Hypnosis in the management of persistent idiopathic orofacial pain – Clinical and psychosocial findings

Pain 136 (2008) 44–52 www.elsevier.com/locate/pain

Hypnosis in the management of persistent idiopathic orofacial pain – Clinical and psychosocial findings Randi Abrahamsen a

a,*

, Lene Baad-Hansen a, Peter Svensson

a,b

Department of Clinical Oral Physiology, School of Dentistry, University of Aarhus, Vennelyst Boulevard 9, DK-8000 Aarhus, Denmark b Department of Oral Maxillofacial Surgery, Aarhus University Hospital, Aarhus, Denmark Received 23 October 2006; received in revised form 8 June 2007; accepted 13 June 2007

Abstract This controlled and patient blinded study tested the effect of hypnosis on persistent idiopathic orofacial pain (PIOP) in terms of clinical and psychosocial findings. Forty-one PIOP were randomized to active hypnotic intervention or simple relaxation as control for five individual 1-h sessions. Primary outcome was average pain intensity scored three times daily in a pain diary using visual analogue scale (VAS). Secondary outcome measures were pain quality assessed by McGill pain questionnaire (MPQ), psychological symptoms assessed by symptom check list (SCL), quality of life assessed by SF36, sleep quality, and consumption of analgesic. Data were compared between groups before and after treatment using ANOVA models and paired t-tests. The change in VAS pain scores from baseline to the last treatment (t4) was (33.1 ± 7.4%) in the hypnosis group and (3.2 ± 5.4%) in the control group (P < 0.03). In the hypnosis group, highly hypnotic susceptible patients had greater decreases in VAS pain scores (55.0 ± 12.3%) when compared to less susceptible patients (17.9 ± 6.7%) (P < 0.02). After the last treatment there were also statistically significant differences between groups in perceived pain area (MPQ) and the use of weak analgesics (P < 0.03). There were no statistically significant changes in SCL or SF36 scores from baseline to t4. In conclusion, hypnosis seems to offer clinically relevant pain relief in PIOP, particularly in highly susceptible patients. However, stress coping skills and unresolved psychological problems need to be included in a comprehensive management plan in order also to address psychological symptoms and quality of life.  2007 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. Keywords: Hypnotic treatment; Persistent idiopathic orofacial pain; Chronic pain; Hypnotic susceptibility; Pain diary; Psychosocial; Coping strategies; Catastrophizing; Sleep quality

1. Introduction Chronic orofacial pain can be very difficult to diagnose and manage since the patients often present very complex and diffuse symptoms without any radiological or clinical pathological findings (Madland et al., 2001). Patients suffering from chronic pain conditions often find their pain intolerable and with great impact on their quality of life (Breivik et al., 2006). Frequently, patients with chronic orofacial pain have tried various kinds of

*

Corresponding author. Tel.: +45 89424023. E-mail address: [email protected] (R. Abrahamsen).

treatments, such as surgery and standard pharmacological treatment with no or little effect on the pain (Hunter, 1992). In addition, mental health plays an important role in maintaining or aggravating chronic pain (Grzesiak, 1991) and there is evidence that cognitive-behavioral intervention can be effective (Dworkin et al., 1994; Turner et al., 2005). Another possible intervention is hypnosis, which is suggested to be effective for chronic pain (National Institutes of Health,, 1995). In a review where the effectiveness of hypnosis on various pain conditions was discussed, the authors found that hypnotic intervention provided substantial pain relief in 75% of the patients (Montgomery et al., 2000). Another recent review of controlled clinical trials in

0304-3959/$34.00  2007 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.pain.2007.06.013

R. Abrahamsen et al. / Pain 136 (2008) 44–52

chronic pain conditions such as migraine, arthritis, low back pain, and cancer has discussed significant reductions in perceived pain with hypnotic analgesia treatment compared to no-treatment or other non-hypnotic interventions (Jensen and Patterson, 2006). However, there is a lack of evidence for the effect of hypnosis on persistent idiopathic orofacial pain (PIOP). A few case reports (Cohen and Hillis, 1979; Gurian, 1985), a pilot study (Clarke and Reynolds, 1991), and two studies of temporomandibular disorders (TMD) have reported some effect of hypnosis (Simon and Lewis, 2000; Winocur et al., 2002). Thus, there is some indication that hypnosis may be an option in the management of PIOP, but systematically performed randomized controlled trials are needed. The aim of this study was in a patient blinded, controlled, and randomized study to test the hypothesis that treatment with hypnosis in patients suffering from PIOP could improve self-reported measures of pain (primary outcome parameter), use of analgesics, sleep quality, health related quality of life, as well as psychological symptoms (secondary outcome parameters). Furthermore, we wanted to explore the relation between hypnotic susceptibility, pain coping strategies, and primary outcome parameters. 2. Materials and methods 2.1. Subjects The study protocol and recruitment of patients were approved by the local Ethical Committee. All patients signed a written informed consent and the study was performed in accordance with the Declaration of Helsinki. Forty-four patients with PIOP were referred to the Department of Clinical Oral Physiology at the School of Dentistry in Aarhus, Denmark, and included in the study. The patients had been suffering from PIOP for more than 6 months with no pathological findings in clinical and radiological examinations in accordance with the following criteria suggested by The International Headache Society, (2004): (1) Facial pain present daily for at least 1 month and persisting for all or most of the day. (2) The pain is deep and poorly localized of moderate or severe intensity, but not unbearable. (3) The pain is confined at onset to a limited area on one side of the head. (4) The pain is without paroxysms, precipitation from trigger areas, autonomic symptoms, sensory loss, and other physical signs; but dysaesthesia may occur. The pain was expressed as atypical facial pain, atypical odontalgia, stomatodynia, or in combination with TMD pains. 2.2. Experimental design Patients were randomly assigned to a hypnosis group (n = 22) or a control group with only relaxation as intervention (n = 22). There was a dropout of three patients in the control group after the first session; one due to private problems and two because they experienced the treatment would not

45

give them any benefit. Data from these three patients were therefore not included in the study. The subjects were blinded to the treatment and had no previous experience with hypnosis. The subjects were informed that two types of hypnotic treatment were tested; one with an audio-CD with which they could practice hypnosis at home and another without the CD. The subjects in the control group believed that they received hypnotic intervention. The clinician was blinded to the hypnotisability during treatment. All data were entered by a blinded assistant. 2.3. Hypnotic intervention 2.3.1. Hypnosis group The hypnotic intervention consisted of progressive relaxation, guided imaginary instructions of a nice safe place, pain suggestions of controlling or changing the pain perception tailored individually and dissociation from the pain (Price and Barber, 1987; Crasilneck, 1995). During the trance state, it was attempted to improve the patient’s individual coping with minor psychological problems and their stress-management skills in daily life according to their needs. Individual CDs with the patient’s preferred pain suggestions were made and used to practice hypnosis at home (Zachariae et al., 1996) (for further information, see Appendix A). The group had on average 5.1 ± 0.8 (range 3–6) sessions of hypnotic intervention. Five treatment sessions were planned. However, a range in treatment sessions occurred since some patients did not complete all sessions. Furthermore some patients were given an extra treatment session since the treating clinician had to go on sick leave during treatment. 2.3.2. Control group The control group had on average 5.3 ± 0.9 sessions (range 3–6) with relaxation and visualizing a nice safe place, however, no further suggestions were given during trance. Likewise five treatment sessions were planned, but a range of three to six sessions also occurred in this group. 2.4. Self-reported pain 2.4.1. Pain diary The patients completed a paper diary of self-reported pain using a 0–10 visual analogue scale (VAS) (Price et al., 1983) three times a day beginning 6 days before treatment start and throughout the treatment period. The diary was checked at every session. The average daily VAS pain scores from 6 days in each of the following periods: before treatment (t0), after treatment 1 (t1), after treatment 2 (t2), after treatment 3 (t3), and after last treatment (t4) were used as the primary outcome parameter. 2.4.2. McGill pain questionnaire A Danish version of McGill pain questionnaire (MPQ) (Melzack, 1975; Drewes et al., 1993) was used at baseline (t0) and after the last treatment (t4). Pain rating indices (PRI) of sensory (S), affective (A), miscellaneous (M), evaluating (E), and total (T) dimension of pain and the present pain indices (PPI), PPI worst, PPI least at baseline (t0) and after the last treatment (t4) were compared between groups.

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2.4.3. Perceived pain area Patients drew their perceived pain area on anatomical drawings of the face and mouth at baseline (t0) and after the last treatment (t4). The pain areas of the face and mouth were digitized, expressed as arbitrary units (Svensson et al., 1998), compared between groups at baseline (t0) and after the last treatment (t4). 2.5. Medication The patients were asked to register their use of analgesics, carbamazepine, and gabapentin from one week before the treatment (t0) and during the last week of the treatment period (t4). The cumulative number of doses of medication one week before inclusion was compared between groups with the cumulative number of doses of medication during last week of treatment. The medication was classified into five groups: (1) non-steroid anti-inflammatory drugs (NSAID); (2) weak analgesics such as paracetamol and acetylsalicylic acid; (3) opioids; (4) carbamazepine; (5) gabapentin. The cumulative number of doses was compared within each medication group. Patients were advised to take their usual analgesics but were allowed to reduce medicine if they felt they were able to do so without any worsening of pain. 2.6. Sleep Self-reported rating of sleep quality (S) was registered on a scale from 0 to 6, where 0 indicates not having slept well at all and 6 indicates sleeping well (the Pittsburgh sleep quality index (PSQI) component 1; Buysse et al., 1989). The scores at baseline (t0) and after the last treatment (t4) were compared between groups. 2.7. Psychological symptoms Psychological symptoms were tested with a Danish version of symptom check list (SCL) which includes 60 items and measures somatization, obsessive compulsive disorder, interpersonal sensitivity, depression, anxiety, hostility, and phobic anxiety (Derogatis and Cleary, 1977; Dworkin and LeResche, 1992). The SCL scores at baseline (t0) and after the last treatment (t4) were compared between groups. 2.8. Quality of life A Danish version of SF36 was used to measure quality of life (Ware et al., 1998). We used this instrument to measure how a subject’s general health was affecting their quality of life in the following domains: general health perception (GH), body pain (BP), physical functioning (PF), mental health (MH), social function (SF), emotional functioning (RE) as well as vitality (VT). Increasing scores reflected improvement of symptoms. The SF36 scores at baseline (t0) and after the last treatment (t4) were compared between groups. 2.9. Hypnotic susceptibility A Danish version of Stanford Hypnotic Clinical Scale (SHCS) (Morgan and Hilgard, 1978) was used to determine the hypnotic susceptibility on a scale from 0 to 5. The SHCS

was administered after the last treatment to ensure that the clinician knowledge of the SHCS score would not bias the clinician’s outcome expectancies. 2.10. Coping strategy Pain coping strategies were registered before treatment using a Danish version of the Coping Strategies Questionnaire (Swartzman et al., 1994). The pain coping strategies were diverting attention, reinterpreting pain sensations, coping self-statements, ignoring pain sensations, praying and hoping, catastrophizing, and increasing activity level. 2.11. Statistics The results are presented as mean values ± SEM. A threeway analysis of variance (ANOVA) was used to analyze the average daily VAS pain scores with group (active or control) as factor and days (6 days) and periods (t0, t1, t2, t3, t4) as the repeated measurement factor. A two-way ANOVA was used for analysis of hypnotic susceptibility and the relative VAS pain changes (%) in patients with high (SHCS 4–5) and low hypnotic susceptibility (SHCS 0–3). Three-way ANOVAs were used to analyze the secondary outcome parameters: PRI (S, A, E, M, T), PPI (least and worst), pain areas (face and mouth), sleep, SF36 (GH, PF, MH, RE, SF, VT), and SCL (SOM, OCD, IS, DEP, ANX, HOS, PHA) scores, with group and susceptibility as factors and time (before and after last treatment) as the repeated measurement factor. The Tukey HSD test was used for post hoc analyses. An unpaired t-test was used to analyze changes in medicine consumption between groups. A Spearman correlation test was used to analyze correlation between coping strategies and changes in VAS pain scores and hypnotic susceptibility. P-values < 0.05 were considered to be statistically significant.

3. Results 3.1. Patients and treatment Six men and 35 women completed the study. The mean age ± SEM of the patients was 56 ± 1.9 years. The pain had persisted for 9.5 ± 0.9 years. Sixty percent of the patients had been in contact with one or more different specialties in the Danish health care system for their pain problem. Seventy-one percent of the patients reported to suffer from additional pain conditions. Thirteen patients had other health problems. Five patients received psychological or psychiatric treatment. Three patients were unemployed, 11 were salaried employees (two working on reduced time due to their facial pain condition), two self-employed, five retired, 14 on early retirement (five due to PIOP, four due to other pain conditions, four due to other diseases), and four had a pending application for work. In the hypnosis group patients completed 5.1 ± 0.8 treatment sessions and in the control group 5.3 ± 0.9. In the hypnosis group two patients (SHCS 4–5) stopped after three sessions and one (SHCS

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3.2. Baseline characteristics There were no differences between treatment groups at baseline in age (P > 0.60), VAS pain diary scores (P > 0.80), treatment sessions (P > 0.50), hypnotic susceptibility (P > 0.25), pain area (P > 0.14), pain duration (P > 0.06), mental health (global severity index, SCL) (P > 0.08), sleep (P > 0.38), and medication (P > 0.18). Regarding SF36 parameters there was a difference between groups in social function (P < 0.02), but no differences in any other parameters (P > 0.70). 3.3. Self-reported pain and pain-related issues 3.3.1. Pain diary The ANOVA indicated a significant Group · Period interaction over all time periods (P < 0.01) and post hoc tests revealed significant differences of VAS pain scores in period t2 (hypnosis group = 1.3 ± 0.4 versus control group = 0.1 ± 0.2; P < 0.02), period t3 (hypnosis group = 1.7 ± 0.5 versus control group = 0.7 ± 0.4; P < 0.001), and period t4 (hypnosis group = 1.9 ± 0.5 versus control group = 0.3 ± 0.3; P < 0.001). Thus, the percentage change in VAS pain scores from baseline to the last treatment was 33.1 ± 7.4% decrease in the hypnosis group and 3.2 ± 5.4% decrease in the control group (P < 0.02) (see Fig. 1). When stratifying by hypnotic susceptibility measured by SHCS the two-way ANOVAs of groups and hypnotic susceptibility (high hypnotic susceptibility SCHS 4–5 and low hypnotic susceptibility SCHS 0–3) indicated a significant main effect of susceptibility (P < 0.01) and groups (P < 0.01) on relative VAS pain changes (%). In the hypnosis group, highly susceptible patients had a significantly greater reduction in VAS pain scores after the last treatment (55.0 ± 12.3% decrease) compared with the less susceptible patients in the hypnosis group (17.9 ± 6.7% decrease) (P < 0.02) as well as compared with less susceptible patients (+1.6 ± 7.3% increase) (P < 0.01) and highly susceptible patients (11.4 ± 7.3% decrease) (P < 0.02) in the control group. Overall we found that 55% of the patients in the hypnosis group improved by 30% while 27% improved by 50% compared to 10% and 5% in the control group. 3.3.2. McGill pain questionnaire The mean present pain intensity (PPI) in the study was (2.8 ± 1.0) at baseline. ANOVAs indicated a significant main effect of time in PPI (least) (P < 0.02). Overall there was a significant decrease in PPI (least) but post

8

Pain Dairy

7

VAS pain score (0-10)

4–5) after four sessions because they felt much better and needed no further treatment. In the control group, one (SHCS 0–3) patient stopped after three sessions and two (SHCS 0–3) after four sessions because they did not experience any progress in the treatment.

47

6 5 4

** ***

3 Control ( N=19)

2

*

***

##

* *** *

### Active (N=22)

1

###

0 1 2 3 4 5 6

Baseline

1 23 4 5 6

t1

1 2 3 4 5 6

t2

1 2 3 4 5 6

t3

1 2 3 4 5 6

t4

Days

Fig. 1. Effect of treatment with hypnosis or control on VAS average pain score (mean ± SEM) in patients with persistent idiopathic orofacial pain (PIOP). Pain was scored daily 6 days before treatment (t0) and 6 days after treatment 1 (t1), treatment 2 (t2), treatment 3 (t3), and treatment (t4). # indicate significant difference between hypnosis and control group in treatment periods (##P < 0.01, ###P < 0.001). *Significant difference from baseline scores in days between hypnosis and control group on separate days (*P < 0.05, **P < 0.01, ***P > 0.001).

hoc tests could not demonstrate differences between baseline and t4 scores for neither the hypnosis group (1.7 ± 0.2 to 1.2 ± 0.2) nor the control group (2.3 ± 0.2 to 2.2 ± 0.3). There were no effects of time, groups, or hypnotic susceptibility on any other MPQ scores (P > 0.06) (Table 1). 3.3.3. Perceived pain area The changes in the facial pain area from baseline to the last treatment were ( 34.9 ± 11.6 arbitrary units) in the hypnosis group versus ( 20.2 ± 10.0 arbitrary units) in the control group (P < 0.01). There was no influence of hypnotic susceptibility on these findings (P < 0.70). ANOVAs of intraoral pain areas indicated no main effects of groups (P < 0.61), time (P < 0.67) or susceptibility (P > 0.50) (Table 1). 3.4. Medication Many of the patients used analgesics on a daily basis such as NSAID (14.7%), weak analgesics (48.8%), and opioids (19.5%). Furthermore carbamazepine (2.4%) and gabapentin (14.6%) were used for treatment of the pain problem. Unpaired t-tests indicated a significant reduction in the use of weak analgesics doses in the hypnosis group from baseline to the last treatment ( 6.6 ± 2.9) compared to the control group ( 0.8 ± 1.3) (P < 0.02) (Table 2). No other significant differences were found for any other types of medication (P > 0.98). The only user of carbamezapine in the hypnosis group reduced the dosage during treatment as her pain problem

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Table 1 Effect of treatment with hypnosis or control in persistent idiopathic orofacial pain (PIOP) patients on various pain-related parameters (mean ± SEM) Active group (N = 22)

Control group (N = 19)

Baseline

t4

McGill pain questionnaire Sensory Affective Evaluating Miscellaneous Total PPI worst PPI least

21.7 ± 3.0 4.2 ± 0.9 4.5 ± 0.9 8.2 ± 1.5 39.0 ± 5.3 4.3 ± 0.2 1.7 ± 0.2

23.8 ± 3.8 4.1 ± 1.0 3.7 ± 0.7 6.4 ± 1.0 37.3 ± 5.5 4.0 ± 0.3 1.2 ± 0.2

25.1 ± 3.6 6.5 ± 1.0 4.5 ± 1.0 10.1 ± 1.0 46.2 ± 5.8 4.6 ± 0.2 2.3 ± 0.3

31.1 ± 4.1 7.8 ± 1.0 4.9 ± 1.0 10.3 ± 1.6 54.1 ± 6.8 4.5 ± 0.2 2.2 ± 0.3

Perceived pain area Face Intraoral

64.9 ± 15.0 14.5 ± 3.4

31.4 ± 7.0a 9.9 ± 3.6

121.5 ± 36.0 14.3 ± 4.7

113.2 ± 40.0 16.3 ± 5.0

1.1 ± 0.1 0.8 ± 0.1 0.5 ± 0.1 0.8 ± 0.1 0.7 ± 0.1 0.4 ± 0.1 0.2 ± 0.0

0.9 ± 0.1 0.8 ± 0.9 0.4 ± 0.1 0.7 ± 0.1 0.5 ± 0.1 0.4 ± 0.1 0.1 ± 0.0

1.4 ± 0.2 1.2 ± 0.2 0.7 ± 0.2 1.1 ± 0.2 0.7 ± 0.2 0.5 ± 0.1 0.3 ± 0.1

1.4 ± 0.2 1.3 ± 0.2 0.8 ± 0.2 1.0 ± 0.2 0.8 ± 0.2 0.6 ± 0.1 0.3 ± 0.1

16.1 ± 1.0 20.9 ± 1.1 76.4 ± 4.6 6.0 ± 0.5 14.0 ± 1.0 8.1 ± 0.4 5.1 ± 0.3

17.2 ± 0.9 23.4 ± 0.9 80.7 ± 3.8 7.1 ± 0.5 14.9 ± 1.1 8.7 ± 0.3 5.0 ± 0.3

15.3 ± 1.1 21.4 ± 1.3 68.8 ± 6.0 5.3 ± 0.5 12.0 ± 1.3 6.4 ± 0.6 5.3 ± 0.3

14.8 ± 1.0 21.1 ± 1.5 68.8 ± 5.7 5.5 ± 0.5 12.3 ± 1.3 7.2 ± 0.6 4.8 ± 0.3

Psychological symptoms (SCL) Somatization Obsessive compulsive Interpersonal sensivity Depression Anxiety Hostility Phobic anxiety Quality of life (SF 36 scores) General health Mental health Physical function Body pain Vitality Social function Emotional function

Baseline

t4

PPI, present pain indices; SCL, symptom check list; Quality of life (SF36). a Significant differences in changes from baseline scores between active and control group (P > 0.03).

improved. One user of gabapentin in the control group reduced gabapentin doses and changed to anti-depressive medication prescribed by her family doctor due to side effects of gabapentin. One patient in the hypnosis group used cannabioids daily for pain relief, but stopped during treatment.

treatment with no differences between the hypnosis group (0.9 ± 0.3) and control group (0.2 ± 0.1) (P < 0.11). There was no significant effect of susceptibility (P > 0.76).

3.5. Sleep

In this study, an extremely high proportion of patients (90.2%) had symptoms of somatization and in fact 53.6% of the patients had scores above psychiatric values. The occurrence of depressive symptoms (80.5%)

3.6. Psychological symptoms (SCL)

ANOVAs of the sleep quality scores indicated improvement in sleep quality from baseline to the last

Table 2 Effect of treatment with hypnosis or control on cumulative medication doses Active group (N = 22)

NSAIDs Weak analgesics Opioids Carbamezapin Gabapentin

Control group (N = 19)

N

Baseline

t4

N

Baseline

t4

3 13 5 1 5

7.3 ± 1.5 17.7 ± 5.3 23.2 ± 3.0 30.0 ± 2.8 29.4 ± 5.1

2.3 ± 2.3 11.2 ± 4.6a 19.0 ± 1.4 24.0 ± 2.8 28.0 ± 5.9

3 7 3 0 1

15.0 ± 1.0 21.9 ± 7.9 17.3 ± 10.2

16.0 ± 2.0 19.9 ± 8.3 19.7 ± 12.4

14.0 ± 8.3

7.0 ± 8.3

Medication. Cumulative medication doses of one week at baseline (t0) and one week after the last treatment (t4) divided into medication groups (mean ± SEM). NSAIDs. One dose = non-steroid anti-inflammatory 600 mg or COX 2 inhibitor 200 mg. Weak analgesics. One dose = paracetamol 500 mg or acetylsalicylic acid 500 mg or Kodamid 25 mg. Opiods. One dose = tramadol 50 mg or dextropoxyphen 65 mg or morphine 10 mg. Carbamezapin one dose = 200 mg. Gabapentin one dose = 400 mg. a Indicates significant difference from baseline (t0) to (t4) values (P < 0.01) in the hypnosis group compared with control group.

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and symptoms of obsessive compulsive disorder (78%) was also high and more than 2/3 of the patients had symptoms of interpersonal sensitivity (70.7%) and anxiety (73.2%). The occurrence of hostility was 58.5% and nearly one-half of the patients had symptoms of phobic anxiety (48.8%). There were no effects of time, groups or susceptibility on any SCL scores (P > 0.06) (Table 1). 3.7. Quality of life (SF36) ANOVAs of SF36 scores showed no significant effect of groups, time or susceptibility in general health (P > 0.18), mental health (P > 0.06), physical function (P > 0.26), vitality (P > 0.76), social function (P > 0.42), or emotional function (P > 0.41) (Table 1). 3.8. Coping strategy There was no correlation between the different coping strategies and changes in VAS pain scores. There was, however, a significant negative correlation between catastrophizing strategy scores and hypnotic susceptibility (P < 0.02). No other coping strategies were found to be correlated to hypnotic susceptibility (Table 3). 4. Discussion 4.1. Effects of hypnosis on self-reported pain A statistically significant difference in VAS pain intensity scores and perceived pain area from baseline to the last treatment was found between the hypnosis group and the control group. An effect of 30% pain reduction is considered to be of clinical relevance (Farrar et al., 2001). In the present study we demonstrated a significantly greater decrease (55 ± 12.3%) in VAS pain scores in highly susceptible patients when compared to the less susceptible patients (17.9 ± 6.7%). Another indication of the treatment effect was the number of dropouts in the two groups. The dropouts were

49

larger in the control group and primarily due to a lack of effect from the treatment, whereas the patients in the hypnosis group, who did not complete treatment stopped because they improved and had no need for further treatment. Thus, treatment with hypnosis, especially in highly susceptible patients, seems to offer clinically relevant pain relief in conditions with PIOP, which otherwise is refractory to most standard pain treatments (Hunter, 1992). The present findings are in accordance with previous reports on the effect of hypnotic treatment in TMD patients (Simon and Lewis, 2000; Winocur et al., 2002) and other chronic pain conditions (Montgomery et al., 2000; Rosen et al., 2001; Gonsalkorale et al., 2003; Jensen and Patterson, 2006). The possible pain relieving mechanisms of hypnosis are still not fully understood as it is difficult to identify the exact neuroanatomical sites in the nociceptive pathways where hypnosis exerts its actions. Experimental pain studies of hypnotic reduction of pain intensity have found reduction in R-III (a spinal nociceptive withdrawal reflex) (Kiernan et al., 1995). In addition, positron emission tomography (PET) and functional brain imaging (fMRI) studies of hypnotic pain modulation have found an increased blood flow associated with activity in the extrastriate area, the anterior cingulate cortical (ACC) area 24, and thalamus and pontomesencephalic brainstem, together with a reduction in blood flow of primary somatosensory cortex (Rainville et al., 1997, 2002; Faymonville et al., 2000, 2006). These findings suggest that hypnotic sensory analgesia could be mediated by descending anti-nociceptive mechanisms. Hypnotic elevations of pain thresholds are unaffected by naloxone and therefore assumed not to be an opioid-dependent control mechanism (Barber and Mayer, 1977). In placebo situations of expected analgesic effect, it is believed that the descending pain inhibitory system is opioid-mediated (Petrovic et al., 2002; Zubieta et al., 2005). However, in a study of patients with irritable bowel syndrome the antagonistic effect of nalaxone in a placebo situation could not be found (Vase et al., 2005). These findings may suggest that there

Table 3 Coping strategies (CSQ) related to hypnotic susceptibility and VAS pain changes (%) (N = 41)

Diverting attention Reinterpreting pain sensations Coping self-statements Ignoring sensations Praying/hoping Catastrophizing Increasing behavioral activities

CSQ score

Susceptibility

8.9 ± 5.3 9.1 ± 7.3 13.9 ± 5.1 9.8 ± 3.1 10.4 ± 6.0 15.5 ± 7.2 9.8 ± 3.6

R = 0.0 R = 0.2 R = 0.1 R = 0.1 R = 0.1 R = 0.5 R = 0.3

VAS pain changes (%) P = 0.99 P = 0.50 P = 0.63 P = 0.64 P = 0.44 P = 0.02a P = 0.13

R = 0.18 R = 0.3 R = 0.2 R = 0.3 R = 0.2 R = 0.3 R = 0.1

P = 0.77 P = 0.16 P = 0.29 P = 0.20 P = 0.40 P = 0.15 P = 0.94

Coping strategies. Spearman’s correlation coefficients (R) between coping strategy questionnaire scores, hypnotic susceptibility and VAS pain reduction in percentage after treatment in patients with persistent idiopathic orofacial pain (PIOP). Susceptibility was determined by a Danish version of Stanford hypnotic clinical scale. a Indicates significant correlation (P < 0.02).

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could be different pain-mediated pathways acting in the same area but using different receptors in conditions with placebo and hypnosis. It could also be argued that chronic pain patients and healthy subjects use different pathways, since most experiments so far have been conducted in healthy volunteers. There was a negative correlation between catastrophizing and hypnotic susceptibility. Three of the patients in the hypnosis group who did not experience pain relief, had very high levels of catastrophizing thinking. This could indicate that patients with high catastrophizing scores might be less susceptible to hypnosis. In future studies these patients might benefit from treatments to address this problem prior to being offered hypnosis. There were no other correlations between the coping strategies and changes in VAS pain scores, indicating that the pain reduction to a great extent is due to the hypnotic treatment and not a result of the patients’ usual coping strategies. 4.2. Secondary outcome parameters Many patients in this study had a history of pain getting worse no matter which treatment had been tried. They had seen several specialists in their search for pain relief with no or very little success. The pain had persisted for a long time and had affected their daily life very much. They suffered greatly from their pain in spite of using opioids or other analgesics daily and they seem to be refractory to normal medical treatment. In this study, there was statistically significant reduction in the use of weak analgesics in the hypnosis group (36%) from baseline to the last treatment but not in the control group (9%). This also indicates that the pain reduction in the hypnosis group is primarily due to treatment and not because of changes in medication. The magnitude of the reduction of weak analgesics in the hypnosis group is also of clinical relevance. However, a longer treatment period is probably needed in order to gradually reduce the use of other analgesics, especially opioids. In the present study, hypnosis improved both selfreported pain and sleep in the hypnosis group, whereas the control group only improved with respect to sleep. Results from an experimental study indicate that sleep deprivation can produce hyperalgesic and pain threshold changes (Lautenbacher et al., 2006). It was suggested that sleep deprivation could affect descending inhibitory control system, for example diffuse noxious inhibitory controls (DNIC) (Lautenbacher et al., 2006). If this is the case the mechanism of hypnosis may not be working at the part of DNIC which is considered to be affected by sleep deprivation. An extremely high prevalence of severe somatization symptoms was found in this study, as well as a high occurrence of symptoms of depression and obsessive

compulsive disorder. There were no effects of the treatment on SCL scores in this study. Again a longer treatment period would probably be needed to break ‘‘the vicious circle’’ pain may have on physical and social function. The psychosocial findings in this study indicate that a relief of unresolved stress and improvement of mental health by psychological or psychiatric interventions could improve the chronic pain conditions as described by Kroenke and Swindle (2000). There was no effect of the treatment on SF36 parameters in this present study. This might also be expected due to the additional pain conditions and other health problems since this patient group is heavily burdened regarding mental and physical health. The present study used a relatively short term treatment period and indicated that especially highly susceptible patients would benefit from this short term treatment tailored only to facial pain; but it might be expected that a longer treatment period would be necessary to have a significant impact on the secondary outcome parameters, especially in patients less susceptible to hypnosis. Furthermore, the additional pain conditions would require specific hypnotic treatment. Finally, it should be mentioned that although this study was designed as a patient-blinded study it is impossible to blind the person performing the hypnosis or control treatment. However the person was unaware of the susceptibility scores and a blinded research assistant collected and entered all the data. Measures of global improvement and satisfaction could be included, but we believe that the present study has contributed with substantially new and clinical relevant information on a very difficult patient group. 5. Conclusions In the present group of PIOP patients, a statistically significant and clinically relevant reduction in VAS pain scores was seen after the last treatment with hypnosis together with a statistically significant reduction in the use of weak analgesics and improved sleep quality. Thus, treatment with hypnosis, which is considered to be safe and without negative side effects, could be a valuable option for PIOP patients, but the abundant psychological symptoms and influence on quality of life as demonstrated in this study also need to be considered.

Acknowledgements This study was conducted with the financial support from ViFAB, Danish Ministry of the Interior and Health and supported by FUT-Calcin Foundation, Danish Dental Association. The authors are grateful to Bente Haugsted for skillful assistance in the laboratory.

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Appendix A

References

A.1. Hypnotic treatment

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1. Induction Progressive muscle relaxation, guided imaginary to a nice, safe place according to individual preference (beach, garden, wood). Feelings of success, calm, peace of mind, and inner strengths were anchored. 2. Pain suggestions according to Price and Barber (1987) and Crasilneck (1995). Suggestions to change pain perception using the patient’s own metaphor for pain. For example to imagine the pain as a figure and changing the colour and size of this pain figure or moving it to another part of the body. Suggestions to decrease and change the pain sensation by substitution the pain with a feeling of warm, cold, or tickling. Suggestions to create a feeling of anaesthesia. Suggestions to change the pain transmission system using the patient’s own metaphor. Dissociation from the pain. 3. Egostrengthening suggestions. 4. Suggestions to let go of: Bad memories and problems using the patient’s own metaphor for it. The feeling of helplessness and remember the inner strength and calm instead. 5. Regression to: Good memories and anchoring of them. Anchor to be used in stressful situations. Time before pain started in order to remember and reimprint a pain free feeling. 6. Future pacing: Imagine to cope and change the pain in situation where the pain usually would be aggravated. 7. Individual regression to and re-imprinting critical life-events related to the onset of the pain. 8. Individual ego state therapy of pain controlling part. 9. Individual metaphor stories to: relieve anxiety, let go of guilt, let go of old habits, regain energy, decrease arousal. 10. Posthypnotic suggestions: To forget thinking about the pain instead let the thoughts become occupied of good memories and favorite activities as a cue whenever they start to think about the pain. To cope with stress: establishing a cue whenever they get agitated they would take a deep breath and remember their inner calm and strength and remain calm. To keep the muscles relaxed whenever they would start to feel a muscle tension they would relax the muscle again. To increase physical and emotional energy. Amnesia of the pain suffering.

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