Sleep-Related Hypermotor Epilepsy: Etiology, Electro-Clinical Features, and Therapeutic Strategies

Brain changes in sleep-related hypermotor epilepsy observed from wakefulness and N2 sleep: A matched case-control study

OBJECTIVE

Sleep-related hypermotor epilepsy (SHE) is a relatively uncommon epilepsy syndrome, characterized by seizures closely related to the sleep cycle. This study aims to explore interictal electroencephalographic (EEG) characteristics in SHE.

METHODS

We compared EEG data from 20 patients with SHE, 20 patients with focal epilepsy (FE), and 14 healthy controls, carefully matched for age, sex, education level, epilepsy duration, and drug-resistant epilepsy.

RESULTS

Our findings revealed distinct patterns of power spectral density in SHE patients during wakefulness and N2 sleep compared to other groups, suggesting potential diagnostic value. During wakefulness, SHE patients showed enhanced frontal lobe power across all frequency bands, but decreased frontal lobe power in low-frequency bands during N2 sleep. Additionally, a positive correlation was found between frontal γ band power and epilepsy duration in SHE patients during N2 sleep but not during wakefulness.

CONCLUSIONS

These findings suggest that interictal EEG abnormalities during wakefulness and N2 sleep might be used as potential biomarkers for the diagnosis of SHE.

SIGNIFICANCE

This study is the first to simultaneously characterize EEG during sleep and wakefulness in SHE patients during interictal periods, with potential utility for diagnosis.

Pathogenic genes implicated in sleep-related hypermotor epilepsy: a research progress update

Sleep-related hypermotor epilepsy (SHE) is a focal epilepsy syndrome characterized by a variable age of onset and heterogeneous etiology. Current literature suggests a prevalence rate of approximately 1.8 per 100,000 persons. The discovery of additional pathogenic genes associated with SHE in recent years has significantly expanded the knowledge and understanding of its pathophysiological mechanisms. Identified SHE pathogenic genes include those related to neuronal ligand- and ion-gated channels (CHRNA4, CHRNB2, CHRNA2, GABRG2, and KCNT1), genes upstream of the mammalian target of rapamycin complex 1 signal transduction pathway (DEPDC5, NPRL2, NPRL3, TSC1, and TSC2), and other genes (CRH, CaBP4, STX1B, and PRIMA1). These genes encode proteins associated with ion channels, neurotransmitter receptors, cell signal transduction, and synaptic transmission. Mutations in these genes can result in the dysregulation of encoded cellular functional proteins and downstream neuronal dysfunction, ultimately leading to epileptic seizures. However, the associations between most genes and the SHE phenotype remain unclear. This article presents a literature review on the research progress of SHE-related pathogenic genes to contribute evidence to genotype-phenotype correlations in SHE and establish the necessary theoretical basis for future SHE treatments.

An unusual presentation of severe obstructive sleep apnea with nocturnal seizure-like movements: A case report

Key Clinical Message

This study suggests that severe obstructive sleep apnea can present as sleep-related epileptic or non-epileptic seizures. A detailed history and physical examination, along with polysomnography and video electroencephalography findings can lead to the correct diagnosis.

Abstract

Obstructive sleep apnea (OSA) is defined by recurrent episodes of the upper airway complete or partial collapse while sleeping. The obstructive episodes result in gradual suffocation that increases breathing attempts till the person is awakened. The main manifestations are excessive daytime sleepiness, snoring, observed episodes of stopped breathing, and abrupt awakenings accompanied by gasping or choking. Nevertheless, there are very few reports of patients with OSA, manifesting other symptoms such as seizure-like movements. Differentiating OSA with nocturnal seizures could be challenging due to their overlapping features. A 53-year-old man presented to the clinic, experiencing seizure-like involuntary movements during nocturnal sleep for the past 2 years with a frequency of 2-3 times per night. Neurologic examinations were normal. Further evaluation with polysomnography revealed impaired arousal followed by seizure-like movements during sleep. Video electroencephalography (EEG) did not show any epileptiform discharges, ruling out the nocturnal seizure diagnosis. The patient was diagnosed with OSA. Subsequently, continuous positive airway pressure (CPAP) treatment resolved all symptoms.

Fearful arousals in sleep terrors and sleep-related hypermotor epileptic seizures may involve the salience network and the acute stress response of Cannon and Selye

We consider the disorders of arousal and sleep-related hypermotor epilepsy as genetic twin-conditions, one without, one with epilepsy. They share an augmented arousal-activity during NREM sleep with sleep-wake dissociations, culminating in sleep terrors and sleep-related hypermotor seizures with similar symptoms. The known mutations underlying the two spectra are different, but there are multifold population-genetic-, family- and even individual (the two conditions occurring in the same person) overlaps supporting common genetic roots. In the episodes of disorders of arousal, the anterior cingulate, anterior insular and pre-frontal cortices (shown to be involved in fear- and emotion processing) are activated within a sleeping brain. These regions overlap with the seizure-onset zones of successfully operated sleep-related hypermotor seizures, and notably, belong to the salience network being consistent with its hubs. The arousal-relatedness and the similar fearful confusion occurring in sleep terrors and hypermotor seizures, make them alike acute stress-responses emerging from sleep; triggered by false alarms. The activation of the anterior cingulate, prefrontal and insular regions in the episodes of both conditions, can easily mobilize the hypothalamo-pituitary-adrenal axis (preparing fight-flight responses in wakefulness); through its direct pathways to and from the salience network. This hypothesis has never been studied.

Progressive structural damage in sleep-related hypermotor epilepsy

This study aimed to explore the alterations in gray matter volume (GMV) based on high-resolution structural data and the temporal precedence of structural alterations in patients with sleep-related hypermotor epilepsy (SHE). After preprocessing of T1 structural images, the voxel-based morphometry and source-based morphometry (SBM) methods were applied in 60 SHE patients and 56 healthy controls to analyze the gray matter volumetric alterations. Furthermore, a causal network of structural covariance (CaSCN) was constructed using Granger causality analysis based on structural data of illness duration ordering to assess the causal impact of structural changes in abnormal gray matter regions. The GMVs of SHE patients were widely reduced, mainly in the bilateral cerebellums, fusiform gyri, the right angular gyrus, the right postcentral gyrus, and the left parahippocampal gyrus. In addition to those regions, the results of the SBM analysis also found decreased GMV in the bilateral frontal lobes, precuneus, and supramarginal gyri. The analysis of CaSCN showed that along with disease progression, the cerebellum was the prominent node that tended to affect other brain regions in SHE patients, while the frontal lobe was the transition node and the supramarginal gyrus was the prominent node that may be easily affected by other brain regions. Our study found widely affected regions of decreased GMVs in SHE patients; these regions underlie the morphological basis of epileptic networks, and there is a temporal precedence relationship between them.

Sleep medicine: Practice, challenges and new frontiers

Sleep medicine is an ambitious cross-disciplinary challenge, requiring the mutual integration between complementary specialists in order to build a solid framework. Although knowledge in the sleep field is growing impressively thanks to technical and brain imaging support and through detailed clinic-epidemiologic observations, several topics are still dominated by outdated paradigms. In this review we explore the main novelties and gaps in the field of sleep medicine, assess the commonest sleep disturbances, provide advices for routine clinical practice and offer alternative insights and perspectives on the future of sleep research.