Associated Malformations in Cases with Neural Tube Defects

Article excerpt

Summary: Associated malformations in cases with neural tube defects: Infants with neural tube defects (NTDs) may have other associated congenital defects. The reported incidence and the types of associated malformations vary between different studies. The purpose of this investigation was to assess the prevalence of associated malformations in a geographically defined population. The prevalences at birth of associated malformations in infants with NTDs were collected between 1979 and 2003 on all infants born in the area covered by the registry of congenital anomalies of Northeastern France in 334,262 consecutive births. Of the 360 infants with NTDs bom during this period, 20.5 % had associated malformations. Associated malformations were more frequent in infants who had encephalocele (37.5 %) than in infants with anencephaly (11.8 %) or infants with spina bifida (23.7 %). Malformations in the face (oral clefts), in the musculoskeletal system, in the renal system, and in the cardiovascular system were the most common other anomalies. In conclusion the overall prevalence of malformations, which was one in five infants, emphasizes the need for a thorough investigation of infants with NTDs. A routine screening for other malformations especially facial clefts, musculoskeletal, renal and cardiac anomalies may need to be considered in infants with NTDs, and genetic counseling seems warranted in most of these complicated cases.

Key-words: Neural tube defects - Congenital anomalies - Birth defects - Anencephaly - Encephalocele - Spina bifida

INTRODUCTION

Neural tube defects (NTDs) are the most common of the severe congenital anomalies of the central nervous system (CNS). Around 20% of the children with NTDs will have a coexisting defect of the non-CNS structures (12).

Studies of NTDs and associated malformations are instructive in understanding embryonic development, identifying the causes of birth defects, determining recurrence risks, and guiding expectations for the efficacy of prevention strategy (12).

However if it has long been known that NTDs are frequently associated with other congenital defects, the reported prevalence at birth and the type of associated birth defects observed vary considerably among diverse studies. It has also not been established whether NTDs are conclusively related to specific types of other congenital defects. There are differences of opinion regarding which organ system is most often affected by associated malformations. Comparisons between older and more recent studies are difficult because a number of what have formerly been regarded as associated malformations are now recognized to be specific syndromes.

Through our surveillance system of congenital anomalies, we evaluated the nature and frequency of malformations that co-occurred with NTDs over a 25-year period.

PATIENTS AND METHODS

The malformations for this study came from 334,262 consecutive births of known outcome, including livebirths, stillbirths and terminations of pregnancy registered by our registry of congenital anomalies, described previously (13). The newborns of 11 hospitals were examined from January 1, 1979, to December 31, 2003. The region of investigation was the city of Strasbourg, France (an urban area), and the area defined by the "département du Bas-Rhin," in which Strasbourg is situated (a rural area). All newborns were registered within the first 8 days postpartum, as were all fetuses. No delivery took place at home in the area under study. Every case was examined by a clinical dysmorphology geneticist. For each infant the type and the exact localisation of the NTD were identified according to the classification of NTD: Anencephaly, Spina bifida and Encephalocele. When a suspected or confirmed case was reported, information was obtained from all available records: prenatal consultation records, maternity files, neonatal unit files, autopsy reports, outpatient clinic files, and pédiatrie surgery files. …