Effect of sleep quality on memory, executive function, and language performance in patients with refractory focal epilepsy and controlled epilepsy versus healthy controls - A prospective study

Temporal association between sleep spindles and ripples in the human anterior and mediodorsal thalamus

Sleep spindles are major oscillatory components of Non-Rapid Eye Movement (NREM) sleep, reflecting hyperpolarization-rebound sequences of thalamocortical neurons. Reports suggest a link between sleep spindles and several forms of high-frequency oscillations which are considered as expressions of pathological off-line neural plasticity in the central nervous system. Here we investigated the relationship between thalamic sleep spindles and ripples in the anterior and mediodorsal nuclei (ANT and MD) of epilepsy patients. Whole-night LFP from the ANT and MD were co-registered with scalp EEG/polysomnography by using externalized leads in 15 epilepsy patients undergoing a Deep Brain Stimulation protocol. Slow (~12 Hz) and fast (~14 Hz) sleep spindles were present in the human ANT and MD and roughly, 20% of them were associated with ripples. Ripple-associated thalamic sleep spindles were characterized by longer duration and exceeded pure spindles in terms of spindle power as indicated by time-frequency analysis. Furthermore, ripple amplitude was modulated by the phase of sleep spindles within both thalamic nuclei. No signs of pathological processes were correlated with measures of ripple and spindle association, furthermore, the density of ripple-associated sleep spindles in the ANT showed a positive correlation with verbal comprehension. Our findings indicate the involvement of the human thalamus in coalescent spindle-ripple oscillations of NREM sleep.

Association between depressive and anxious symptoms with cognitive function and quality of life in drug-resistant epilepsy

•Depressive/anxious disorders and cognitive impairment are frequent comorbidities in epilepsy and have a more deleterious effect in DRE.•Studies concerning the relationship between anxiety and depression and cognitive performance in DRE are scarce.•Higher scores in HADS are associated with lower QOLIE-31 scores and might be considered as predictors of QOL in DRE.•A relationship between anxious and depressive symptoms -measured with HADS and SCL-90R- and cognition might not exist.•There remains an unexplored study area regarding this relationship which requires more attention to improve the assessment of DRE.

Light exposure behaviors predict mood, memory and sleep quality

Ample research has shown that light influences our emotions, cognition, and sleep quality. However, little work has examined whether different light exposure-related behaviors, such as daytime exposure to electric light and nighttime usage of gadgets, especially before sleep, influence sleep quality and cognition. Three-hundred-and-one Malaysian adults (Mean_Age±SD = 28 ± 9) completed the Light Exposure Behavior Assessment tool that measured five light exposure behaviors. They also completed the Morningness-Eveningness Questionnaire, Positive and Negative Affect Schedule, Pittsburgh Sleep Quality Index, and single items assessing trouble in memory and concentration. A partial least square structural equation model, showing 72.72% predictive power, revealed that less use of wearable blue filters outdoors during the day and more within one hour before sleep predicted early peak time (direct effect = -0.25). Increased time spent outdoors predicted a positive affect (direct effect = 0.33) and a circadian phase advancement (direct effect: rising time = 0.14, peak time = 0.20, retiring time = 0.17). Increased use of mobile phone before sleep predicted a circadian phase delay (direct effect: retiring time = -0.25; rising time = -0.23; peak time = -0.22; morning affect = -0.12), reduced sleep quality (direct effect = 0.13), and increased trouble in memory and concentration (total effect = 0.20 and 0.23, respectively). Increased use of tunable, LED, or dawn-simulating electric light in the morning and daytime predicted a circadian phase advancement (direct effect: peak time = 0.15, morning affect = 0.14, retiring time = 0.15) and good sleep quality (direct effect = -0.16). The results provide valuable insights into developing a healthy light diet to promote health and wellness.

Does epileptic activity impair sleep-related memory consolidation in epilepsy? A critical and systematic review

STUDY OBJECTIVES

People with epilepsy often complain about disturbed sleep and cognitive impairment. Beyond seizures, the occurrence of interictal epileptic activity during sleep is also increasingly recognized to negatively impact cognitive functioning, including memory processes. The aim of this study was to critically review the effect of interictal epileptic activity on sleep-related memory consolidation.

METHODS

PubMed and PsychINFO databases were systematically searched to identify experimental studies that investigated sleep-related memory consolidation and the relationships between sleep-related epileptic activity and memory in adults and children with epilepsy. This review also highlights hypotheses regarding the potential pathophysiological mechanisms.

RESULTS

A total of 261 studies were identified; 27 of these met selection criteria. Only 13 studies prospectively assessed the effect of sleep on memory in epilepsy. Most studies reported no alteration of sleep-related memory consolidation in patients, with either similar retention levels following a period containing sleep (n = 5) or improved memory performance postsleep (n = 4). Two studies in children with epilepsy found impaired sleep-related memory consolidation. Ten studies, of which 6 were in childhood epilepsy syndromes, reported a debilitating effect of sleep-related epileptic activity on memory functioning.

CONCLUSIONS

Conclusions from existing studies were hampered by small sample sizes, heterogeneous patient groups, and variations in memory assessment techniques. Overall, results to date preclude any definitive conclusions on the alteration of sleep-related memory consolidation in epilepsy. We discuss methodological considerations specific to people with epilepsy and provide suggestions on how to best investigate the relationship between epileptic activity, sleep, and memory consolidation in future studies.

CITATION

Latreille V, Schiller K, Peter-Derex L, Frauscher B. Does epilepticimpair sleep-related memory consolidation in epilepsy? A critical and systematic review. J Clin Sleep Med. 2022;18(10):2481-2495.

Sleep and Temporal Lobe Epilepsy – Associations, Mechanisms and Treatment Implications

In this systematic review, we aim to describe the association between temporal lobe epilepsy (TLE) and sleep, with bidirectional links in mechanisms and therapeutic aspects. Sleep stages may variably impact seizure occurrence, secondary generalization and the development, frequency and distribution of interictal epileptiform discharges. Conversely, epilepsy affects sleep micro- and macroarchitecture. TLE, the most frequent form of drug resistant epilepsy (DRE), shares an enduring relationship with sleep, with some intriguing potential mechanisms specific to anatomic localization, linking the two. Sleep characteristics of TLE may also inform localizing properties in persons with DRE, since seizures arising from the temporal lobe seem to be more common during wakefulness, compared to seizures of extratemporal origin. Polysomnographic studies indicate that persons with TLE may experience excessive daytime somnolence, disrupted sleep architecture, increased wake after sleep onset, frequent shifts in sleep stages, lower sleep efficiency, decreased rapid eye movement (REM) sleep, and possibly, increased incidence of sleep apnea. Limited literature suggests that effective epilepsy surgery may remedy many of these objective and subjective sleep-related concerns, via multipronged effects, apart from reduced seizure frequency. Additionally, sleep abnormalities also seem to influence memory, language and cognitive-executive function in both medically controlled and refractory TLE. Another aspect of the relationship pertains to anti-seizure medications (ASMs), which may contribute significantly to sleep characteristics and abnormalities in persons with TLE. Literature focused on specific aspects of TLE and sleep is limited, and heterogeneous. Future investigations are essential to understand the pathogenetic mechanisms linking sleep abnormalities on epilepsy outcomes in the important sub-population of TLE.

Clinical utility of Epitrack for differentiating profiles and patterns of post-surgical change in memory and quality of life in patients with drug-resistant epilepsy

PURPOSE

To assess whether performance in attention and executive functions evaluated with the Epitrack screening tool before surgery can differentiate memory and quality of life (QOL) profiles, and detect different post-surgical change patterns in these variables in patients with epilepsy.

METHODS

This is a longitudinal study. Seventy-seven patients with drug-resistant epilepsy (mean age = 37.91) underwent a neuropsychological assessment before and one year after surgery. Epitrack, a screening tool that exclusively evaluates attention and executive functioning, was administered in the pre-surgical assessment, and verbal and visual memory and QOL were assessed before and after surgery.

RESULTS

Patients with impaired Epitrack performance had poorer verbal and visual memory than those with intact Epitrack performance, regardless of the time point (for all, p < 0.0001). They also showed a post-surgical decline in immediate verbal recall (p = 0.04) and discriminability (p = 0.001). Patients with intact Epitrack performance did not exhibit this decline. Epitrack total score significantly contributed to 13 and 11% of the variance of post-surgical changes in immediate verbal recall and discriminability, respectively. Epitrack groups did not differ in QOL profiles or changes, but post-surgical immediate verbal recall improvements were related to post-surgical QOL improvements.

CONCLUSION

Our findings underline the utility of Epitrack screening tool to detect different patterns of verbal and visual memory dysfunction, as well as to predict post-surgical verbal memory decline in patients with drug-resistant epilepsy. Patients with lower pre-surgical Epitrack scores appear to be at increased risk for post-surgical memory decline.

The use of rodent models to better characterize the relationship among epilepsy, sleep, and memory

Epilepsy, a neurological disorder characterized by recurrent seizures, is known to be associated with impaired sleep and memory. Although the specific mechanisms underlying these impairments are uncertain, the known role of sleep in memory consolidation suggests a potential relationship may exist between seizure activity, disrupted sleep, and memory impairment. A possible mediator in this relationship is the sleep spindle, the characteristic electroencephalographic (EEG) feature of non-rapid-eye-movement (NREM) sleep in humans and other mammals. Growing evidence supports the idea that sleep spindles, having thalamic origin, may mediate the process of long-term memory storage and plasticity by generating neuronal conditions that favor these processes. To study this potential relationship, a single model in which memory, sleep, and epilepsy can be simultaneously observed is of necessity. Rodent models of epilepsy appear to fulfill this requirement. Not only do rodents express both sleep spindles and seizure-induced sleep disruptions, but they also allow researchers to invasively study neurobiological processes both pre- and post- epileptic onset via the artificial induction of epilepsy (a practice that cannot be carried out in human subjects). However, the degree to which sleep architecture differs between rodents and humans makes direct comparisons between the two challenging. This review addresses these challenges and concludes that rodent sleep studies are useful in observing the functional roles of sleep and how they are affected by epilepsy.

Diffusion Abnormality in Temporal Lobe Epilepsy Patients With Sleep Disorders: A Diffusion Kurtosis Imaging Study

BACKGROUND

Patients with temporal lobe epilepsy (TLE) frequently complain of poor sleep quality, which is a condition that clinicians are typically neglecting. In this study, Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and Athens Insomnia Scale (AIS) were used to assess the sleep status of patients with temporal lobe epilepsy (TLE). Simultaneously diffusion kurtosis imaging (DKI) was applied to examine the white matter microstructure abnormalities in patients with TLE and sleep disorders.

METHODS

TLE patients who have been diagnosed in the cardio-cerebrovascular ward of the Yanan University Affiliated Hospital from October 2020 to August 2021 were recruited. Finally, 51 patients and 30 healthy controls were enrolled in our study, with all subjects completing the sleep evaluation questionnaire and undergoing a DKI examination. Using independent sample t-test, analysis of variance (ANOVA), and Mann-Whitney U test to compare groups.

RESULTS

Thirty patients (58.82%) complained of long-term sleep difficulties. The overall differences among the evaluation of AIS, ESS, and PSQI are significant (P = 0.00, P = 0.00, P = 0.03). The scores of AIS, ESS in Left and Right-TLE (L/R-TLE) with sleep disorders, as well as PSQI in L-TLE, are statistically higher than the control group (P = 0.00, P = 0.00, P = 0.00, P = 0.00, P = 0.02). L-TLE with sleep disorders showed decreased MK on affected sides (P = 0.01). However, statistical differences in MD and FA have not been observed (P = 0.34, P = 0.06); R-TLE with sleep disorders showed significantly decreased MK and increased MD on affected sides (P = 0.00, P = 0.00), but FA's statistical difference has not been observed (P = 0.20).

CONCLUSIONS

TLE patients with sleep disorders have different DKI parameters than individuals who do not have sleep issues. During this process, the kurtosis parameter (MK) was more sensitive than the tensor parameters (MD, FA) in detecting the patient's aberrant white matter diffusion. DKI may be a better choice for in vivo investigation of anomalous craniocerebral water diffusion.

Relationship between sleep quality and cognitive performance in patients with epilepsy

PURPOSE

To investigate the relationship between self-reported sleep quality and cognitive function in patients with epilepsy (PWE), as well as anxiety and depressive symptoms and patient quality of life (QoL).

METHODS

This multicenter cross-sectional study included PWE aged ≥12 years who were receiving ≥1 anti-seizure medication (ASM) and had not been diagnosed with a sleep disorder. Patients completed the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), the Montreal Cognitive Assessment test (MoCA), the Hospital Anxiety and Depression Scale (HADS), and the Quality of Life in Epilepsy Inventory-10 (QOLIE-10).

RESULTS

The study enrolled 150 patients aged 16-83 years, mean age (standard deviation [SD]) 40.6 (15.2) years; 58.7% were female and 75.3% had focal epilepsy. Mean (SD) PSQI score was 4.71 (3.08), 44.4% of patients had impaired sleep quality (PSQI score ≥5), 19.9% had pathologic excessive daytime sleepiness (ESS score >12), and 32.7% had mild cognitive impairment (MoCA score <26). Within the PSQI, sleep disturbance (P = 0.036) and use of sleep medication (P = 0.006) scores were significantly higher in patients with mild cognitive impairment. Multiple regression analysis showed older age (regression coefficient [B], -0.086; 95% confidence interval [CI], -0.127, -0.045; P < 0.001) and the use of sleep medication component of the PSQI [B, -1.157; 95% CI, -2.064, -0.220; P = 0.013) were independently associated with lower MoCA score. Poor sleep quality was associated with probable anxiety and depression symptoms, and directly correlated with reduced QoL.

CONCLUSIONS

In PWE, sleep quality was not significantly independently associated with mild cognitive impairment, although poor sleep quality had a negative effect on mood and QoL.

Sleep scoring based on video-electroencephalography monitoring in an Epileptology Unit: Comparison with polysomnography

The aim of the study was to compare the performance of video- electroencephalography (EEG) monitoring and standard polysomnography for sleep scoring in an Epileptology Unit. We calculated the level of agreement between two methods of sleep scoring, using either 27-electrode video-EEG or polysomnography for 1 night in 22 patients admitted to our Epileptology Unit. Independent experts manually scored sleep using the American Academy of Sleep Medicine 2017 guidelines. We evaluated the number of sleep cycles and their distribution on hypnogram, total sleep time, sleep efficiency, sleep and rapid eye movement sleep-onset latency, wake after sleep-onset, and sleep stages. We then extracted sub-samples of recordings to examine the agreement in microarousal and rapid eye movement scoring. We used Bland and Altman plots and Cohen's kappa test to measure agreement. Bland and Altman plots showed at least 95% agreement for all studied sleep parameters with the exception of wake after sleep onset, where there was an 11 min difference. Cohen's kappa test showed an agreement for the recognition of microarousal (0.89) and of rapid eye movements (0.96) in sub-samples. Video-EEG represents an acceptable alternative tool for sleep architecture study in patients admitted to an Epileptology Unit.

Sleep profile and Polysomnography in patients with drug-resistant temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS) and the effect of epilepsy surgery on sleep-a prospective cohort study

OBJECTIVES

We analyzed changes in sleep profile and architecture of patients with drug-resistant TLE-HS using three validated sleep questionnaires- Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), NIMHANS Comprehensive Sleep Disorders, and polysomnography (PSG). We studied the effect of epilepsy surgery in a subset of patients.

METHODS

In this prospective observational cohort study, sleep profile of 40 patients with drug-resistant TLE-HS was compared to 40 healthy matched controls. Sleep architecture of 22 patients was studied by overnight PSG and compared to 22 matched controls. Sleep profile was reassessed in 20 patients after a minimum period of three months after epilepsy surgery.

RESULTS

The mean PSQI was higher among patients compared to controls(P=0.0004) while mean ESS showed no difference. NCSDQ showed fewer patients feeling refreshed after a night's sleep compared to controls (p=0.006). PSG revealed a higher time in bed (p=0.0001), longer total sleep time (p=0.006) and more time spent in NREM stage 1 (p=0.001) and stage 2 (p=0.005) while spending less time in stage 3 (p=0.039) among TLE patients. Sleep efficiency was worse in patients on ≥3 ASMs compared to those on 2 ASMs (p-0.044). There was no change in mean ESS (p=0.48) or PSQI (p=0.105) after surgery.

CONCLUSIONS

Patients with drug-resistant TLE-HS have an altered sleep profile and architecture. Patients on ≥3 ASMs have a lower sleep efficiency. Reassessment at short intervals after epilepsy surgery did not reveal significant changes in sleep profile.

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

Sleep-related hypermotor epilepsy (SHE) is a group of clinical syndromes with heterogeneous etiologies. SHE is difficult to diagnose and treat in the early stages due to its diverse clinical manifestations and difficulties in differentiating from non-epileptic events, which seriously affect patients' quality of life and social behavior. The overall prognosis for SHE is unsatisfactory, but different etiologies affect patients' prognoses. Surgical treatment is an effective method for carefully selected patients with refractory SHE; nevertheless, preoperative assessment remains challenging because of the low sensitivity of noninvasive scalp electroencephalogram and imaging to detect abnormalities. However, through a careful analysis of semiology, the clinician can deduce the potential epileptogenic zone. This paper summarizes the research status of the background, etiology, electro-clinical features, diagnostic criteria, prognosis, and treatment of SHE to provide a more in-depth understanding of its pathophysiological mechanism, improve the accuracy in the diagnosis of this group of syndromes, and further explore more targeted therapy plans.

Sleep disturbance and cognitive decline in multiple sclerosis patients with isolated optic neuritis as the first demyelinating event

PURPOSE

Multiple sclerosis (MS) patients whose first demyelinating event is optic neuritis have been claimed to display a milder disease course and reduced physical disability. Our aim was to investigate the impact of the clinical features of the first clinical episode on cognitive disability and sleep dysfunction in MS.

METHODS

A total of 26 (10 with optic neuritis as the first clinical event) MS patients were recruited. A comprehensive sleep study was performed, and a panel of tests were administered to examine cognitive and motor performance. Serum levels of sleep-related mediators orexin-A and melatonin were measured by enzyme-linked immunosorbent assay. Subjective sleep quality was evaluated by Pittsburgh sleep quality test, and daytime excessive sleepiness was tested by Epworth sleepiness scale.

RESULTS

MS patients with the first clinical episode of optic neuritis and patients with at least one optic neuritis attack exhibited increased daytime sleepiness, higher sleep efficiency and NREM duration and lower total wake time. Patients with a history of optic neuritis obtained more favorable scores in neuropsychological tests measuring executive functions and complex attention as compared to those who had never experienced optic neuritis. Melatonin and orexin-A levels were lower in patients with optic neuritis onset. The higher no. of optic neuritis attacks was associated with reduced wake time and higher symbol digit modalities test scores.

CONCLUSIONS

Having a history of optic neuritis is associated with improved sleep quality and executive functions but increased daytime sleepiness. Reduction of orexin-A and melatonin levels might be one of the underlying mechanisms.