Hypsarrhythmia

Abstract

To determine the frequency and significance of the EEG features of hypsarrhythmia, we analyzed the pre-ACTH records of 53 consecutive patients with infantile spasms for the severity of the following abnormalities: disorganization of background, slowing, high amplitude, spike activity, and for the presence or absence of each of the following patterns and variants: electrodecremental discharges, absence of normal sleep activity, relative normalization, hemihypsarrhythmia, burst suppression (BS), occipital hypsarrhythmia, interhemispheric asymmetry, and interhemispheric synchronization. We calculated a total score indicating the severity of the hypsarrhythmia for each record. The hypsarrhythmia variant patterns occurred frequently in up to 69% of the records. Patients with cerebral dysgenesis were more likely to have hemihypsarrhythmia or BS pattern persistent throughout the EEG. Patients with history of perinatal hypoxia-ischemia were more likely to have absence of normal sleep activity. The occurrence of each of the other variant patterns did not correlate with etiology. Favorable outcome did not correlate with the occurrence, or absence, of any of the variant patterns but was associated with faster background activity (< 75% delta), a lower total hypsarrhythmia score (< or = 10), and with absence of electrodecremental discharges on the pre-ACTH EEG. We conclude that variant patterns of hypsarrhythmia are frequent, generally do not correlate with prognosis, and thus are best included within the definition of hypsarrhythmia. The severity of the hypsarrhythmia, however, does have significant prognostic implications.

Vigabatrin therapy implicates neocortical high frequency oscillations in an animal model of infantile spasms

“…However, subsequently many investigators have described numerous variations from this prototypic pattern that are now referred to as “modified” hypsarrhythmia (Hrachovy et al , 1984, Kramer et al , 1997, Hussain et al , 2015). One such EEG pattern is hypsarrhythmia with interhemispheric synchronization.…”

Long-Range Temporal Correlations Reflect Treatment Response in the Electroencephalogram of Patients with Infantile Spasms

“…Researchers and clinicians have tried to quantify various characteristics of hypsarrhythmia in an attempt to ameliorate the subjectivity of the assessment (Sue et al 1997). Some groups have attempted to quantitatively describe the underlying functional and neuronal network that facilitates hypsarrhythmia through EEG-fMRI (Siniatchkin et al 2007), source analysis methods (Japaridze et al 2013), and detection of fast oscillations (Kobayashi et al 2015).…”

Neuronal Networks in West Syndrome as Revealed by Source Analysis and Renormalized Partial Directed Coherence

“…Slow wave activity and not epileptifom discharges has been proposed to specifically represent the hypsarrhythmia because in some cases this EEG phenomenon consists of either only high-voltage slow wave activity or a combination of slow waves and very little spike/sharp wave activity (Alva-Moncayo et al, 2002, Hrachovy andFrost, 2003). Moreover, interictal slow wave activity has been associated with poor developmental outcome in West syndrome (Kramer et al, 1997).…”