Chapter 16.2 - Neural tube defects

Summary

Introduction

Despite advances in prevention, diagnosis, and treatment, neural tube defects (NTDs) remain a major source of morbidity and mortality in the United States and throughout the world. Daily consumption of 400 µg of folic acid before conception dramatically reduced the occurrence of NTDs, but prior to the institution of food fortification, only 29% of reproductive-aged women in the United States were taking a supplement containing this amount [1]. Although routine cereal grain fortification has resulted in a 19% decrease in prevalence, the prevalence values per 10 000 births remain 4.18, 3.37, and 2.90 respectively for Hispanic, non-Hispanic white, and non-Hispanic black women [2]. It is estimated that 23% of pregnancies in which the fetus is diagnosed with an NTD end in elective termination, but the remainder ultimately are delivered. Furthermore, the prenatal management of spina bifida differs depending on the country: as a rule, there is more support for aggressive and intensive treatment in Asia and some regions of the United States than in Europe, although immigration patterns may be changing this.

Although folate supplementation and advances in care may be decreasing the mortality associated with spina bifida, the 5-year mortality remains 79 per 1000 spina bifida births [3]. The mortality is as high as 35% among those with symptoms of brainstem dysfunction secondary to the Chiari II malformation [4]. In addition to sphincter dysfunction and lower extremity paralysis, 81% of affected children have hydrocephalus requiring treatment [5]. Although newer techniques are available for the treatment of hydrocephalus such as endoscopic third ventriculostomy and choroid plexus cauterization, these are not particularly effective in the infant with myelomeningocele, and shunts with all of their problems remain the mainstay of treatment. Roughly 70% of affected individuals have an IQ above 80, but only 37% are able to live independently as adults and one-third need daily care [6]. The economic cost of caring for these patients is large. A recent estimate of incremental direct medical costs for the first year of life for a child with spina bifida compared with those without was $52415 for the first year of life and $560000 for the lifetime in 2003 dollars [7, 8].