Hypnosis for Acute Procedural Pain: A Critical Review

Procedural pain is a significant problem for a wide variety of surgical procedures. There is the anxiety and discomfort for patients but also substantial expenses for pain medication. In the USA, in 2002, that was estimated to be $560-$635 billion USD. Added to this problem are the side effects of pain management drugs which can include death.

Hypnosis has a long history of pain management, but the level of effectiveness and mechanisms of action are still not well studied or understood. This review paper seeks to assess the evidence for effectiveness by statistical and methodological assessment of 29 randomised controlled clinical trials.

Methodological quality was assessed using the 5-point Jadad score. In order to account for the difficulty in blinding of hypnosis practitioners, a maximum of four points were awarded: 1 point added if the study was randomised; 1 point added if the randomisation was appropriate; 1 point deducted if the randomisation was inappropriate; 1 point added if withdrawals and dropouts were explained and; 1 point added if the experimental and hospital staff were blinded to treatment assignment.

Types of medical treatment tested included, bone marrow aspiration, lumbar puncture, burn debridement and other surgical and medical procedures including abortion, venepuncture and angioplasty.

Some studies incorporated hypnotic treatment immediately prior or during surgical treatment while other commenced days before the procedure.

Pain was most often measured with a single VAS score. The reviewers complained of inadequate controls but nevertheless concluded that hypnosis seemed to at least be as effective as cognitive behavioural approaches and play therapy and was more effective than distraction techniques.

Hypnosis was shown to be beneficial in 75% of studies with medical procedures but was not shown to reduce post-operative pain.

Interventions with more than one hypnosis session reported more significant positive effects than did studies involving only one session. Applying hypnosis at least one day before the procedure was more effective.

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Hypnosis in Patients with Perceived Stress – a systematic review

This paper is a systematic review of randomised clinical trials (RCTs) investigating the effect of hypnosis on perceived stress and coping. Nine randomised trials predating 2016 were selected for review. 365 participants met the inclusion criteria. Most patients (211) were female medical students aged between 20-25. In three studies, mean ages were between 30-42 years. Perceived stress was measured by a range of questionnaires and immunological data was also collected. All nine studies showed signs of high risk of bias. Six out of nine reported reduction in stress due to hypnosis. Immunological results were inconclusive.

In summary the reviewers state the lack of evidence is a result of lack of good studies. The current studies reviewed had poor designs, small sample sizes and incomplete reporting. Nevertheless, the positive results reported in 6 studies suggest further more detailed studies are warranted.

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Can hypnosis displace the threshold for visual consciousness?

These studies investigated the effect of posthypnotic suggestion on peripheral visual inattention. Participants sat in a dim-lit room with a headset and an LCD. A chinrest was fitted 60cm from the screen and random numbers were flashed on the screen in central or peripheral areas of vision. The experiment was conducted on subjects with high and low scores of hypnotic susceptibility. Subjects were given suggestions for narrowing of visual focus and the ignoring of any activity in the peripheral vison outside central area of focus.

Finding 1: The contrast between the High and Low sociability showed that posthypnotic suggestion was able to hamper the Highs ability to perceive peripheral visual stimulus.

Finding 2: In a further ‘priming’ experiment where peripheral stimulus was able to affect attention to central focus in the Lows showed that no such effect was observed in Highs.

Finding 3: In a further ‘discrimination’ experiment the Highs performed equally as well as the Lows in recognising the peripheral stimulus indicating the Highs were still perceiving the peripheral stimulus, but the posthypnotic suggestion was causing them to ignore it.

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Intestinal Microbiome in Irritable Bowel Syndrome before and after Gut-Directed Hypnotherapy

This is the first paper to ever study the potential effect of hypnotherapy on gut microbiome. The study was limited by a small sample size (38 IBS patients), lack of control subjects and some difficulties in data collection about diets.

Faecal samples were collected from a heterogeneous groups of IBS patients of males and females with varying severity and symptoms from constipation to diarrhea.

Assays were conducted before and after 10 weekly group sessions of Gut-directed hypnotherapy. An RNA heatmap showed microbial characteristics appeared to remain largely unchanged after the invention of hypnotherapy. Bacterial diversity remained stable and none of the observed changes in abundance were significant after controlling for multiple testing. Nevertheless, the majority of patients did experience marked reductions in severity of IBS symptoms leading the researchers to hypothesise that hypnotherapy acts at higher levels of brain gut axis including psychological mechanisms and modulation of processing of interoceptive stimuli.

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Brain Activity and Functional Connectivity Associated with Hypnosis

This study was a very detailed and well controlled study of brain activity associated with hypnosis. 57 subjects with either very high or very low levels of hypnotisability were subjected to various conscious conditions during functional magnetic resonance imaging. All subjects underwent four conditions in the scanner: rest, memory retrieval, and two different hypnosis experiences.  These studies confirmed and extended the results of previous studies using similar methodologies measuring brain physiology. Three brain regions were observed to consistently show altered activity in response to hypnosis as compared to controls experiencing memory and rest. Similar to previous studies, hypnotic state was characterised by decreased low frequency amplitude in the dorsal anterior cingulate cortex. The dACC plays a role in attention control determining what we should attend and what we should ignore. Its selective hypnotically induced deactivation is in alignment with the theory that hypnosis invoked a suspension of critical judgment and an ability to immerse oneself in the task and suspend judgement and reduce awareness of alternatives.

Their second finding was that of increased functional connectivity between the executive control and the insular portion of the salience network from rest states to hypnosis states in highly susceptible subjected compared to lows. Since the insula is involved in the processing of body control and experience, emotion, empathy and pain processing this fits well with previous clinical observations of hypnotherapy affecting these experiences and perceptions.

The third finding was an uncoupling of the connectivity between the executive control network and default mode network during hypnosis. They hypothesise the engagement of the hypnotic state is associated with detachment from internal mental processes such as mind wandering and self-reflection supporting the idea hypnosis is a different state of consciousness rather than a reduced level of arousal.

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Hypnotherapy to Reduce Hot Flashes: Examination of Response Expectancies as a Mediator of Outcomes

This paper explored the role that expectancy plays during hypnosis intervention for hot flashes. It also investigated the effectiveness of hypnosis in the reduction of hot flashes symptoms.

Previous studies have shown up to 59% reduction in hot flashes frequency in response to hypnotherapy.  This randomised study of 172 postmenopausal women tested whether the expectancy of hypnotherapy treatment played in significant role in the outcome of treatment. A small but potentially statistically insignificant improvement of 11% was observed indicating the majority of the positive outcome observed was due mainly to the hypnotic procedure.

This is quite an interesting study as it attempts to tease out the relative roles played by a placebo contribution (expectancy) versus the contribution of hypnotic suggestion. In this study it appears as nearly all the positive effect was a result of hypnosis and not placebo.

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Neurophysiology of Hypnosis

This is a review article summarising studies using neuroimaging and electrophysiological techniques to investigate changes in brain physiology and activity when people enter an hypnotic state.

Positive Emission Topography Studies.

Increases and reductions in blood flow to various regions of the brain in response to hypnotic procedures have been observed. There is a problem in knowing whether these changes are a result of a hypnotic state per se or whether they are attributable to a general response to the hypnotic procedure. Measuring these changes and correlating them with other measurements of specific subjects, hypnotic susceptibility has been used to filter the changes which can be directly attributable to the hypnotic state from those which are more likely to attribute to the hypnotic procedure in general, such as the alteration in brain function in response to the volume of the therapist voice.   In one study, increase in brain activity was observed in precuneus and meso-frontal brain areas. Reduced activity was observed in lateral fronto-parietal regions usually active in attention demanding tasks. However, there are many divergent findings between different studies and it seems there is still not a clear consensus on what it happening.

Electroencephalography.

Similar strategies comparing hypnotic susceptibility with hypnosis induced EEG patters show highly hypnotisable subjects have less phase synchronisation in frontal brain areas as well as increased activity in the left hemisphere and over anterior regions of cortex. Also, highly hypnotisable subjects have more labile fronto-parietal networks and are thereby more responsive to hypnotic induction.

Highly hypnotisable subjects generate more theta power then low subjects but some studies suggest this is more likely due to a side effect of relaxation.

How can hypnosis modulate pain perception?

Studies have shown hypnosis as an adjunct to conscious intravenous sedation provides better preoperative pain and anxiety relief. Several studies have suggested this is partially due to selective deactivation of the anterior cingulate cortex in response to hypnotic suggestion. The decreased activity being associated with decreasing unpleasantness of a painful stimulus.

Hypnosis as a substitute for Hysteria.

Highly hypnotisable subjects have been shown to be more responsive to suggestions of induced hysteria.

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Alopecia Areata Hypnosis for Psychological Wellbeing

Severe and prolonged forms of alopecia areata can have serious psychological effects that can lead to significant reductions in a persons quality of life. Long term symptoms in 21 participants with refractory alopecia areata were examined. Over a 6-month period, participants received 10 hypnotherapy sessions. Post-treatment, participants anxiety, amelioration of alexithymia, depression and mental well-being was evaluated. Results indicated there was a significant improvement throughout all areas which was also maintained up to 6 months after the treatment finished.

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Anxiety Reduction in Preoperative Adults

This study investigates the potential effectiveness of hypnotherapy in the reduction of preoperative anxiety. Seventy eight participants were randomly assigned into one of three treatment groups. The first group received standard hospital care. The second group received attention-control therapy consisting of listening and support without hypnotherapy. The third group received hypnotherapy treatment which included suggestions for well-being. Pre and post intervention anxiety was measured. A third anxiety measurement taken after entrance into the operating theatre, immediately prior to surgery.

Patients in the hypnosis group showed significantly reduced levels of anxiety post-intervention compared to the other two control groups. The most dramatic differences were seen between the three groups immediately prior to surgery. The hypnosis group recorded a 56% reduction in anxiety compared with baseline anxiety. The attention-control group showed a 10% increase in anxiety and the standard treatment control group showed 47% increase in anxiety. This study strongly supports the use of hypnosis in the prevention of preoperative anxiety.

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Group Hypnotherapy Treatment for Drug Addiction

This paper studied the effect of group hypnotherapy sessions on methadone patients who were still using street heroin.  Ten patients were divided into two groups with five in each group. There was no control group. Both groups received hypnotherapy and urine test were used to assess the effectiveness of the treatment 6 and 24 months post treatment.

One patient did not complete treatment due to a major operation, the remaining 9 (90%) completed treatment. All patients (100%) completely stopped use of any street drugs and results remained stable for 6 months after end of treatment. Two years after end of intervention, 7 out of the 9 (78%) remained clean of use of heroin.

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