Presented at the Neonatal Society 2010 Spring Meeting.

Tsakmakis MV, Gowda K, Thoresen M, Luyt K

Background: Seizures during the neonatal period are associated with a 20% risk of mortality and a significant risk of neurodevelopmental impairment. Previous population based studies report an incidence of 1.5 (1) – 2.0 (2) per 1000 live births in term gestation infants. However, published epidemiological studies of neonatal seizures were all conducted in the pre-therapeutic hypothermia era and have not included continuous amplitude integrated EEG (aEEG) or magnetic resonance imaging (MRI) for diagnostic criteria. A recent 2008 UK survey of neonatal seizure management highlighted the infrequent use of diagnostic MRI (performed in 10%).

Aim: The aim of this study was to determine the incidence, aetiological associations and outcomes of seizures in term infants in a single large level 3 perinatal centre.

Methods: Cohort study of all term infants (>37 weeks gestation) delivered in a single level 3 centre in the UK from 1/12/2004 to 31/10/2009 (59 months). Infants admitted with seizures were identified prospectively through a perinatal morbidity surveillance system. 

Results: 78 term infants with seizures were identified during this period (incidence of 3.1/1000 live births). The mortality rate was 11.5% (9/78). 50% (39/78) were treated with therapeutic hypothermia. 93.5% (73/78) had aEEG monitoring and 87.1 % (68/78) had brain MRI performed. 54.4% of MRIs performed in the neonatal period demonstrated abnormalities. Aetiological classification: global cerebral hypoxia-ischaemia (HI) (53/78; 68%), arterial or venous ischaemic stroke (9/78; 11.5%), hypoglycaemia (3/78; 3.8%), drug withdrawal (3/78; 3.8%), cerebral haemorrhage (2/78; 2.6%), cerebral dysgenesis (1/78; 1.3%), inborn errors of metabolism (1/78; 1.3%), familial/genetic syndromes (1/78; 1.3%), hyponatraemia (1/78; 1.3%) and unknown aetiology (4/78; 5.1%).

Conclusion: This is the first report of a large inborn population of term infants with seizures, where both MRI and aEEG have been used to aid diagnosis. The overall incidence of seizures was higher, with a lower associated mortality rate than previously reported. Due to our high uptake of MR imaging we report a higher incidence of arterial and venous ischaemic stroke than previous population based studies. This study highlights the importance of MR imaging in term infants presenting with seizures.

References
1. Saliba et al. Am J Epidemiol. 1999 Oct 1; 150(7): 763-9
2. Ronen et al. Pediatr. 1999 Jan; 134(1): 71-5