Hagberg G

Changing panorama of cerebral palsy in Sweden. VIII. Prevalence and origin in the birth year period 1991-94

Abstract Aim:  The aim of the study was to describe the prevalence and origin of cerebral palsy (CP), which is the tenth report from the western Swedish study.

The changing panorama of cerebral palsy in Sweden. V. The birth year period 1979-82

ABSTRACT. The prevalence of cerebral palsy (CP) in Swedish infants born in the four‐year period 1979–82 is reported and related to the prevalence in infants bom during the twenty‐year period 1959–78. In 1979–82 it was 2.17 per 1000 livebirths, 1.23 for children bom at term and 0.94 for preterms, which means that the rising trend since the beginning of the 1970s persisted. The most pronounced rise, from 0.18 per 1000 livebirths in the period 1967–70 to 0.67 in 1979–82 was found in the subgroup of preterms with spastic/ataxic diplegia. The severity of motor disability and the relative frequency of mental retardation, infantile hydrocephalus and epilepsy among preterm CP children successively increased over the same period of time. The livebirth prevalence of CP in term infants increased slightly but non‐significantly during the period 1967–82. The birthweight‐specific prevalence of CP per 1000 newborns surviving the first week of life increased in all birthweight groups during the period 1967–82, significantly for birthweights below 1500 g and over 2 500 g. The rising prevalence of CP was concomitant with a parallel fall in perinatal mortality, especially in very preterm infants. In the 1980s, severely multi‐handicapped, very preterm children, only exceptionally seen among CP children born in the 1960s and 1970s, has become a matter of concern.

Decreasing Perinatal Mortality–Increase in Cerebral Palsy Morbidity?

Ever-increasing efforts to help high-risk babies to survive at birth and in the neonatal period are important and necessary. There are good prospects-i.e., many healthy survivors-but also the disadvantage-a slowly increasing group of children who have sustained brain injuries, some of them with several serious impairments. These assertions are made in reports concerning the epidemiology of cerebral palsy (CP) published in the recent issues of this journal (1, 2). Is this a true and generally representative pattern? And, if so, how can it occur, despite all medical efforts and new technologies? General achievements: Positive side. The perinatal mortality (PNM) in most developed countries all over the world has been decreasing during recent decades, although the starting-points, the rates of decrease and the present rates of PNM differ from one region to another. The lowest rates are reported from the Nordic countries and from Japan. The decline there has occurred in all the birthweight groups, but it is most striking among very low birthweight infants (Fig. 1). In Sweden in 1973 PNM was 819 per 1 OOO births for birthweights of less than 1 OOO g. In 1983 it was 364 and now it is still lower (Fig. 1). The decrease in PNM has not resulted in any “compensatory” increase in mortality later on during the first year of life (3). The decline in infant mortality in the 1970s and early 1980s in Sweden has been due to the fall in the early neonatal mortality rate, which has mainly affected low birthweight infants (3). The gain in terms of the improved survival rate for non-handicapped infants is a large one, but it is hidden in the health statistics and therefore easily neglected. The gain is greater when there is a high starting-level of PNM followed by a rapid decline and it becomes gradually smaller as the PNM decreases and the decline levels off. There may be many reasons for the decline, such as living standards and patterns and the quality of perinatal care. It is reasonable to assume that an initial substantial decrease from a high PNM level can be achieved with simple improvements in these respects at relatively low costs and with parallel effects on long-term morbidity. At a later stage, more sophisticated measures and expansive care programs are needed to achieve a further reduction, but these may increase the risks of long-term morbidity-which constitutes the disadvantage of such developments. Risk of CP and birthweight. The risk of CP increases sharply with decreasing birthweight. Fig. 2 shows statistics from Sweden, 1973-76. Similar results are reported from Western Australia and the United Kingdom (4). The liveborn prevalence of CP is 40 times higher in a very low birthweight infant than in one of normal birthwe;ght. Since many more low birthweight infants survive and yet are at a relatively high risk of CP, the overall CP morbidity rate will automatically increase, unless a substantially improved outcome in survivors can be achieved.

Infantile hydrocephalus epidemiology: an indicator of enhanced survival.

The epidemiology of infantile hydrocephalus in the birth years 1973-90 was investigated in west Sweden. The study revealed a significant increase in prevalence from 1973-8 and 1979-82 considered due to the enhanced survival of very and extremely preterm infants. The increase did not continue from 1983-90. This could indicate an improved outcome in preterm survivors as the neonatal survival rate continued to increase. The striking predominance of a perinatal/neonatal aetiology in very preterm hydrocephalic infants could be confirmed: 89% born from 1983-90 had suffered a confirmed postpartum intraventricular haemorrhage. In infants born at term, prenatal origins, mainly maldevelopments, dominated. The outcome in very preterm surviving infants with infantile hydrocephalus was poor: 73% had cerebral palsy, 52% epilepsy, 22% severe visual disability, and 55% were mentally retarded. Despite the increased survival resulting in a majority of healthy infants, there is an accumulating cohort of hydrocephalic children.

Epidemiology of infantile hydrocephalus in Sweden. II. Origin in infants born at term.

ABSTRACT. The aetiology of infantile hydrocephalus (IH) was studied in a population‐based series of 141 children with IH, born at term in southwestern Sweden 1967–82. A prenatal aetiology was present in 81 children (57%), a pre‐ and perinatal in 6(4%), a perinatal in 27(19%), and a postnatal in 8(6%); the origin in 19 children (13%) remained untraceable. A variety of aetiologies were revealed or indicated among prenatal conditions. The dominant intrauterine infection was toxoplasmosis. The predominant perinatal condition was posthaemorrhagic IH. The broad outline of outcome differed between pathogenetic groups. Children with a clear prenatal onset of IH were found to be at high risk for early death or multiple neurological impairments. Thirteen of 63(21%) within this group had died before 2 years of age and 34 of the 50(68%) survivors showed major neurological dysfunction. This contrasted to the incidences of 3% deaths and 30% sequelae in children with IH of other onset.

Epidemiology of infantile hydrocephalus in Sweden. I. Birth prevalence and general data.

ABSTRACT. The Hvebirth prevalence of infantile simple hydrocephalus (IH) was investigated in a Swedish population‐based survey. The study comprised all liveborn infants with IH apparent before the age of one year and born in the study area between 1967‐82. A total of 202 infants fulfilled these criteria; of these, 141 (70 %) were born at term and 61 (30 %) were preterm. The mean prevalence was 0.53 per 1000, with a slightly increasing trend from 0.48 in 1967‐70 to 0.63 in 1979‐82. The increase was entirely referable to the preterm group, in which the prevalence rose from 0.13 per 1000 in 1967‐70 to 0.30 in 1979‐82. There was no tendency to an increase in the term group. In 12 of 23 children born very preterm the origin of the IH was a diagnosed cerebral haemorrhage. This is compatible with the increased risk of the latter condition that has been found in very preterm newborns. The mortality among children with IH was highest before the age of one year (15 %), after which it was 1.2 % per year.

Infantile Hydrocephalus–the Impact of Enhanced Preterm Survival

ABSTRACT. The epidemiology of infantile hydrocephalus (IH) in the birth years 1983‐86 was investigated in the south‐western health care region of Sweden. The study was made as a continuation of a previous one which had shown a significant increase in the prevalence of IH in 1967‐82. That rise was entirely referable to the relatively larger number of preterm IH infants born in 1979‐82 and was considered to be due to the enhanced survival, especially of very preterm infants. The present series comprised 57 liveborn IH infants‐27 preterms and 30 born at term. The livebirth prevalence of IH was 0.64 per 1000, 0.30 for preterm and 0.34 for fullterm infants. The high prevalence of preterm IH infants in 1979‐82 had persisted, but had not increased further. This might indicate an improved outcome in preterm survivors in the period 1983‐86, as the survival rate had continued to increase. The striking predominance of a perinatal aetiology of IH in very preterm infants could be confirmed: 90 % had had intraventricular haemorrhages verified by ultrasound in the postpartum period. The outcome in very preterm surviving infants with IH was still alarmingly poor: 78% had cerebral palsy, 72 % mental deficiency, and 56 % epilepsy.

Head growth in Rett syndrome

The longitudinal development of head growth was investigated in girls with Rett syndrome. Measurements were taken retrospectively from different kinds of records. Growth retardation was expressed in standard deviation (SD) scores. In classic types, the mean head circumference fell successively to 2 SD scores below the norm at the age of 4 y. After the age of 8 y it stabilized close to –3 SD scores. The degree of deceleration correlated strongly to the age at which a deceleration of 1 SD score had occurred. In forme fruste variants, the mean head circumference was within normal limits; however, it was significantly below the norm (–0.8 SD scores). Body height deviated to –2 SD scores at the age of 6 y and was highly correlated to decline in head growth. When head growth was related to the severity of motor disability, there was a continuum from almost normal head growth with well‐preserved gross motor function and some preserved fine motor function to a marked deceleration in head growth with maximum gross and fine motor disability.

Infantile hydrocephalus: declining prevalence in preterm infants

The prevalence and aetiological panorama of infantile hydrocephalus in western Sweden have been followed since the late 1960s. A significant increase in the live birth prevalence of very preterm infants with infantile hydrocephalus was found, from 6.99 per 1000 in the birth year period 1973‐78 to 25.37 in 1983‐86, and owing to an increased survival of very preterm infants with a high risk of hydrocephalus, secondary to an intraventricular haemorrhage occurring in the perinatal period. In the present study covering the birth years 1991–94, a declining prevalence to 13.69 per 1000 very preterm infants was found. In moderately preterm and term groups, mostly with prenatal aetiologies, the prevalence was unchanged. Outcome in surviving children with infantile hydrocephalus remained essentially the same as in previous studies, indicating that the underlying aetiology is the most decisive factor with respect to ensuing neuroimpairments.

Infantile hydrocephalus in preterm, low‐birth‐weight infants—a nationwide Swedish cohort study 1979–1988

All Swedish infants with shunt‐treated infantile hydrocephalus, born during the period 1979–88 at 34 weeks gestational age and of low birth weight, were studied. Ninety‐six infants were born before 32 weeks and 50 at 32–34 weeks. The mean gestational age in the very preterm group gradually decreased from 29.5 to 27.3 weeks. The mean live birth prevalence was 15.9 per 1000 very preterm infants, and 5.1 per 1000 moderately preterm infants. No significant secular prevalence trends were found. The perinatal mortality decreased successively. The slowly decreasing trend in moderately preterm infants may imply better outcome in survivors. The slightly increasing trend in very preterm infants could be explained by more survivors in the low gestational age group. The aetiology was considered perinatal in 94% of the very preterm group and in 56% of the moderately preterm group; prenatal in 1% and 32% of infants, respectively. Additional neuropimairments were present in 82% of infants, cerebral palsy being the commonest (74%).