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Articles by Michal Granot in JoVE

 JoVE Clinical and Translational Medicine

Een experimentele paradigma voor de Voorspelling van de post-operatieve pijn (PPOP)


JoVE 1671 1/27/2010

Department of Anesthesiology and Pain Medicine, University of Washington School of Medicine

Diffuse schadelijke remmende controle, tijdelijke sommatie en wond hyperalgesie testen aangetoond in de obstetrische patiënt. Deze tests te evalueren remmende en prikkelende mechanismen van pijn verwerken en worden hier gebruikt om endogene analgesie te beoordelen op verschillende tijdstippen tijdens de zwangerschap en de periode tot peripartum helpen onthullen individuele s risico op aanhoudende pijn.

Other articles by Michal Granot on PubMed

Enhancement of the Perception of Systemic Pain in Women with Vulvar Vestibulitis

The aim of this study was to determine whether the characteristics of systemic pain perception and anxiety differ between women with vulvar vestibulitis and healthy women.

Psychophysics of Phasic and Tonic Heat Pain Stimuli by Quantitative Sensory Testing in Healthy Subjects

The increased use of quantitative sensory testing in the study of pain raises the need to characterize various aspects of psychophysical response to noxious stimulation in healthy subjects. The present study aims to address several issues regarding the use of heat pain stimuli: (a) Are pain scores for short-term repeated phasic stimuli consistent? (b) Does an exposure to tonic heat pain stimulus cause sensitization and change the scores for subsequent phasic stimuli? and (c) Are pain scores for phasic and tonic heat pain correlated? To address these questions, a series of four phasic heat pain stimuli of 47 degrees C were given to the forearms of 70 healthy volunteers, over the course of an hour. Pain scores by Visual Analog Scale (VAS) were obtained for each stimulus. In 50 subjects, a tonic heat pain of 70s duration at 47.5 degrees C was given between the first and second phasic stimuli. Pain scores were obtained at four points along this tonic stimulus. Repeated measures ANOVA and a sensitive post hoc analysis indicated that, while the pain perception was reduced on the second, nearly immediate trial, subsequent VAS scores of pain perception were not different from the first (#1: 35.2+/-19.2; #2: 31.4+/-20.2, #3: 33.0+/-21.6; and #4: 33.2+/-20.1, respectively), with strong correlation among the phasic tests. The average tonic pain score was 53.7+/-23.1. Administration of tonic pain stimuli did not result in different VAS scores of subsequent phasic pain stimuli, compared to those subjects who did not receive tonic pain stimuli. Tonic and phasic pain were positively correlated (e.g., r=0.45,p<0.001 for the first phasic stimuli). However, no relation was found between the level of perceived pain, either for phasic or for tonic stimuli, and presence or absence of temporal summation during the tonic pain. In conclusion: (i) phasic pain scores assessments at 30' and 60' after baseline is consistent; (ii) tonic heat pain, despite relatively high VAS scores, does not cause a change in the scoring of subsequent phasic stimuli; and (iii) phasic and tonic pain scores correlate with each other. Thus, the normal pattern of pain perception is stable and not altered by single tonic pain stimulation.

Postcesarean Section Pain Prediction by Preoperative Experimental Pain Assessment

Postcesarean section pain is a common cause of acute pain in obstetrics, yet pain relief and patient satisfaction are still inadequate in many cases. The present study was conducted to determine whether preoperative assessment of experimental pain perception by quantitative sensory tests could predict the level of postcesarean section pain.

Spirituality and Care of Prostate Cancer Patients: a Pilot Study

To explore the integration of spirituality into medical care for African-American men coping with prostate cancer.

Vulvar Vestibulitis Severity--assessment by Sensory and Pain Testing Modalities

Vulvar vestibulitis syndrome (VVS) is a common cause of dyspareunia in pre-menopausal women. Previous quantitative sensory test (QST) studies have demonstrated reduced vestibular pain thresholds in these patients. Here we try to find whether QST findings correlate to disease severity. Thirty-five vestibulitis patients, 17 with moderate and 18 with severe disorder, were compared to 22 age matched control women. Tactile and pain thresholds for mechanical pressure and thermal pain were measured at the posterior fourcette. Magnitude estimation of supra-threshold painful stimuli were obtained for mechanical and thermal stimuli, the latter were of tonic and phasic types. Pain thresholds were lower and supra-threshold magnitude estimations were higher in VVS patients, in agreement with disease severity. Cut-off points were defined for results of each test, discriminating between moderate VVS, severe VVS and healthy controls, and allowing calculation of sensitivity and specificity of the various tests. Our findings show that the best discriminative test was mechanical pain threshold obtained by a simple custom made 'spring pressure device'. This test had the highest kappa value (0.82), predicting correctly 88% of all VVS cases and 100% of the severe VVS cases. Supra-threshold pain magnitude estimation for tonic heat stimulation also had a high kappa value (0.73) predicting correctly 82% overall with a 100% correct diagnosis of the control group. QST techniques, both threshold and supra-threshold measurements, seem to be capable of discriminating level of severity of this clinical pain syndrome.

Gender Differences in the Perception of Chest Pain

This study investigated gender differences in pain perception as characterized by pain symptoms in patients diagnosed with unstable angina pectoris. Twenty-nine women and 32 men were asked to characterize their chest pain using a semi-open questionnaire assessing pain intensity (by numerical rating), pain location, pain characteristics, complaints following chest pain, factors that evoked or reduced chest pain, and whether the chest pain was related to heart disease. Significant gender differences were found. Women scored the intensity of their chest pain significantly higher than men (Chi-square 14.8, P < 0.0001), and related their chest pain less to heart disease (Chi-square 24.6, P < 0.0001). The women described an atypical clinical picture of chest pain that was significantly different from men's. The results are discussed in light of pschological theories regarding gender differences in pain perception. These findings imply the need for special attention to the unique clinical pictures that appear for women and men.

Association Between Quantitative Sensory Testing, Treatment Choice, and Subsequent Pain Reduction in Vulvar Vestibulitis Syndrome

The chronic pain syndrome of vulvar vestibulitis is a major cause of sexual dysfunction, and complete cure is not always achieved. The aim of the study was to determine whether the psychophysical characteristics of systemic pain perception predict treatment choice and outcome. Ninety women with vulvar vestibulitis syndrome were evaluated by using quantitative sensory testing with heat pain threshold measurements and pain scores for suprathreshold stimuli applied to the forearm, blood pressure measurements, and an assessment of the number of other pain disorders. Women were free to choose a surgical procedure (ie, vestibulectomy), one of the possible nonsurgical treatments (eg, biofeedback, cognitive-behavioral therapy, or hypoallergic agents), or to avoid treatment entirely. Eight months later, women reported the success of the treatment on the basis of reduction in the level of vulvar pain. Vestibulectomy demonstrated the best therapeutic effectiveness (chi2, 26.4; P <.0001). Women who chose this type of treatment had lower pain scores (P =.038) and fewer pain syndromes other than the vulvar pain (P =.025). Logistic regression analysis, controlling for the effect of vestibulectomy, indicated that lower experimental pain scores (P =.044), fewer pain disorders (P =.023), and higher systolic blood pressure (P =.039) are predictive variables for reduction of vulvar pain. An assessment of systemic pain perception might be helpful in choosing the optimal treatment and in predicting its success. PERSPECTIVE: The present study suggests that pain perception variables might be of value in the prediction of treatment choice and outcome among women with vulvar vestibulitis.

Primary and Secondary Vulvar Vestibulitis Syndrome: Systemic Pain Perception and Psychophysical Characteristics

Women with primary and secondary vulvar vestibulitis syndrome (VVS) report similar vulvar pain symptoms; however, it is not clear whether these subsets have similar pain and psychophysical characteristics. This study evaluated systemic pain perception, cardiovascular measures, and anxiety level in women with primary and secondary VVS.

Perceptions of Breast Cancer Among Arab Israeli Women

The incidence of breast cancer is increasing among Arab Israeli women, yet few Arab women over the age 50 take advantage of free mammography available to them. In this study we attempted to identify social and cultural aspects of the Arab Israeli woman's life that may reduce screening attendance for early detection of breast cancer. This qualitative study consisted of 6 focus groups. The fundamental theme identified as a barrier to prevention behavior was the role of the Arab woman in society expressed as marrying, having children and being totally committed to her family. In this model, without these roles her life is purposeless and her place in society is lost. The women perceived the chain of events that begins with screening for breast cancer as possibly resulting in cancer diagnosis and having breast cancer will lead to an inability to fulfill female roles. This feedback mechanism inherent in the chain of events may be the cause of the low rates of compliance in performing early detection and mammography. Interventions aimed at increasing the rate of Arab women's performance of mammography should take these issues into consideration.

Psychological Factors Associated with Perception of Experimental Pain in Vulvar Vestibulitis Syndrome

This study assessed the association between pain perception and psychological variables in women with vulvar vestibulitis syndrome (VVS) by comparing 28 VVS women with 50 healthy women. We assessed non genital systemic pain perception with quantitative sensory testing by administering experimental pain stimuli to the forearm. The VVS women demonstrated a lower pain threshold and a higher magnitude estimation of pain, combined with a higher trait anxiety, increased somatization, and a lower body image. Among the VVS women, nonvaginal pain catastrophizing was significantly related to reported pain during coitus. A cluster analysis revealed four subtypes of VVS women, as characterized by levels of pain and personality variables. I suggest implications for the assessment and treatment of women suffering from painful coitus.

The Roles of Pain Catastrophizing and Anxiety in the Prediction of Postoperative Pain Intensity: a Prospective Study

This study was a prospective investigation of the extent to which psychologic variables could be predictive of postoperative pain. Study aims were: 1) to evaluate whether an assessment of pre-operative distress factors could predict the intensity of postoperative pain; and 2) to characterize the unique pattern in which anxiety and pain catastrophizing scores relate to postoperative pain.

Association Between Regional Idiopathic Neuropathy and Salivary Involvement As the Possible Mechanism for Oral Sensory Complaints

The idiopathic sensorial disturbances of burning mouth syndrome (BMS), taste disturbances (dysgeusia), and dry mouth (xerostomia) have recently been recognized as one entity and given the generic name of oral sensorial complaints (OSC). However, not all patients with OSC complain of all three disturbances, and the underlying mechanism of OSC has not yet been elucidated. This study sought to determine whether OSC was associated with the alteration of oral sensory perception, salivary profile and/or personality traits. It examined 35 patients with OSC and 19 controls. Sensory perception was assessed by Quantitative Sensory Testing (QST) applied to the tongue, including thresholds for thermal sensations and pain, and the magnitude estimation of tonic suprathreshold heat pain stimuli. The salivary profile included flow rate and compositional analysis. Personality traits were examined by both state and trait anxiety and somatization scoring. Results showed significantly elevated thermal sensory thresholds and decreased pain scores for tonic heat pain. In addition, there was an increased level of somatization in the OSC group as compared to the control group (15.1 +/- 1.5 vs. 6.6 +/- 2.1, respectively; P = .003). Concomitantly, altered salivary composition (elevated Na, K, Cl, Ca, IgA, and amylase concentrations)-but not salivary flow rate reduction-was observed in those patients despite their complaints of oral dryness. All parameters were similar among the patients with OSC regardless of their type of complaint. Linear regression analysis revealed that an elevated warm sensory threshold was associated with higher levels of salivary K and Cl concentrations in the patients with OSC. These findings may be attributed to a regional small fiber idiopathic neuropathy affecting oral sensation and salivary secretion in OSC. Alternatively, a primary idiopathic salivary dysfunction might cause sensory neural dysfunction at the receptor level by changing the oral cavity milieu. PERSPECTIVE: Based on the salivary, psychophysical, and personality traits analysis currently presented, as well as on the available literature, we hypothesize that a comprehensive mechanism for OSC is based on a regional neuropathy, which is expressed by complaints of BMS, taste disturbances, and/or xerostomia. All are clearly distinguishable from similar conditions with established organic/therapeutic-related etiologies.

Catastrophizing Labor Pain Compromises Later Maternity Adjustments

The purpose of this study was to evaluate the impact of labor pain intensity and labor pain catastrophizing on maternity blues and postpartum social functioning.

Personality Traits Associated with Perception of Noxious Stimuli in Women with Vulvar Vestibulitis Syndrome

Vulvar vestibulitis syndrome (VVS) is associated with enhanced pain sensitivity. The present study explores the role of personality on the perception of noxious stimuli among women with VVS. More specifically, the aim of the study was to explore whether the personality traits assessed by Cloninger's Tridimensional Personality Questionnaire (TPQ) (harm avoidance [HA], novelty seeking [NS], and reward dependence [RD]) are associated with the augmented pain perception in women with VVS. Quantitative sensory tests were applied to the forearm of 98 women with VVS and 135 control subjects, all of whom completed the TPQ. The women with VVS scored higher than the control subjects on HA and RD with no significant differences in NS. Linear regression analyses revealed that in the VVS group, lower pain thresholds and higher magnitude estimations of suprathreshold pain stimuli were associated with higher HA and RD scores. The enhanced pain perception among women with VVS might reflect their tendency to respond intensely to signals of reward and to elevate the perceived risk. This might lead them to avoid hazards by overestimating the level of potential harm, as represented by greater pain sensitivity. The association between personality traits assessed by Cloninger's Tridimensional Personality Questionnaire, ie, harm avoidance, novelty seeking, and reward dependence, and the enhanced perception of noxious stimuli in vulvar vestibulitis syndrome might suggest neurochemical mechanisms of pain experience affected by personality, with possible application for future treatment approaches toward pain disorders.

Domestic Violence Among Druze Women in Israel As Reflected by Health Status and Somatization Level

Women with a history of physical or emotional abuse demonstrate a higher incidence of medical disorders but may be reluctant to disclose the abuse to health care providers. The present study explored whether measures of health status may serve as an indication of violence against women. Sixty-two Druze women (18-50 years old) completed health status (SF-36 survey), somatization (Brief Symptom Inventory-BSI), and abuse (the Abuse Assessment Screen-AAS) questionnaires during a visit to the family physician in the community primary care clinic. Higher somatization symptoms and diminished health status were associated with severity of violence. Results attest to the value of these measures as an additional indirect device for screening victims of domestic violence in general and among traditional societies in particular.

Efficacy of Suppository Analgesia in Postabortion Pain Reduction

Termination of pregnancy is a painful procedure. Currently, there are no sufficient data regarding the best mode to reduce this pain. The aim of the study was to evaluate postabortion pain levels and to examine the analgesic effect of three different generic types of suppositories provided at the end of the surgical procedure prior to awakening from general anesthesia.

The Association Between Somatization and Perceived Ability: Roles in Dysmenorrhea Among Israeli Arab Adolescents

The aim of this study was to investigate whether somatization and attitudes toward menstruation predict the incidence of pain intensity and dysmenorrhea among Israeli Arab adolescent females.

Contact Heat-evoked Temporal Summation: Tonic Versus Repetitive-phasic Stimulation

Temporal summation (TS) is usually evoked by repetitive mechanical or electrical stimuli, and less commonly by tonic heat pain. The present study aimed to examine the TS induction by repetitive-phasic versus tonic heat pain stimuli. Using 27 normal volunteers, we compared the extent of summation by three calculation methods: start-to-end pain rating difference, percent change, and double-logarithmic regression of successive ratings along the stimulation. Subjects were tested twice, and the reliability of each of the paradigms was obtained. In addition, personality factors related to pain catastrophizing and anxiety level were also correlated with the psychophysical results. Both paradigms induced significant TS, with similar increases for the repetitive-phasic and the tonic paradigms, as measured on 0-100 numerical pain scale (from 52.9+/-11.7 to 80.2+/-15.5, p<0.001; and from 38.5+/-13.3 to 75.8+/-18.3, p<0.001, respectively). The extent of summation was significantly correlated between the two paradigms, when calculated by absolute change (r=0.543, p=0.004) and by regression (r=0.438, p=0.025). Session-to-session variability was similar for both paradigms, relatively large, yet not biased. As with other psychophysical parameters, this poses some limitations on TS assessment in individual patients over time. The extent of TS induced by both paradigms was found to be associated with anxiety level and pain catastrophizing. Despite some dissimilarity between the repetitive-phasic and the tonic paradigms, the many similarities suggest that the two represent a similar physiological process, even if not precisely the same. Future clinical applications of these tests will determine the clinical relevance of the TS paradigms presented in this study.

Chapter 27 Quantitative Sensory Testing

Pain Catastrophizing, Response to Experimental Heat Stimuli, and Post-cesarean Section Pain

This prospective study assessed the relation between pain catastrophizing, response to experimental pain stimuli, and pain perceived by women after elective cesarean sections. Forty-seven women who were scheduled for elective cesarean section were enrolled in the study. Magnitude estimation to suprathreshold phasic and tonic heat pain stimuli was assessed 1 or 2 days before surgery. Women completed the Pain Catastrophizing Scale after the heat stimuli and again on the first postoperative day. During the first and second postoperative days, perception of pain intensity was assessed by visual analog scale at each analgesia request. A multiple regression analysis revealed that pain on the first postoperative day was predicted by patient response to preoperative tonic heat stimuli (r(2) = .167, P = .008). Pain on the second postoperative day was predicted by preoperative pain catastrophizing (r(2) = .139, P = .021). No significant association was observed between preoperative response to heat stimuli or pain catastrophizing and the patient's analgesic consumption in the obstetrical ward. It is concluded that pain catastrophizing and response to experimental tonic heat pain correlate with post-cesarean section pain. PERSPECTIVE: This article presents psychological and psychophysical measures that may be of help in the prediction of post-cesarean section pain. It may therefore contribute to the treatment of the sequelae of the most common major surgical procedure performed in women in their reproductive years.

Clinical and Experimental Pain Perception is Attenuated in Patients with Painless Myocardial Infarction

The lack of pain alarm in painless myocardial infarction (MI) leads to increased morbidity and mortality, since patients do not seek medical treatment in a timely manner. We aimed to explore whether reduced systemic pain perception in response to experimental stimuli and pain related personality variables characterizes painless MI patients.

Determinants of Endogenous Analgesia Magnitude in a Diffuse Noxious Inhibitory Control (DNIC) Paradigm: Do Conditioning Stimulus Painfulness, Gender and Personality Variables Matter?

Descending modulation of pain can be demonstrated psychophysically by dual pain stimulation. This study evaluates in 31 healthy subjects the association between parameters of the conditioning stimulus, gender and personality, and the endogenous analgesia (EA) extent assessed by diffuse noxious inhibitory control (DNIC) paradigm. Contact heat pain was applied as the test stimulus to the non-dominant forearm, with stimulation temperature at a psychophysical intensity score of 60 on a 0-100 numerical pain scale. The conditioning stimulus was a 60s immersion of the dominant hand in cold (12, 15, 18 degrees C), hot (44 and 46.5 degrees C), or skin temperature (33 degrees C) water. The test stimulus was repeated on the non-dominant hand during the last 30s of the conditioning immersion. EA extent was calculated as the difference between pain scores of the two test stimuli. State and trait anxiety and pain catastrophizing scores were assessed prior to stimulation. EA was induced only for the pain-generating conditioning stimuli at 46.5 degrees C (p=0.011) and 12 degrees C (p=0.003). EA was independent of conditioning pain modality, or personality, but a significant gender effect was found, with greater EA response in males. Importantly, pain scores of the conditioning stimuli were not correlated with EA extent. The latter is based on both our study population, and on additional 82 patients, who participated in another study, in which EA was induced by immersion at 46.5 degrees C. DNIC testing, thus, seems to be relatively independent of the stimulation conditions, making it an easy to apply tool, suitable for wide range applications in pain psychophysics.

Objective Correlate of Subjective Pain Perception by Contact Heat-evoked Potentials

The method of pain-evoked potentials has gained considerable acceptance over the last 3 decades regarding its objectivity, repeatability, and quantifiability. The present study explored whether the relationship between pain-evoked potentials and pain psychophysics obtained by contact heat stimuli is similar to those observed for the conventionally used laser stimulation. Evoked potentials (EPs) were recorded in response to contact heat stimuli at different body sites in 24 healthy volunteers. Stimuli at various temperatures were applied to the forearm (43 degrees C, 46 degrees C, 49 degrees C, and 52 degrees C) and leg (46 degrees C and 49 degrees C). The amplitudes of both components (N2 and P2) were strongly associated with the intensity of the applied stimuli and with subjective pain perception. Yet, regression analysis revealed pain perception and not stimulus intensity as the major contributing factor. A significant correlation was found between the forearm and the leg for both psychophysics and EPs amplitude. PERSPECTIVE: Contact heat can generate readily distinguishable evoked potentials on the scalp, consistent between upper and lower limbs. Although these potentials bear positive correlation with both stimulus intensity and pain magnitude, the latter is the main contributor to the evoked brain response.

Prediction of Chronic Post-operative Pain: Pre-operative DNIC Testing Identifies Patients at Risk

Surgical and medical procedures, mainly those associated with nerve injuries, may lead to chronic persistent pain. Currently, one cannot predict which patients undergoing such procedures are 'at risk' to develop chronic pain. We hypothesized that the endogenous analgesia system is key to determining the pattern of handling noxious events, and therefore testing diffuse noxious inhibitory control (DNIC) will predict susceptibility to develop chronic post-thoracotomy pain (CPTP). Pre-operative psychophysical tests, including DNIC assessment (pain reduction during exposure to another noxious stimulus at remote body area), were conducted in 62 patients, who were followed 29.0+/-16.9 weeks after thoracotomy. Logistic regression revealed that pre-operatively assessed DNIC efficiency and acute post-operative pain intensity were two independent predictors for CPTP. Efficient DNIC predicted lower risk of CPTP, with OR 0.52 (0.33-0.77 95% CI, p=0.0024), i.e., a 10-point numerical pain scale (NPS) reduction halves the chance to develop chronic pain. Higher acute pain intensity indicated OR of 1.80 (1.28-2.77, p=0.0024) predicting nearly a double chance to develop chronic pain for each 10-point increase. The other psychophysical measures, pain thresholds and supra-threshold pain magnitudes, did not predict CPTP. For prediction of acute post-operative pain intensity, DNIC efficiency was not found significant. Effectiveness of the endogenous analgesia system obtained at a pain-free state, therefore, seems to reflect the individual's ability to tackle noxious events, identifying patients 'at risk' to develop post-intervention chronic pain. Applying this diagnostic approach before procedures that might generate pain may allow individually tailored pain prevention and management, which may substantially reduce suffering.

The Experience of Being a Shift-leader in a Hospital Ward

This paper is a report of a study to explore the experience of being a shift-leader, and how these nurses view the management of their shift.

Can We Predict Persistent Postoperative Pain by Testing Preoperative Experimental Pain?

Although it is recognized that medical and surgical procedures may lead to persistent postoperative pain, predicting which patients are at risk for developing chronic pain presents an ongoing challenge. Clinical observations indicate that similar invasive procedures associated with consequent peripheral tissue damage can cause a wide range of pain experience. This broad variability is likely a consequence of the diversity in the central pain processing of the peripherally generated noxious stimulation. Therefore, advanced psychophysical measures that dynamically represent central pain modulation mechanisms may be used to determine an individual's susceptibility to developing persistent postoperative pain. This review highlights how, and to what extent, preoperative experimental pain testing can be utilized in predicting persistent postoperative pain.

Enhanced Presurgical Pain Temporal Summation Response Predicts Post-thoracotomy Pain Intensity During the Acute Postoperative Phase

Recent evidence points to an association between experimental pain measures obtained preoperatively and acute postoperative pain (POP). We hypothesized that pain temporal summation (TS) might be an additional predictor for POP insofar as it represents the neuroplastic changes that occur in the central nervous system following surgery. Therefore, a wide range of psychophysical tests (TS to heat and mechanical repetitive stimuli, pain threshold, and suprathreshold pain estimation) and personality tests (pain catastrophizing and anxiety levels) were administered prior to thoracotomy in 84 patients. POP ratings were evaluated on the 2nd and 5th days after surgery at rest (spontaneous pain) and in response to activity (provoked pain). Linear regression models revealed that among all assessed variables, enhanced TS and higher pain scores for mechanical stimulation were significantly associated with greater provoked POP intensity (overall r2 = 0.225, P = .008). Patients who did not demonstrate TS to both modalities reported lower scores of provoked POP as compared with patients who demonstrated TS in response to at least 1 modality (F = 4.59 P = .013). Despite the moderate association between pain catastrophizing and rest POP, none of the variables predicted the spontaneous POP intensity. These findings suggest that individual susceptibility toward a greater summation response may characterize patients who are potentially vulnerable to augmented POP. PERSPECTIVE: This study proposed the role of pain temporal summation assessed preoperatively as a significant psychophysical predictor for acute postoperative pain intensity. The individual profile of enhanced pain summation is associated with the greater likelihood of higher postoperative pain scores.

Women's Sexual Pain Disorders

Women's sexual pain disorders include dyspareunia and vaginismus and there is need for state-of-the-art information in this area.

The Association Between Supra-physiological Levels of Estradiol and Response Patterns to Experimental Pain

The precise mechanism by which gonadal hormones influence pain perception is still obscure. However, no studies have examined experimental pain responses at supra-physiological hormone levels. This study explored the influence of pharmacological estradiol (E2) levels on the stability of pain perception obtained via quantitative sensory testing. A repeated measures design was used with 31 women, treated by a same In Vitro Fertilization (IVF) protocol. Patterns of experimental pain response were assessed in three different sessions (baseline, down regulation, maximal ovarian stimulation). Correlations between hormonal levels (E2, progesterone, luteinizing hormone (LH)) and pain perceptions were assessed at each session. While in the entire sample the pattern of response to pain stimulations remained unchanged regardless of hormonal manipulations, a greater pain sensitivity was associated with supra-physiological levels of E2 during the maximal ovarian stimulation session (for 47 degrees C stimulation: r=.383, p=0.044). Mixed model repeated measures ANOVA indicated that participants who over-responded to the ovarian stimulation session (E2 > 10,500 pmol/l) showed significant enhanced pain responses under this condition (p=0.004). No correlations between progesterone, LH and experimental pain perception were found in any of the study sessions. Although pain perceptions at different E2 levels remained constant, the enhancement of pain scoring at supra-physiological E2 levels, underscore the possible role of sex hormones in pain modulation and experience.

Recommendations on Terminology and Practice of Psychophysical DNIC Testing

Prediction of Perineal Trauma During Childbirth by Assessment of Striae Gravidarum Score

To explore the association between striae gravidarum (SG) and the risk for perineal trauma (PT) in childbirth.

A Psychophysical Study of Endogenous Analgesia: the Role of the Conditioning Pain in the Induction and Magnitude of Conditioned Pain Modulation

Endogenous analgesia (EA) can be examined experimentally using a conditioned pain modulation (CPM) paradigm. While noxious conditioning stimulation intensities (CSIs) are mainly used, it has not been fully investigated in the same experimental design whether the experienced conditioning pain level affects CPM responses. The principal goal of the present study was to characterize CPM induction and magnitudes evoked by various conditioning pain levels. Furthermore, we explored associations between conditioning pain reports and CPM responses across various CSIs. Thirty healthy, young, right-handed males were tested with a parallel CPM paradigm. Three different CSIs (hand water-immersion) induced mild, moderate and intense pain levels, rated 12.41 ± 7.85, 31.57 ± 9.56 and 58.1 ± 11.43, respectively (0-100 numerical pain scale) (P < 0.0001). Contact-heat 'test-stimulus' levels were compared before and during conditioning. Within the group, (i) CPM was induced only by the moderate and intense CSIs (Ps ≤ 0.001); (ii) no difference was demonstrated between the magnitudes of these CPM responses. Regression analysis revealed that CPM induction was independent of the perceived conditioning pain level, but associated with the absolute CSI (P < 0.0001). Conditioning pain levels were correlated across all CSIs, as were CPM magnitudes (Ps ≤ 0.01). We conclude that among males, (i) once a CPM response is evoked by a required conditioning pain experience, its magnitude is not further affected by increasing conditioning pain and (ii) CPM magnitudes are inter-correlated, but unrelated to conditioning pain reports. These observations may suggest that CPM responses represent an intrinsic element of an individual's EA processes, which are not significantly affected by the experienced conditioning pain.

Characteristics of Attachment Style in Women with Dyspareunia

In this study, the authors explored the relations among painful experience during sexual intercourse, attachment style, and somatization. The authors assessed these variables by self-report of dyspareunia (painful vaginal intercourse) and by completion of the Experience in Close Relationships Scale and the short version of the Brief Symptom Inventory. The sample included 110 women, 45 of whom reported painful intercourse and were defined as the dyspareunia group, and the remaining 65 were defined as the control group. The dyspareunia group showed greater incidence, compared with the control group, of insecure attachment styles defined by higher scores of anxiety and/or avoidance as well as higher somatization levels. Regression analyses revealed that increased level of somatization and higher level of avoidance predicted higher probability for dyspareunia. The authors' findings suggest that women with higher frequency of physical complaints in various body areas and insecure attachment style are more susceptible to report pain during intercourse.

Characteristics of Response to Experimental Pain in Sexually Abused Women

Women with a history of sexual abuse (SA) commonly report greater pain symptoms. It is still unclear whether enhanced pain susceptibility is the result of altered pain processing and response. Therefore, this pilot study aimed to explore pain sensitivity to experimentally induced pain and associated psychology in women with a history of severe SA.

The Effect of Post-surgical Neuroplasticity on the Stability of Systemic Pain Perception: A Psychophysical Study

BACKGROUND: Surgery-induced neuroplasticity at spinal and supra-spinal levels is assumed to evoke a clinical acute post-operative pain (cAPOP) experience, which is expressed by allodynia and/or hyperalgesia. It remains unclear whether the systemic pain perception measured outside the incision area remains unchanged and whether it is affected by the presence of cAPOP. AIMS: This study explored whether the systemic perception of experimental pain would be altered towards hypersensitivity following elective gynecological surgery unmasked by opioids. METHODS: A perioperative psychophysical evaluation of heat pain thresholds (HPT) and pain estimations were obtained in a remote bodily area before and after surgery among 35 women. RESULTS: The ratings for both pain dimensions of intensity and unpleasantness remained stable following surgery. However, there was a reduction found in HPT the day after surgery (43.6±2.2°C to 42.2±3.1°C, p=0.002). This reduction was associated with lower HPT measured before surgery (r=.56, p<0.000) and with higher cAPOP intensity obtained at rest (r=-.44, p=0.008). CONCLUSIONS: This post-surgical allodynia, as reflected by the systemic enhancement of pain perception, may represent plasticity in the central pain pathways at the supra-spinal level. Pre-surgical assessment of a patient's pain perception profile may predict certain pain dimensions of post-surgical pain plasticity. The evaluation of individual pain profiles may contribute to a mechanism-based approach aimed to attenuate the cAPOP.

Cognitive Manipulation Targeted at Decreasing the Conditioning Pain Perception Reduces the Efficacy of Conditioned Pain Modulation

Although painfulness of the conditioning stimulus (CS) is required for the activation of conditioned pain modulation (CPM), it is still unclear whether CPM expression depends on the objective physical intensity of the CS or the subjective perception of its pain. Accordingly, we cognitively manipulated the perceived CS pain, rendering the physical aspects of the CPM paradigm untouched. Baseline CPM was measured among 48 young healthy male subjects using the parallel paradigm with contact heat as test pain and hand immersion in hot water as CS. Subjects were then randomized into 4 groups, all of which were cognitively manipulated as to the CS-induced pain: group 1, placebo (CS less painful); group 2, nocebo (CS more painful); and groups 3 and 4, the informed control groups for groups 1 and 2, respectively. CPM was reassessed after the manipulation. Comparing the groups by MANCOVA (multivariate analysis of covariance) revealed that placebo exerted decreased CS pain and consequent attenuation of CPM magnitudes, while nocebo elicited increased CS pain, but without CPM elevation (P<.0001). Within the placebo group, the reduction in CS pain was associated with diminished CPM responses (r=0.767; P=.001); however, no such relationship characterized the nocebo group. Pain inhibition under CPM seems to depend on the perceived level of the CS pain rather than solely its physical intensity. Cognitively decreasing the perceived CS pain attenuates CPM magnitude, although a ceiling effect may limit CPM enhancement after cognitively increased CS pain. These findings emphasize the relevance of cognitive mechanisms in determining endogenous analgesia processes in humans.

Control: Patients' Aggression in Psychiatric Settings

Psychiatric patient assaults on staff are a serious problem, affecting staff, patients, and organizations. To understand the etiology of aggressive events, researchers have documented characteristics of aggressive patients, their victims, and to a lesser degree, the patient-provider interaction. Missing in the literature is how staff's different perceptions of aggressive incidents might impact their reactions. In this study, we conducted in-depth, semistructured interviews with 11 health care professionals working in a psychiatric ward in one Israeli psychiatric hospital. Through content analysis, we revealed two main themes: patients' and providers' controllability over patients' aggression. From the intersection of these two themes, four prototypes of the aggressive encounter emerged: the power struggle, the therapeutic encounter, inverse power relations, and victim-to-victim encounters, each distinctively characterized by different emotional, cognitive, and behavioral responses. We discuss our findings in light of attribution theory, which carries important theoretical and practical implications for handling aggression.

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