Hj Huisjes

OBSTETRICAL CONDITION AND NEONATAL NEUROLOGICAL MORBIDITY - AN ANALYSIS WITH THE HELP OF THE OPTIMALITY CONCEPT

In order to increase understanding of the origin of neonatal neurological morbidity, the relationship between the obstetrical and neonatal neurological conditions was studied in a 3-year cohort containing 3162 singleton infants. The infants were neurologically examined at term age according to the technique described by Prechtl. Obstetrical data were documented extensively. Prechtls optimality concept was applied in the analysis. A statistically significant relationship was found between the obstetrical and neonatal neurological optimality scores. There was no sex difference in the obstetrical optimality, whereas there was in the neurological optimality, to the advantage of the girls. It could be shown that obstetrical conditions such as acidemia, preterm birth and intrauterine growth retardation have a stronger relationship to neurological morbidity when the accompanying obstetrical optimality is lower. In obstetrical practice the application of the optimality concept to obstetrical and neurological data is a helpful complementary refinement.

PERINATAL CORRELATES OF MAJOR AND MINOR NEUROLOGICAL DYSFUNCTION AT SCHOOL AGE - A MULTIVARIATE-ANALYSIS

A prospective study was carried out on 747 infants: 147 neurologically abnormal, 300 with mild neurological abnormalities and 300 normal infants. They were re‐examined at nine years of age, with special attention being paid to minor neurological dysfunction (MND). Extensive data on obstetrical abnormality, risk factors contributing significantly to later handicap were low one‐minute Apgar scores, a disturbed neonatal course, low social‐class and interval complications: obstetrical events were conspicuous by their absence. Two aetiologically and clinically distinct kinds of MND were distinguished on the basis of a neurological cluster profile: MND‐1 (one or two abnormal clusters) was only associated with a birthweight below the 2·3 centile and male gender, and MND‐2 (more than two abnormal clusters) was associated with neonatal neurological findings, social class, obstetrical optimality score and gender.

PERINATAL RISK FACTORS AND MINOR NEUROLOGICAL DYSFUNCTION: SIGNIFICANCE FOR BEHAVIOUR AND SCHOOL ACHIEVEMENT AT NINE YEARS

A prospective study was carried out on 133 neurologically deviant infants, 205 with mild abnormalities and 230 normal newborns to compare behavioural and cognitive development with neonatal and nine‐year‐old neurological condition. Overtly handicapped children were excluded. Major determinants of school failure were the severity of minor neurological dysfunction (MND) and social class. Main risk factors for distractable and clumsy behaviour were MND classification and male sex; for troublesome behaviour male sex and interval complicatons after two years of age; and for timid behaviour, family adversity. Definite neonatal neurological deviancy contributed both directly and by its association with MND to problems in behaviour and scholastic abilities. Mild neonatal neurological abnormalities and adverse obstetrical events contributed only indirectly to behavioural and learning problems. Preterm birth (<34 weeks) was the sole obstetric variable directly related to some of the outcome variables. The difference between home and school perception of the childrens behaviour is emphasized.

Preterm or small-for-gestational-age infants

In 166 full term, small-for-gestational-age (FT-SGA), 53 preterm, appropriate-for-gestational-age (PT-AGA), 27 PT-SGA and 206 FT-AGA infants a neurological examination at the age of 6 years was carried out. Data were collected on behaviour and school achievement. Major and minor neurological abnormalities were more frequent in the three low birth weight groups, especially in the PT-SGA group. Multivariate analysis showed that the development of major and minor neurological abnormalities was explained by a varying set of risk factors, in which besides prematurity and growth retardation, neonatal neurological condition, social class, neonatal course and interval complications were preponderant. The results suggest a temporal difference in potentially harmful factors: for neurological handicap early in pregnancy, for minor neurological dysfunction (MND) the second half of gestation and the first 2 years of life. No striking behavioural differences were found between the three low birth weight groups and the FT-AGA group; behaviour was related to neonatal and follow-up neurological condition, sex, gestational age and birth weight to a limited extent only. Three (4%) of the preterms entered a special school (already at the age of 6). School achievement was mainly related to the present neurological condition and social class, which underlines the importance of the latter.

OBSTETRICAL-NEONATAL NEUROLOGICAL RELATIONSHIP - A REPLICATION STUDY

A study concerning the relationship between neonatal neurological abnormality and 3 parameters of pre- and perinatal condition in a birth cohort of 1507 infants was replicated in a second cohort of 1655 infants. The 3 parameters chosen were preterm birth, intrauterine growth retardation and neonatal acidemia. The neurological examination in the second cohort was carried out by other examiners than in the first cohort. The incidence of neurological abnormality was again found to be raised in all 3 categories and again least in the acidemic subgroup. Also the finding could be confirmed that only in about half of the neurologically abnormal infants could the 3 parameters have exerted any effect at all, which implies the necessity of further analysis. This replication study shows that neurological examination in the newborn period is a reliable tool for the evaluation of the condition of infants with respect to their pre- and perinatal history.

Minor neurological dysfunction from birth to 12 years. I : Increase during late school-age

To study the hypothesis that the frequency of minor neurological dysfunction (MND) stabilizes around the age of nine years, two groups of the Groningen Perinatal Project (GPP) were reexamined at 12 years. The study group (N = 174) was selected on the basis of the presence of MND at nine years; the control group comprised 172 neurologically normal children. The hypothesis was rejected: extrapolation of the findings to the total GPP population showed that the over‐all rate of MND increased. Control children who developed MND were mainly boys who had been neurologically abnormal at birth or were born preterm and/or had experienced an adversity in combination with asphyxia. Interval complications between nine and 12 years were related to the emergence of MND.

NEUROLOGICALLY DEVIANT NEWBORNS: NEUROLOGICAL AND BEHAVIOURAL DEVELOPMENT AT THE AGE OF SIX YEARS

Of 1655 newborns examined neurologically at term, 80 were found to be abnormal. 76 were traced at six years of age, together with a control group of 77 neonatally normal children. In the study group five children had died, six were severely handicapped and 21 had minor neurological dysfunction (MND). In the control group two had died and four had MND. Obstetrical and neonatal paediatric effects, as well as complications in the intervening years, appeared to have a cumulative effect on the relationship between the neonatal neurological condition and the neurological findings at six years. There were no large differences in behaviour between the study group and the controls, but the study‐group MND children showed a stronger tendency for undesirable behaviour and poor school achievements. Although environmental influences are preponderent for the development of behaviour and school performance, a contribution of both neonatal and later neurological conditions seems likely.

Is clonidine a behavioural teratogen in the human

Twenty-two children prenatally exposed to clonidine and no other hypotensive drugs were compared at a mean age of 6.3 +/- 1.6 years to a non-exposed control group, matched for degree of maternal hypertension, sex, birthweight and gestational age. There were no differences in head circumference, neurological findings, school performance and a number of behavioural characteristics except for a marginal excess of hyperactivity and an excess of sleep disturbances in the study group. It is questionable whether the differences represent a direct effect of clonidine on prenatal development but the dose-effect relationship and the fact that the same effects have been found in rats suggest that this may be so.

IS MINOR NEUROLOGICAL DYSFUNCTION AT 12 YEARS RELATED TO BEHAVIOUR AND COGNITION

Behavioural and cognitive development at 12 years were studied in 172 children with and 174 children without minor neurological dysfunction (MND). MND could be differentiated into line manipulative disability, co‐ordination problems, hypotonia and choreiform dyskinesia. Fine manipulative disability related significantly to problems of cognition and behaviour; co‐ordination problems t o cognitive problem; and hypotonia and choreiform dyskinesia to behavioural problems, the former more than the latter. Socio‐economic status and family adversity contributed to the risk for development of both cognitive and behavioural problems; gender did not. The onset of puberty seemed to change these relationships: follow‐up is needed for definite conclusions.

Minor neurological dysfunction after the onset of puberty: association with perinatal events

In order to study the hypotheses that puberty is related to a decrease of minor neurological dysfunction (MND) and that persisting MND is associated with perinatal factors, two groups (174 normal, 172 MND) of the Groningen Perinatal Project were followed from 12 to 14 years. At 14 years almost all the children had entered puberty (n = 329) defined as the presence of three or more puberty signs. In the MND group 55% of the children were normal at 14 years and in 45% MND signs were still present, though in a less extensive form. The latter phenomenon was most clear in children who had just begun puberty. The effect of puberty was similar in both sexes. MND which persisted into puberty was related to neonatal neurological deviancy, lower social class, lower obstetrical optimality score and male sex. After differentiation with specific MND clusters, it appeared that fine manipulative disability was associated with neonatal neurological deviancy, with minor physical anomalies and with lower social class; choreiform dyskinesia with asphyxia; hypotonia with constitutionally related factors; and coordination problems with pre-maturity (< 32 weeks).