The Long-term Consequences of Neonatal Encephalopathy in the Hypothermia Era

Rationale:

Therapeutic hypothermia (TH) became the standard of care treatment for neonates with moderate and severe neonatal encephalopathy (NE) in most industrialized countries about 10 years ago. Although TH is effective in reducing mortality and the incidence of severe developmental disabilities, various morbidities are still frequent in survivors. Moreover, because the focus of previous follow-up studies has been restricted to mortality rates and the most severe forms of morbidities, it is wrong to conclude that TH minimizes all developmental deficits. In fact, recent literature reports frequent cognitive and behavioural difficulties at school entry in children with NE-TH without severe disabilities. Although these difficulties can be less impressive than cerebral palsy and intellectual disability, their negative impacts on a child's self-determination and family well-being are not less important and their nature and extend need to be comprehensively assessed.

Aims and Hypotheses:

• To compare higher-order cognitive, socialization, and psycho-emotional abilities using comprehensive standardized assessments of outcomes between 9-year-old children with NE-TH and age- and sex-matched peers without NE.

Hypothesis 1: Children with NE-TH will display lower IQ, executive functioning, attention, social cognition, and self-esteem, but more anxiety and behavioural and peer problems than age- and sex-matched peers without NE-TH.

• To compare structural brain integrity using quantitative MRI between 9-year-old children with NE-TH and age- and sex-matched peers without NE.

Hypothesis 2: Children with NE-TH will present with smaller total and regional (basal ganglia, hippocampus, cerebellum) brain volumes, altered cortical and subcortical morphometry, and widespread white matter microstructural and myelination alterations when compared to age- and sex-matched peers without NE-TH.

• To evaluate the relationships between cognitive, psycho-emotional and motor skills at 9 years and (1) individual and perinatal risk factors and (2) structural brain integrity at 9 years.

Hypothesis 3: A combination of individual (e.g., socio-economic), perinatal factors (e.g., neonatal brain injury) and markers of aberrant brain integrity (e.g., volume, microstructure) will be associated with domain-specific deficits at 9 years in children with NE-TH.

Population:

Children born between 2014 and 2018, who received whole-body cooling to an esophageal temperature of 33.5°C initiated within the first 6 hours of life, continued for 72 hours, and then they were slowly rewarmed for moderate or severe NE at one of the two centers will be approached. Eligibility for TH at our institutions followed those established in previous TH trials. Participants with a history of (1) congenital infections, (2) genetic or metabolic disorders, or (3) major brain malformations (e.g., lissencephaly), as well as (4) any contraindication for MRI (e.g., metal implant, claustrophobia), are ineligible.

For each of two same-sex and same-age NE-TH participants, a matched control for age (+/- 6 months of mean age) and sex will be recruited. Participants born at term (gestational age ≥37 weeks), without neonatal complication, will be considered as ineligible controls. Inclusion criteria for the controls include the same were similar to the NE-TH group, and a previous history of neurodevelopmental delay or disorder, or a traumatic brain injury were the specific exclusion cirteria for the comparison group.

Assessment procedure:

For this study, enrollees will complete one study visit to perform standardized evaluations and a brain MRI. Children will have the opportunity to familiarize themselves with the MRI environment on a mock scanner before the MRI and to watch a movie or listen to the music of their choice during the acquisition. Parents will be invited to complete a series of questionnaires during their child's testing or at a moment of their choice via a provided secure link. The visit will start with the outcome evaluations that are the most cognitively demanding and breaks will be provided as necessary. Outcome evaluations will be conducted by trained research staff or trainees blinded to the details of the child's neonatal and developmental history, and group allocation (i.e., NE-TH vs. control) to the extent possible. The choice of outcome measures has been made based on their clinical significance, psychometric properties, and availability in both French and English, considering the bilingual context of Quebec, Canada.

Inclusion criteria

• born between 2014 and 2018
• received whole-body cooling to an esophageal temperature of 33.5°C initiated within the first 6 hours of life, continued for 72 hours, and then they were slowly rewarmed received TH for moderate or severe NE

Exclusion criteria

Participants with a history of

• congenital infections
• genetic or metabolic disorders
• major brain malformations (e.g., lissencephaly) and
• any contraindication for MRI (e.g., metal implant, claustrophobia)