“Sleep epileptology”—a new field of sleep medicine and epileptology

Abstract

Epilepsy is a chronic brain disease characterized by repetitive epileptic seizures. The cumulative incidence rate by age 85 years is high at 4.4%. Epileptic seizures tend to occur during sleep and exhibit abnormal motor and behavior symptoms (AMBS) during sleep [1].The progress of the two research fields of sleep medicine and epileptology has been advancing with the recent development of long-term monitoring using video-polysomnography with full-montage EEG (V-PSG), various brain imaging technologies, and genetic screening systems. Great attention has been paid to the close relationship between the two fields, accumulating fruitful research findings. In light of these achievements, we are at the stage of creating a new research field, sleep epileptology. In this preface I give a brief outline of a number of key findings and significant achievements in sleep epileptology. Janz [2] examined 2825 epilepsy patients with generalized tonic-chronic seizures and investigated the association between the seizures and the sleep/wake cycle through clinical observation. Symptoms were classified into three groups: sleep epilepsy with seizures occurring during sleep (44%), awakening epilepsy with seizures occurring shortly after awakening (33%), and diffuse epilepsy with seizures occurring with no correlation to the sleep/waking cycle (23%). In the International Classification of Sleep Disorders (ICSD), third edition (ICSD-3, 2014), the most widely used classification system for sleep disorders, sleep-related epilepsy, which includes both sleep epilepsy (e.g., nocturnal frontal lobe epilepsy) and awakening epilepsy (e.g., juvenile myoclonic epilepsy), accounts for 77% of incidents of epilepsy.Clinical seizures in nocturnal frontal lobe epilepsy occur mostly during non-REM sleep and rarely during REM sleep. The reason would be that thalamocortical hypersynchrony during non-REM sleep promotes epileptic seizure generation.The introduction of V-PSG into clinical practice in the 1990s has enabled highly accurate differential analysis for AMBS during sleep; furthermore, it has played an important role in detecting a large body of useful clinical information for treating patients, which includes abnormal sleep architecture, sleep disorders (such as insomnias and sleep apneas), seizures and interictal/ictal EEG abnormalities which would often be overlooked in the daytime. For instance, the incidence rate of subjective sleep disorders was high among epileptic patients, at approximately 40%, and the disorders have been confirmed by several V-PSG diagnoses such as degradation in the quantity and quality of nocturnal sleep.Recently, fine EEG changes called cyclic alternating pattern (CAP) in intractable epilepsy, which indicate unstable non-REM sleep, have been observed at a high rate among patients with intractable epilepsy. It has also been suggested that CAP may trigger epileptic seizures (CAP-related seizures). These sleep disorders are caused by epileptic seizures, whereas epileptic seizures can also be caused by the disorders. This m...

Abnormal behaviors during sleep from the viewpoint of sleep epileptology: current and future perspectives on diagnosis

“…In this paper, I propose a clinical-practice based classification of the underlying diseases of ABDS and present perspectives from some of the best research on pathophysiological relations between parasomnias and epilepsy, both representing typical ABDS. I also argue that it is imperative to develop a novel approach based on sleep epileptology (Chiba 2019), a field which targets the interface between sleep medicine and epileptology to uncover the pathophysiology behind ABDS. classification of Breen et al (Breen et al 2018) who incorporated the latest insights into the International Classification of Sleep Disorders (ICSD), third edition (ICSD-3, 2014) (American Academy of Sleep Medicine 2014).…”

“…Intractable epilepsy is complicated by PNES at high rates. Among patients referred to outpatient epilepsy centers, 5 to 25% are considered to have PNES, while 25 to 40% of patients evaluated in inpatient epilepsy monitoring units for intractable seizures are diagnosed with PNES (Chiba 2019;Szaflarski et al 2000). Since patients with intractable epilepsy develop high-frequent PNES, it is important to make an accurate differential diagnosis differentiating true seizures from PNES.…”