Pain and sleep: From reaction to action

Functional connectivity between medial pulvinar and cortical networks as a predictor of arousal to noxious stimuli during sleep

The interruption of sleep by a nociceptive stimulus is favoured by an increase in the pre-stimulus functional connectivity between sensory and higher level cortical areas. In addition, stimuli inducing arousal also trigger a widespread electroencephalographic (EEG) response reflecting the coordinated activation of a large cortical network. Because functional connectivity between distant cortical areas is thought to be underpinned by trans-thalamic connections involving associative thalamic nuclei, we investigated the possible involvement of one principal associative thalamic nucleus, the medial pulvinar (PuM), in the sleeper's responsiveness to nociceptive stimuli. Intra-cortical and intra-thalamic signals were analysed in 440 intracranial electroencephalographic (iEEG) segments during nocturnal sleep in eight epileptic patients receiving laser nociceptive stimuli. The spectral coherence between the PuM and 10 cortical regions grouped in networks was computed during 5 s before and 1 s after the nociceptive stimulus and contrasted according to the presence or absence of an arousal EEG response. Pre- and post-stimulus phase coherence between the PuM and all cortical networks was significantly increased in instances of arousal, both during N2 and paradoxical (rapid eye movement [REM]) sleep. Thalamo-cortical enhancement in coherence involved both sensory and higher level cortical networks and predominated in the pre-stimulus period. The association between pre-stimulus widespread increase in thalamo-cortical coherence and subsequent arousal suggests that the probability of sleep interruption by a noxious stimulus increases when it occurs during phases of enhanced trans-thalamic transfer of information between cortical areas.

Interactive effects of pain and arousal state on heart rate and cortical activity in the mouse anterior cingulate and somatosensory cortices

Sensory disconnection is a hallmark of sleep, yet the cortex retains some ability to process sensory information. Acute noxious stimulation during sleep increases the heart rate and the likelihood of awakening, indicating that certain mechanisms for pain sensing and processing remain active. However, processing of somatosensory information, including pain, during sleep remains underexplored. To assess somatosensation in natural sleep, we simultaneously recorded heart rate and local field potentials in the anterior cingulate (ACC) and somatosensory (S1) cortices of naïve, adult male mice, while applying noxious and non-noxious stimuli to their hind paws throughout their sleep-wake cycle. Noxious stimuli evoked stronger heart rate increases in both wake and non-rapid eye movement sleep (NREMS), and resulted in larger awakening probability in NREMS, as compared to non-noxious stimulation, suggesting differential processing of noxious and non-noxious information during sleep. Somatosensory information differentially reached S1 and ACC in sleep, eliciting complex transient and sustained responses in the delta, alpha, and gamma frequency bands as well as somatosensory evoked potentials. These dynamics depended on sleep state, the behavioral response to the stimulation and stimulation intensity (non-noxious vs. noxious). Furthermore, we found a correlation of the heart rate with the gamma band in S1 in the absence of a reaction in wake and sleep for noxious stimulation. These findings confirm that somatosensory information, including nociception, is sensed and processed during sleep even in the absence of a behavioral response.

Effect of Different Administration Routes of Dexmedetomidine on Postoperative Delirium in Elderly Patients Undergoing Elective Spinal Surgery: A Prospective Randomized Double-Blinded Controlled Trial

BACKGROUND

Intravenous dexmedetomidine has been reported to decrease the occurrence of postoperative delirium (POD) in elderly patients. Nevertheless, some previous studies have indicated that intratracheal dexmedetomidine and intranasal dexmedetomidine are also effective and convenient. The current study aimed to compare the effect of different administration routes of dexmedetomidine on POD in elderly patients.

METHODS

We randomly allocated 150 patients (aged 60 years or more) scheduled for spinal surgery to receive intravenous dexmedetomidine (0.6 μg/kg), intranasal dexmedetomidine (1 μg/kg) before anesthesia induction, or intratracheal dexmedetomidine (0.6 µg/kg) after anesthesia induction. The primary outcome was the frequency of delirium during the first 3 postoperative days. The secondary outcomes were the incidence of postoperative sore throat (POST) and sleep quality. Adverse events were recorded, and routine treatment was performed.

RESULTS

Compared with the intranasal group, the intravenous group had a significantly lower occurrence of POD within 3 days (3 of 49 [6.1%] vs 14 of 50 [28.0%]; odds ratio [OR], 0.17; 95% confidence intervals [CIs], 0.05-0.63; P < .017). Meanwhile, patients in the intratracheal group had a lower incidence of POD than those in the intranasal group (5 of 49 [10.2%] vs 14 of 50 [28.0%]; OR, 0.29; 95% CI, 0.10-0.89; P < .017). Whereas, there was no difference between the intratracheal and intravenous groups (5 of 49 [10.2%] vs 3 of 49 [6.1%]; OR, 1.74; 95% CI, 0.40-7.73; P > .017). The rate of POST was lower in the intratracheal group than that in the other 2 groups at 2 hours after surgery (7 of 49 [14.3%] vs 12 of 49 [24.5%] vs 18 of 50 [36.0%], P < .017, respectively). Intravenous dexmedetomidine had the lowest Pittsburgh Sleep Quality Index score on the second morning after surgery (median [interquartile range {IQR}]: 4 [3-5] vs 6 [4-7] vs 6 [4-7], P < .017, respectively). Compared with the intranasal group, the intravenous group had a higher rate of bradycardia and a lower incidence of postoperative nausea and vomiting ( P < .017). The intranasal group was associated with the highest incidence of hypertension ( P < .017).

CONCLUSIONS

For patients aged ≥60 years undergoing spinal surgery, compared with the intranasal route of dexmedetomidine, intravenous and intratracheal dexmedetomidine reduced the incidence of early POD. Meanwhile, intravenous dexmedetomidine was associated with better sleep quality after surgery, and intratracheal dexmedetomidine resulted in a lower incidence of POST. Adverse events were mild in all 3 administration routes of dexmedetomidine.

Predictive coding, multisensory integration, and attentional control: A multicomponent framework for lucid dreaming

Lucid dreaming (LD) is a mental state in which we realize not being awake but are dreaming while asleep. It often involves vivid, perceptually intense dream images as well as peculiar kinesthetic sensations, such as flying, levitating, or out-of-body experiences. LD is in the cross-spotlight of cognitive neuroscience and sleep research as a particular case to study consciousness, cognition, and the neural background of dream experiences. Here, we present a multicomponent framework for the study and understanding of neurocognitive mechanisms and phenomenological aspects of LD. We propose that LD is associated with prediction error signals arising during sleep and occurring at higher or lower levels of the processing hierarchy. Prediction errors are resolved by generating a superordinate self-model able to integrate ambiguous stimuli arriving from sensory periphery and higher-order cortical regions. While multisensory integration enables lucidity maintenance and contributes to peculiar kinesthetic experiences, attentional control facilitates multisensory integration by dynamically regulating the balance between the influence of top-down mental models and the precision weighting of bottom-up sensory inputs. Our novel framework aims to link neural correlates of LD with current concepts of sleep and arousal regulation and provide testable predictions on interindividual differences in LD as well as neurocognitive mechanisms inducing lucid dreams.

Cortical monitoring of cardiac activity during rapid eye movement sleep: the heartbeat evoked potential in phasic and tonic rapid-eye-movement microstates

Sleep is a fundamental physiological state that facilitates neural recovery during periods of attenuated sensory processing. On the other hand, mammalian sleep is also characterized by the interplay between periods of increased sleep depth and environmental alertness. Whereas the heterogeneity of microstates during non-rapid-eye-movement (NREM) sleep was extensively studied in the last decades, transient microstates during rapid-eye-movement (REM) sleep received less attention. REM sleep features two distinct microstates: phasic and tonic. Previous studies indicate that sensory processing is largely diminished during phasic REM periods, whereas environmental alertness is partially reinstated when the brain switches into tonic REM sleep. Here, we investigated interoceptive processing as quantified by the heartbeat evoked potential (HEP) during REM microstates. We contrasted the HEPs of phasic and tonic REM periods using two separate databases that included the nighttime polysomnographic recordings of healthy young individuals (N = 20 and N = 19). We find a differential HEP modulation of a late HEP component (after 500 ms post-R-peak) between tonic and phasic REM. Moreover, the late tonic HEP component resembled the HEP found in resting wakefulness. Our results indicate that interoception with respect to cardiac signals is not uniform across REM microstates, and suggest that interoceptive processing is partially reinstated during tonic REM periods. The analyses of the HEP during REM sleep may shed new light on the organization and putative function of REM microstates.

Intracortical Functional Connectivity Predicts Arousal to Noxious Stimuli during Sleep in Humans

Nociceptive stimuli disrupt sleep, but may, or may not, entail an arousal. While arousal reactions go along with the activation of a widespread cortical network, the factors enabling such activation remain unknown. Here we used intracranial EEG in humans to test the relation between the cortical activity immediately preceding a noxious stimulus and the capacity of such a stimulus to trigger arousal. Intracranial EEG signals were analyzed during all-night sleep in 14 epileptic patients (4 women), who received laser stimuli slightly above their individual pain threshold. During 5 s preceding each stimulus, the functional correlation (spectral phase-coherence) between the main spinothalamic sensory area (posterior insula) and 12 other brain regions, grouped in four networks, as well as their spectral contents, were contrasted according to the presence of a stimulus-induced arousal, and then fed into a logistic regression model to assess their predictive value. Enhanced prestimulus phase-coherence between the sensory posterior insula and neocortical and limbic areas increased significantly the probability of arousal to nociceptive stimuli, in both slow-wave (N2) and rapid eye movements/paradoxical sleep. Furthermore, during N2 sleep, arousal was facilitated by stimulus delivery in periods of attenuated slow-wave activity. Together, these data indicate that sleep micro-states with enhanced interareal communication facilitate information transfer from sensory to higher-order cortical areas, and hence physiological arousal.SIGNIFICANCE STATEMENT Sleep is commonly subdivided into stages based on specific electrophysiological characteristics; however, within each single sleep stage, the functional state of the brain is continuously changing. Here we show that the probability for a phasic noxious stimulus to entail an arousal is modulated by the prestimulus interareal phase-coherence between sensory and higher-level cortical areas. Fluctuations in interareal communication immediately before the noxious stimulus may determine the responsiveness to incoming input by facilitating or preventing the transfer of noxious information from sensory to multiple higher-level cortical networks.

Acupressure on Anxiety and Sleep Quality After Cardiac Surgery: A Randomized Controlled Trial

PURPOSE

To determine the effect of acupressure on anxiety and sleep quality after cardiac surgery.

DESIGN

A randomized pre-post test control group design.

METHODS

Patients after cardiac surgery were divided into two groups: the intervention group (n = 50), who received acupressure on four different acupoints plus standard care, and the control group (n = 50), who received only standard care. Patients were admitted to the surgical clinic from the intensive care unit after 3 or 4 days of surgery. The levels of anxiety and sleep quality were evaluated during three postoperative days starting from their first day in the surgical clinic.

FINDINGS

Among the patients in the intervention group, the usage of acupressure decreased the level of anxiety and increased the sleep quality significantly compared with the control group (P < .05).

CONCLUSIONS

Our findings showed that acupressure decreased the level of anxiety and improved the sleep quality in the surgical clinic after cardiac surgery.

Psychological support of esophageal cancer patient?

Important questions are still open about psychological aspects in esophageal cancer (EC) and about the related psychological support. How to cope with the cancer diagnosis and poor prognosis: a psychological counselling may be a valid option to personalize the communication to patients with a poor prognosis. How to cope with long chemoradiotherapy: after neoadjuvant therapy, patients know that curative process is not completed, and they perceive the severity of the neoadjuvant side effects, considering themselves "fragile" and far from a healthy condition before the major surgery they are going to undergo. Therefore, this is a particularly crucial point when psychological support may be useful. How to cope with change of nutritional habits: esophagectomy for cancer strongly impairs nutritional function in the early postoperative period and feeding Jejunostomy impairs emotional function. How to cope with sleep disturbances: most cancer patients report disturbed sleep after cancer diagnosis and/or following cancer treatment. Psychological intervention aims to identify underlying concerns worsening sleep quality. How to cope with postoperative complications: the occurrence of such complications reduces patient's satisfaction and has a negative effect on doctor-patient relationship. How to cope with long-term functions impairment: EC patients need a plan for the future.

Randomized clinical trial of psychological support and sleep adjuvant measures for postoperative sleep disturbance in patients undergoing oesophagectomy

BACKGROUND

Major surgery such as oesophagectomy requires a postoperative stay in intensive care. Painful stimuli lead to sleep disturbance and impairment in quality of life. The aim of this study was to evaluate the effect of psychological counselling and sleep adjuvant measures on postoperative quality of sleep and quality of life.

METHODS

This RCT was performed between January 2013 and October 2015. Patients undergoing oesophagectomy for cancer were randomized into one of four groups receiving: psychological counselling plus sleep adjuvant measures during the ICU stay; psychological counselling alone; sleep adjuvant measures alone during the ICU stay; or standard care. The primary endpoint was impairment in quality of life measured using the European Organisation for Research and Treatment of Cancer C30-QL2 questionnaire between admission for surgery and discharge from hospital. The secondary endpoint was impairment in quality of sleep assessed by means of the Pittsburgh Sleep Quality Index between admission for surgery and hospital discharge.

RESULTS

The local ethics committee approved the early termination of the study because of relevant changes in the ICU setting. Some 87 patients were randomized and 74 patients were evaluated in the analysis. Psychological counselling reduced the impairment in quality of life (odds ratio 0·23, 95 per cent c.i. 0·09 to 0·61) and in quality of sleep (odds ratio 0·27, 0·10 to 0·73).

CONCLUSION

Perioperative psychological support reduces impairment in quality of life and quality of sleep after oesophagectomy. Registration number: NCT01738620 (http://www.clinicaltrials.gov).

Sleep spindles and human cortical nociception: a surface and intracerebral electrophysiological study

KEY POINTS

Sleep spindle are usually considered to play a major role in inhibiting sensory inputs. Using nociceptive stimuli in humans, we tested the effect of spindles on behavioural, autonomic and cortical responses in two experiments using surface and intracerebral electroencephalographic recordings. We found that sleep spindles do not prevent arousal reactions to nociceptive stimuli and that autonomic reactivity to nociceptive inputs is not modulated by spindle activity. Moreover, neither the surface sensory, nor the insular evoked responses were modulated by the spindle, as detected at the surface or within the thalamus. The present study comprises the first investigation of the effect of spindles on nociceptive information processing and the results obtained challenge the classical inhibitory effect of spindles.

ABSTRACT

Responsiveness to environmental stimuli declines during sleep, and sleep spindles are often considered to play a major role in inhibiting sensory inputs. In the present study, we tested the effect of spindles on behavioural, autonomic and cortical responses to pain, in two experiments assessing surface and intracerebral responses to thermo-nociceptive laser stimuli during the all-night N2 sleep stage. The percentage of arousals remained unchanged as a result of the presence of spindles. Neither cortical nociceptive responses, nor autonomic cardiovascular reactivity were depressed when elicited within a spindle. These results could be replicated in human intracerebral recordings, where sleep spindle activity in the posterior thalamus failed to depress the thalamocortical nociceptive transmission, as measured by sensory responses within the posterior insula. Hence, the assumed inhibitory effect of spindles on sensory inputs may not apply to the nociceptive system, possibly as a result of the specificity of spinothalamic pathways and the crucial role of nociceptive information for homeostasis. Intriguingly, a late scalp response commonly considered to reflect high-order stimulus processing (the 'P3' potential) was significantly enhanced during spindling, suggesting a possible spindle-driven facilitation, rather than attenuation, of cortical nociception.

Impact of a Script-based Communication Intervention on Patient Satisfaction with Pain Management

Pain is a common complaint among hospitalized patients no matter the diagnosis. Pain has a negative effect on many aspects of a patient's life, including quality of life, sleep, and activities of daily living as well as increased health care expenses. The aim of this study was to evaluate the effectiveness of an intervention (script-based communication, use of white boards, and hourly rounding) related to pain management on patient satisfaction with nurses' management of pain. A prospective, quasi-experimental pretest-posttest design was used. Data were collected from two units that provided care for patients with a variety of medical-surgical diagnoses in a hospital located in an academic health sciences center in the southern United States. When nurses used clear and consistent communication with patients in pain, a positive effect was seen in patient satisfaction with pain management over time. This intervention was simple and effective. It could be replicated in a variety of health care organizations.

Sleep disturbances and quality of life in postoperative management after esophagectomy for esophageal cancer

Background

The aims of this prospective study were to analyze the predictors of postoperative sleep disturbance after esophagectomy for cancer and to identify patients at risk for postoperative hypnotic administration.

Methods

Sixty two consecutive patients who underwent cancer-related esophagectomy were enrolled in this study from May 2011 to February 2012. Data about perioperative management, postoperative complications, ICU stay, and vasopressor, hypnotic, and painkiller administration were retrieved. The EORTC QLQ-C30 was used and global quality of life (QL2 item) and sleep disturbance (SL item) were the primary endpoints. Univariate and multivariate analyses were performed.

Results

Postoperative request of hypnotics independently predicted bad quality of life outcome. Sleep disturbance after esophagectomy was independently predicted by the duration of dopamine infusion in the ICU and the daily request of benzodiazepines. Even in this case, only sleep disturbance at diagnosis revealed to be an independent predictor of hypnotic administration need. ROC curve analysis showed that sleep disturbance at diagnosis was a good predictor of benzodiazepine request (AUC = 73%, P = 0.02).

Conclusions

The use of vasopressors in the ICU affects sleep in the following postoperative period and the use of hypnotics is neither completely successful nor lacking in possible consequences. Sleep disturbance at diagnosis can successfully predict patients who can develop sleep disturbance during the postoperative period.

Sleep disorders and systemic lupus erythematosus

Objective

Sleep disturbances are often seen in rheumatic diseases, including systemic lupus erythematosus (SLE). However, the prevalence of sleep disorders in SLE as well as the contributing factors to their occurrence remain poorly understood. The aim of this paper is to review the clinical and psychobiological data on the relationship between sleep disturbances and SLE.

Method

We performed a systematic search of MEDLINE, EMBASE and PsychINFO, using MeSH headings and keywords for “sleep disorders” and “SLE.”

Results

Nine studies reporting the relationship between sleep disorders and SLE were found. Prevalence rates of sleep disorders ranged between 55% and 85%; differences in assessment techniques appeared to be a major source of this variability. In the majority of the studies an association between sleep disorders and disease activity, pain and fatigue has been reported. Psychosocial variables, depression, steroid use, and the role that sleep disruption has on pain, inflammation and cytokines, have been hypothesized as possible psychobiological factors.

Conclusions

Sleep disorders appear to occur in more than half of patients with SLE and appear to be associated with disease activity. Pain and fatigue are also related to sleep disorders. Among the hypotheses on the possible mechanisms underlining the association between sleep disorders and SLE, psychosocial/psychological factors, especially depression, were the most frequently reported.