Neonatal seizures

Neonatal seizures are common and may be the first manifestations of neurological dysfunction after a variety of insults. Neonatal seizures are clinically significant because very few are idiopathic. Further investigation leading to prompt diagnosis of the underlying condition is important because many of the aetiologies have specific treatments which, when used early, may improve the prognosis.

Neonatal seizures cause further neuronal compromise, but it is not clear whether this leads to further clinically significant neuronal injury in all, or even many seizures. Many of the clinical studies examining outcome associated with seizure activity have been confounded by the prognosis associated with the underlying aetiology. It is also unclear if adverse neurodevelopmental outcome, occurring as a consequence of seizures, can be prevented by current treatment. Many clinicians are therefore uncertain when to treat seizures and how to assess the adequacy of treatment.1

The immature brain seems more prone to seizures; these are more common in the neonatal period than during any other time throughout life. This may reflect the earlier development of excitatory synapses, predominating over inhibitory influences at early stages of maturation. The incidence of clinical seizures in infants born at term is 0.7–2.7 per 1000 live births.2-6 The incidence is higher in preterm infants, ranging from 57.5 to 132 per 1000 live births3 7 (< 1500 g birthweight). The incidence of electrographic, clinically silent seizures is unknown. Continuous EEG monitoring of infants after one clinical seizure showed that 79% of subsequent EEG seizures were clinically silent.8 Such phenomena seem to be more common in preterm infants.6