Thompson Score for Hypoxic Ischaemic Encephalopathy (HIE)

Thompson HIE Score explained

The Thompson HIE score is a neonatal scoring system used in the assessment of the severity of perinatal asphyxia. The score was also found to have a high sensitivity and specificity for hypoxic ischaemic encephalopathy adverse outcomes (death or severe disability).

Birth asphyxia is the delay in establishing spontaneous breathing/crying immediately after birth of the newborn and usually results in impaired gas exchange, hypoxia and metabolic acidosis.

Hypoxic Ischemic Encephalopathy (HIE) is the term commonly used to describe the neurological syndrome that occur following perinatal asphyxia. HIE is caused by severe perinatal asphyxia with secondary cerebral ischemia.

15%-20% of HIE cases die during the neonatal period whilst a further 30% of neonates who survive, go on to suffer from neurodevelopment disorders.

This HIE score consists in a set of clinical signs associated with central nervous system dysfunction in neonates and is often used alongside the APGAR score to evaluate the status of neonates with birth asphyxia.

The final score sums the individual points and is interpreted as follows:

• 0-10: HIE Mild severity
• 11-14: HIE Moderate severity
• ≥15: HIE Severe

In normothermic infants, HIE scores greater than 10 during the first week of life predicts an abnormal outcome (100% sensitivity and 61% specificity).

About the original study

During the original study, 45 infants with developed hypoxic ischaemic encephalopathy after birth were assessed and in 43 infants at least one cranial ultrasound examination took place.

35 of the infants also underwent a full neurological examination at 12 months of age

58% of the infants were normal and 42% were abnormal (cerebral palsy and developmental delay). The hypoxic ischaemic encephalopathy score was found to be highly predictive for outcome.

The best correlation with outcome was the peak score of 15 or higher where a positive predictive value of 92% and a negative predictive value of 82% for abnormal outcome were discovered, with a sensitivity and specificity of 71% and 96%, respectively.

Example of HIE score as predictor of adverse outcomes

Thorsen et al evaluated 142 newborns with perinatal asphyxia that underwent therapeutic hypothermia, in a four-year study and found that the median Thompson score was 9 (interquartile range: 8 to 12).

Death before discharge occurred in 23.9% and severe epilepsy in 21.1% of the cases. In total, 59.2% of the patients had multiple organ failure. Whilst the Thompson score was not associated with multiple organ failure, scores of 12 or greater were associated with death before discharge and development of severe epilepsy.

References

Original reference

Thompson CM, Puterman AS, Linley LL, Hann FM, van der Elst CW, Molteno CD, Malan AF. The value of a scoring system for hypoxic ischaemic encephalopathy in predicting neurodevelopmental outcome. Acta Paediatr. 1997;86(7):757-61.

Validation

Bhagwani DK, Sharma M, Dolker S, Kothapalli S. To Study the Correlation of Thompson Scoring in Predicting Early Neonatal Outcome in Post Asphyxiated Term Neonates. J Clin Diagn Res. 2016; 10(11): SC16–SC19.

Other references

Thorsen et al. The Thompson Encephalopathy Score and Short-Term Outcomes in Asphyxiated Newborns Treated With Therapeutic Hypothermia. Pediatric Neurology; Volume 60, July 2016, Pages 49-53.

Murray DM, Bala P, O'Connor CM, Ryan CA, Connolly S, Boylan GB. The predictive value of early neurological examination in neonatal hypoxic-ischaemic encephalopathy and neurodevelopmental outcome at 24 months. Dev Med Child Neurol. 2010;52(2):e55-9.