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Lookup NU author(s): Professor Judith Rankin
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Introduction: Congenital hydrocephalus (CH) is an aetiologically heterogeneous central nervous system abnormality characterised by an imbalance in the production and reabsorption of cerebrospinal fluid leading primarily to enlargement of the ventricles and associated with cerebral atrophy and mental deterioration in severe eases. The prevalence of CH varies substantially depending on the inclusion criteria of the study, in particular, whether or not neural tube defects (NTDs) associated with hydrocephalus are included. The commonest underlying cause of obstructive CH is stenosis of the aqueduct of Sylvius or occlusion of Magendic's and Lsc/ifaj's foramina, often genetically determined. Congenital infections, intracranial haemorrhages and tumours can also result in Ci I (2). However, the majority of cases of CI I are of unexplained aetiology. This population-based regional study reports the prevalence, birth outcome, associated anomalies and the sensitivity of antenatal diagnosis of CH not associated with NTDs, in the Northern Health Region for the twelve years 1985-1990. Methods: Population: The former Northern Region is a defined geographical area comprising the counties of Cumbria, Northumberland, Durham, Cleveland and Tyne and Wear. It has a population of three million and approximately 30,000 births per year. Survey: Cases of CH were identified through the Northern Congenital Abnormality Survey (NorCAS). NorCAS is an ongoing, population-based register of major congenital malformations occurring to mothers resident in the former Northern Region, irrespective of when they were first identified or whether they resulted in spontaneous abortions, terminations of pregnancy or registered births. Cases are notified from multiple sources and are checked for duplication before being entered onto the database. Further details of data collection have been described previously (1). Study sample: All cases with a final postnatal diagnosis of CH ([CD 9 code 742.3) (3), which had been delivered between 1985 and 1996, formed the case series. To investigate trends in sensitivity of antenatal diagnosis, the twelve-year period was divided into two equal periods: 1985-1990 and 1991-1990. Cases of Q-1 associated with NTDs were excluded. The annual numbers of regional births were obtained from the Office for National Statistics. Results: 185 cases of CH not associated with NTDs were notified to the NorCAS between 1985-199(5. Of these, 81 (43.8%) were of unexplained congenital aetiology; 20 (14.1 %) were due to stenosis of the aqueduct of Sylvias; 29 (15.7%) were consequences of the atresia of foramina of Magendie and Luschka (including Dandy-Walker syndrome, five of which were associated with chromosomal anomalies); a further 10 (5.4%) and 37 (20.0%) cases were associated with chromosomal and structural anomalies respectively; and 2 (1.1%) were caused by congenital infections (one hy toxoplasmosis and one by cytomegalovirus). There were 174 (94.1%) singleton pregnancies and 11 (5.9%) twin cases. Sex was recorded in 97.3% of cases; the male/female ratio was 1.5. The mean (±SD) maternal age was 26.5 (5.4) years (range 15-45); 168 (90.8%) cases were women aged less than 35 years. Prevalence rate: The total prevalence of CI 1 was 3.7 (95 % CI 3.2 to 4.3) per 10,000 births and terminations, which oscillated over the years but showed an upward trend with the highest rate being in 1995. There was a significant increase in the total prevalence for CH from 1.94 per 10.000 in 1985 to 4.1 in 1996 (x2 test for linear trend = 5.36, p = 0.02). The birth prevalence of CH was 2.5 per 10,000 births. There were considerable annual fluctuations in the birth prevalence from 1.2 to 3.4 per 10,000 births, with no discernible linear trend (yf test for linear trend = 0.12. p = 0.73). Antenatal diagnosis: Antenatal detection by routine ultrasound screening of all types of CH improved during 1991-1996 compared with 1985-1990; undetected cases decreased from 36.9% in 1985-1990 to 17.8% in 19911996 (p = 0.006) and the proportion of early detected (before 24 weeks of gestation) cases increased from 29.8% in 1985-1990 to 56.4% in 19911996 (p = 0.0005). Isolated CH: Cases of CH of idiopathic origin (81), due to either aqueduct stenosis (18), Dandy-Walker syndrome (15) or congenital infection (2), were recorded as a single condition (isolated CH). Of 81 cases of idiopathic Cl 1, eight (9.9%) aborted spontaneously, 21 (25.9%) were terminated, 10 (12.3%) were stillbirths and 42 (51.8%) were livebirths. Of the 42 livebirths, 30 (71.4%) were alive at one year. The sensitivity of antenatal detection by routine ultrasound screening improved during 1991-1991) compared with 1985-1990: 53.2% of cases were diagnosed before 24 weeks of gestation in 1991-1996 compared with 26.5% in 1985-1990 (p = 0.029). There was an increase in the proportion of terminations from 17.6% in 1985-1990 to 31.9% in 1991-1996. The proportion of stillbirths and infant deaths decreased from 47.0% to 12.8%; in contrast, the proportion of children alive at one year increased from 52.6% of livebirths in 1985-1990 to 87.0% in 1991-1996. CH associated with a chromosomal anomaly: Of the 15 (8,1 %) cases of CI I (5 due to Dandy-Walker syndrome and 10 idiopathic CH) associated with a chromosomal anomaly, ten were trisomies: three cases each of trisomy 21 and trisomy 18, two of trisomy 13 and two other trisomies; three were translocations, one case was an autosomal deletion and one was an autosomal duplication. Eleven of the 15 were diagnosed antenatally (9 before 24 weeks of gestation). Of these 15 cases, eight were terminated, one was a spontaneous abortion, two resulted in intrauterine death, three died in infancy and one (with autosomal duplication) survived the first year of life. CH associated with other structural anomalies: Fifty-four (29.2%) cases of CH were associated with other structural anomalies. There were two spontaneous abortions, 20 terminations of pregnancy, six stillbirths, 14 infant deaths and 12 children were alive at one year. Conclusion: The total prevalence of CH increased significantly, while the birth prevalence did not change over the twelve years of the study. The difference in the trends can be attributed to an improvement in antenatal detection of CH (including isolated CH) by routine ultrasound screening and, consequently, to an increase in the number of terminations. One-year survival improved in the group of isolated CH of unexplained aetiology but not in the group of CI I associated with structural anomalies. © Hippokrates Verlag.
Author(s): Rankin J; Glinianaia SV
Publication type: Article
Publication status: Published
Journal: European Journal of Pediatric Surgery, Supplement
Year: 1999
Volume: 9
Issue: 1
Pages: 46
Print publication date: 01/01/1999
ISSN (print): 0939-6764
ISSN (electronic):
Publisher: Hippokrates Verlag in MVS Medizinverlage Stuttgart GmbH & Co.KG
PubMed id: 10661797
