Neonatal seizures are the most common neurological event in newborns, showing higher prevalence in preterm than in full-term infants. In the majority of cases they represent acute symptomatic phenomena, the main etiologies being intraventricular haemorrhage, hypoxic-ischemic encephalopathy, central nervous system infections and transient metabolic derangements.Current definition of neonatal seizures requires detection of paroxysmal EEG-changes, and in preterm newborns the incidence of electrographic-only seizures seems to be particularly high, further stressing the crucial role of electroencephalogram monitoring in this population. Imaging work-up includes an integration of serial cranial ultrasound and brain magnetic resonance at term-equivalent age. Unfavourable outcomes following seizures in preterm infants include death, neurodevelopmental impairment, epilepsy, cerebral palsy, hearing and visual impairment. As experimental evidence suggests a detrimental role of seizures per se in determining subsequent outcome, they should be promptly treated with the aim to reduce seizure burden and long-term disabilities. However, neonatal seizures show low response to conventional anticonvulsant drugs, and this is even more evident in preterm newborns, due to intrinsic developmental factors. As a consequence, as literature does not provide any specific guidelines, due to the lack of robust evidence, off-label medications are often administered in clinical practice.
Neonatal seizures occur in their majority in close temporal relation to an acute brain injury or systemic insult, and are accordingly defined as acute symptomatic or provoked seizures. However less frequently, unprovoked seizures may also present in the neonatal period as secondary to structural brain abnormalities, thus corresponding to structural epilepsies, or to genetic conditions, thus corresponding to genetic epilepsies. Unprovoked neonatal seizures should be thus considered as the clinical manifestation of early onset structural or genetic epilepsies that often have the characteristics of early onset epileptic encephalopathies. In this review, we address the conundrum of neonatal seizures including acute symptomatic, remote symptomatic, provoked, and unprovoked seizures, evolving to post-neonatal epilepsies, and neonatal onset epilepsies. The different clinical scenarios involving neonatal seizures, each with their distinct post-neonatal evolution are presented. The structural and functional impact of neonatal seizures on brain development and the concept of secondary epileptogenesis, with or without a following latent period after the acute seizures, are addressed. Finally, we underline the need for an early differential diagnosis between an acute symptomatic seizure and an unprovoked seizure, since it is associated with fundamental differences in clinical evolution. These are crucial aspects for neonatal management, counselling and prognostication. In view of the above aspects, we provide an outlook on future strategies and potential lines of research in this field.
The majority of neonatal seizures are of acute symptomatic origin, and their occurrence is associated with higher mortality and morbidity compared with the general population, even if there is conflicting evidence of a detrimental effect per se. Etiology is considered the main determinant of outcome, but other factors, including gestational age, brain damage severity, neonatal neurological examination, and electroencephalographically (EEG) interictal and ictal characteristics are also related to neurodevelopmental outcome or death. Therefore, accuracy in early prognostication since the neonatal period can be improved by conveniently integrating different clinical and instrumental findings.The aim of this review is first to review the outcome of newborns with seizures (mortality, epilepsy, cerebral palsy, and intellectual disability), second to review the risk factors for adverse outcome after seizures in the newborn period, considering clinical, EEG/amplitude-integrated EEG, and neuroimaging findings associated with adverse outcome and lack of response to treatment, and finally to review published scoring systems for predicting neurologic outcome after neonatal seizures.
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