Nocturnal epileptic seizures versus the arousal parasomnias

Disorders of Arousal: A Chronobiological Perspective

Non-rapid eye movement (NREM) sleep parasomnias are characterized by motor and emotional behaviors emerging from incomplete arousals from NREM sleep and they are currently referred to as disorders of arousal (DoA). Three main clinical entities are recognized, namely confusional arousal, sleep terror and sleepwalking. DoA are largely present in pediatric populations, an age in which they are considered as transitory, unhabitual physiological events. The literature background in the last twenty years has extensively shown that DoA can persist in adulthood in predisposed individuals or even appear de novo in some cases. Even though some episodes may arise from stage 2 of sleep, most DoA occur during slow wave sleep (SWS), and particularly during the first two sleep cycles. The reasons for this timing are linked to the intrinsic structure of SWS and with the possible influence on this sleep phase of predisposing, priming and precipitating factors for DoA episodes. The objective of this paper is to review the intrinsic sleep-related features and chronobiological aspects affecting SWS, responsible for the occurrence of the majority of DoA episodes during the first part of the night.

Are Absence Epilepsy and Nocturnal Frontal Lobe Epilepsy System Epilepsies of the Sleep/Wake System?

System epilepsy is an emerging concept interpreting major nonlesional epilepsies as epileptic dysfunctions of physiological systems. I extend here the concept of reflex epilepsy to epilepsies linked to input dependent physiological systems. Experimental and clinical reseach data were collected to create a coherent explanation of underlying pathomechanism in AE and NFLE. We propose that AE should be interpreted as epilepsy linked to the corticothalamic burst-firing mode of NREM sleep, released by evoked vigilance level oscillations characterized by reactive slow wave response. In the genetic variation of NFLE the ascending cholinergic arousal system plays an essential role being in strong relationship with a gain mutation of the nicotinic acethylcholin receptors, rendering the arousal system hyperexcitable. I try to provide a more unitary interpretation for the variable seizure manifestation integrating them as different degree of pathological arosuals and alarm reactions. As a supporting hypothesis the similarity between arousal parasomnias and FNLE is shown, underpinned by overlaping pathomechanism and shared familiarity, but without epileptic features. Lastly we propose that both AE and NFLE are system epilepsies of the sleep-wake system representing epileptic disorders of the antagonistic sleep/arousal network. This interpretation may throw new light on the pathomechanism of AE and NFLE.

Tobacco habits in nocturnal frontal lobe epilepsy

The beneficial effect of nicotine has been reported in autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) patients, but not tested in sporadic cases. Recently, a nicotine defect in the arousal pathway has been hypothesized even in sporadic NFLE patients and their relatives. This case-control family study was designed to test whether NFLE subjects were more likely to use tobacco than controls, as an indirect marker of cholinergic arousal system dysregulation. At least four relatives were included for each NFLE proband and control. Each subject was questioned about tobacco habits; 434 individuals were recruited. Moreover, we compared NFLE patients with age- and sex-matched controls to determine whether they are more likely to use tobacco. We found a slightly higher trend of tobacco use in NFLE probands compared to that in control subjects; we did not find any significant difference in the distribution of tobacco use among NFLE group compared to that in the control group.

Biperiden for treatment of somnambulism in adolescents and adults with or without epilepsy: clinical observations

BACKGROUND

Sleepwalking in adolescents and adults may lead to serious injuries and require treatment. Anecdotal treatment recommendations include benzodiazepines (which also work in focal seizures of the frontal lobe that are an important differential diagnosis), imipramine and amitriptyline.

METHODS

We assessed in a follow-up study of 4 years (medium, range: 2-7 years) the usefulness of the antiparkinsonian drug biperiden (Akineton©), an acetylcholine antagonist with high affinity for muscarinic M1-type receptors, in four consecutive cases of arousal disorder with sleepwalking and confusional behavior in adolescents and adults with or without epilepsy who did not respond to diazepam, clonazepam or amitriptyline.

FINDINGS

The adjunctive use of biperiden was associated with reduction or remission of sleepwalking episodes in four consecutive treatment-refractory cases of arousal disorder with sleepwalking and confusional behavior. In contrast, biperiden showed no effect in a patient with REM behavioral disorder.

INTERPRETATION

Although our observations do not and cannot establish the efficacy or safety of biperiden, it may be useful to consider biperiden for treatment of sleepwalking, if needed. A putative cholinergic mechanism of arousal disorders, including sleepwalking, provides a reasonable hypothesis why the anticholinergic agent biperiden might work. Evidence for efficacy and safety from randomized controlled trials is needed to confirm our preliminary observations.

Physiopathogenetic Interrelationship between Nocturnal Frontal Lobe Epilepsy and NREM Arousal Parasomnias

Aims. To build up a coherent shared pathophysiology of NFLE and AP and discuss the underlying functional network. Methods. Reviewing relevant published data we point out common features in semiology of events, relations to macro- and microstructural dynamism of NREM sleep, to cholinergic arousal mechanism and genetic aspects. Results. We propose that pathological arousals accompanied by confused behavior with autonomic signs and/or hypermotor automatisms are expressions of the frontal cholinergic arousal function of different degree, during the condition of depressed cognition by frontodorsal functional loss in NREM sleep. This may happen either if the frontal cortical Ach receptors are mutated in ADNFLE (and probably also in genetically not proved nonlesional cases as well), or without epileptic disorder, in AP, assuming gain in receptor functions in both conditions. This hypothesis incorporates the previous “liberation theory” of Tassinari and the “state dissociation hypothesis” of Bassetti and Terzaghi). We propose that NFLE and IGE represent epileptic disorders of the two antagonistic twin systems in the frontal lobe. NFLE is the epileptic facilitation of the ergotropic frontal arousal system whereas absence epilepsy is the epileptic facilitation of burst-firing working mode of the spindle and delta producing frontal thalamocortical throphotropic sleep system. Significance. The proposed physiopathogenesis conceptualize epilepsies in physiologically meaningful networks.

Epilepsy and sleep

PURPOSE OF REVIEW

There is a complex relationship between epilepsy, sleep and sleep disorders. Recent studies have provided new insights into the links between the disorders that may facilitate differential diagnosis and treatment but may also improve our understanding of underlying pathophysiological mechanisms.

RECENT FINDINGS

Sleep and sleep deprivation have long been recognized to influence interictal epileptiform discharges and seizures. More recent studies have shown that primary sleep disorders such as obstructive sleep apnoea may worsen epilepsy and treatment of these sleep disorders can lead to improved seizure control. Seizures may interfere with night-time sleep structure and cause excessive day-time somnolence (EDS). Antiepileptic drugs may also cause EDS or influence sleep. Despite more frequent use of video-electroencephalographic telemetry and polysomnography, the differential diagnostic challenges between nonrapid eye movement parasomnia and nocturnal frontal lobe epilepsy remain. There is also ongoing debate regarding the possibility of a common pathogenic background for parasomnias and nocturnal seizures that is summarized in the review.

SUMMARY

Accurate identification and diagnosis of sleep disorders as well as epilepsy is clinically important to ensure optimal treatment of both epilepsy and sleep disorders. Further studies of these nocturnal events may advance our understanding of underlying pathological mechanisms and the complex relationship between sleep and epilepsy.

Increased frequency of arousal parasomnias in families with nocturnal frontal lobe epilepsy: a common mechanism?

PURPOSE

Retrospective observations disclosed an overlap between parasomnias and nocturnal frontal lobe epilepsy (NFLE) not only in patients but also in their relatives, suggesting a possible common pathogenetic mechanism. This study aimed to verify whether relatives of patients with NFLE have a higher frequency of parasomnias, namely arousal disorders, and thereby shed light on the still unknown pathophysiologic mechanisms underlying NFLE.

METHODS

We undertook a case-control family study in which we recruited NFLE probands and healthy controls, matched for age, sex, education, and geographic origin. At least four relatives were included for each proband and control. Each subject underwent a standardized interview, with application of the International Classification of Sleep Disorders-Revised (ICSD-R 2001) minimal criteria to diagnose the lifetime prevalence of the main parasomnias.

RESULTS

Four hundred fifty-eight individuals were recruited: 33 NFLE probands, 200 relatives of probands, 31 controls, and 194 control relatives. All NFLE probands but one have sporadic NFLE. The lifetime prevalence of the following parasomnias differed in proband relatives versus control relatives: arousal disorders [odds ratio (OR) 4.7, 95% confidence interval (CI) 2.0-11.6; p < 0.001] and nightmares (OR 2.6, 95% CI 1.6-4.2; p < 0.001) were more frequent among NFLE proband relatives. In the secondary analysis comparing NFLE probands to controls, arousal disorders (OR 6.3, 95% CI 1.3-31.7; p = 0.023) and bruxism (OR 5.4, 95% CI 1.3-21.7; p = 0.017) were more frequent among NFLE probands.

DISCUSSION

The higher frequency of arousal disorders in NFLE families suggests an intrinsic link between parasomnias and NFLE and an abnormal (possibly cholinergic) arousal system as a common pathophysiologic mechanism.

NREM arousal parasomnias and their distinction from nocturnal frontal lobe epilepsy: a video EEG analysis

STUDY OBJECTIVES

To describe the semiological features of NREM arousal parasomnias in detail and identify features that can be used to reliably distinguish parasomnias from nocturnal frontal lobe epilepsy (NFLE).

DESIGN

Systematic semiologial evaluation of parasomnias and NFLE seizures recorded on video-EEG monitoring.

PATIENTS

120 events (57 parasomnias, 63 NFLE seizures) from 44 subjects (14 males). Interventions. The presence or absence of 68 elemental clinical features was determined in parasomnias and NFLE seizures. Qualitative analysis of behavior patterns and ictal EEG was undertaken. Statistical analysis was undertaken using established techniques.

RESULTS

Elemental clinical features strongly favoring parasomnias included: interactive behavior, failure to wake after event, and indistinct offset (all P < 0.001). Cluster analysis confirmed differences in both the frequency and combination of elemental features in parasomnias and NFLE. A diagnostic decision tree generated from these data correctly classified 94% of events. While sleep stage at onset was discriminatory (82% of seizures occurred during stage 1 or 2 sleep, with 100% of parasomnias occurring from stage 3 or 4 sleep), ictal EEG features were less useful. Video analysis of parasomnias identified three principal behavioral patterns: arousal behavior (92% of events); non-agitated motor behavior (72%); distressed emotional behavior (51%).

CONCLUSIONS

Our results broadly support the concept of confusion arousals, somnambulism and night terrors as prototypical behavior patterns of NREM parasomnias, but as a hierarchical continuum rather than distinct entities. Our observations provide an evidence base to assist in the clinical diagnosis of NREM parasomnias, and their distinction from NFLE seizures, on semiological grounds.