5.7 million grant for a project on children with spina bifida, The Spina Bifida Assessment of Neurobehavioral Development-International (SANDI) Project. The lead institution in this project is the University of Texas-Houston Health Science Center. In addition, The Hospital for Sick Children in Toronto represents a second data collection site. Other participating institutions include the Baylor College of Medicine and the University of Virginia, along with clinics at Texas Children's Hospital, Shriners Hospital for Children, and Memorial Hermann Children's Hospital in Houston, and The Hospital for Sick Children and MacMillan Rehabilitation Centre in Toronto.

To learn more about the SANDI Project, please visit http://ped1.med.uth.tmc.edu/spinabifida or contact nurse study coordinator, Irene Townsend, R.N. at 713.500.3678 or email her at Irene.T.Townsend@uth.tmc.edu.

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