The role of prior pain experience and expectancy in psychologically and physically induced pain

Cognitive theories regarding symptom formation suggest that environmental factors such as warnings of impending pain and earlier experiences with pain can lead to a cognitive schema in which pain is selectively monitored. This study evaluated the role of prior experience with pain in the development of expectancy induced somatoform pain. Subjects from two experimental groups were connected to a sham stimulator and told to expect a headache. One of these groups, the physical stimulation first group, was exposed to pain induction by ice water and by pressure prior to the sham stimulation. A second group, the sham stimulation first group, received the sham stimulation followed by the cold water and pressure pain induction techniques. Subjects in the physical stimulation first group showed significant increases in their pain reports as settings on the sham stimulator were increased. Significant increases were not noted in the sham stimulation first group. The two groups did not differ in the number of subjects reporting pain or the mean maximal pain reported during the sham stimulation. Duration of cold water tolerance and the time until the analgesic threshold level for cold water were significantly shorter in subjects who had the sham stimulation first. This study suggests that prior pain can influence the reactivity to external suggestion for pain but does not increase the frequency of pain reports. It does suggest that the selective monitoring induced during the sham stimulation may influence later pain behaviours as was seen during the cold water tolerance testing.     

Situational syncope induced by belching

We describe a case of situational syncope induced by belching. The patient showed severe syncope with a high-degree atrioventricular block just after belching, but has not experienced syncope or dizziness over a 3-month follow-up after permanent pacemaker implantation.     

Marital satisfaction and psychophysiological responsiveness in spouses of patients with chronic pain

The primary purpose of this study was to investigate the relationship between spouse marital satisfaction and spouse solicitousness to their physiological responsiveness during marital interactions about pain. Twenty-six couples engaged in a series of structured marital interactions about neutral and pain-related topics while monitored for skin conductance (SC) and heart rate (HR). There was strong support for the role of spouses’ marital satisfaction in predicting their physiological responsiveness. The more satisfied a spouse, the more physiologically reactive the spouses were when listening to the patient describe pain, and the less reactive when responding to it. Dissatisfied spouses demonstrated the opposite pattern. They autonomically deactivated when hearing about the pain and became reactive when responding to it. Solicitousness was not a significant predictor of the spouses’ physiological responsiveness. Block’s (1981) proposed physiological mechanism for the origin of solicitousness in spouses did not receive support. It appears that responding in any fashion may lessen the magnitude of arousal in maritally satisfied spouses, whereas dealing with pain-related topics produces unpleasant arousal in dissatisfied spouses.     

A psychophysiological causal model of pain report validity.

The validity of the pain report is vitally important but difficult to assess because pain is a personal experience. Human laboratory research affords an opportunity to investigate validity because one can measure the consistency and sensitivity of pain ratings produced in response to known stimuli. This article presents 2 levels of evidence characterizing the validity of the pain report measure. The within-subject agreement of pain report with known stimulus variation quantifies the criterion validity, or accuracy, of the measure. Causal modeling defines a second, between-subject, level of construct validity by suggesting a psychophysiological mechanism determining the observed individual variation in accuracy. We analyzed pain rating data obtained in a laboratory study where 100 subjects (56 men and 44 women) experienced varied levels of painful fingertip electrical stimulation, delivered in random order across 144 trials. Unknown to the subjects, there were only 3 stimulus intensities. Accuracy, defined operationally as the proportion of variance in pain report explained by stimulus level, ranged from 0.07 to 0.91 with a median of 0.64. Hypothesized determinants of accuracy comprised current intensity, event-related late near field evoked potentials, skin conductance response, heart rate, and pupil diameter change. We limited the evoked potential measures to the amplitude of the negative peak at 150 msec (N150amp) and combined the latter 3 measures to form a single index of overall sympathetic nervous system arousal (Arousal). Although men chose higher stimulus levels for the experiment and had higher Arousal than did women, their mean pain reports and their Accuracy did not differ from those of female subjects. We constructed a sequence of path analysis models designed to clarify the causal contributions of current intensity, N150amp, and Arousal, and to determine whether these relationships differ in men and women. The final model revealed a direct causal chain. Stimulus current determined the amplitude of N150amp (possibly an indicator of attention). N150amp in turn determined Arousal, and Arousal emerged as the sole determinant of the Accuracy of the pain report. In addition, this latter effect differed across the sexes. Men who experienced higher levels of Arousal gave more accurate pain reports than those who had lower levels, but women who had higher levels of Arousal gave less accurate pain reports than those with lower levels. Thus construct validation emerged, not from direct stimulus-response correlation, but from the elucidation of a causal chain that related stimulus to response.     

Self-report and psychophysiological effects of Lamaze preparation: an analogue of labor pain

Eighty nulliparous college female undergraduates were cast randomly into a series of eight treatment conditions representing all possible combinations of the three major components of the Lamaze method of childbirth preparation (relaxation training, informative lectures, and breathing exercises). Assessments of the efficacy of these pain coping strategies were subsequently made in the context of a 1-hour session involving twenty 80-second exposures to a laboratory pain stimulus, patterned so as to resemble labor contractions. Dependent variables included self-reported pain, systolic and diastolic blood pressure, frontalis EMG, and heart rate. Results of the study indicated that relaxation training comprises the most therapeutically active component of the Lamaze treatment regimen, with significant effects (treatments X trials) on self-reported pain, frontalis EMG, and heart rate. The implications of these findings are discussed from the perspective of designing new, and hopefully more efficacious, methods of preparing women for labor and delivery.     

Negative emotional responses elicited by the anticipation of pain in others: psychophysiological evidence

Limited evidence is available about factors influencing observers' anticipatory emotional responses to another's pain. We investigated fear and distress towards the threat of pain in others, and the moderating role of observers' psychopathic traits and catastrophizing about their own or others' pain. Thirty-six dyads of healthy participants were randomly assigned to either the role of observer or observed participant. Both participants were instructed that 1 colored slide (blue or yellow) signalled that a pain stimulus could possibly be delivered to the observed participant (=pain signal), whereas no pain stimulus would be delivered when a differently colored slide was presented (=safety signal). Observers' self-reported fear, fear-potentiated startle, and corrugator electromyography activity during pain and safety signals were measured. Furthermore, observers rated the presence of pain after each trial allowing assessment of observers' perceptual sensitivity to others' pain. Results indicated that self-reported fear, fear-potentiated startle, and corrugator electromyography activity were augmented during pain signals compared to safety signals. Moreover, these negative emotional responses were heightened in observers highly catastrophizing about others' pain, but reduced in observers with heightened psychopathic traits. Psychopathic traits were also related with a diminished perceptual sensitivity to others' pain. The results are discussed in light of affective-motivational perspectives on pain. PERSPECTIVE: This study investigated observers' negative emotional responses in anticipation of pain in another, and the moderating role of observers' psychopathic traits and pain catastrophizing. Knowledge about characteristics influencing observers' emotional response to others' pain may provide insight into why observers engage in particular behaviors when faced with another in pain.     

Psychophysiological factors in myofascial pain

The interaction of the body and mind in stress syndromes; the input from the mind which influences the neurological functions regulating physiological responses; and the metabolic changes that result are discussed. Treatment direction is based on clinical experience and previously published theories. The synergistic effect of psychological and physiological treatment in stress syndromes is mandatory for permanent reduction of the negative feedback loop. Coordination of treatment by the physician and therapist is optimum.     

Adult attachment and reports of pain in experimentally‐induced pain

Attachment theory has been proposed as a framework for understanding the development of chronic pain, with evidence supporting the overrepresentation of insecure attachment styles in chronic pain populations and links between insecure attachment and factors known to impact one's ability to cope with pain. The present study sought to extend two earlier studies exploring the relationships between adult attachment and communication of an acute pain experience, in anticipation of providing insight into individual differences in vulnerability in development of chronic pain. It was hypothesised that: (a) fearful attachment would be associated with perceptions of the pain as less intense, and (b) anxious attachment would be associated with lower pain thresholds. A convenience sample of 82 healthy adults completed self‐report measures of attachment, neuroticism, and negative affect prior to taking part in a coldpressor pain inducement task. Results demonstrated that fearful attachment was associated with lower levels of pain intensity throughout the coldpressor task. In addition, dismissing attachment was also associated with less intense pain, as well as increased coldpressor endurance (tolerance) in the presence of a known assessor. These associations were retained after controlling for measures of neuroticism, negative affect, age, and social desirability. The results of this study are consistent with the proposition that fearful and dismissing individuals tend to mask their underlying distress caused by the pain experience, potentially leading to difficulties coping with pain over time.     

Acidic buffer induced muscle pain evokes referred pain and mechanical hyperalgesia in humans

While tissue acidosis causes local deep-tissue pain, its effect on referred pain and mechanical muscle hyperalgesia is unknown. The aim of this study was to investigate a human experimental acidic muscle pain model using a randomized, controlled, single-blinded study design. Seventy-two subjects (36 female) participated in three visits, each involving one 15 min intramuscular infusion into the anterior tibialis muscle: acidic phosphate buffer (pH 5.2) at 40 ml/h (N=69) or 20 ml/h (N=54), normal phosphate buffer (pH 7.3) at 40 ml/h (N=70), or isotonic saline at 40 ml/h (N=19). Pain ratings and pressure sensitivity of superficial and deep tissues were assessed before, during, and 20 min after infusion. Acidic buffer produced light to moderate, rate-dependent, muscle pain (not sex-dependent) compared to the control infusions, that referred pain to the ankle in 80% of women and 40% of men. Pain did not vary across self-reported menstrual phases. Pressure pain thresholds (PPTs) were reduced over the infused muscle with acidic infusion, defined as primary mechanical hyperalgesia. PPTs decreased at the ankle in those with referred pain in response to acidic buffer, i.e. referred mechanical hyperalgesia, but not at the foot. No pain or changes in PPTs occurred in the contralateral leg. These results demonstrate muscle acidosis can lead to local and referred pain and hyperalgesia, with significant sex differences in development of referred pain.     

Psychological factors in low back pain

Even though low back pain is one of the commonest diseases, little is known about its aetiology, its natural history and its treatment. This may explain why the myth exists that low back pain is often psychogenic in origin or that psychological factors are often at least involved in low back pain. The aim of the early studies on low back pain and psychological factors was to try to divide these pains into functional (psychogenic) and organic, according to the aetiology. The aim of the studies was to predict the quality and success of the treatment. According to the current view, it is not meaningful to try to dichotomize low back pain in this way. According to the earlier literature, both conversion hysteria and psychoses were the main cause of psychogenic low back pain. More recent studies do not, however, support this view. It seems that the most common psychiatric disturbances associated with low back pain are neuroses and neurotic traits. There is controversy as to how often psychological factors are involved in low back pain. Population studies have shown that this association may be weaker than was thought earlier. It seems that individuals who suffer from low back pain, more often than others, have aggression problems and weaknesses in their ego function and more frequently have problems in interpersonal relations and sexual problems. There is no clear picture of what kind of psychotherapy is best suited to low back pain patients who have mental problems. The results attained by learning therapy and also with multidisciplinary ward programs seem quite promising.     

心理因素与下腰痛

尽管临床上下腰痛很常见,但目前仍有很多不明确的问题,文章从下腰痛发生的影响因素及生理、心理学机制等方面,对心理因素与下腰痛的相关性进行了综述。指出一些下腰痛患者表现出“抑郁-疑病-癔病”之神经三联征的个性特征;并建议在下腰痛的处理上对患者的心理和躯体成分予以同样重视。     

妊娠晚期下腰及骨盆痛影响因素分析

目的了解妊娠晚期孕妇下腰及骨盆痛发生率及其影响因素。方法采用问卷调查对1 254例妊娠晚期孕妇进行下腰、骨盆痛及其相关因素调查、分析。1 254例妇女在孕36周常规产前检查时接受问卷调查,包括:年龄,身高,肥胖指数,受教育程度,是否失业,城市或农村人口,有无保姆,孕前有否腰痛,前次妊娠有否腰痛,疼痛部位、程度、性质、加重及缓解方法,孕妇活动能力(日常活动,家务劳动,户外活动)等。结果妊娠晚期孕妇下腰及骨盆痛发生率为48.96%。身高,受教育程度,是否失业及有无保姆与疼痛无明显关系。低龄、高龄孕妇较适龄孕妇更易腰痛。超重孕妇更易腰痛。孕前有腰痛及前次妊娠有腰痛者在本次妊娠中发生腰痛比例增大。城乡孕妇腰痛发生率有较大差异。久站最易加重腰痛,卧位可以明显减轻疼痛。下腰及骨盆痛对妊娠晚期孕妇的活动影响较大。结论妊娠晚期孕妇下腰及骨盆痛发生率高,对于某些影响因素有必要采取相应的有效干预措施以提高孕妇的生活质量。     

Mechanically induced pelvic pain and organic dysfunction in a patient without low back pain

Previous reports have identified mechanical disorders of the lumbar spine as a cause of pelvic pain and organic dysfunction (PPOD) in patients with low back pain. Less common however, are reports of mechanically induced pelvic pain and organic dysfunction in patients without accompanying low back pain. This report details the examination findings and treatment response of a patient with pelvic pain, organic dysfunction and clinical evidence of lower sacral nerve root compression (LSNRC) in whom low back pain was not an accompanying finding. Despite the absence of low back pain however, clinical evaluation revealed the characteristic findings of mechanically induced pelvic pain and organic dysfunction secondary to lower sacral nerve root irritation or compression as a result of a mechanical disorder of the low back. As in long standing cases of mechanically induced pelvic pain and organic dysfunction in which low back pain is present, this case also exhibited severe and widespread involvement of the pelvic organs. In spite of numerous failed attempts at treatment directed at the symptomatic component of the patients disorder, complete resolution of symptoms was achieved by manipulative treatment directed at the mechanical disorder of the lumbar spine.     

The impact of psychologically different patient groups on outcome after a vocational rehabilitation program for long-term spinal pain patients

A better knowledge of differential treatment outcomes for subgroups of chronic spinal pain patients may, for instance, help clinicians in treatment planning or pain researchers in treatment outcome research. The purpose of this prospective study was to evaluate the predictive validity of a subgroup classification based on the Swedish version of the (West Haven Yale) Multidimensional Pain Inventory, the MPI-S. Patients referred to a vocational rehabilitation program were classified into one of three groups, labeled 'adaptive copers', 'dysfunctional' patients, and 'interpersonally distressed' patients, and followed over an 18-month follow-up period. The outcome variables were absence from work (defined as sick listing plus early retirement), general health status, and utilization of health care resources. To our knowledge, the predictive validity of the MPI subgroups has not been evaluated regarding sick listing and early retirement after rehabilitation. As hypothesized, the results showed that the 'dysfunctional' patient group had significantly more registered absences from work and reported higher utilization of health care, over the follow-up period compared to the 'adaptive copers'. Furthermore, as hypothesized, the 'interpersonally distressed' and 'dysfunctional' patient groups report a poorer general health status than the 'adaptive copers' over the whole follow-up period. However, contrary to our hypothesis, the proportion of improved patients did not differ significantly between the subgroups. Altogether, the predictive validity of the MPI-S subgroup classification was mainly confirmed. The clinical implications of this study suggest that the matching of treatment to patient needs may enhance treatment outcome, reduce pain and suffering among chronic spinal pain patients and facilitate a better health economic allocation of treatment resources.