Neonatal suppression-burst without epileptic seizures: expanding the electroclinical phenotype of STXBP1-related, early-onset encephalopathy

Early-onset epileptic encephalopathies (EOEEs) are characterised by epileptic seizures beginning in the first months of life, abnormal background EEG activity, and are associated with severe developmental delay and poor prognosis. Mutations and deletions in the STXBP1 gene are associated with Ohtahara syndrome, also known as “early infantile epileptic encephalopathy”. We report an infant affected by EOEE with a 9q34.11 deletion that encompassed the genes STXBP1 and SPTAN1. The infant presented with neonatal encephalopathy without epileptic seizures and an EEG pattern varying from highly discontinuous to suppression-burst. This was followed by West syndrome at 2 months with atypical hypsarrhythmia and spasms, easily controlled by therapy. Our findings suggest that molecular analysis of STXBP1 should be considered for newborns affected by neonatal encephalopathy associated with a peculiar EEG pattern, even in the absence of neonatal epileptic seizures.