Epilepsy in Angelman syndrome and the most common electroencephalographic findings

Abstract

Angelman syndrome is a genetic disorder characterised by severe mental retardation, subtle dysmorphic facial features, a characteristic behavioural phenotype, seizures and abnormalities in video electroencephalograms (video EEG). Angelman syndrome may be associated with genetic mechanisms involving the region of chromosome 15q11-13. Up to 90% of cases have epileptic seizures, usually in the early years of life. Videoelectroencephalography patterns with some typical characteristics associated with Angelman syndrome have been reported, although these are not specific to it, and as such it is also useful for early diagnosis, especially in the first months or years of life. To characterise the videoelectroencephalography findings of 17 patients diagnosed with Angelman syndrome, and compare them with previously published studies. We conducted a retrospective observational study of 34 video EEGs performed on 17 patients diagnosed with Angelman syndrome at the clinical neurophysiology service of the Puerta de Hierro University Hospital in Madrid between 2019 and 2022. The primary objective was to characterise the videoelectroencephalographic findings and compare them with previously published studies. As secondary objectives, we analysed the patterns proposed by Dan and Boyd, and other demographic, genetic and clinical data. Video EEG supported the clinical suspicion in our study, as baseline brain activity was altered in all the patients. We identified a pattern similar to those defined by Dan and Boyd in 88% of the cases, and the type III pattern was the most common in our series. These findings confirm that video EEG is highly sensitive for the diagnosis of Angelman syndrome, and very useful as a diagnostic biomarker in the early stages of life.