Pharmacological management of chronic neuropathic pain - consensus statement and guidelines from the Canadian Pain Society.

Neuropathic pain (NeP), generated by disorders of the peripheral and central nervous system, can be particularly severe and disabling. Prevalence estimates indicate that 2% to 3% of the population in the developed world suffer from NeP, which suggests that up to one million Canadians have this disabling condition. Evidence-based guidelines for the pharmacological management of NeP are therefore urgently needed. Randomized, controlled trials, systematic reviews and existing guidelines focusing on the pharmacological management of NeP were evaluated at a consensus meeting. Medications are recommended in the guidelines if their analgesic efficacy was supported by at least one methodologically sound, randomized, controlled trial showing significant benefit relative to placebo or another relevant control group. Recommendations for treatment are based on degree of evidence of analgesic efficacy, safety, ease of use and cost-effectiveness. Analgesic agents recommended for first-line treatments are certain antidepressants (tricyclics) and anticonvulsants (gabapentin and pregabalin). Second-line treatments recommended are serotonin noradrenaline reuptake inhibitors and topical lidocaine. Tramadol and controlled-release opioid analgesics are recommended as third-line treatments for moderate to severe pain. Recommended fourth-line treatments include cannabinoids, methadone and anticonvulsants with lesser evidence of efficacy, such as lamotrigine, topiramate and valproic acid. Treatment must be individualized for each patient based on efficacy, side-effect profile and drug accessibility, including cost. Further studies are required to examine head-to-head comparisons among analgesics, combinations of analgesics, long-term outcomes, and treatment of pediatric and central NeP.

What's in a Name? Health Care Providers' Perceptions of Pediatric Pain Patients Based on Diagnostic Labels.

OBJECTIVES: Diagnostic labels can help patients better understand their symptoms and can influence providers' treatment planning and patient interactions. Recurrent pain is common in childhood; however, there are various diagnostic labels used. The objective of this study was to evaluate the influence of diagnostic labels on pediatric health care providers' perceptions of pediatric chronic pain patients. MATERIALS AND METHODS: Using an online survey, providers were randomly assigned to 1 of 2 vignette conditions (differing only in diagnostic label provided) and completed questionnaires about their perceptions of the vignette patient. RESULTS: Responses from 58 participants were analyzed. The 2 groups, based on diagnostic conditions used (fibromyalgia and chronic widespread pain) did not differ significantly on general demographics and health care providers' perceptions of the patient. Perceived origin of the pain influenced providers' perceptions; pain of a perceived medical origin was negatively correlated with stigmatization and positively correlated with sympathy. Perceived psychological origin was positively correlated with stigmatization and providers' age. DISCUSSION: Health care providers' perceptions of children's pain are more likely influenced by the presumed etiology rather than the diagnostic label used. Pain believed to be more medically based was associated with more positive reactions from providers (ie, less stigmatization). Older providers in particular perceived the patient more negatively if they believe the pain to be psychologically based. The findings of this pediatric study replicated findings from adult literature on chronic pain, suggesting that children and adults are subject to negative perceptions from health care providers when the providers believe the pain to be psychological in origin.

The effect of pain on involuntary and voluntary capture of attention.

BACKGROUND: There is converging evidence for the notion that pain affects a broad range of attentional domains. This study investigated the influence of pain on the involuntary capture of attention as indexed by the P3a component in the event-related potential derived from the electroencephalogram. METHODS: Participants performed in an auditory oddball task in a pain-free and a pain condition during which they submerged a hand in cold water. Novel, infrequent and unexpected auditory stimuli were presented randomly in a series of frequent standard and infrequent target tones. P3a and P3b amplitudes were observed to novel, unexpected and target-related stimuli, respectively. RESULTS: Both electrophysiological components were characterized by reduced amplitudes in the pain compared with the pain-free condition. Hit rate and reaction time to target stimuli did not differ between the two conditions presumably because the experimental task was not difficult enough to exceed attentional capacities under pain conditions. CONCLUSIONS: These results indicate that voluntary attention serving the maintenance and control of ongoing information processing (reflected by the P3b amplitude) is impaired by pain. In addition, the involuntary capture of attention and orientation to novel, unexpected information (measured by the P3a) is also impaired by pain. Thus, neurophysiological measures examined in this study support the theoretical positions proposing that pain can reduce attentional processing capacity. These findings have potentially important implications at the theoretical level for our understanding of the interplay of pain and cognition, and at the therapeutic level for the clinical treatment of individuals experiencing ongoing pain.

Development and preliminary validation of a postoperative pain measure for parents.

Parents are now primarily responsible for the at home assessment and treatment of their children's pain following minor surgery. Although some research has suggested that parents underestimate their children's pain following surgery, no behavioral measure exists to assist parents in pain assessment. The Postoperative Pain Measure for Parents was developed based on cues parents reported using to assess their children's pain (e.g. changes in appetite, activity level). The purpose of the present study was to develop and validate this measure by examining the relation between parent-report of child behaviors and child-rated pain. Subjects were 110 children (56.4% male) aged 7-12 years undergoing day surgery at a tertiary-care children's hospital and their parents. Parents and children completed a pain diary for the 2 days following surgery. Children rated their pain and emotional distress and parents rated the presence or absence of specific behaviors from a checklist. Correlations were conducted between each of the 29 behavioral items and child-rated pain on Day 1; 14 items with correlations less than 0.30 were dropped. The remaining 15 items were subjected to a principal axis factor analysis. A one-factor solution was the best fit for the data. The items were then summed to yield a total score out of 15. Internal consistency reliabilities for the measure and correlations with child-rated pain were high on both days following surgery. Child-rated pain and emotional distress were moderately correlated. The Postoperative Pain Measure for Parents was also positively correlated with child-rated emotional distress on both days following surgery. As child-rated pain decreased from Day 1 to Day 2, so did scores on the behavioral measure. The Postoperative Pain Measure for Parents was successful in discriminating between children who had undergone no/low pain surgeries and children who had undergone moderate to high pain surgeries. There were no significant differences in scores on the behavioral measure for child age or sex. Using a cut-off score of six out of 15, the measure showed excellent sensitivity (> 80%) and specificity (> 80%) in selecting children who reported clinically significant levels of pain. This study provides preliminary evidence for the use of the Postoperative Pain Measure for Parents as a valid assessment tool with children between the ages of 7-12 years following day surgery. It is internally consistent and strongly related to child-rated pain. Future research should explore the use of this measure with a younger sample and children with developmental delays.

Self-administration of over-the-counter medication for pain among adolescents.

OBJECTIVE: To examine over-the-counter (OTC) medication use and self-administration of medication among adolescents. DESIGN: In-person survey. SETTINGS: Three public junior high schools in Halifax, Nova Scotia. PARTICIPANTS: Six hundred fifty-one junior high school students (7th, 8th, and 9th grades). MAIN OUTCOME MEASURES: A questionnaire regarding OTC medication use and self-administration for head: stomach; ear and throat; muscle, joint, and back; and menstrual pains. RESULTS: Of those who reported taking medication, many adolescents (58.7%-95.9%) reported taking OTC medications for each pain. Medications and knowledge about medications were obtained from a variety of sources, primarily parents. Self-administration was widespread; 58.3% to 75.9% of adolescents reported taking an OTC medication for pain without first checking with an adult in the previous 3 months. Self-administration of medication without the knowledge of adults increased significantly from grades 7 to 9 for all types of pain. Girls tended to self-administer medication more than boys. Higher levels of pain frequency and intensity were related to higher levels of self-administration for all pains except muscle, joint, and back pain. Adolescents reported that they began to self-administer medication between the ages of 11 and 12 years. CONCLUSIONS: Although a relatively responsible picture of self-administration of medication emerges, some adolescents engaged in inappropriate OTC medication use (eg, the common use of aspirin), highlighting the importance of providing adolescents with correct information about these medications.

The disruptive effect of chronic pain on mismatch negativity.

OBJECTIVE: To investigate the effect of chronic pain on processes that generate the mismatch negativity (MMN). METHODS: Twelve participants with a diagnosis of chronic intractable pain were tested before and after pain treatment. During testing, event-related potentials were recorded while participants performed tasks of varying difficulty. RESULTS: The amplitude of the MMN was found to be greater following a nerve block procedure compared to MMN amplitude when participants were experiencing chronic pain. This effect was found to occur in the MMN for difficult-to-detect tones elicited while participants were performing a simultaneous cognitively demanding visual task. MMN amplitude was found to be greater with attention to difficult-to-detect deviants during pain but not in no pain conditions. CONCLUSIONS: These results provide an electrophysiological correlate of previous findings that high levels of pain disrupt cognition during the performance of demanding tasks.

Low-concentration morphine infusion does not compromise packed red blood cell transfusion.

Regulations currently prohibit co-administration (through the same line) of red blood cell transfusions with continuous morphine infusions for pain management, resulting in additional intravenous access or interrupted analgesic therapy in seriously ill children. Packed cells that had been in contact with morphine 0.1 or 1.0 mg/mL and infused through a mock central venous catheter system showed no evidence of hemolysis when compared with control samples. There is thus no need to interrupt analgesic therapy or start another venous access line in order to give a coincident blood transfusion.

Children's self-report of postoperative pain intensity and treatment threshold: determining the adequacy of medication.

OBJECTIVE: Many studies have shown indirectly that children are undermedicated for postoperative pain. In this study, we used a pain self-report scale to examine this more directly. METHODS: We performed a survey with 63 children who were postoperative from minor, uncomplicated surgery. Using the self-report scale, we determined the pain intensity at time of interview, the worst pain experienced postoperatively, and the intensity of pain that the subject felt to warrant pharmacologic intervention (the "treatment threshold"). A subgroup of 48 children was asked to indicate on the scale the intensities that represented mild, moderate, and severe pain. RESULTS: Mean (SD) pain at time of interview was 1.9 (1.7) on the 0-6 scale. Mean worst postoperative pain was 3.8 (1.8). The mean for treatment threshold was 3.2 (1.8). We found gender differences in regard to the judgments about the intensities representing mild, moderate, and severe pain, with girls rating these lower than did boys. Twenty-five percent of subjects reported pain that was mild, 29% reported moderate pain, and 46% reported severe pain. CONCLUSIONS: We found that 51% of subjects were undermedicated for postoperative pain, being required to suffer pain that was above their treatment threshold. By determining each subject's treatment threshold and estimate of moderate pain, we have better defined the intensity at which pain becomes clinically significant.

Pain treatment thresholds in children after major surgery.

OBJECTIVE: The objectives of this study were to use a self-report pain scale to examine child pain treatment thresholds after major surgery (i.e., the level of pain they are comfortable with before requiring analgesia), as well as to examine agreement between mother-, nurse-, and child-rated pain treatment thresholds. METHODS: Twenty-five children aged 6 to 16 years were interviewed for 3 consecutive days after major surgery. Subjects used the Faces Pain Scale to rate their current pain, worst postoperative pain, and pain level at which they would like to receive analgesia (the pain treatment threshold). Parents and nurses also estimated the child pain treatment thresholds. RESULTS: For day 1, mean pain was 1.86 of a maximum of 6, mean worst pain was 4.16, and mean pain treatment threshold was 2.28. For day 2, these values were 1.90, 4.10, and 2.54, and for day 3 they were 1.62, 4.56, and 1.85, respectively. Mean scores for all 3 days were as follows: pain, 1.79; worst pain, 4.15; and pain treatment threshold, 2.33. Although mother-nurse ratings were correlated (0.471), mother-child and nurse-child ratings were not significantly correlated. Using the pain treatment threshold as the criterion, 36% of our subjects were undermedicated after the first day of surgery. CONCLUSION: Pain treatment thresholds seem to be lower in children after major as compared with minor surgery. Parents and nurses are not accurate in rating child pain treatment thresholds. Parents tended to overestimate their child's pain treatment threshold, whereas nurses were less consistent in their scoring.

Cues parents use to assess postoperative pain in their children.

OBJECTIVE: Very little is known about the cues parents use to assess pain in their children. This study has described the cues (verbal and nonverbal) parents reported using to determine how their children felt following surgery. DESIGN AND SUBJECTS: The subjects were 176 parents of children undergoing short-stay or day surgery. Using pain diaries, parents were asked to provide written responses to the question "Did your child give you any clues on how they were feeling?" for the day of surgery and 2 days after their children's surgery. Parents also provided ratings of their children's pain five times per day using a visual analogue scale. SETTING: The study was conducted at a tertiary care children's hospital. RESULTS AND CONCLUSIONS: Parents frequently cited using verbal report and appetite as cues to how their children were feeling. A variety of other cue types were also reported by parents, including activity level, sleep quality, visible/audible discomfort, and physiological observations. Cue types were not significantly related to the child's gender, and only one cue type was significantly related to the child's age (appetite was used more often for older children than younger children). The presence or absence of illness behavior cues (e.g., protective behavior, visible/audible discomfort) as well as disruptions to normal behavior pattern cues (e.g., sleep, level of activity) was related, in the expected direction, to the pain intensity ratings. This study provides insights into the cues parents use to assess pain in their children and serves as a foundation for future studies on parents' assessment of children's pain.

Agreement between child and parent reports of pain.

OBJECTIVE: Parents are often the primary source of information regarding their children's pain in both research and clinical practice. However, parent-child agreement on pain ratings has not been well established. The objective of the present study was to examine agreement between child- and parent-rated pain following minor surgery. SETTING: Tertiary care children's hospital. PARTICIPANTS: A total of 110 children (56.4% male) aged 7-12 years undergoing surgery and their parents. OUTCOME MEASURES: Parents and children independently rated pain intensity by using a 7-point Faces Pain Scale on the day of the child's surgery and the following 2 days. RESULTS: Correlations (both Pearson's and intraclass correlation coefficients) indicated a highly significant relationship between child and parent ratings. However, kappa statistics indicated only poor to fair agreement beyond chance. Parents tended to underestimate their children's pain on the day of surgery and the following day, but not on the second day following surgery. When children's and parents' pain ratings for each of the 3 days were collapsed into a no-pain/low-pain group or a clinically significant pain group, kappa statistics indicated fair to good agreement. Parents demonstrated low levels of sensitivity in identifying when their children were experiencing clinically significant pain. CONCLUSIONS: Correlations between parent and child pain reports do not accurately represent the relationship between these ratings and in fact overestimate the strength of the relationship. Parents' underestimation of their child's pain may contribute to inadequate pain control.

Successful treatment of painful crises of Fabry disease with low dose morphine.

Fabry disease is an X-linked disorder characterized in childhood by angiokeratoma, corneal opacities, and pain. At age 7 years our patient began experiencing an intermittent intense "burning" sensation within his feet and hands (acroparesthesias). Treatment with aspirin, acetaminophen, acetominophen with codeine, and phenytoin was unsuccessful. Carbamazepine and phenytoin reduced the frequency and duration of painful crises to 3-4 times annually. A treatment plan was developed consisting of a low-dose morphine infusion with increasing dosage until pain was relieved. Over the subsequent 28 months, we have had experienced treating 7 crises with morphine given as 0.06 mg/kg IV push, followed by a continuous infusion of 0.02 mg/kg/hr with amitriptyline 0.25 mg/kg at bedtime. Pain control is immediate, with the infusion gradually tapered after 24 hours.

Pharmacological management of chronic neuropathic pain: revised consensus statement from the Canadian Pain Society.

BACKGROUND: Neuropathic pain (NeP), redefined as pain caused by a lesion or a disease of the somatosensory system, is a disabling condition that affects approximately two million Canadians. OBJECTIVE: To review the randomized controlled trials (RCTs) and systematic reviews related to the pharmacological management of NeP to develop a revised evidence-based consensus statement on its management. METHODS: RCTs, systematic reviews and existing guidelines on the pharmacological management of NeP were evaluated at a consensus meeting in May 2012 and updated until September 2013. Medications were recommended in the consensus statement if their analgesic efficacy was supported by at least one methodologically sound RCT (class I or class II) showing significant benefit relative to placebo or another relevant control group. Recommendations for treatment were based on the degree of evidence of analgesic efficacy, safety and ease of use. RESULTS: Analgesic agents recommended for first-line treatments are gabapentinoids (gabapentin and pregabalin), tricyclic antidepressants and serotonin noradrenaline reuptake inhibitors. Tramadol and controlled-release opioid analgesics are recommended as second-line treatments for moderate to severe pain. Cannabinoids are now recommended as third-line treatments. Recommended fourth-line treatments include methadone, anticonvulsants with lesser evidence of efficacy (eg, lamotrigine, lacosamide), tapentadol and botulinum toxin. There is support for some analgesic combinations in selected NeP conditions. CONCLUSIONS: These guidelines provide an updated, stepwise approach to the pharmacological management of NeP. Treatment should be individualized for each patient based on efficacy, side-effect profile and drug accessibility, including cost. Additional studies are required to examine head-to-head comparisons among analgesics, combinations of analgesics, long-term outcomes and treatment of pediatric, geriatric and central NeP.

Pediatric pain: prevalence, assessment, and management in a teaching hospital.

The goal of this study was to examine the prevalence, assessment and management of pediatric pain in a public teaching hospital. The study sample consisted of 121 inpatients (70 infants, 36 children, and 15 adolescents), their families, 40 physicians, and 43 nurses. All participants were interviewed except infants and children who could not communicate due to their clinical status. The interview included open-ended questions concerning the inpatients' pain symptoms during the 24 h preceding data collection, as well as pain assessment and pharmacological/non-pharmacological management of pain. The data were obtained from 100% of the eligible inpatients. Thirty-four children/adolescents (28%) answered the questionnaire and for the other 72% (unable to communicate), the family/health professional caregivers reported pain. Among these 34 persons, 20 children/adolescents reported pain, 68% of whom reported that they received pharmacological intervention for pain relief. Eighty-two family caregivers were available on the day of data collection. Of these, 40 family caregivers (49%) had observed their child's pain response. In addition, 74% reported that the inpatients received pharmacological management. Physicians reported that only 38% of the inpatients exhibited pain signs, which were predominantly acute pain detected during clinical procedures. They reported that 66% of patients received pharmacological intervention. The nurses reported pain signs in 50% of the inpatients, which were detected during clinical procedures. The nurses reported that pain was managed in 78% of inpatients by using pharmacological and/or non-pharmacological interventions. The findings provide evidence of the high prevalence of pain in pediatric inpatients and the under-recognition of pain by health professionals.

Pain's impact on adaptive functioning.

BACKGROUND: Pain interferes with the functioning of typical children, but no study has examined its effect on children with pre-existing intellectual disabilities (ID). METHODS: Caregivers of 63 children observed their children for 2-h periods and recorded in 1-week diaries: pain presence, cause, intensity and duration. Caregivers also recorded the children's performance of pre-existing skills during each period. Proportion of skills displayed when pain was present and absent was compared. Fifty caregivers completed a second set of observations when pain was present and absent. RESULTS: Comparison of the first set of observations indicated children displayed significantly more abilities (64%) when pain-free (Pain-Free Day 1), than when pain was present (54%; Pain Day 1). Children displayed 64% of their possible abilities during Pain-Free Day 2, but only 53% during Pain Day 2. Pain impacted all areas of function (communication, daily living, social and motor skills). Children's physical and demographic characteristics did not moderate the impact of pain on function, but functioning of children with more severe ID was most impacted by pain. CONCLUSIONS: Children perform fewer adaptive skills when pain is present. This could affect long-term functioning as well, through reduced practice of skills.

Pediatric pain: prevalence, assessment, and management in a teaching hospital

The goal of this study was to examine the prevalence, assessment and management of pediatric pain in a public teaching hospital. The study sample consisted of 121 inpatients (70 infants, 36 children, and 15 adolescents), their families, 40 physicians, and 43 nurses. All participants were interviewed except infants and children who could not communicate due to their clinical status. The interview included open-ended questions concerning the inpatients’ pain symptoms during the 24 h preceding data collection, as well as pain assessment and pharmacological/non-pharmacological management of pain. The data were obtained from 100% of the eligible inpatients. Thirty-four children/adolescents (28%) answered the questionnaire and for the other 72% (unable to communicate), the family/health professional caregivers reported pain. Among these 34 persons, 20 children/adolescents reported pain, 68% of whom reported that they received pharmacological intervention for pain relief. Eighty-two family caregivers were available on the day of data collection. Of these, 40 family caregivers (49%) had observed their child’s pain response. In addition, 74% reported that the inpatients received pharmacological management. Physicians reported that only 38% of the inpatients exhibited pain signs, which were predominantly acute pain detected during clinical procedures. They reported that 66% of patients received pharmacological intervention. The nurses reported pain signs in 50% of the inpatients, which were detected during clinical procedures. The nurses reported that pain was managed in 78% of inpatients by using pharmacological and/or non-pharmacological interventions. The findings provide evidence of the high prevalence of pain in pediatric inpatients and the under-recognition of pain by health professionals.

Anaesthesia for a patient with Friedreich's ataxia and cardiomyopathy.

Friedreich's ataxia is an inherited neuromuscular disorder often associated with significant cardiac disease. We report a case of Friedreich's ataxia in a 13-year-old girl with ulcerative colitis and hypertrophic cardiomyopathy who was successfully managed for subtotal colectomy with general anaesthesia and epidural narcotic. Anaesthetic considerations included the maintenance of fluid volume and stable cardiovascular variables in the intra- and postoperative periods.

Perceived urgency and the anaesthetist: responses to common operating room monitor alarms.

Increasing numbers and varieties of electronic monitors are used in hospital operating rooms. Many of these are equipped with auditory alarms which are loud, insistent, or irritating, and thus are frequently disabled by the anaesthetist. This study was planned to evaluate two components of auditory alarm design which may influence the usefulness of the alarm: the perceived urgency of the auditory signal and its correlation with the urgency of the corresponding clinical situation. We also assessed the ability of practising anaesthetists to identify the monitor or condition responsible for the alarm. Sixty-four anaesthetists attending a national conference assessed ten common operating room alarm sounds for perceived urgency. Results were compared with the urgency of the corresponding clinical situation as determined by 12 senior anaesthetists. Discrepancies between the clinical and perceived urgencies of several monitor alarms were found, and there was no correlation between the two measures. The subjects were also tested for their ability to identify the alarm sounds correctly. The overall correct identification rate was 33%, and only two monitors were correctly identified by more than 50% of the subjects. The results of this study have implications for design and use of auditory alarms in hospitals and suggest the need for further research.

Preliminary validation of an observational pain checklist for persons with cognitive impairments and inability to communicate verbally.

To obtain a preliminary validation of the Non-Communicating Children's Pain Checklist for individuals with an inability to communicate verbally, 32 caregivers of individuals with cognitive impairments aged 3 to 44 years retrospectively completed the Non-Communicating Children's Pain Checklist and rated item usefulness (0 to 10). In the second part of the study 33 caregivers completed the Checklist after two painful (e.g. burns, falls, surgery), one distressful (e.g. unwanted grooming, feared animal/noise), and one calm event (e.g. watching television). Checklist scores did not correlate with the age, sex, or physical limitations of individuals with an inability to communicate verbally. In the first part of the study Cronbach's alpha was 0.66; all mean usefulness ratings exceeded 5 out of 10. In the second part of the study after four items were removed, Cronbach's alpha was 0.79. Checklist scores during pain correlated with numerical ratings of pain intensity did not differ between the two pain events, and differed significantly from calm scores. Differences in Checklist scores during pain and distress were found for two subscales. The Checklist exhibits internal consistency, and preliminary evidence suggests it can detect pain and is reliable over time.