Functional abdominal pain in childhood and adolescence increases risk for chronic pain in adulthood

A few studies of long-term outcomes for pediatric functional abdominal pain (FAP) have assessed acute non-abdominal pain at follow-up, but none has assessed chronic pain. We followed a cohort of pediatric patients with FAP (n = 155) and a well control group (n = 45) prospectively for up to 15 years. Participants ranged in age from 18 to 32 years at a follow-up telephone interview. FAP patients were classified as Resolved (n = 101) versus Unresolved (n = 54) at follow-up, based on whether they reported symptoms consistent with the adult Rome III criteria for a functional gastrointestinal disorder. Headache symptoms and reports of chronic non-abdominal pain also were assessed at follow-up. In the Unresolved group, 48.1% reported one or more sites of chronic non-abdominal pain at follow-up, compared to 24.7% in the Resolved group and 13.3% in the control group, p < 0.01. More than half (57.4%) of the Unresolved group endorsed symptoms consistent with International Headache Society criteria for headache, compared to 44.6% of the Resolved group and 31% of controls, p < 0.05. One-third of the Unresolved group reported both headache and one or more sites of chronic non-abdominal pain at follow-up, compared to 17.8% of the Resolved group and 4.4% of controls. Youth with FAP that persists into adulthood may be at increased risk for chronic pain and headache. Examination of central mechanisms that are common across chronic pain disorders may enhance understanding of this subgroup of FAP.     

Baroreflex sensitivity associated hypoalgesia in healthy states is altered by chronic pain

While experimental baroreceptor stimulation is known to elicit hypoalgesia in healthy individuals, the impact of spontaneous baroreflex sensitivity (BRS) on acute pain responses is not known. We tested for associations between BRS and pain responses in healthy individuals, whether these associations are altered in chronic low back pain (CLBP), and the role of alpha-2 adrenergic (ADRA2) mechanisms in these effects. Twenty-five healthy controls and 21 CLBP subjects completed three acute pain tasks after receiving placebo or an intravenous ADRA2 antagonist (yohimbine hydrochloride, 0.4 mg/kg) across two sessions in counterbalanced order. Resting pre-drug spontaneous BRS was assessed using the sequence method. CLBP subjects displayed lower resting BRS^Down than controls (p < .05). Drug × BRS^Down interactions indicated that significant BRS-related hypoalgesia on thermal pain threshold and tolerance was eliminated with yohimbine (p’s < .05). Subject Type × BRS^Up interactions on finger pressure (MPQ-Sensory) and ischemic tasks (MPQ-Sensory, pain threshold, intra-task numeric intensity ratings) indicated that inverse BRS/pain associations in controls (p’s < .05) were absent in CLBP subjects. Subject Type × Drug × BRS^Down interactions on finger pressure MPQ-Sensory and intra-task numeric intensity ratings (p’s < .05) indicated that for controls, yohimbine attenuated the significant inverse BRS/pain sensitivity associations noted under placebo. In contrast, CLBP subjects displayed a nonsignificant positive BRS/pain association under placebo, with yohimbine producing an inverse association similar to controls (significant for MPQ-Sensory). Results suggest presence of spontaneous BRS-related hypoalgesia in healthy individuals that is partially mediated by ADRA2 mechanisms, and that CLBP blunts BRS-related hypoalgesia. As a group, the CLBP subjects do not manifest baroreceptor-induced antinociception.     

Attentional bias to pain and social threat in pediatric patients with functional abdominal pain and pain-free youth before and after performance evaluation

This study investigated attentional biases for pain and social threat versus neutral stimuli in 54 youth with functional abdominal pain (FAP) and 53 healthy control subjects (ages 10 to 16 years). We assessed attentional bias using a visual probe detection task (PDT) that presented pain and social threat words in comparison to neutral words at conscious (1250 ms) and preconscious (20 ms) presentation rates. We administered the PDT before and after random assignment of participants to a laboratory stressor—failure versus success feedback regarding their performance on a challenging computer game. All analyses controlled for trait anxiety. At the conscious rate of stimulus presentation, FAP patients exhibited preferential attention toward pain compared with neutral stimuli and compared with the control group. FAP patients maintained preferential attention toward conscious pain stimuli after performance feedback in both failure and success conditions. At the preconscious rate of stimulus presentation, FAP patients’ attention was neutral at baseline but increased significantly toward pain stimuli after performance feedback in both failure and success conditions. FAP patients’ somatic symptoms increased in both failure and success conditions; control youth’s somatic symptoms only increased after failure. Regarding social threat, neither FAP nor control youth exhibited attentional bias toward social threat compared with neutral stimuli at baseline, but both FAP and control youth in the failure condition significantly increased attention away from social threat after failure feedback. Results suggest that FAP patients preferentially attend to pain stimuli in conscious awareness. Moreover, performance evaluation may activate their preconscious attention to pain stimuli.     

Increased wind-up to heat pain in women with a childhood history of functional abdominal pain

Idiopathic or functional abdominal pain (FAP) is common in school-age children and typically reflects a functional gastrointestinal disorder (FGID). FGIDs in adults have been distinguished by enhanced responses of the central nervous system to pain stimuli, known as central sensitization. This study investigated whether adolescents and young adults with a history of pediatric FAP (n = 144), compared with well control subjects (n = 78), showed enhanced central sensitization demonstrated by greater temporal summation (wind-up) to brief, repetitive heat pulses. We also assessed the role of gender and trait anxiety in wind-up to heat pain. Women with a history of FAP showed greater wind-up to heat pain than men with a history of FAP (P < .05) and well control subjects of both genders (P < .05). Results were similar for FAP participants whose abdominal pain was ongoing at follow-up and those whose pain had resolved. Although anxiety was significantly higher in the FAP group compared with control subjects (P < .01) and in women compared with men (P < .05), anxiety did not explain the increased wind-up observed in women with a childhood history of FAP. Results suggest that women with a pediatric history of FAP may have a long-term vulnerability to pain associated with enhanced central nervous system responses to pain stimuli.     

Hypoalgesia to pressure pain in referred pain areas triggered by spatial summation of experimental muscle pain from unilateral or bilateral trapezius muscles

Animal and human experimental studies have suggested the importance of spatial summation in the nociception processing and in the activation of descending inhibition. However, the relationship between the areas (size) of muscles stimulated and the recruitment of descending inhibition has not been addressed. Consequently, we tested whether bilateral versus unilateral injection of hypertonic saline into trapezius muscles caused hypoalgesia to pressure pain (pressure pain thresholds, PPTs) in the local pain areas (the trapezius muscles) and the referred pain areas (the posterolateral neck muscles). Two groups of volunteers participated. One group received a unilateral injection (one injection) and the other group bilateral injections (two injections). In the bilateral group, hypertonic saline was injected in one trapezius first, and 45 s later, while pain was still present from the first injection, a second injection was performed into the contralateral trapezius muscle. The saline-evoked time to maximal pain was significantly shorter after the second injection than after the first injection. More subjects developed referred pain after the bilateral compared with the unilateral injection. In the referred pain areas, the PPTs 7.5 and 15 min after the second injection were significantly increased compared with the first injection, while no changes in the PPT were observed in local and referred pain areas after unilateral injection. This suggests that the induction of descending inhibition was triggered by spatial summation during the later phase of experimentally induced muscle pain. The present experimental model might be used for further investigation of descending inhibition related to the spatial characteristics of nociceptive stimuli in humans.     

Differential changes in functional disability and pain intensity over the course of psychological treatment for children with chronic pain

Patients presenting for treatment of chronic pain often believe that pain reduction must be achieved before returning to normal functioning. However, treatment programs for chronic pain typically take a rehabilitative approach, emphasizing decreasing pain-related disability first with the expectation that pain reduction will follow. This information is routinely provided to patients, yet no studies have systematically examined the actual trajectories of pain and disability in a clinical care setting. In this study of youth with chronic pain (N = 94, 8 to 18 years), it was hypothesized that 1) functional disability and pain would decrease over the course of psychological treatment for chronic pain and 2) functional disability would decrease more quickly than pain intensity. Participants received cognitive behavioral therapy (CBT) for pain management (M = 5.6 sessions) plus standard medical care. The Functional Disability Inventory and a Numeric Rating Scale of average pain intensity were completed by the child at every CBT session. Hierarchical linear modeling was conducted to examine the longitudinal trajectories of disability and pain. Standardized estimates of the slopes of change were obtained to test differences in rates of change between pain and disability. Results showed an overall significant decline in functional disability over time. Although pain scores reduced slightly from pretreatment to posttreatment, the longitudinal decline over treatment was not statistically significant. As expected, the rate of change of disability was significantly more rapid than pain. Evidence for variability in treatment response was noted, suggesting the need for additional research into individual trajectories of change in pediatric pain treatment.     

A typology of pain coping strategies in pediatric patients with chronic abdominal pain

This study aimed to identify clinically meaningful profiles of pain coping strategies used by youth with chronic abdominal pain (CAP). Participants (n=699) were pediatric patients (ages 8-18 years) and their parents. Patients completed the Pain Response Inventory (PRI) and measures of somatic and depressive symptoms, disability, pain severity and pain efficacy, and perceived competence. Parents rated their children's pain severity and coping efficacy. Hierarchical cluster analysis based on the 13 PRI subscales identified pain coping profiles in Sample 1 (n=311) that replicated in Sample 2 (n=388). Evidence was found of external validity and distinctiveness of the profiles. The findings support a typology of pain coping that reflects the quality of patients' pain mastery efforts and interpersonal relationships associated with pain coping. Results are discussed in relation to developmental processes, attachment styles, and treatment implications.     

Increased sensitivity to heat pain in chronic low blood pressure

While in elevated blood pressure reduced sensitivity to acute pain has been well established, little is known about possible alterations in pain perception within the lower range of blood pressure. In this study, sensitivity to heat pain was assessed in 40 subjects with chronic hypotension (mean blood pressure 96.5/57.7mmHg) and 40 normotensive control persons (mean blood pressure 121.8/77.2mmHg). Employing a contact thermode, heat stimuli were applied to the forearm. Pain threshold and tolerance were determined. Participants furthermore rated subjective intensities and unpleasantness of tonic heat stimuli (45.5–47.5°C) on visual analogue scales and in a questionnaire. Possible confounding of sensitivity to heat pain with skin temperature, temperature sensitivity and mood was controlled for. In addition to blood pressure, functional features of the arterial baroreceptor system were related to pain experience. Therefore, estimates for the input on the baroreceptors, as well as baroreflex sensitivity were obtained. Hypotensive individuals exhibited markedly reduced pain threshold and pain tolerance, as well as increased sensory and affective pain experience. The measures related to the baroreceptor system were not associated with pain experience, suggesting that no significant modulation of heat pain occurs through this system. The results of this study complete the findings on hypertension‐related hypoalgesia and suggest an inverse relationship between blood pressure and pain sensitivity across the whole blood pressure spectrum. Furthermore, increased proneness of hypotensive individuals to clinical pain may be discussed.     

胶囊内镜在慢性腹痛患者中的应用价值

目的探讨胶囊内镜在慢性腹痛中的诊断价值和安全性。方法对2008年8月至2009年11月期间不明原因的慢性腹痛患者24例进行胶囊内镜检查,同期12例体检者作为对照组。观察两组患者的小肠运转时间、病变及部位、图像质量及顺应性。结果所有受检者在胶囊内镜检查过程中无任何不适和并发症,均顺利完成检查,所得图像清晰。胶囊1～3d自然排出。腹痛组小肠转运时间为（252．69±95．19）min,体检组小肠运转时间为（209．33±34．32）min。其中腹痛组4例胶囊未通过回盲瓣,体检组1例胶囊未通过回盲瓣。检出病变有胃溃疡、小肠炎症、克罗恩病、小肠NSAIDs溃疡、息肉、间质瘤及肠道寄生虫等。结论胶囊内镜检查无痛苦,成功率高,对病变检出率高,对不明原因慢性腹痛患者有较好的诊断价值。     

Temporal daily associations between pain and sleep in adolescents with chronic pain versus healthy adolescents

Adolescents with chronic pain frequently report sleep disturbances, particularly short sleep duration, night wakings, and poor sleep quality. Prior research has been limited by assessment of subjectively reported sleep only and lack of data on daily relationships between sleep and pain. The current study utilized multilevel modeling to compare daily associations between sleep and pain in adolescents with chronic pain and healthy adolescents. Ninety-seven adolescents (n = 39 chronic pain; n = 58 healthy) aged 12-18, 70.1% female participated. Adolescents completed pain diary ratings (0-10 NRS) and actigraphic sleep monitoring for 10 days. Actigraphic sleep variables (duration, efficiency, WASO) and self-reported sleep quality were tested as predictors of next-day pain, and daytime pain was tested as a predictor of sleep that night. Effects of age, gender, study group, and depressive symptoms on daily associations between sleep and pain were also tested. Multivariate analyses revealed that nighttime sleep (p < .001) and minutes awake after sleep onset (WASO) (p < .05) predicted next-day pain, with longer sleep duration and higher WASO associated with higher pain. Contrary to hypotheses, neither nighttime sleep quality nor sleep efficiency predicted pain the following day. The interaction between nighttime sleep efficiency and study group was significant, with adolescents with pain showing stronger associations between sleep efficiency and next-day pain than healthy participants (p = .05). Contrary to hypotheses, daytime pain did not predict nighttime sleep. Daily associations between pain and sleep suggest that further work is needed to identify specific adolescent sleep behaviors (e.g., compensatory sleep behaviors) that may be targeted in interventions.     

Behavioral and psychosocial factors associated with insomnia in adolescents with chronic pain

This study aimed to (1) identify differences in sleep behaviors, sleep quality, pre-sleep arousal and prevalence of insomnia symptoms in adolescents with chronic pain compared to a healthy age and sex-matched cohort and (2) examine pain intensity, pubertal development, depression, and pre-sleep arousal as risk factors for insomnia symptoms. Participants included 115 adolescents, 12-18 years of age (73.0% female), 59 youth with chronic pain and 56 healthy youth. During a home-based assessment, adolescents completed validated measures of pain, sleep quality, sleep hygiene, pre-sleep arousal, depressive symptoms, and pubertal development. Findings revealed a significantly higher percentage of adolescents with chronic pain reporting symptoms of insomnia (54.2%) compared to healthy adolescents (19.6%), p < .001. Youth with chronic pain also reported higher cognitive and somatic arousal at bedtime, and lower sleep quality compared to the healthy cohort. In a logistic regression, two factors emerged as significant predictors of insomnia, having chronic pain (OR = 6.09) and higher levels of cognitive pre-sleep arousal (OR = 1.24). Level of pain intensity did not predict insomnia. While sleep disruption may initially relate to pain, these symptoms may persist into a separate primary sleep disorder over time due to other behavioral and psychosocial factors. Assessment of insomnia may be important for identifying behavioral targets for the delivery of sleep-specific interventions to youth with chronic pain.     

Functional abdominal pain patient subtypes in childhood predict functional gastrointestinal disorders with chronic pain and psychiatric comorbidities in adolescence and adulthood

Although pediatric functional abdominal pain (FAP) has been linked to abdominal pain later in life, childhood predictors of long-term outcomes have not been identified. This study evaluated whether distinct FAP profiles based on patterns of pain and adaptation in childhood could be identified and whether these profiles predicted differences in clinical outcomes and central sensitization (wind-up) on average 9years later. In 843 pediatric FAP patients, cluster analysis was used to identify subgroups at initial FAP evaluation based on profiles of pain severity, gastrointestinal (GI) and non-GI symptoms, pain threat appraisal, pain coping efficacy, catastrophizing, negative affect, and activity impairment. Three profiles were identified: high pain dysfunctional, high pain adaptive, and low pain adaptive. Logistic regression analyses controlling for age and sex showed that, compared with pediatric patients with the low pain adaptive profile, those with the high pain dysfunctional profile were significantly more likely at long-term follow-up to meet criteria for pain-related functional gastrointestinal disorder (FGID) (odds ratio: 3.45, confidence interval: 1.95 to 6.11), FGID with comorbid nonabdominal chronic pain (odds ratio: 2.6, confidence interval: 1.45 to 4.66), and FGID with comorbid anxiety or depressive psychiatric disorder (odds ratio: 2.84, confidence interval: 1.35 to 6.00). Pediatric patients with the high pain adaptive profile had baseline pain severity comparable to that of the high pain dysfunctional profile, but had outcomes as favorable as the low pain adaptive profile. In laboratory pain testing at follow-up, high pain dysfunctional patients showed significantly greater thermal wind-up than low pain adaptive patients, suggesting that a subgroup of FAP patients has outcomes consistent with widespread effects of heightened central sensitization.     

Lead intoxication due to ayurvedic medications as a cause of abdominal pain in adults

Background: Though a majority of cases of lead intoxication come from occupational exposures, traditional and folk remedies have also been reported to contain toxic amounts of lead. We present a large series of patients with lead poisoning due to intake of Ayurvedic medicines, all of whom presented with unexplained abdominal pain.

Methodology: This was a retrospective, observational case series from a tertiary care center in India. The charts of patients who underwent blood lead level (BLL) testing as a part of workup for unexplained abdominal pain between 2005 and 2013 were reviewed. The patients with lead intoxication (BLLs?>25?μg/dl) were identified and demographics, history, possible risk factors, clinical presentation and investigations were reviewed. Treatment details, duration, time to symptomatic recovery, laboratory follow-up and adverse events during therapy were recorded.

Results: BLLs were tested in 786 patients with unexplained abdominal pain and high levels were identified in 75 (9.5%) patients, of which a majority (73 patients, 9.3%) had history of Ayurvedic medication intake and only two had occupational exposure. Five randomly chosen Ayurvedic medications were analyzed and lead levels were impermissibly high (14–34,950?ppm) in all of them. Besides pain in abdomen, other presenting complaints were constipation, hypertension, neurological symptoms and acute kidney injury. Anemia and abnormal liver biochemical tests were observed in all the 73 patients. Discontinuing the Ayurvedic medicines and chelation with d-penicillamine led to improvement in symptoms and reduction in BLLs in all patients within 3–4 months.

Conclusion: The patients presenting with severe recurrent abdominal pain, anemia and history of use of Ayurvedic medicines should be evaluated for lead toxicity. Early diagnosis in such cases can prevent unnecessary investigations and interventions, and permits early commencement of the treatment.     

Negative association between resting blood pressure and chest pain in people undergoing exercise stress testing for coronary artery disease

Sustained and acute increases in blood pressure can dampen pain in experimental animals and humans. The most important clinical implication of this relationship may be the phenomenon of silent cardiac ischemia. High blood pressure is common in people at risk for cardiac ischemia and may reduce angina, the key symptom of life-threatening ischemia. The relationship between resting blood pressure and angina was examined in 904 people undergoing exercise stress testing for coronary artery disease. The presence or absence of ischemia was documented with single photon emission computed tomography (SPECT). Participants with ischemia had higher scores on the McGill Pain Questionnaire (MPQ) following exercise though this was moderated significantly by diastolic blood pressure (DBP), especially in women. People with higher pre-exercise resting DBP who displayed SPECT-diagnosed ischemia had MPQ scores comparable to people who did not display ischemia, independent of age, exercise duration, medication, and cardiac history. Awareness of the potential association between blood pressure and angina may provide patients with coronary artery disease and their physicians’ important guidance.     

Development and feasibility testing of a Pain Neuroscience Education program for children with chronic pain: treatment protocol

Background

Current treatment for adults with chronic pain often includes Pain Neuroscience Education (PNE) to make people understand the nature underlying their pain and thus provides a clear rational for a biopsychosocial approach. Despite recommendations to use Pain Neuroscience Education as well in children with chronic pain, a specific program, tailored to children aged 6–12 years is lacking.

The effects of static muscular contraction on blood pressure, heart rate, pain ratings and pressure pain thresholds in healthy individuals and patients with fibromyalgia.

Aberrations of cardiovascular regulation and dysfunction of endogenous pain modulation have been reported in fibromyalgia (FM) patients. This study aimed at investigating the interactions between cardiovascular regulation and pain perception during static muscle contractions. Seventeen FM patients and 17 healthy controls performed a standardised static contraction (m. quadriceps femoris dx) until exhaustion. Blood pressure (BP), heart rate (HR), ratings of exertion/fatigue and pain intensity as well as pressure pain thresholds (PPTs) (at m. quadriceps dx and m. deltoideus dx) were assessed before, during and 15 min following contraction. Systolic and diastolic BP increased during contraction (p<0.001) and decreased following contraction (p<0.001) in both groups alike. A significant increase in HR was seen during contraction in FM patients (p<0.001), but not in healthy controls (difference between groups p<0.02). The rated exertion/fatigue and pain intensity increased more during contraction and remained elevated longer following contraction in the patient group. PPTs were lower in patients compared to controls at both sites at all times (p<0.001). No group differences in PPT changes over time were found. In conclusion, no indication of an attenuated cardiovascular response to exercise was found in our FM patients. The more pronounced HR increase in patients during contraction was most likely due to deconditioning. No exercise related change in PPTs was seen in either group, most likely due to insufficient exercise intensity, but the contraction induced pain was more pronounced in the FM patients.     

Association between blood pressure measures and recurrent headache in adolescents: cross-sectional data from the HUNT-Youth study

The relationship between blood pressure and headache in youth has not been explored and the objective of the present study was to provide data on this association in an adolescent population. Cross-sectional data from a large population-based survey, the Young-HUNT study, on 5,847 adolescents were used to evaluate the association between blood pressure (systolic, diastolic, mean arterial and pulse pressure) and recurrent headache, including migraine and tension-type headache. Increasing pulse pressure was inversely related to recurrent headache prevalence, and both tension-type headache and migraine. For systolic blood pressure such an inverse relationship was present for recurrent headache and tension-type headache prevalence. For migraine, the results were not significant, although there was a tendency in the same direction (p = 0.05). High-pulse pressure has previously been found to be inversely related to the prevalence of migraine and tension-type headache in an adult population. This inverse relationship has now been demonstrated to be present among adolescents also, supporting the results from a previous study in adults, that blood pressure regulation may be linked to the pathophysiology of headache.