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Published on: September 6, 2017
Fetal heart rate evolution and brain imaging findings in preterm infants with severe cerebral palsy
Masahiro Nakao1, Yukiko Nanba2, Asumi Okumura3
1Recurrence Prevention Committee, The Japan Obstetric Compensation System for Cerebral Palsy, Japan Council for Quality Health Care, Tokyo, Japan; Department of Obstetrics and Gynecology, Mie University Graduate School of Medicine, Mie, Japan; Department of Obstetrics and Gynecology, Sakakibara Heart Institute, Tokyo, Japan.
Insights
Fetal heart rate patterns can help identify brain injury timing in preterm infants with severe cerebral palsy. Persistent non-reassuring patterns and bradycardia significantly increase the risk of basal ganglia-thalamus injury.
Area of Science:
- Neonatal neurology
- Obstetrics
- Fetal monitoring
Background:
- Cerebral palsy (CP) is more prevalent in preterm infants.
- Fetal heart rate (FHR) monitoring aids in estimating the timing of brain injury and its relation to delivery.
- Understanding injury timing and type can inform preventive obstetrical care.
Purpose of the Study:
- To investigate the link between the timing of insults and the specific type of brain injury in preterm infants diagnosed with severe CP.
- To compare risk factors for basal ganglia-thalamus (BGT) injury versus white matter (WM) and watershed (WS) injuries.
Main Methods:
- Longitudinal study using a nationwide CP database (2009-2014).
- Included preterm infants (28-33 weeks gestation) with severe CP (GMFCS levels 3-5).
- FHR patterns evaluated by blinded obstetricians; brain MRI findings assessed by a blinded pediatric neurologist.
Main Results:
- Of 140 eligible infants, 57% had presumed antenatal CP onset, 13% intrapartum.
- Basal ganglia-thalamus injury observed in 34% of infants.
- Continuous bradycardia and persistently non-reassuring FHR patterns significantly elevated risk for BGT injury.
Conclusions:
- Antenatal insults are presumed causes in the majority of severe CP cases in preterm infants.
- While WM-WS injury is common, severe acute hypoxia-ischemia is a key prenatal etiology for severe CP in this population.
- FHR monitoring is crucial for identifying infants at high risk for specific brain injury types.
Background:
Cerebral palsy is more common among preterm infants than among full-term infants. Although there is still no clear evidence that fetal heart rate monitoring effectively reduces cerebral palsy incidence, it is helpful to estimate the timing of brain injury leading to cerebral palsy and the causal relationship with delivery based on the fetal heart rate evolution patterns. Understanding the relationship between the timing and the type of brain injury can help to identify preventive measures in obstetrical care.
Objective:
This study aimed to examine the relationship between the timing of insults and the type of brain injury in preterm infants with severe cerebral palsy.
Study Design:
This longitudinal study was based on a nationwide database for cerebral palsy. The data of infants with severe cerebral palsy (equivalent to levels 3-5 of the Gross Motor Function Classification System-Expanded and Revised), born between 2009 and 2014 at 28 to 33 weeks of gestation, were included. The intrapartum fetal heart rate evolution patterns were evaluated by 3 obstetricians blinded to clinical information other than gestational age at birth, and these were categorized after agreement by at least 2 of the 3 reviewers into (1) continuous bradycardia, (2) persistently nonreassuring (prenatal onset), (3) reassuring-prolonged deceleration, (4) Hon's pattern (intrapartum onset), (5) persistently reassuring (pre- or postnatal onset), and (6) unclassified. Infant brain magnetic resonance imaging findings at term-equivalent age were assessed by a pediatric neurologist blinded to the background details, except for gestational age at birth and corrected age at image acquisition, and these were categorized as (1) basal ganglia-thalamus, (2) white matter, (3) watershed cortex or subcortex, (4) stroke, (5) normal, and (6) unclassified based on the predominant site involved. The risk factors for the basal ganglia-thalamus group were compared with those of the combined white matter and watershed injuries group.
Results:
Among 1593 infants with severe cerebral palsy, 231 were born at 28 to 33 weeks of gestation, and 140 met the eligibility criteria. Fetal heart rate evolution patterns were categorized as bradycardia (17% [24]); persistently nonreassuring (40% [56]); reassuring-prolonged deceleration (7% [10]); reassuring-Hon (6% [8]); persistently reassuring (7% [10]); and unclassified (23% [32]). Cerebral palsy was presumed to have an antenatal onset in 57% of infants and to have been caused by intrapartum insult in 13% of infants. Magnetic resonance imaging showed that 34% (n=48) of infants developed basal ganglia-thalamus-dominant brain injury. Of the remaining 92 infants, 43% (60) showed white matter injuries, 1% (1) showed watershed injuries, 4% (5) showed stroke, 1% (1) had normal findings, and 18% (25) had unclassified findings. Infants with continuous bradycardia (adjusted odds ratio, 1033.06; 95% confidence interval, 15.49-68,879.92) and persistently nonreassuring fetal heart rate patterns (61.20; 2.09-1793.12) had a significantly increased risk for basal ganglia-thalamus injury.
Conclusion:
Severe cerebral palsy was presumed to have an antenatal onset in 57% of infants and to have been caused by intrapartum insult in only 13% of infants born at 28 to 33 weeks of gestation. Although the white matter-watershed injury was predominant in the study populations, severe acute hypoxia-ischemia may be an important prenatal etiology of severe cerebral palsy in preterm infants.
