Three percent of all newborns in Canada are born with some type of congenital anomaly, also called "birth defects". This rate increases in the first 2 years of life to 7%, asother congenital anomalies not apparent in the newborn are diagnosed. Congenital anomalies are the leading cause of infant death in Canada. 15 The birth of a child with a severe congenital anomaly represents a personal tragedy for the child and its family. Many congenital anomalies are treatable; others are not. Residual health concerns can affect the quality of life, impose chronic disabilities, and carry with them social, financial and psychological burdens. 16
Among the most common congenital anomalies are congenital heart anomalies, urinary tract anomalies, cleft lip and palate, limb abnormalities including clubbed feet, and NTDs. Included among the NTDs are the more commonly recognized abnormalities of anencephaly and spina bifida cystica (commonly referred to as spina bifida), including meningocele, meningomyelocele and lipomeningocele. 12 Other NTDs less commonly encountered are encephalocele, craniorachischisis, double neural tube defects, acranium, exencephaly, faciocranioschisis and faciocraniorachischisis.
Figure 1 illustrates some of these NTDs. The most severe of the NTDs are invariably lethal, often resulting in spontaneous miscarriage and stillbirth. Less severe NTDs, including lipomeningocele, encephalocele and spina bifida, are usually not lethal and have a survival rate in infancy of over 90% of those born in North America. 17
Until recently, congenital anomalies were viewed by health professionals, and as a consequence by lay people, as a fact of life about which nothing could be done. We now have solid evidence that the congenital anomaly risk can be reduced substantially by increasing the intake of the B vitamin folic acid and its naturally occurring folate forms.
Yes, most certainly. Improved health care and prolonged survival mean that everyone, every day, will interact with, work with, work for and encounter individuals born with congenital anomalies, including spina bifida and other milder NTDs. Spina bifida is the most common cause of ambulatory disability due to a congenital anomaly. 17 18
In Canada, the birth prevalence of NTDs has been declining gradually. The 1997 national rate was 7.5 per 10,000 total births (live births and stillbirths), or about 260 affected births per year, down from a rate of 11.6 per 10,000 total births in 1989. 19 Possible reasons for this decrease in the rate of NTD births include increased vitamin supplementation and increased use of prenatal diagnosis with subsequent pregnancy termination. There are only limited national data to estimate rates of termination of affected pregnancies following prenatal diagnosis.
The rates of NTDs tend to be higher in the eastern provinces than in western Canada. Certain ethnic groups, including people of Celtic, Northern Chinese and Sikh heri tage, are at higher risk of having children with NTDs. 18 20 23 It remains unclear to what extent these risks are due to genetic predisposition, cultural dietary preferences or a combination of factors (see later section on Etiology of NTDs).
Newborns with severe NTDs, such as anencephaly and craniorachischisis, die in the first days of life. No treatment is available to alter their clinical course, and supportive care is provided. The majority of infants born with spina bifida survive, requiring extensive medical and surgical care. In the United States, the estimated fatality rate in infancy is 10%. 17 Long term outcome studies have documented survival into the third decade of life in 52% 17 and in 68% 24 of NTD-affected people who had surgical treatment as newborns.
The lifetime implications for those with multiple impairments and for their families can be challenging. 16 For spina bifida and other anomalies, management of the health care concerns is best done by a multispecialty team. The level of the meningomyelocele influences the overall range of predicted outcome. 25 Those with sacral and lumbosacral lesions fare best, as compared with those with thoracolumbar NTDs. Ability to ambulate independently, urinary and bowel continence, degree of developmental delay and school performance vary according to the level of spinal lesion and the neurological deficit. Over 90% of affected people have an associated Arnold-Chiari malformation of the brain and hydrocephalus requiring shunting. Shunt revisions are frequently necessary. Secondary disabilities in the adult meningomyelocele population include obesity, hydronephrosis and renal failure, pressure ulcers, loss of ambulation, osteoporosis, contractures, social isolation and depression. 26 28
The estimated monetary costs of spina bifida are substantial. In Canada a decade ago, hospital and rehabilitation services alone were estimated to cost $42,507 during the first 10 years of life for a child with spina bifida. 29 These costs have, without a doubt, increased substantially, although accurate figures are not available. In the United States it is estimated that $200 million annually are spent in direct medical costs for individuals with spina bifida. 30 The lifetime economic cost to society per person with spina bifida is about $258,000 USD. 31