Original articleTeenage Outcome After Being Born at Term With Moderate Neonatal Encephalopathy
Introduction
Cognitive abilities play an increasingly important role in today’s society. Already from preschool, and throughout the school years, children face exacting demands on “executive” abilities such as planning, organization, speed, attention, flexibility, and initiative. Thus, except for requirements of coping with theoretical problems at school, there are also heavy demands on other, more subtle cognitive abilities. A main clinical area of concern in neuropediatrics is “developmental disorders”, including impairments of cognitive, motor, visual, and hearing functions.
During the last decades, the amount of research in the field of specific cognitive dysfunctions with clinical correlates such as attention-deficit hyperactivity disorder, deficits in attention, motor control, and perception (DAMP), developmental coordination disorder, and autism spectrum disorders [1], [2], [3], [4] has increased tremendously. This research has led to new insights, including better methods for identifying children with cognitive problems. In addition, knowledge about how to provide appropriate educational intervention has emerged.
Children with specific prenatal or perinatal complications run the risk of developing neurologic sequelae [5]. Perinatal asphyxia is a major cause of neurologic sequelae in term infants [6]. The American Academy of Pediatrics and the American College of Obstetrics and Gynecology define perinatal asphyxia according to clinical and biochemical indices [7]. In a study from western Sweden [8], comprising more than 40,000 live infants, a 5-minute Apgar score of <7 was used to deliniate a “low Apgar score group”. The incidence was found to be 6.9/1000 live born infants. When children with opioid-induced respiratory depression, severe congenital infections, neuromuscular disorders, and malformations were excluded (i.e., other main causes of a low Apgar score), the incidence of “birth asphyxia” was found to be 5.4/1000 in live born term infants. The incidence of birth asphyxia with hypoxic-ischemic encephalopathy in that study was 1.8/1000 live-born term infants. A strong perinatal predictor of later neurologic outcome is the presence and severity of encephalopathy [9]. Approximately half of all children born at term with perinatal asphyxia develop clinical neurologic signs of hypoxic-ischemic encephalopathy during the first days of life [8], [10]. Hypoxic-ischemic encephalopathies are classified according to degree of severity—mild (I), moderate (II), and severe (III), respectively [6] (Table 1).
Children with mild hypoxic-ischemic encephalopathy (I) do not appear to have an increased risk of sequelae [8], whereas among children with severe hypoxic-ischemic encephalopathy (III) almost all die or develop severe cerebral palsy with mental retardation and epilepsy. Approximately half of those with moderate hypoxic-ischemic encephalopathy (II) developed cerebral palsy, whereas the development of the remainder of the group was reported to be “normal” at follow-up at age 18 months [8]. However, in the clinical follow-up study by Robertson and Finer [11], cognitive dysfunctions—as reflected by problems with arithmetic, reading, and spelling—were reported also in children without cerebral palsy.
After a systematic review of follow-up studies, Dilenge and collaborators [12] concluded that (a) 30-50% of children with grade II hypoxic-ischemic encephalopathy had mental deficits at follow-up, and (b) making a prognosis in the neonatal period (based on available outcome studies) is difficult. In a Swedish study of term and near term children born in 1969-78 and who required cardiopulmonary resuscitation at birth, two groups of subjects were monitored into young adulthood [13], [14]. Subjects who had died or had developed neurologic impairments before the age of 18 months, i.e., classified as severe with respect to clinical course, were excluded. The clinical and neuropsychological follow-up of those who had had mild (n = 37 and 20, respectively) or moderate (n = 16 and 11, respectively) hypoxic-ischemic encephalopathy revealed no major differences between the resuscitated children and a control group, with respect to school achievements, social adjustments, and cognitive abilities.
A Spanish study [15] reported neuropsychological deficits in adolescents who had suffered moderate perinatal asphyxia. Besides, Marlow et al. [16] have recently demonstrated neuropsychological and educational problems in 7-year-old schoolchildren after neonatal encephalopathy.
Because knowledge about long-term outcome is required for making reasonable prognoses, and for tailoring service needs with regards to clinical assessment of cognitive functioning, we set out to study outcome in late adolescence of a total population birth cohort, born at term, with Apgar score <7 at 5 minutes and moderate encephalopathy in the perinatal period but without cerebral palsy at follow-up. Our hypothesis was that there might be a substantial group with cognitive dysfunctions in the absence of cerebral palsy.
Section snippets
Participants
The study population consisted of all 97,468 children born in Sweden in 1985. Of these, 684 (7.1/10,000) were born at term with an Apgar score of <7 at 5 minutes (“low Apgar score group”) (Fig 1). Of these 684, 73 (11%) had died, 60 of whom in the neonatal period and 13 between the age of 1 month and 15 years. The neonatal records of 51 children could not be found. The remaining 560 records were evaluated. The records of children who had been in the neonatal unit were classified according to
Children Without Reported Problems
Eight of 28 children (29%) in the moderate neonatal encephalopathy group and 12 of 15 (80%) in the sibling group had no reported problems (P < 0.01). When only those 3 of 14 (21%) probands who had a control sibling were included in the analysis, the difference remained significant (P < 0.01).
Neurologic and Medical Problems
Specific neurologic diagnoses (n = 8) reported in the neonatal encephalopathy group were: hearing impairment (n = 5), brachial plexus palsy (n = 1), pes equinovarus (n = 1), and “benign epilepsy” (n = 1).
Discussion
Fewer than one in three of all children with neonatal encephalopathy and no cerebral palsy (or other major neuro-impairments) were reported to be without problems in their late teens. The impairing problems reported in this subgroup ranged from learning disability and learning problems through motor control problems, attention-deficit hyperactivity disorder, and peer difficulties.
There are different perspectives on clinical outcomes after different kinds of risk situations in newborn children:
Clinical Implications and Conclusions
We conclude that it is time to reconsider motor functioning as being the major and exclusive measure of neurologic outcome after asphyxia. This assertion is in line with the ongoing discussion regarding the need for a new definition of cerebral palsy, i.e., a broader definition that in addition to the motor impairment, also takes into account the child’s cognitive functioning [29], [30]. A longer term follow-up, by a pediatrician/neuropediatrician and a clinical child psychologist with
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