Hypsarrhythmia paroxysm index: A tool for early prediction of infantile spasms

Hypsarrhythmia paroxysm intensities that initiate and render physical and mental retardation irreversible in West syndrome

PURPOSE

The present study would like to investigate the effect of hypsarrhythmia paroxysms on neurological examination findings.

MATERIAL AND METHOD

This study enrolled 48 children with normal cranial magnetic resonance imaging (cMRI) findings who were previously untreated with adrenocorticotropic hormone (ACTH) and had no history of asphyxia or anoxia at birth, no underlying disease, and no history of head trauma or central nervous system infection. In these children, duration of treatment delay (DTD) was calculated, HPs in NREM sleep were counted, and neurological examination findings were identified. During the study, sometimes the 'countable hypsarrhythmia paroxysms index' (cHPI) and sometimes the 'durational hypsarrhythmia paroxysm index (dHPI)' was estimated. The onset of neurological examination findings, the onset of physical and mental retardation and the time when physical and mental retardation became irreversible were investigated. The children were stratified into 5 groups based on DTD and attempts were made to prevent the recurrence of aborted ISs by ACTH treatment.

RESULTS

I- When 'cHPI = 4/min'; mild growth retardation may be noticed. II- When 'cHPI = 6/min' and 'dHPI = 25%'; reduced eye tracking and reduced movement may be observed. III- When 'cHPI = 8/min' and 'dHPI >32%'; reduced eye tracking and reduced movement become evident, and neurological examination findings are reversible. IV- When 'dHPI = 45%'; partially permanent, mild motor and psychiatric sequelae develop. V- When 'dHPI >49%'; neurological examination findings become irreversible. VI- No relationship was found between neurological examination findings the early onset of ISs.

CONCLUSION

WS cannot be treated unless DCHP is elucidated.

Nutritional vitamin B12 deficiency-associated Infantile epileptic spasms syndrome: Clinico-neurophysiological presentation, response to treatment, and neurodevelopmental outcome

INTRODUCTION

Nutritional vitamin B12 deficiency has been shown to cause Infantile epileptic spasms syndrome (IESS) in infants in anecdotal studies.

METHODS

In this retrospective cohort study, we intended to study the clinical presentation, neurophysiological, laboratory abnormalities, treatment, and neurodevelopmental outcome at 6-months in infants presenting with IESS secondary to nutritional vitamin B12 deficiency (NVBD) and to compare these variables from the rest of the infants with IESS without vitamin B12 deficiency. We included only spasm-free cases or those who showed at least a 50% reduction in spasm frequency on D7 after starting oral/parenteral vitamin B12. We used well-validated measurement tools like the Developmental Assessment Scale for Indian Infants (DASII), Child Feeding Index (CFI), Burden of amplitudes and epileptiform discharges (BASED) score, countable Hypsarrhythmia paroxysm index (cHPI), durational Hypsarrhythmia paroxysm index (dHPI), and Early childhood epilepsy severity scale (E-CHESS) score for documenting these variables.

RESULTS

Data from 162 infants with IESS (21 caused by NVBD) were included in our study. The NVBD group had more patients residing in the rural region, with lower socioeconomic status, vegetarian mothers and poor complementary feeding index (p<0.001 for all). The NVBD group also had less number of patients requiring antiseizure medications (ASMs) and hormonal therapy(p<0.001), remained seizure free at six months (p=0.008), lower number of clusters per day (p=0.02) and the number of spasms per clusters at presentation (p=0.03), lower BASED score (p=0.03) and cHPI, dHPI at presentation (p<0.001). All of them remained spasm-free, with normal electroencephalogram at 6-months. Development quotient at baseline, at 6-months, and improvement in development quotient between these two-time points were more in the vitamin B12 deficiency group (p<0.001). All of them had clinical features of pre-ITS (infantile tremor syndrome) or ITS and it was found to be the only independent predictor of NVBD in infants with IESS. Mothers of all these infants had low serum vitamin B12 levels (<200 pg/ml).

CONCLUSIONS

Nutritional vitamin B12 deficiency may cause IESS in infants. Hence, vitamin B12 deficiency needs to be ruled out in patients with IESS without any definite etiology.

Scoring Systems for the Evaluation of Hypsarrhythmia

SUMMARY

Hypsarrhythmia is a well-recognized EEG pattern and it has been long known as a feature of one of the more severe forms of epilepsy early in life with adverse consequences if not recognized and treated promptly. Yet, it has been difficult to objectively quantify its varied manifestations and link them to the clinical severity of epilepsy, implications for treatment, or the overall seizure and developmental outcome of young patients. This is not for want of effort, for there have been several approaches to score hypsarrhythmia ever since its initial recognition as a unique EEG pattern. In this article, we review the different methods proposed to score hypsarrhythmia and highlight the challenges inherent to each one of them.

Automated detection of ripple oscillations in long-term scalp EEG from patients with infantile spasms

Objective.Scalp high-frequency oscillations (HFOs) are a promising biomarker of epileptogenicity in infantile spasms (IS) and many other epilepsy syndromes, but prior studies have relied on visual analysis of short segments of data due to the prevalence of artifacts in EEG. Here we set out to robustly characterize the rate and spatial distribution of HFOs in large datasets from IS subjects using fully automated HFO detection techniques.Approach.We prospectively collected long-term scalp EEG data from 12 subjects with IS and 18 healthy controls. For patients with IS, recording began prior to diagnosis and continued through initiation of treatment with adrenocorticotropic hormone (ACTH). The median analyzable EEG duration was 18.2 h for controls and 84.5 h for IS subjects (∼1300 h total). Ripples (80-250 Hz) were detected in all EEG data using an automated algorithm.Main results.HFO rates were substantially higher in patients with IS compared to controls. In IS patients, HFO rates were higher during sleep compared to wakefulness (median 5.5 min^-1and 2.9 min^-1, respectively;p = 0.002); controls did not exhibit a difference in HFO rate between sleep and wakefulness (median 0.98 min^-1and 0.82 min^-1, respectively). Spatially, IS patients exhibited significantly higher rates of HFOs in the posterior parasaggital region and significantly lower HFO rates in frontal channels, and this difference was more pronounced during sleep. In IS subjects, ACTH therapy significantly decreased the rate of HFOs.Significance.Here we provide a detailed characterization of the spatial distribution and rates of HFOs associated with IS, which may have relevance for diagnosis and assessment of treatment response. We also demonstrate that our fully automated algorithm can be used to detect HFOs in long-term scalp EEG with sufficient accuracy to clearly discriminate healthy subjects from those with IS.

Status Epilepticus Manifested as Continuous Epileptic Spasms

Objective: The etiology and outcome of status epilepticus with continuous epileptic spasms have not been fully understood; and only rare cases have been reported in the literature. Here, we described 11 children, who manifested continuous epileptic spasms with various etiologies and different outcomes. Methods: This is a case series study designed to systematically review the charts, video-electroencephalography (video-EEG), magnetic resonance images, and longitudinal follow-up of patients who presented continuous epileptic spasms lasting more than 30 min. Results: Median age at onset was 2 years old, ranging from 2 months to 5.6 years. The etiology of continuous epileptic spasms for these 11 cases consisted of not only some known electro-clinical epilepsy syndromes like West Syndrome and Ohtahara Syndrome, but also secondary symptomatic continuous epileptic spasms, caused by acute encephalitis or encephalopathy, which extends the etiological spectrum of continuous epileptic spasms. The most characteristic feature of these 11 cases was prolonged epileptic spasms, lasting for a median of 13.00 days (95% CI: 7.26-128.22 days). The interictal EEG findings typically manifested as hypsarrhythmia or its variants, including burst suppression. Hospital stays were much longer in acute symptomatic cases than in primary epileptic syndromic cases (59.67 ± 50.82 vs. 15.00 ± 1.41 days). However, the long-term outcomes were extremely poor in the patients with defined electro-clinical epilepsy syndromes, including severe motor and intellectual developmental deficits (follow-up of 4.94 ± 1.56 years), despite early diagnosis and treatment. Continuous epileptic spasms were refractory to corticosteroids, immuno-modulation or immunosuppressive therapies, and ketogenic diet. Conclusion: Continuous epileptic spasms were associated with severe brain impairments in patients with electro-clinical syndromes; and required long hospital stays in patients with acute symptomatic causes. We suggest to include continuous epileptic spasms in the international classification of status epilepticus, as a special form. Further investigations are required to better recognize this condition, better understand the etiology, as well as to explore more effective treatments to improve outcomes.

Quantitative Characteristics of Hypsarrhythmia in Infantile Spasms

Infantile spasms is a type of epilepsy characterized by clinical seizures termed "spasms" and often an electroencephalographic (EEG) pattern known as hypsarrhythmia. Multiple studies have shown that the interrater reliability for human visual recognition of hypsarrhythmia is poor. Quantitative measurements of this EEG pattern would provide objective basis for identification; however, the basic temporal and spectral characteristics of hypsarrhythmia have never been assessed. Thus, we measured EEG amplitude and power spectra in 21 infantile spasms patients before and after treatment, as well as 21 control subjects. The hypsarrhythmia EEG pattern was associated with (1) high broadband amplitude, especially in frontal and central brain regions, (2) high median power in the delta and alpha frequency bands, and (3) low spectral edge frequency. Our results indicate that hypsarrhythmia can be quantitatively distinguished from data without hypsarrhythmia. Introduction of these quantitative measures into clinical practice may increase diagnostic accuracy, expediting proper treatment and improving outcomes.

Identification of Hypsarrhythmia in Children with Microcephaly Infected by Zika Virus

Hypsarrhythmia is an electroencephalographic pattern specific to some epileptic syndromes that affect children under one year of age. The identification of this pattern, in some cases, causes disagreements between experts, which is worrisome since an inaccurate diagnosis can bring complications to the infant. Despite the difficulties in visually identifying hypsarrhythmia, options of computerized assistance are scarce. Aiming to collaborate with the recognition of this electropathological pattern, we propose in this paper a mathematical index that can help electroencephalography experts to identify hypsarrhythmia. We performed hypothesis tests that indicated significant differences in the groups under analysis, where the p-values were found to be extremely small.

Strength and stability of EEG functional connectivity predict treatment response in infants with epileptic spasms

OBJECTIVE

Epileptic spasms (ES) are associated with pathological neuronal networks, which may underlie characteristic EEG patterns such as hypsarrhythmia. Here we evaluate EEG functional connectivity as a quantitative marker of treatment response, in comparison to classic visual EEG features.

METHODS

We retrospectively identified 21 ES patients and 21 healthy controls. EEG data recorded before treatment and after ≥10 days of treatment underwent blinded visual assessment, and functional connectivity was measured using cross-correlation techniques. Short-term treatment response and long-term outcome data were collected.

RESULTS

Subjects with ES had stronger, more stable functional networks than controls. After treatment initiation, all responders (defined by cessation of spasms) exhibited decreases in functional connectivity strength, while an increase in connectivity strength occurred only in non-responders. There were six subjects with unusually strong pre-treatment functional connectivity, and all were responders. Visually assessed EEG features were not predictive of treatment response.

CONCLUSIONS

Changes in network connectivity and stability correlate to treatment response for ES, and high pre-treatment connectivity may predict favorable short-term treatment response. Quantitative measures outperform visual analysis of the EEG.

SIGNIFICANCE

Functional networks may have value as objective markers of treatment response in ES, with potential to facilitate rapid identification of personalized, effective treatments.