Neurological outcomes and mortality after neonatal seizures with electroencephalographical verification. A systematic review.

AIM: To conduct a systematic review of post-neonatal neurological outcomes and mortality following neonatal seizures with electroencephalographical verification. METHODS: The databases Medline, Embase and Web of Science were searched for eligible studies. All abstracts were screened in a blinded fashion between research team members and reports found eligible were obtained and screened in full text by two members each. From studies included, outcome results for post-neonatal epilepsy, cerebral palsy, intellectual disability, developmental delay, mortality during and after the neonatal period and composite outcomes were extracted. A quality assessment of each study was performed. RESULTS: In total, 5518 records were screened and 260 read in full text. Subsequently, 31 studies were included, containing cohorts of either mixed or homogenous etiologies. Follow-up time and gestational ages varied between studies. No meta-analysis could be performed due to the low number of studies with comparable outcomes and effect measures. Reported cumulative incidences of outcomes varied greatly between studies. For post-neonatal epilepsy the reported incidence was 5-84%, for cerebral palsy 9-78%, for intellectual disability 24-67%, for developmental delay 10-67% and for mortality 1-62%. Subgroup analysis had more coherent results and in cohorts with status epilepticus a higher incidence of post-neonatal epilepsy from 46 to 84% was shown. CONCLUSION: The large variation of reported incidences for neurological outcomes and mortality found even when restricting to cohorts with electroencephalographically verified neonatal seizures indicates selection bias as a significant confounder in existing studies. Population-based approaches are thus warranted to correctly predict outcomes in this group.

Validation of central nervous system-induced seizures and other neurological variables in the Swedish Neonatal Quality Register.

AIM: We sought to validate neurological variables and relevant International Classification of Diseases, Tenth Revision (ICD-10) codes in the Swedish Neonatal Quality (SNQ) Register. METHODS: Register data were collected for 351 neonates, born between January 2009 and December 2016, who were treated at a neonatal unit in the Stockholm region on 385 occasions. They were eligible if the check-box for central nervous system (CNS)-induced seizures was ticked. The Register data, including relevant ICD-10 codes, were validated by checking the patients' electronic medical charts. RESULTS: Most of the neonates were born at term (76%) and weighed >2500 g (80%). The variable CNS-induced seizures had a positive predictive value of 46%. The ICD-10 diagnosis P90.9A had a positive predictive value of 90%. This comprises seizures validated with electroencephalography, amplitude-integrated electroencephalography or continuous function monitoring. The majority of the associated neurological variables in the Register had positive predictive values above 85%. CONCLUSION: When the check-box was ticked for central nervous system-induced seizures, most of the neurological variables in the Register had high validity. However, the CNS-induced seizures variable per se had a lower positive predictive value. Future SNQ Register-based studies of such neonatal seizures should also include ICD-10 P90.9A.