Pain and non-pain processing during hypnosis: a thulium-YAG event-related fMRI study

"Close your eyes and relax": the role of hypnosis in reducing anxiety, and its implications for the prevention of cardiovascular diseases

Anxiety is the most common form of mental health disorder, affecting millions of people worldwide. Psychosocial interventions such as mindfulness and cognitive behavioral therapy (CBT) have been suggested as an effective treatment in the management of general anxiety and anxiety disorders, with emerging evidence also suggesting the effectiveness of hypnosis. Moreover, anxiety has shown to be linked to the onset and development of several cardiovascular diseases (CVD), which are the leading cause of global death. In this paper, we review the current literature to examine the role that anxiety has on the onset and development of CVD and summarize the current knowledge on the role that hypnosis and hypnotherapy have in reducing anxiety, also explaining how this can impact the cardiovascular system and the prevention of CVD. Review of the evidence suggests that hypnosis and hypnotherapy are effective in treating anxiety and may positively affect the heart and the cardiovascular system, reducing sympathetic activation and increasing parasympathetic tone, potentially preventing the onset of CVD related to increased sympathetic activation. However, further studies are required to further understand how hypnosis and hypnotherapy affect the cardiovascular system through investigation of the neurophysiological components of the hypnotic state and of the mind-body relationship. Healthcare systems should embed mental health screening in patients at risk of developing CVD as part of the clinical pathway and consider the role that hypnosis and hypnotherapy may play in the management of CVD.

Cognitive simulation along with neural adaptation explain effects of suggestions: a novel theoretical framework

Hypnosis is an effective intervention with proven efficacy that is employed in clinical settings and for investigating various cognitive processes. Despite their practical success, no consensus exists regarding the mechanisms underlying well-established hypnotic phenomena. Here, we suggest a new framework called the Simulation-Adaptation Theory of Hypnosis (SATH). SATH expands the predictive coding framework by focusing on (a) redundancy elimination in generative models using intrinsically generated prediction errors, (b) adaptation due to amplified or prolonged neural activity, and (c) using internally generated predictions as a venue for learning new associations. The core of our treatise is that simulating proprioceptive, interoceptive, and exteroceptive signals, along with the top-down attenuation of the precision of sensory prediction errors due to neural adaptation, can explain objective and subjective hypnotic phenomena. Based on these postulations, we offer mechanistic explanations for critical categories of direct verbal suggestions, including (1) direct-ideomotor, (2) challenge-ideomotor, (3) perceptual, and (4) cognitive suggestions. Notably, we argue that besides explaining objective responses, SATH accounts for the subjective effects of suggestions, i.e., the change in the sense of agency and reality. Finally, we discuss individual differences in hypnotizability and how SATH accommodates them. We believe that SATH is exhaustive and parsimonious in its scope, can explain a wide range of hypnotic phenomena without contradiction, and provides a host of testable predictions for future research.

Neuroscientific results of experimental studies on the control of acute pain with hypnosis and suggested analgesia

This narrative review summarizes a representative collection of electrophysiological and imaging studies on the neural processes and brain sources underlying hypnotic trance and the effects of hypnotic suggestions on the processing of experimentally induced painful events. It complements several reviews on the effect of hypnosis on brain processes and structures of chronic pain processing. Based on a summary of previous findings on the neuronal processing of experimentally applied pain stimuli and their effects on neuronal brain structures in healthy subjects, three neurophysiological methods are then presented that examine which of these neuronal processes and structures get demonstrably altered by hypnosis and can thus be interpreted as neuronal signatures of the effect of analgesic suggestions: (A) On a more global neuronal level, these are electrical processes of the brain that can be recorded from the cranial surface of the brain with magnetoencephalography (MEG) and electroencephalography (EEG). (B) On a second level, so-called evoked (EPs) or event-related potentials (ERPs) are discussed, which represent a subset of the brain electrical parameters of the EEG. (C) Thirdly, imaging procedures are summarized that focus on brain structures involved in the processing of pain states and belong to the main imaging procedures of magnetic resonance imaging (MRI/fMRI) and positron emission tomography (PET). Finally, these different approaches are summarized in a discussion, and some research and methodological suggestions are made as to how this research could be improved in the future.

Brain Functional Correlates of Resting Hypnosis and Hypnotizability: A Review

This comprehensive review delves into the cognitive neuroscience of hypnosis and variations in hypnotizability by examining research employing functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and electroencephalography (EEG) methods. Key focus areas include functional brain imaging correlations in hypnosis, EEG band oscillations as indicators of hypnotic states, alterations in EEG functional connectivity during hypnosis and wakefulness, drawing critical conclusions, and suggesting future research directions. The reviewed functional connectivity findings support the notion that disruptions in the available integration between different components of the executive control network during hypnosis may correspond to altered subjective appraisals of the agency during the hypnotic response, as per dissociated and cold control theories of hypnosis. A promising exploration avenue involves investigating how frontal lobes' neurochemical and aperiodic components of the EEG activity at waking-rest are linked to individual differences in hypnotizability. Future studies investigating the effects of hypnosis on brain function should prioritize examining distinctive activation patterns across various neural networks.

Effect of Hypnosis on Pain, Anxiety, and Quality of Life in Female Patients with Fibromyalgia: Prospective, Randomized, Controlled Study

This prospective, randomized, controlled study aimed to investigate the effects of standardized adjuvant hypnosis on pain, depression, anxiety, aerobic exercise practices, quality of life, and disease impact score in female patients with fibromyalgia syndrome (FMS). This study included 47 female patients with FMS who had been under treatment for at least six months. The hypnosis group (n = 24) received a total of three hypnosis sessions and was taught to patients' self-hypnosis. The patients in this group practiced self-hypnosis for six months. During this period, all patients also continued their medical treatment. The Visual Analogue Scale (VAS) was used to determine the intensity of pain. At the end of the six-month follow-up period, it was determined that the patients of FMS with hypnosis therapy had lower pain intensity, FMS symptoms, depression, and anxiety symptoms, and better well-being than those in the control group (p < .05). Standardized hypnosis is an effective method in reducing pain, depression and anxiety symptoms and improving quality of life in patients with FMS.

Dynamic processes of mindfulness-based alterations in pain perception

Mindfulness-based processes have been shown to enhance attention and related behavioral responses, including analgesia, which is discussed as an effective method in the context of pain interventions. In the present review, we introduce the construct of mindfulness, delineating the concepts, factors, and processes that are summarized under this term and might serve as relevant components of the underlying mechanistic pathways in the field of pain. We also discuss how differences in factors such as definitions of mindfulness, study design, and strategies in mindfulness-based attention direction may need to be considered when putting the findings from previous studies into a whole framework. In doing so, we capitalize on a potential dynamic process model of mindfulness-based analgesia. In this respect, the so-called mindfulness-based analgesia may initially result from improved cognitive regulation strategies, while at later stages of effects may be driven by a reduction of interference between both cognitive and affective factors. With increasing mindfulness practice, pathways and mechanisms of mindfulness analgesia may change dynamically, which could result from adaptive coping. This is underlined by the fact that the neural mechanism of mindfulness analgesia is manifested as increased activation in the ACC and aINS at the beginner level while increased activation in the pINS and reduced activation in the lPFC at the expert level.

The neural basis of pain during labor

Characterizing a labor pain-related neural signature is a key prerequisite for devising optimized pharmacologic and nonpharmacologic labor pain relief methods. The aim of this study was to describe the neural basis of labor pain and to provide a brief summary of how epidural anesthesia may affect pain-related neuronal activity during labor. Possible future directions are also highlighted. By taking advantage of functional magnetic resonance imaging, brain activation maps and functional neural networks of women during labor that have been recently characterized were compared between pregnant women who received epidural anesthesia and those who did not. In the subgroup of women who did not receive epidural anesthesia, labor-related pain elicited activations in a distributed brain network that included regions within the primary somatosensory cortex (postcentral gyrus and left parietal operculum cortex) and within the traditional pain network (lentiform nucleus, insula, and anterior cingulate gyrus). The activation maps of women who had been administered epidural anesthesia were found to be different-especially with respect to the postcentral gyrus, the insula, and the anterior cingulate gyrus. Parturients who received epidural anesthesia were also compared with those who did not in terms of functional connectivity from selected sensory and affective regions. When analyzing women who did not receive epidural anesthesia, marked bilateral connections from the postcentral gyrus to the superior parietal lobule, supplementary motor area, precentral gyrus, and the right anterior supramarginal gyrus were observed. In contrast, women who received epidural anesthesia showed fewer connections from the postcentral gyrus-being limited to the superior parietal lobule and supplementary motor area. Importantly, one of the most noticeable effects of epidural anesthesia was observed in the anterior cingulate cortex-a primary region that modulates pain perception. The increased outgoing connectivity from the anterior cingulate cortex in women who received epidural anesthesia indicates that the cognitive control exerted by this area might play a major role in the relief from labor pain. These findings not only affirmed the existence of a brain signature for pain experienced during labor, but they also showed that this signature can be altered by the administration of epidural anesthesia. This finding raises a question about the extent to which the cingulo-frontal cortex may exert top-down influences to gate women's experiences of labor-related pain. Because the anterior cingulate cortex is also involved in the processing and modulation of emotional content, such as fear and anxiety, a related question is about the extent to which the use of epidural anesthesia can affect different components of pain perception. Finally, inhibition of anterior cingulate cortex neurons may represent a potential new therapeutic target for alleviating labor-associated pain.

A neurophenomenological approach to non-ordinary states of consciousness: hypnosis, meditation, and psychedelics

No contemporary unifying framework has been provided for the study of non-ordinary states of consciousness (NSCs) despite increased interest in hypnosis, meditation, and psychedelics. NSCs induce shifts in experiential contents (what appears to the experiencer) and/or structure (how it appears). This can allow the investigation of the plastic and dynamic nature of experience from a multiscale perspective that includes mind, brain, body, and context. We propose a neurophenomenological (NP) approach to the study of NSCs which highlights their role as catalysts of transformation in clinical practice by refining our understanding of the relationships between experiential (subjective) and neural dynamics. We outline the ethical implications of the NP approach for standard conceptions of health and pathology as well as the crucial role of experience-based know-how in NSC-related research and application.

Virtual reality hypnosis in the management of pain: Self-reported and neurophysiological measures in healthy subjects

BACKGROUND

Virtual reality hypnosis (VRH) has emerged as a new and promising option for pain management. Nonetheless, neural dynamics of pain modulation during VRH have not been investigated yet. The aim of this study was to measure the effects of VRH on pain, combining neurophysiological and self-reported measurements.

METHODS

Eighteen healthy subjects underwent noxious electrical stimulations in both normal wakefulness and VRH conditions. Dissociation, absorption, time perception, anxiety, pain intensity and unpleasantness, heart rate variability and breathing were reported for each condition. EEG signals were analysed using event-related potentials (ERP) and time-frequency response (TFR) time-locked to stimuli. Neurophysiological features were correlated with self-reported data.

RESULTS

VRH condition was associated with lower pain and higher dissociation. VRH significantly decreased amplitudes of N100 and P200 ERP components, reduced EEG power between 1 and 5 Hz from 100 to 560 ms, and increased EEG power from 5 to 11 Hz from 340 to 800 ms. These findings were observed at frontal, central and posterior electrodes. Heart rate variability was significantly higher and breathing frequency reduced with VRH. Correlations were found between the self-reported level of pain and ERP components.

CONCLUSION

VRH modulates cerebral pain processes and body physiology, leading to reduced pain levels. These findings offer a first insight on the analgesic mechanisms of VRH and suggest that VRH is an effective approach to reduce experimental pain.

SIGNIFICANCE

VRH decreases experimental pain perception, increases subject level of dissociation and modulates cerebral pain processing mechanisms. Pain can be managed with analgesic medication but also through complementary interventions. Among these, hypnosis and virtual reality (VR) are known to reduce pain for patients and healthy individuals. In recent years, an innovative technique combining hypnosis and VR has been proposed to help patients in managing pain. However, to our knowledge, no study has focused on the underlying mechanisms of this VR/hypnosis combination. We showed that VR combined with hypnosis decreases experimental pain, increases dissociation and influences EEG modulation.

Hypnosis for pain and anxiety management in cognitively impaired older adults undergoing scheduled lumbar punctures: a randomized controlled pilot study

Background

Core cerebrospinal fluid (CSF) amyloid and tau biomarker assessment has been recommended to refine the diagnostic accuracy of Alzheimer’s disease. Lumbar punctures (LP) are invasive procedures that might induce anxiety and pain. The use of non-pharmacological techniques must be considered to reduce the patient’s discomfort, in this setting. The objective of this study was to examine the efficacy of hypnosis on anxiety and pain associated with LP.

Methods

A monocentric interventional randomized-controlled pilot study is conducted in a university geriatric day hospital. Cognitively impaired patients aged over 70 were referred for scheduled LP for the diagnostic purpose (CSF biomarkers). The participants were randomly assigned either to a hypnosis intervention group or usual care. Pain and anxiety were both self-assessed by the patient and hetero-evaluated by the operator.

Results

We included 50 cognitively impaired elderly outpatients (women 54%, mean age 77.2 ± 5.0, mean Mini-Mental State Examination score 23.2 ± 3.5). Hypnosis was significantly associated with reduced self-assessed (p < 0.05) and hetero-assessed anxiety (p < 0.01). Hetero-evaluated pain was significantly lower in the hypnosis group (p < 0.05). The overall perception of hypnosis was safe, well-accepted, and feasible in all the participants of the intervention group with 68% perceiving the procedure as better or much better than expected.

Conclusions

This pilot study suggested that hypnosis was feasible and may be used to reduce the symptoms of discomfort due to invasive procedures in older cognitively impaired patients. Our results also confirmed the overall good acceptance of LP in this population, despite the usual negative perception.

Trial registration

ClinicalTrials.gov NCT04368572. Registered on April 30, 2020.

Neural functional correlates of hypnosis and hypnoanalgesia: Role of the cingulate cortex

Hypnosis is a hetero-induced or self-induced altered state of consciousness that involves focused attention and reduced peripheral awareness. It is determined by response to suggestions and can be used in the management of various clinical conditions. Nowadays there is growing attention to the neurobiological correlates of hypnosis because of its future clinical applications. The greater attention is due to the wide range of applications that might stem from its knowledge. Functional neuroimaging studies show that hypnosis affects attention by modulating the activation of the anterior cingulate cortex and other brain areas, modifying the conflict monitoring and cognitive control. During hypnoanalgesia, several changes in brain functions occur in all the areas of the pain network, and other brain areas. Among these, the anterior cingulate cortex is significantly involved in modulating the activity of pain circuits under hypnosis, both in the affective, sensory-cognitive, and behavioral aspects. The study of the functionality of the cingulate cortices, mainly the anterior and medial portions, appears to be crucial for better understanding the hypnotic phenomena, related to both the neurocognitive and somatosensory aspects.

French Survey on Pain Perception and Management in Patients with Locked-In Syndrome

Patients with locked-in syndrome (LIS) may suffer from pain, which can significantly affect their daily life and well-being. In this study, we aim to investigate the presence and the management of pain in LIS patients. Fifty-one participants completed a survey collecting socio-demographic information and detailed reports regarding pain perception and management (type and frequency of pain, daily impact of pain, treatments). Almost half of the LIS patients reported experiencing pain (49%) that affected their quality of life, sleep and cognition. The majority of these patients reported that they did not communicate their pain to clinical staff. Out of the 25 patients reporting pain, 18 (72%) received treatment (60% pharmacological, 12% non-pharmacological) and described the treatment efficacy as 'moderate'. In addition, 14 (56%) patients were willing to try other non-pharmacological treatments, such as hypnosis or meditation. This study provides a comprehensive characterization of pain perception in LIS patients and highlights the lack of guidelines for pain detection and its management. This is especially pertinent given that pain affects diagnoses, by either inducing fatigue or by using pharmacological treatments that modulate the levels of wakefulness and concentration of such patients.

Functional Changes in Brain Activity Using Hypnosis: A Systematic Review

Hypnosis has proven a powerful method in indications such as pain control and anxiety reduction. As recently discussed, it has been yielding increased attention from medical/dental perspectives. This systematic review (PROSPERO-registration-ID-CRD42021259187) aimed to critically evaluate and discuss functional changes in brain activity using hypnosis by means of different imaging techniques. Randomized controlled trials, cohort, comparative, cross-sectional, evaluation and validation studies from three databases—Cochrane, Embase and Medline via PubMed from January 1979 to August 2021—were reviewed using an ad hoc prepared search string and following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. A total of 10,404 articles were identified, 1194 duplicates were removed and 9190 papers were discarded after consulting article titles/abstracts. Ultimately, 20 papers were assessed for eligibility, and 20 papers were included after a hand search (n^total = 40). Despite a broad heterogenicity of included studies, evidence of functional changes in brain activity using hypnosis was identified. Electromyography (EMG) startle amplitudes result in greater activity in the frontal brain area; amplitudes using Somatosensory Event-Related Potentials (SERPs) showed similar results. Electroencephalography (EEG) oscillations of θ activity are positively associated with response to hypnosis. EEG results showed greater amplitudes for highly hypnotizable subjects over the left hemisphere. Less activity during hypnosis was observed in the insula and anterior cingulate cortex (ACC).

Hypnosis as sole anesthesia for oral surgery: The egg of Columbus

BACKGROUND AND OVERVIEW

Hypnosis, despite its effectiveness, has been neglected. The aim of this study is to show the effectiveness and manageability of hypnosis as a stand-alone technique in dentistry.

CASE DESCRIPTION

Three patients underwent 6 oral surgery procedures (surgical third-molar removal, implant surgery, maxillary bone augmentation, and mucogingival surgery) with hypnosis as the only anesthetic. Two of the 3 patients had difficulties: 1 was sensitive to multiple chemicals, had Addison disease, and had previously experienced anaphylactic reactions to local anesthetics; the other was allergic to lidocaine and had undergone a paradoxical reaction to pharmacologic sedation in the past. All 3 patients had 2 preoperative sessions each to assess their perioperative risk, level of anxiety, hypnotic susceptibility, and capacity to develop full hypnotic analgesia. On a surgery day, hypnosis was induced and hypnotic analgesia was obtained according to a standard protocol, a procedure taking no more than 9 minutes in each case. Each surgical procedure was then completed successfully with the patient in a painless condition of full relaxation and sense of well-being, with stable cardiovascular parameters. None of the patients required postoperative analgesics, which were prescribed for use as needed.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Hypnosis is a valuable tool in dentistry, enabling the safe and rapid relief of anxiety and phobia and raising patient pain thresholds to the level of surgical analgesia. Unlike drugs and equipment, it is always readily available, cost-free, and has no adverse effects when administered by competent professionals. Hypnosis can be used for sedation in most patients and as a stand-alone technique in those with appropriate hypnotic susceptibility, improving the well-being and safety of patients.

Nurse's knowledge and perceptions on communicative hypnosis: an observational study

Background and aim of the study.

Much evidence shows that hypnotic communication can have a pain-relieving effect and reduce complications such as anxiety, insomnia and depression. Whenever this technique was applied, the use of pharmaceuticals was reduced, there were fewer side effects, shorter hospitalization times frames and lower treatment costs. The aim of this study is to evaluate the knowledge and perceptions of nurses about hypnotic communication and the causes for which this technique is not frequently used. A secondary objective pointed to measuring the effectiveness of an educational event on hypnosis.

Method.

The evaluation was done by directly administering an anonymous and voluntary survey created ad hoc, in a pre-test and post-test modality, to nurses subscribed to a four-hour formative event on hypnotic communication organized in 2019 by the Nursing Order, Province of Ravenna.

Results.

78 nurses (85.7%) participated in the study. The analysis of the pre-test results shows a gap of knowledge regarding hypnotic communication. The variation of answers between the pre-test and post-test (T-Student) has shown a radical difference in knowledge (95%-100% correct answers). The main causes were found regarding the lack of use for hypnotic communication: stereotypes and prejudices related to this technique and insufficient university education.

Conclusions.

The implementation of this technique, effective and efficient under various aspects, requires a preliminary creation of culture regarding this theme, capable of surpassing the stereotypes and resistances brought by a lack of theoretical elements.

The neural mechanisms of immediate and follow-up of the treatment effect of hypnosis on smoking craving

Hypnosis has a therapeutic effect on substance dependence. However, its neural basis remains unclear, which impedes its further clinical applications. This study investigated the mechanisms of smoking treatment based on hypnosis from two perspectives: immediate and follow-up effects. Twenty-four smokers screened from 132 volunteers underwent hypnosis suggestion and performed a smoking-related cue task twice during functional magnetic resonance imaging (fMRI) scanning (in normal and hypnotic states). The number of cigarettes smoked per day was recorded at follow-up visits. The smokers reported decreased craving after hypnosis. The activations in the right dorsal lateral prefrontal cortex (rDLPFC), the left insula and the right middle frontal gyrus (rMFG), and the functional connectivity between the rDLPFC and the left insula were increased in the hypnotic state. The reduced craving was related to the DLPFC-insula network, which reflected the immediate mechanism of hypnosis on smoking. The number of cigarette use at the 1-week and 1 month follow-up was correlated with the rMFG activation which reflecting hypnotic depth, suggesting the follow-up effect of hypnosis on smoking depended on the trait of smokers. We identified two different mechanisms of hypnosis effect on smoking, which have important implications for design and optimization of hypnotic treatments on mental disorders.

Hypnotic Anesthesia for Blepharoplasty Surgery: A Case Report

Introduction: Blepharoplasty, which is performed for either functional or cosmetic purposes, is one of the most common surgeries around the world. This procedure can be performed under either local or general anesthesia. It depends on the surgical indication, patient’s demand, surgeon’s plan, and need for auxiliary operations. It has been proved that both local and general anesthesia have different complications. Hypnosis is a skill by which hypnotherapists can make changes in perceptual experience and can be used instead of anesthetic drugs on some occasions. The present study was conducted to survey the effectiveness of hypnosis used as an alternative to anesthesia procedures. Case Presentation: A 54-year-old woman was scheduled for bilateral upper lid cosmetic blepharoplasty. Hypnotic anesthesia was conducted owing to her fear of anesthesia and drug-related side effects. Hypnotic anesthesia was accomplished by a hypnotherapist who was an anesthesiologist, and the operation was done without any surgical complications. Conclusions: Hypnosis may be a good alternative to local anesthesia and lead to a reduction in analgesics consumption.

Now You See One Letter, Now You See Meaningless Symbols: Perceptual and Semantic Hypnotic Suggestions Reduce Stroop Errors Through Different Neurocognitive Mechanisms

Compelling literature has suggested the possibility of adopting hypnotic suggestions to override the Stroop interference effect. However, most of these studies mainly reported behavioral data and were conducted on highly hypnotizable individuals. Thus, the question of the neural locus of the effects and their generalizability remains open. In the present study, we used the Stroop task in a within-subject design to test the neurocognitive effects of two hypnotic suggestions: the perceptual request to focus only on the central letter of the words and the semantic request to observe meaningless symbols. Behavioral results indicated that the two types of suggestions did not alter response time (RT), but both favored more accurate performance compared to the control condition. Both types of suggestions increased sensory awareness and reduced discriminative visual attention, but the perceptual request selectively engaged more executive control of the prefrontal cortex (PFC), and the semantic request selectively suppressed the temporal cortex activity devoted to graphemic analysis of the words. The present findings demonstrated that the perceptual and the semantic hypnotic suggestions reduced Stroop errors through common and specific top-down modulations of different neurocognitive processes but left the semantic activation unaltered. Finally, as we also recruited participants with a medium level of hypnotizability, the present data might be considered potentially representative of the majority of the population.

Use of hypnosis preoperatively for surgery of the spine: Pilot study

INTRODUCTION

Hypnosis is a technique requiring no drugs that acts during the three phases of surgery, reducing stress at the pre-surgical phase and the adminstration of anesthetic drugs during the intraoperative phase, as well as leading to improved management of postoperative pain and quality of life management.

MATERIAL ET METHOD

We carried out a retrospective study of 46 patients operated on for herniated disc or one or two-level laminectomy without arthrodesis. All patients benefited from a preoperative hypnosis session and completed a questionnaire about their possible concerns. The day after surgery, patients completed a second questionnaire on their postoperative experience following hypnosis.

RESULTATS

Our results indicate that this technique had a positive impact on the management of preoperative stress (80% of patients) and on postoperative quality of life (48% of patients). Pain measured by decreased from 4.8/10 preoperatively to 0.9/10 postoperatively.

CONCLUSION

Our results are consistent with previous findings in the literature as to the positive contribution of this technique in the management of preoperative stress and patient quality of life. Further studies are however required involving considerably larger cohorts and more extensive surgeries to confirm the effect of this technique on management of anesthesia and pain in spine surgery.

Hypnosis Associated with 3D Immersive Virtual Reality Technology in the Management of Pain: A Review of the Literature

Hypnosis is well documented in the literature in the management of acute and chronic pain. Virtual reality (VR) is currently gaining credibility in the same fields as hypnosis for medical applications. Lately, the combination of hypnosis and VR was considered. The aim of this scoping review is to understand the current studied contexts and effects of virtual reality hypnosis (VRH) for the management of pain. We searched on PubMed, Taylor & Francis Online, and ProQuest databases with the following terms: “virtual reality,” “3D,” “hypnosis,” and “pain”. We included 8 studies that combined hypnosis and VR. All articles are in English. Two included healthy volunteers and six are clinical studies. Short-term results indicated significant decreases in pain intensity, pain unpleasantness, time spent thinking about pain, anxiety, and levels of opioids. However, results are not consistent for all patients all the days. VR alone seems to reduce pain independently of the hypnotizability level. One study claimed that VR and hypnosis could alter each other’s effects and another argued that VR did not inhibit the hypnotic process and may even facilitate it by employing visual imagery. We cannot affirm that VR added value to hypnosis when they are combined. These trials and case series gave us indications about the possible applications of VRH in different contexts. Additional randomized clinical trials on VRH in the future will have to test this technique in clinical practice and help define guidelines for VRH utilization in pain management.

Functional human brain connectivity during labor and its alteration under epidural analgesia

This study used functional magnetic resonance imaging to explore the neural networks of pain during labor and its relief. It was hypothesized that epidural analgesia would affect the neural activities and the underlying network connectivity. Analysis using dynamic causal modelling and functional connectivity was performed to investigate the spatial activity and network connection of labor pain with and without epidural analgesia. This Institutional Review Board approved study acquired Magnetic Resonance Imaging from 15 healthy women of spontaneous normal delivery (with/without epidural analgesia = 7/8, aged 29.6 ± 2.3 and 29.3 ± 4.8 years old respectively) using a 1.5 Tesla scanner. Numerical rating score of pain was evaluated by a research nurse in the beginning of the first stage of labor and approximately 30 min after imaging examination. Six regions of interested from the activated clusters and literature were selected for dynamic causal modelling, which included primary and secondary somatosensory cortex, middle frontal gyrus, anterior cingulate cortex, insula and lentiform. Functional connectivity was calculated from selected sensory and affective regions. All analyses were performed by using software of statistical parametric mapping version 8 and CONN functional connectivity toolbox. The result showed that the experience of labor pain can lead to activations within a distributed brain network. The pain relief from epidural analgesia can be accompanied with altered functional connectivity, which was most evident in the cingulo-frontal system. The present study, therefore, provides an overview of a pain-related neural network that occur during labor and upon epidural analgesia.

Autonomic Cardiac Reactivity to Painful Procedures Under Hypnosis in Pediatric Emergencies: A Feasibility Study

Pain sensation is characterized by abrupt changes in central nervous system activity producing autonomic reactivity. While clinical hypnosis has demonstrated its benefits for children in pain management, it is not clear whether hypnosis modulated autonomic pain response in children in clinical conditions. Here, we studied autonomic responses under hypnosis to sutures in pediatric emergencies. For that, 42 children (mean age: 6.5 years, range 1.5 to 13) were divided into two groups consecutively (hypnosis and control groups), according to their choice. Time-frequency analysis was applied on RR intervals (heart rate interbeat intervals, or RRI) to estimate parasympathetic reactivity based on high frequency power (HF) and the Analgesia Nociception Index (ANI®) and on sympathetic reactivity (low frequency power [LF]) and LF/HF ratio). We observed that RRI and LF/HF ratio varied according to suture and hypnosis (p < 0.05): RRI was higher and LF/HF ratio was lower during sutures in the hypnosis group in comparison to the control group whereas HF and ANI® increased only during hypnosis. To conclude, hypnosis in pediatric emergencies reduces sympathetic cardiac pain reactivity and could be a marker of pain relief under hypnosis, while parasympathetic activity seems to be a better marker of hypnosis.

Neurophenomenology of near-death experience memory in hypnotic recall: a within-subject EEG study

The neurobiological basis of near-death experiences (NDEs) is unknown, but a few studies attempted to investigate it by reproducing in laboratory settings phenomenological experiences that seem to closely resemble NDEs. So far, no study has induced NDE-like features via hypnotic modulation while simultaneously measuring changes in brain activity using high-density EEG. Five volunteers who previously had experienced a pleasant NDE were invited to re-experience the NDE memory and another pleasant autobiographical memory (dating to the same time period), in normal consciousness and with hypnosis. We compared the hypnosis-induced subjective experience with the one of the genuine experience memory. Continuous high-density EEG was recorded throughout. At a phenomenological level, we succeeded in recreating NDE-like features without any adverse effects. Absorption and dissociation levels were reported as higher during all hypnosis conditions as compared to normal consciousness conditions, suggesting that our hypnosis-based protocol increased the felt subjective experience in the recall of both memories. The recall of a NDE phenomenology was related to an increase of alpha activity in frontal and posterior regions. This study provides a proof-of-concept methodology for studying the phenomenon, enabling to prospectively explore the NDE-like features and associated EEG changes in controlled settings.

HYPNOTIC GLOVE ANESTHESIA INDUCES SKIN TEMPERATURE CHANGES IN ADULT VOLUNTEERS: A Prospective Controlled Pilot Study

This study assessed whether a focal glove hypnotic hand anesthesia induced thermal changes within the area of hypnotic protection. Skin temperature of hands, wrists, and forearms was continuously recorded bilaterally using infrared thermography in 30 volunteers. Thermal recordings were obtained prior to, after glove building, and after its withdrawal, with the contralateral upper limb serving as control side. Analgesic glove induced a statistically significant difference in temperature variation within the hand, wrist, and distal forearm on the glove side, compared with proximal forearm and control side. Hypnotic glove analgesia provides significant changes in skin temperature within protected areas. Further research is required to determine the mechanisms of these objective changes induced by hypnosis.

Determining Brain Mechanisms that Underpin Analgesia Induced by the Use of Pain Coping Skills

Objective

Cognitive behavioral therapies decrease pain and improve mood and function in people with osteoarthritis. This study assessed the effects of coping strategies on the central processing of knee pain in people with osteoarthritis of the knees.

Methods

Mechanical pressure was applied to exacerbate knee pain in 28 people with osteoarthritis of the knee. Reports of pain intensity and functional magnetic resonance imaging measures of pain-related brain activity were recorded with and without the concurrent use of pain coping skills.

Results

Coping skills led to a significant reduction in pain report (Coping = 2.64 ± 0.17, Not Coping = 3.28 ± 0.15, P < 0.001). These strategies were associated with increased activation in pain modulatory regions of the brain (medial prefrontal and rostral anterior cingulate cortices, Pcorrected < 0.05) and decreased pain-related activation in regions that process noxious input (midcingulate cortex, supplementary motor area, secondary somatosensory cortex, and anterior parietal lobule, Pcorrected < 0.05). The magnitude of the decrease in pain report during the use of pain coping strategies was found to be proportional to the decrease in pain-related activation in brain regions that code the aversive/emotional dimension of pain (anterior insula, inferior frontal gyrus, orbitofrontal cortex, Pcorrected < 0.05) but did not differ between groups with and without training in coping skills. However, training in coping skills reduced the extent to which brain responses to noxious input were influenced by anxiety.

Conclusions

The results of this study support previous reports of pain modulation by cognitive pain coping strategies and contribute to the current understanding of how analgesia associated with the use of pain coping strategies is represented in the brain.

Hypnosis for cingulate-mediated analgesia and disease treatment

Hypnosis is a technique that induces changes in perceptual experience through response to specific suggestions. By means of functional neuroimaging, a large body of clinical and experimental studies has shown that hypnotic processes modify internal (self-awareness) as well as external (environmental awareness) brain networks. Objective quantifications of this kind permit the characterization of cerebral changes after hypnotic induction and its uses in the clinical setting. Hypnosedation is one such application, as it combines hypnosis with local anesthesia in patients undergoing surgery. The power of this technique lies in the avoidance of general anesthesia and its potential complications that emerge during and after surgery. Hypnosedation is associated with improved intraoperative comfort and reduced perioperative anxiety and pain. It ensures a faster recovery of the patient and diminishes the intraoperative requirements for sedative or analgesic drugs. Mechanisms underlying the modulation of pain perception under hypnotic conditions involve cortical and subcortical areas, mainly the anterior cingulate and prefrontal cortices as well as the basal ganglia and thalami. In that respect, hypnosis-induced analgesia is an effective and highly cost-effective alternative to sedation during surgery and symptom management.

The top-down regulation from the prefrontal cortex to insula via hypnotic aversion suggestions reduces smoking craving

Hypnosis has been shown to have treatment effects on nicotine addiction. However, the neural basis of these effects is poorly understood. This preliminary study investigated the neural mechanisms of hypnosis-based treatment on cigarette smoking, specifically, whether the hypnosis involves a top-down or bottom-up mechanism. Two groups of 45 smokers underwent a smoking aversion suggestion and viewed smoking-related pictures and neutral pictures. One group underwent functional magnetic resonance imaging scanning twice (control and hypnotic states), whereas the other group underwent two electroencephalograph sessions. Our study found that self-reported smoking craving decreased in both groups following hypnosis. Smoking cue-elicited activations in the right dorsal lateral prefrontal cortex (rDLPFC) and left insula (lI) and the functional connectivity between the rDLPFC and lI were increased in the hypnotic state compared with the control state. The delta band source waveforms indicated the activation from 390 to 862 ms at the rDLPFC and from 490 to 900 ms at the lI was significantly different between the smoking and neutral conditions in the hypnotic state, suggesting the activation in the rDLPFC preceded that in the lI. These results suggest that the decreased smoking craving via hypnotic aversion suggestions may arise from the top-down regulation of the rDLPFC to the lI. Our findings provide novel neurobiological evidence for understanding the therapeutic effects of hypnosis on nicotine addiction, and the prefrontal-insula circuit may serve as an imaging biomarker to monitor the treatment efficacy noninvasively.

What's in a word? How instructions, suggestions, and social information change pain and emotion

Instructions, suggestions, and other types of social information can have powerful effects on pain and emotion. Prominent examples include observational learning, social influence, placebo, and hypnosis. These different phenomena and their underlying brain mechanisms have been studied in partially separate literatures, which we discuss, compare, and integrate in this review. Converging findings from these literatures suggest that (1) instructions and social information affect brain systems associated with the generation of pain and emotion, and with reinforcement learning, and that (2) these changes are mediated by alterations in prefrontal systems responsible for top-down control and the generation of affective meaning. We argue that changes in expectation and appraisal, a process of assessing personal meaning and implications for wellbeing, are two potential key mediators of the effects of instructions and social information on affective experience. Finally, we propose a tentative model of how prefrontal regions, especially dorsolateral and ventromedial prefrontal cortex may regulate affective processing based on instructions and socially transmitted expectations more broadly.

New directions in hypnosis research: strategies for advancing the cognitive and clinical neuroscience of hypnosis

This article summarizes key advances in hypnosis research during the past two decades, including (i) clinical research supporting the efficacy of hypnosis for managing a number of clinical symptoms and conditions, (ii) research supporting the role of various divisions in the anterior cingulate and prefrontal cortices in hypnotic responding, and (iii) an emerging finding that high hypnotic suggestibility is associated with atypical brain connectivity profiles. Key recommendations for a research agenda for the next decade include the recommendations that (i) laboratory hypnosis researchers should strongly consider how they assess hypnotic suggestibility in their studies, (ii) inclusion of study participants who score in the middle range of hypnotic suggestibility, and (iii) use of expanding research designs that more clearly delineate the roles of inductions and specific suggestions. Finally, we make two specific suggestions for helping to move the field forward including (i) the use of data sharing and (ii) redirecting resources away from contrasting state and nonstate positions toward studying (a) the efficacy of hypnotic treatments for clinical conditions influenced by central nervous system processes and (b) the neurophysiological underpinnings of hypnotic phenomena. As we learn more about the neurophysiological mechanisms underlying hypnosis and suggestion, we will strengthen our knowledge of both basic brain functions and a host of different psychological functions.

Hypnosis for burn-related pain: Case studies and a review of the literature

Burn injuries create severe pain and psychological distress that are highly variable between patients. Distinct types of pain during various stages of injury and recovery make treatment complex. Standard pharmacological treatment of pain can have adverse effects and is not effective in treating anxiety and other psychological issues. Researchers have proposed that integrating clinical hypnosis as a complementary therapy can be highly beneficial to burn patients and their healthcare providers. The existing literature is reviewed and specific hypnosis techniques are discussed. Evidence exists indicating that adjunctive hypnosis is effective at reducing pain and procedural anxiety. Implementing a multidisciplinary burn care team that includes clinical hypnosis and focuses on the patients’ psychological health as well as pain reduction is likely to result in faster healing and reduced distress for patients and caregivers alike.

Hypnotizability and Placebo Analgesia in Waking and Hypnosis as Modulators of Auditory Startle Responses in Healthy Women: An ERP Study

We evaluated the influence of hypnotizability, pain expectation, placebo analgesia in waking and hypnosis on tonic pain relief. We also investigated how placebo analgesia affects somatic responses (eye blink) and N100 and P200 waves of event-related potentials (ERPs) elicited by auditory startle probes. Although expectation plays an important role in placebo and hypnotic analgesia, the neural mechanisms underlying these treatments are still poorly understood. We used the cold cup test (CCT) to induce tonic pain in 53 healthy women. Placebo analgesia was initially produced by manipulation, in which the intensity of pain induced by the CCT was surreptitiously reduced after the administration of a sham analgesic cream. Participants were then tested in waking and hypnosis under three treatments: (1) resting (Baseline); (2) CCT-alone (Pain); and (3) CCT plus placebo cream for pain relief (Placebo). For each painful treatment, we assessed pain and distress ratings, eye blink responses, N100 and P200 amplitudes. We used LORETA analysis of N100 and P200 waves, as elicited by auditory startle, to identify cortical regions sensitive to pain reduction through placebo and hypnotic analgesia. Higher pain expectation was associated with higher pain reductions. In highly hypnotizable participants placebo treatment produced significant reductions of pain and distress perception in both waking and hypnosis condition. P200 wave, during placebo analgesia, was larger in the frontal left hemisphere while placebo analgesia, during hypnosis, involved the activity of the left hemisphere including the occipital region. These findings demonstrate that hypnosis and placebo analgesia are different processes of top-down regulation. Pain reduction was associated with larger EMG startle amplitudes, N100 and P200 responses, and enhanced activity within the frontal, parietal, and anterior and posterior cingulate gyres. LORETA results showed that placebo analgesia modulated pain-responsive areas known to reflect the ongoing pain experience.

Effectiveness of medical hypnosis for pain reduction and faster wound healing in pediatric acute burn injury: study protocol for a randomized controlled trial

BACKGROUND

Burns and the associated wound care procedures can be extremely painful and anxiety-provoking for children. Burn injured children and adolescents are therefore at greater risk of experiencing a range of psychological reactions, in particular posttraumatic stress disorder, which can persist for months to years after the injury. Non-pharmacological intervention is critical for comprehensive pain and anxiety management and is used alongside pharmacological analgesia and anxiolysis. However, effective non-pharmacological pain and anxiety management during pediatric burn procedures is an area still needing improvement. Medical hypnosis has received support as a technique for effectively decreasing pain and anxiety levels in adults undergoing burn wound care and in children during a variety of painful medical procedures (e.g., bone marrow aspirations, lumbar punctures, voiding cystourethrograms, and post-surgical pain). Pain reduction during burn wound care procedures is linked with improved wound healing rates. To date, no randomized controlled trials have investigated the use of medical hypnosis in pediatric burn populations. Therefore this study aims to determine if medical hypnosis decreases pain, anxiety, and biological stress markers during wound care procedures; improves wound healing times; and decreases rates of traumatic stress reactions in pediatric burn patients.

METHODS/DESIGN

This is a single-center, superiority, parallel-group, prospective randomized controlled trial. Children (4 to 16 years, inclusive) with acute burn injuries presenting for their first dressing application or change are randomly assigned to either the (1) intervention group (medical hypnosis) or (2) control group (standard care). A minimum of 33 participants are recruited for each treatment group. Repeated measures of pain, anxiety, stress, and wound healing are taken at every dressing change until ≥95 % wound re-epithelialization. Further data collection assesses impact on posttraumatic stress symptomatology, speed of wound healing, and parent perception of how easy the dressing change is for their child.

DISCUSSION

Study results will elucidate whether the disease process can be changed by using medical hypnosis with children to decrease pain, anxiety, and stress in the context of acute burn wounds.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12615000419561.

Hypnosis modulates behavioural measures and subjective ratings about external and internal awareness

In altered subjective states, the behavioural quantification of external and internal awareness remains challenging due to the need for reports on the subjects' behalf. With the aim to characterize the behavioural counterpart of external and internal awareness in a modified subjective condition, we used hypnosis during which subjects remain fully responsive. Eleven right-handed subjects reached a satisfactory level of hypnotisability as evidenced by subjective reports on arousal, absorption and dissociation. Compared to normal wakefulness, in hypnosis (a) participants' self-ratings for internal awareness increased and self-ratings for external awareness decreased, (b) the two awareness components tended to anticorrelate less and the switches between external and internal awareness self-ratings were less frequent, and (c) participants' reaction times were higher and lapses in key presses were more frequent. The identified imbalance between the two components of awareness is considered as of functional relevance to subjective (meta)cognition, possibly mediated by allocated attentional properties brought about by hypnosis. Our results highlight the presence of a cognitive counterpart in resting state, indicate that the modified contents of awareness are measurable behaviourally, and provide leverage for investigations of more challenging altered conscious states, such as anaesthesia, sleep and disorders of consciousness.

Pain modulation in waking and hypnosis in women: event-related potentials and sources of cortical activity

Using a strict subject selection procedure, we tested in High and Low Hypnotizable subjects (HHs and LHs) whether treatments of hypoalgesia and hyperalgesia, as compared to a relaxation-control, differentially affected subjective pain ratings and somatosensory event-related potentials (SERPs) during painful electric stimulation. Treatments were administered in waking and hypnosis conditions. LHs showed little differentiation in pain and distress ratings between hypoalgesia and hyperalgesia treatments, whereas HHs showed a greater spread in the instructed direction. HHs had larger prefrontal N140 and P200 waves of the SERPs during hypnotic hyperalgesia as compared to relaxation-control treatment. Importantly, HHs showed significant smaller frontocentral N140 and frontotemporal P200 waves during hypnotic hypoalgesia. LHs did not show significant differences for these SERP waves among treatments in both waking and hypnosis conditions. Source localization (sLORETA) method revealed significant activations of the bilateral primary somatosensory (BA3), middle frontal gyrus (BA6) and anterior cingulate cortices (BA24). Activity of these contralateral regions significantly correlated with subjective numerical pain scores for control treatment in waking condition. Moreover, multivariate regression analyses distinguished the contralateral BA3 as the only region reflecting a stable pattern of pain coding changes across all treatments in waking and hypnosis conditions. More direct testing showed that hypnosis reduced the strength of the association of pain modulation and brain activity changes at BA3. sLORETA in HHs revealed, for the N140 wave, that during hypnotic hyperalgesia, there was an increased activity within medial, supramarginal and superior frontal gyri, and cingulated gyrus (BA32), while for the P200 wave, activity was increased in the superior (BA22), middle (BA37), inferior temporal (BA19) gyri and superior parietal lobule (BA7). Hypnotic hypoalgesia in HHs, for N140 wave, showed reduced activity within medial and superior frontal gyri (BA9,8), paraippocampal gyrus (BA34), and postcentral gyrus (BA1), while for the P200, activity was reduced within middle and superior frontal gyri (BA9 and BA10), anterior cingulate (BA33), cuneus (BA19) and sub-lobar insula (BA13). These findings demonstrate that hypnotic suggestions can exert a top-down modulatory effect on attention/preconscious brain processes involved in pain perception.

Mechanisms of hypnosis: toward the development of a biopsychosocial model

Evidence supports the efficacy of hypnotic treatments, but there remain many unresolved questions regarding how hypnosis produces its beneficial effects. Most theoretical models focus more or less on biological, psychological, and social factors. This scoping review summarizes the empirical findings regarding the associations between specific factors in each of these domains and response to hypnosis. The findings indicate that (a) no single factor appears primary, (b) different factors may contribute more or less to outcomes in different subsets of individuals or for different conditions, and (c) comprehensive models of hypnosis that incorporate factors from all 3 domains may ultimately prove to be more useful than more restrictive models that focus on just 1 or a very few factors.

Pain perception and hypnosis: findings from recent functional neuroimaging studies

Hypnosis modulates pain perception and tolerance by affecting cortical and subcortical activity in brain regions involved in these processes. By reviewing functional neuroimaging studies focusing on pain perception under hypnosis, the authors aimed to identify brain activation-deactivation patterns occurring in hypnosis-modulated pain conditions. Different changes in brain functionality occurred throughout all components of the pain network and other brain areas. The anterior cingulate cortex appears to be central in modulating pain circuitry activity under hypnosis. Most studies also showed that the neural functions of the prefrontal, insular, and somatosensory cortices are consistently modified during hypnosis-modulated pain conditions. Functional neuroimaging studies support the clinical use of hypnosis in the management of pain conditions.

Hypnosis and imaging of the living human brain

Over more than two decades, studies using imaging techniques of the living human brain have begun to explore the neural correlates of hypnosis. The collective findings provide a gripping, albeit preliminary, account of the underlying neurobiological mechanisms involved in hypnotic phenomena. While substantial advances lend support to different hypotheses pertaining to hypnotic modulation of attention, control, and monitoring processes, the complex interactions among the many mediating variables largely hinder our ability to isolate robust commonalities across studies. The present account presents a critical integrative synthesis of neuroimaging studies targeting hypnosis as a function of suggestion. Specifically, hypnotic induction without task-specific suggestion is examined, as well as suggestions concerning sensation and perception, memory, and ideomotor response. The importance of carefully designed experiments is highlighted to better tease apart the neural correlates that subserve hypnotic phenomena. Moreover, converging findings intimate that hypnotic suggestions seem to induce specific neural patterns. These observations propose that suggestions may have the ability to target focal brain networks. Drawing on evidence spanning several technological modalities, neuroimaging studies of hypnosis pave the road to a more scientific understanding of a dramatic, yet largely evasive, domain of human behavior.

Hypnoanalgesia and the study of pain experience: from Cajal to modern neuroscience

Santiago Ramón y Cajal (1852–1934) did not only contribute to neurobiology and neurohistology. At the end of the 19th century, he published one of the first clinical reports on the employment of hypnotic suggestion to induce analgesia (hypnoanalgesia) in order to relieve pain in childbirth. Today, the clinical application of hypnoanalgesia is considered an effective technique for the treatment of pain in medicine, dentistry, and psychology. However, the knowledge we have today on the neural and cognitive underpinnings of hypnotic suggestion has increased dramatically since Cajal’s times. Here we review the main contributions of Cajal to hypnoanalgesia and the current knowledge we have about hypnoanalgesia from neural and cognitive perspectives.

Hypnotic approaches for chronic pain management: clinical implications of recent research findings

The empirical support for hypnosis for chronic pain management has flourished over the past two decades. Clinical trials show that hypnosis is effective for reducing chronic pain, although outcomes vary between individuals. The findings from these clinical trials also show that hypnotic treatments have a number of positive effects beyond pain control. Neurophysiological studies reveal that hypnotic analgesia has clear effects on brain and spinal-cord functioning that differ as a function of the specific hypnotic suggestions made, providing further evidence for the specific effects of hypnosis. The research results have important implications for how clinicians can help their clients experience maximum benefits from hypnosis and treatments that include hypnotic components.

Elucidating unconscious processing with instrumental hypnosis

Most researchers leverage bottom-up suppression to unlock the underlying mechanisms of unconscious processing. However, a top-down approach - for example via hypnotic suggestion - paves the road to experimental innovation and complementary data that afford new scientific insights concerning attention and the unconscious. Drawing from a reliable taxonomy that differentiates subliminal and preconscious processing, we outline how an experimental trajectory that champions top-down suppression techniques, such as those practiced in hypnosis, is uniquely poised to further contextualize and refine our scientific understanding of unconscious processing. Examining subliminal and preconscious methods, we demonstrate how instrumental hypnosis provides a reliable adjunct that supplements contemporary approaches. Specifically, we provide an integrative synthesis of the advantages and shortcomings that accompany a top-down approach to probe the unconscious mind. Our account provides a larger framework for complementing the results from core studies involving prevailing subliminal and preconscious techniques.

Neurophysiological correlates of dissociative symptoms

OBJECTIVE

Dissociation is a mental process with psychological and somatoform manifestations, which is closely related to hypnotic suggestibility and essentially shows the ability to obtain distance from reality. An increased tendency to dissociate is a frequently reported characteristic of patients with functional neurological symptoms and syndromes (FNSS), which account for a substantial part of all neurological admissions. This review aims to investigate what heart rate variability (HRV), EEG and neuroimaging data (MRI) reveal about the nature of dissociation and related conditions.

METHODS

Studies reporting HRV, EEG and neuroimaging data related to hypnosis, dissociation and FNSS were identified by searching the electronic databases Pubmed and ScienceDirect.

RESULTS

The majority of the identified studies concerned the physiological characteristics of hypnosis; relatively few investigations on dissociation related FNSS were identified. General findings were increased parasympathetic functioning during hypnosis (as measured by HRV), and lower HRV in patients with FNSS. The large variety of EEG and functional MRI investigations with diverse results challenges definite conclusions, but evidence suggests that subcortical as well as (pre)frontal regions serve emotion regulation in dissociative conditions. Functional connectivity analyses suggest the presence of altered brain networks in patients with FNSS, in which limbic areas have an increased influence on motor preparatory regions.

CONCLUSIONS

HRV, EEG and (functional) MRI are sensitive methods to detect physiological changes related to dissociation and dissociative disorders such as FNSS, and can possibly provide more information about their aetiology. The use of such measures could eventually provide biomarkers for earlier identification of patients at risk and appropriate treatment of dissociative conditions.