Outcome at early school age and adolescence after hypothermia-treated hypoxic-ischaemic encephalopathy: an observational, population-based study

Abstract

Objective: We aimed to describe long-term outcomes following hypoxic-ischaemic encephalopathy (HIE) treated with therapeutic hypothermia (TH).

Design: Prospective, population-based observational study.

Setting: Tertiary level neonatal intensive care units and neonatal outpatient clinic, Karolinska University Hospital, Stockholm, Sweden.

Patients: Sixty-six infants treated with TH due to HIE between 2007 and 2009.

Interventions: At 6-8 years and 10-12 years of age, children were assessed using a standardised neurological examination, the Movement Assessment Battery for Children, Second Edition (MABC-2) and the Wechsler Intelligence Scales for Children IV/V. Parents completed the Five-to-Fifteen (FTF) questionnaire.

Main outcome measures: Adverse outcome among survivors was defined as cerebral palsy (CP), epilepsy, hearing or visual impairment, full-scale IQ (FSIQ) below 85, attention deficit disorder with/without hyperactivity, autism spectrum disorder or developmental coordination disorder.

Results: Mortality was 12%. Seventeen per cent of survivors developed CP. Mean FSIQ was normal in children without major neuromotor impairment. Assessment in early adolescence revealed emerging deficits in 26% of children with a previously favourable outcome. The proportion of children exhibiting executive difficulties increased from 7% to 19%. This was reflected also by a significantly increased proportion of children with an FTF score >90th percentile compared with norms in early adolescence. The proportion of children with an MABC-2 score ≤5th percentile was also significantly increased compared with norms.

Conclusions: Survivors without major neuromotor impairment have normal intelligence. The incidence of executive difficulties appears to be increased in this patient population. More subtle difficulties may go undetected at early school-age.

Keywords: child development; neonatology; neurology; paediatrics.