Epidemiology of Trauma History and Body Pain: A Retrospective Study of Community-Based Australian Women.

OBJECTIVE: To assess whether body pain was associated with different trauma histories (physical injury vs. interpersonal injury [IPI]) within Australian women, along with body pain and trauma history associations with biological and psychological (biopsycho) confounders. METHODS: A retrospective cross-sectional analysis was conducted on the Australian Longitudinal Study on Women's Health (ALSWH) 1973-1978 birth cohort wave 6 data. Relevant life events were categorized into two types of traumatic experience and included as exposure variables in a multinomial regression model for body pain subgroups. Also, subgroup analyses considered trauma and pain effects and interactions on biopsycho burden. RESULTS: The unadjusted multinomial regression model revealed that a history of physical injury was found to be significantly associated with body pain severity, as was a history of IPI trauma. After the model was adjusted to include biopsycho confounders, the association between IPI and body pain was no longer significant, and post hoc analysis revealed the relationship was instead mediated by biopsycho confounders. Women with a history of IPI and body pain were also found to have the greatest biopsycho (physical functioning, stress, anxiety, and depression) burden. DISCUSSION: The relationship between IPI and body pain was found to be mediated by biopsycho burden, whereas the relationship between physical injury and body pain was not. Also, a history of IPI was associated with a greater biopsycho burden than was a history of physical injury. These results suggest there is clinical value in considering the comprehensive trauma history of patients with pain when developing their biopsychosocial model of care.

#MindinBody - feasibility of vigorous exercise (Bikram yoga versus high intensity interval training) to improve persistent pain in women with a history of trauma: a pilot randomized control trial.

BACKGROUND: The neurobiology of persistent pain shares common underlying psychobiology with that of traumatic stress. Modern treatments for traumatic stress often involve bottom-up sensorimotor retraining/exposure therapies, where breath, movement, balance and mindfulness, are used to target underlying psychobiology. Vigorous exercise, in particular Bikram yoga, combines many of these sensorimotor/exposure therapeutic features. However, there is very little research investigating the feasibility and efficacy of such treatments for targeting the underlying psychobiology of persistent pain. METHODS: This study was a randomized controlled trail (RCT) comparing the efficacy of Bikram yoga versus high intensity interval training (HIIT), for improving persistent pain in women aged 20 to 50 years. The participants were 1:1 randomized to attend their assigned intervention, 3 times per week, for 8 weeks. The primary outcome measure was the Brief Pain Inventory (BPI) and further pain related biopsychosocial secondary outcomes, including SF-36 Medical Outcomes and heart rate variability (HRV), were also explored. Data was collected pre (t0) and post (t1) intervention via an online questionnaire and physiological testing. RESULTS: A total of 34 women were recruited from the community. Analyses using ANCOVA demonstrated no significant difference in BPI (severity plus interference) scores between the Bikram yoga (n = 17) and the HIIT (n = 15). Women in the Bikram yoga group demonstrated significantly improved SF-36 subscale physical functioning: [ANCOVA: F(1, 29) = 6.17, p = .019, partial eta-squared effect size (ηp2) = .175 and mental health: F(1, 29) = 9.09, p = .005, ηp2 = .239; and increased heart rate variability (SDNN): F(1, 29) = 5.12, p = .013, ηp2 = .150, scores compared to the HIIT group. Across both groups, pain was shown to decrease, no injuries were experienced and retention rates were 94% for Bikram yoga and 75% for HIIT . CONCLUSIONS: Bikram yoga does not appear a superior exercise compared to HIIT for persistent pain. However, imporvements in quality of life measures and indicator of better health were seen in the Bikram yoga group. The outcomes of the present study suggest vigorous exercise interventions in persistent pain cohorts are feasible. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ( ACTRN12617001507370 , 26/10/2017).

Return to Work After Traumatic Injury: Increased Work-Related Disability in Injured Persons Receiving Financial Compensation is Mediated by Perceived Injustice.

Purpose Traumatic injury is a leading cause of work disability. Receiving compensation post-injury has been consistently found to be associated with poorer return to work. This study investigated whether the relationship between receiving compensation and return to work was associated with elevated symptoms of psychological distress (i.e., anxiety, depression, and posttraumatic stress disorder) and perceived injustice. Methods Injured persons, who were employed at the time of injury (n = 364), were recruited from the Victorian State Trauma Registry, and Victorian Orthopaedic Trauma Outcomes Registry. Participants completed the Hospital Anxiety and Depression Scale, Posttraumatic Stress Disorder Checklist, Injustice Experience Questionnaire, and appraisals of pain and work status 12-months following traumatic injury. Results Greater financial worry and indicators of actual/perceived injustice (e.g., consulting a lawyer, attributing fault to another, perceived injustice, sustaining compensable injury), trauma severity (e.g., days in hospital and intensive care, discharge to rehabilitation), and distress symptoms (i.e., anxiety, depression, PTSD) led to a twofold to sevenfold increase in the risk of failing to return to work. Anxiety, post-traumatic stress and perceived injustice were elevated following compensable injury compared with non-compensable injury. Perceived injustice uniquely mediated the association between compensation and return to work after adjusting for age at injury, trauma severity (length of hospital, admission to intensive, and discharge location) and pain severity. Conclusions Given  that perceived injustice is associated with poor return to work after compensable injury, we recommend greater attention be given to appropriately addressing psychological distress and perceived injustice in injured workers to facilitate a smoother transition of return to work.

Testing the reliability and validity of a Transition Map for older adults in long term care settings.

Mapping individual patterns of decline in older adults may aid coordinating long term aged care. This study developed a new scale (Transition Maps) to summarise the overall care pathway for long term aged care residents, in a simplified manner incorporating mapping concepts. Transition Maps were developed using mixed methods in two phases, and based on expert opinion, literature review, and input from aged care health professionals. Four professions (primary physician, nurse, allied health, lifestyle services) generated 147 Transition Maps for 38 residents living in a long term care. Preliminary construct validity and inter-rated reliability were evaluated. Results showed that Inter-rater reliability of agreement with the overall care pathway for each resident was kappa = 0.492. Consensus was lowest between nurse care managers and primary physicians (kappa = 0.384), and highest between nurse managers and Lifestyle Services (kappa = 0.77). Preliminary testing of the Transition Map scale provides initial support of construct validity and inter-rater reliability and provides some evidence that Transition Maps can improve the coordination of long term aged care.

Contact heat sensitivity and reports of unpleasantness in communicative people with mild to moderate cognitive impairment in Alzheimer's disease: a cross-sectional study.

BACKGROUND: Compared to healthy controls, people with Alzheimer's disease (AD) have been shown to receive less pain medication and report pain less frequently. It is unknown if these findings reflect less perceived pain in AD, an inability to recognize pain, or an inability to communicate pain. METHODS: To further examine aspects of pain processing in AD, we conducted a cross-sectional study of sex-matched adults ≥65 years old with and without AD (AD: n = 40, female = 20, median age = 75; control: n = 40, female = 20, median age = 70) to compare the psychophysical response to contact-evoked perceptual heat thresholds of warmth, mild pain, and moderate pain, and self-reported unpleasantness for each percept. RESULTS: When compared to controls, participants with AD required higher temperatures to report sensing warmth (Cohen's d = 0.64, p = 0.002), mild pain (Cohen's d = 0.51, p = 0.016), and moderate pain (Cohen's d = 0.45, p = 0.043). Conversely, there were no significant between-group differences in unpleasantness ratings (p > 0.05). CONCLUSIONS: The between-group findings demonstrate that when compared to controls, people with AD are less sensitive to the detection of thermal pain but do not differ in affective response to the unpleasant aspects of thermal pain. These findings suggest that people with AD may experience greater levels of pain and potentially greater levels of tissue or organ damage prior to identifying and reporting injury. This finding may help to explain the decreased frequency of pain reports and consequently a lower administration of analgesics in AD.

Feeling the burn: When it looks like it hurts, and belongs to me, it really does hurt more.

We examined changes in pain sensitivity in the rubber hand illusion (RHI). Experiment 1 investigated changes in pain tolerance immediately after a "healthy" and "wounded" RHI when immersing the hand in a cold pressor ice bath. There was 19% increased pain tolerance and increased perception detection threshold after the healthy RHI, but 11% reduction after the wounded RHI. Experiment 2 examined pain experience during the wounded RHI with capsaicin-induced hyperalgesia. Pain intensity and unpleasantness was higher on the illusion arm during the synchronous RHI, compared with asynchronous trials. There was no change in pain experience on the control arm, and both arms had similar pain sensitivity after the experiment. Our results highlight the impact of embodying a substitute limb on pain, with increased tolerance and reduced tactile sensitivity when the fake limb is healthy and apparently pain-free, but increased pain sensitivity when the self-attributed limb appears to be wounded.

Polypharmacy and chronic pain: harm exposure is not all about the opioids.

OBJECTIVE AND DESIGN: Individuals seeking treatment for chronic pain in multidisciplinary pain management services are typically already on high doses of pain medications. This cross-sectional cohort study of patients with long-term chronic pain examined profiles of polypharmacy and pain medication-related harm exposure. SETTING: Multidisciplinary pain management service. SUBJECTS: The cohort comprised 224 patients taking medications for their pain (1-9 medications; mean = 3.19) with an average pain duration of 10.33 years. METHODS: The Medication Quantification Scale III (MQS-III) was used to examine potential harm exposure. We generated detriment scores for simple analgesics, adjunctive therapies (e.g., anticonvulsants), opioids, and benzodiazepines. RESULTS: The total MQS-III score was correlated with the total number of medications, but not with age. Almost 10% of patients took medications from all four categories, with most taking medications from two (37%) to three (35%) classes. Eighty percent of patients were taking opioids, accounting for 41% of total MQS scores. Five primary profiles of potential medication-related harms were identified: high harm from all medication categories (N = 12); above average harm from single category-simple analgesics (N = 76), adjunctive analgesics (N = 59), or opioids (N = 46); and above average opioid and benzodiazepine harm (N = 31). CONCLUSIONS: While treatment with multiple medications for synergistic or adjunctive effects may assist in medical management of chronic pain, this approach generates increased potential harm exposure. We show that the majority of detriment comes from medications other than opioids and highlight the importance of profiling all pain medications contributing to polypharmacy in clinical pain studies.

Symptoms of PTSD Associated With Painful and Nonpainful Vicarious Reactivity Following Amputation.

Although the experience of vicarious sensations when observing another in pain have been described postamputation, the underlying mechanisms are unknown. We investigated whether vicarious sensations are related to posttraumatic stress disorder (PTSD) symptoms and chronic pain. In Study 1, 236 amputees completed questionnaires about phantom limb phenomena and vicarious sensations to both innocuous and painful sensory experiences of others. There was a 10.2% incidence of vicarious sensations, which was significantly more prevalent in amputees reporting PTSD-like experiences, particularly increased arousal and reexperiencing the event that led to amputation (φ = .16). In Study 2, 63 amputees completed the Empathy for Pain Scale and PTSD Checklist-Civilian Version. Cluster analyses revealed 3 groups: 1 group did not experience vicarious pain or PTSD symptoms, and 2 groups were vicarious pain responders, but only 1 had increased PTSD symptoms. Only the latter group showed increased chronic pain severity compared with the nonresponder group (p = .025) with a moderate effect size (r = .35). The findings from both studies implicated an overlap, but also divergence, between PTSD symptoms and vicarious pain reactivity postamputation. Maladaptive mechanisms implicated in severe chronic pain and physical reactivity posttrauma may increase the incidence of vicarious reactivity to the pain of others.

Implementation of sustainable evidence-based practice for the assessment and management of pain in residential aged care facilities.

Pain is common in residential aged care facilities (RACFs). In 2005, the Australian Pain Society developed 27 recommendations for good practice in the identification, assessment, and management of pain in these settings. This study aimed to address implementation of the standards and evaluate outcomes. Five facilities in Australia participated in a comprehensive evaluation of RACF pain practice and outcomes. Pre-existing pain management practices were compared with the 27 recommendations, before an evidence-based pain management program was introduced that included training and education for staff and revised in-house pain-management procedures. Post-implementation audits evaluated the program's success. Aged care staff teams also were assessed on their reports of self-efficacy in pain management. The results show that before the implementation program, the RACFs demonstrated full compliance on 6 to 12 standards. By the project's completion, RACFs demonstrated full compliance with 10 to 23 standards and major improvements toward compliance in the remaining standards. After implementation, the staff also reported better understanding of the standards (p < .001) or of facility pain management guidelines (p < .001), increased confidence in therapies for pain management (p < .001), and increased confidence in their training to assess pain (p < .001) and recognize pain in residents with dementia who are nonverbal (p = .003). The results show that improved evidence-based practice in RACFs can be achieved with appropriate training and education. Investing resources in the aged care workforce via this implementation program has shown improvements in staff self-efficacy and practice.

Prevalence and relevance of pain in older persons.

SETTING: With the ageing of the world's population, any health problem which adversely affects quality of life in older persons becomes increasingly salient. Persistent pain is one of the most prevalent health conditions faced by adults of advanced age, and is recognized as a major concern for this segment of the population. RESULTS: Numerous epidemiologic surveys suggest that pain is most common during the late middle-aged phase of life (55-65 years) and continues at approximately the same prevalence into older age (65+). This is true regardless of the anatomical site or the pathogenic cause of pain. The one exception appears to be pain associated with degenerative joint disease (e.g., osteoarthritis) which shows an exponential increase until at least 90 years of age. Common age associated conditions like dementia may result in a reduced frequency and intensity of pain. Daily pain is a major risk factor for developing disability and the oldest age cohorts are most vulnerable. Discretionary and higher order physical activities appear most affected, while basic activities of daily living may be modified but are rarely ceased altogether. Similar relationships have been documented for risk of depression and mood disturbance in older persons with persistent pain. Despite such well characterized adverse impacts, pain often remains poorly treated in older persons. This occurs across all health care settings examined (i.e., emergency, acute, outpatient, long-term care). CONCLUSION: Improved knowledge for both health professionals and patients, addressing the current research gaps and expansion of age-appropriate pain management services will be required to better meet the needs of our rapidly ageing population.

Clinical pharmacology of analgesic medicines in older people: impact of frailty and cognitive impairment.

Pain is highly prevalent in frail older people who often have multiple co-morbidities and multiple medicines. Rational prescribing of analgesics in frail older people is complex due to heterogeneity in drug disposition, comorbid medical conditions, polypharmacy and variability in analgesic response in this population. A critical issue in managing older people with pain is the need for judicious choice of analgesics based on a comprehensive medical and medication history. Care is needed in the selection of analgesic medicine to avoid drug-drug or drug-disease interactions. People living with dementia and cognitive impairment have suboptimal pain relief which in part may be related to altered pharmacodynamics of analgesics and challenges in the systematic assessment of pain intensity in this patient group. In the absence of rigorously controlled trials in frail older people and those with cognitive impairment a pharmacologically-guided approach can be used to optimize pain management which requires a systematic understanding of the pharmacokinetics and pharmacodynamics of analgesics in frail older people with or without changes in cognition.

Testing an educational nursing intervention for pain assessment and management in older people.

OBJECTIVE: This study aimed to examine the effectiveness of a structured educational nursing intervention on pain assessment and management in older hospitalized people. DESIGN: A non-equivalent control group interventional design. SETTING: Geriatric evaluation and management units in two metropolitan Australian hospitals. PATIENTS: In total, 192 patients participated, with 32 different patients recruited consecutively for the pre-intervention, intervention, and 3-month post-intervention stages from each unit. INTERVENTIONS: Nurses in the intervention group received a structured intervention comprising 6 hours of instruction and 2 hours of clinical demonstration. Nurses in the control group received "usual" staff development activities. OUTCOME MEASURES: Five assessment tools for pain were used: the visual analog scale, the Faces Pain Scale-Revised, the Short-Form McGill Pain Questionnaire, the Pain Assessment in Advanced Dementia Tool, and the Abbey Pain Scale. Data were also collected on nurses' use of pain assessment tools and their use of non-pharmacological and pharmacological methods of managing pain. RESULTS: Improvements were observed in pain intensity at rest and on movement in the intervention unit at the post-intervention stage and at the 3-month post-intervention stage. There was also a trend for patients to be prescribed analgesics on a fixed dose schedule following implementation of the program in the intervention unit. CONCLUSIONS: The comprehensive intervention enabled change in practice and improvements in pain intensity, and the assessment and management of pain. Future research is needed on implementing the intervention with a multidisciplinary team of health professionals in a subacute environment.

The relationship between the readiness for change and clinical outcomes in response to multidisciplinary pain management.

OBJECTIVE: The pain stages of change questionnaire (PSOCQ) has been designed to assess the willingness of chronic pain patients to engage in self-management approaches. This study sought to examine the utility of the PSOCQ as a predictor of treatment completion and the relationship with treatment outcome. DESIGN: A convenience sample, uncontrolled, pre- and post-intervention cohort design. SETTING: Multidisciplinary pain management center. PATIENTS: Two hundred and sixty-one participants with chronic nonmalignant pain. INTERVENTIONS: Eight-week program of either cognitive behavioral therapy group or a functional restoration group. OUTCOME MEASURES: Brief Pain Inventory average pain rating. The Short Form Health Survey (SF-36 version 2) mental health and physical functioning subscales as well as the PSOCQ. RESULTS: Results suggest that those higher on precontemplation and lower on the other scales are less likely to complete treatment. A two-way multiple analysis of variance also found that when comparing those who progress through stages with those who stagnate or regress, "progressors" show significantly more improvement in measures of mood and functionality but not pain. The treatment groups did not appear to have significantly different outcomes in terms of stage of change. CONCLUSIONS: These findings suggest that the PSOCQ may be useful in making treatment more efficient, both by predicting who is less likely complete treatment and by providing targeted treatments according to patients' readiness to engage in self-management.

Effective treatments for pain in the older patient.

By 2050, the number of older persons across the globe will exceed the number of younger people for the first time in history. Chronic conditions, especially pain, will rise in prevalence as the population ages. Controlling pain in this unique subset of the population demands careful attention to pharmacokinetic and pharmacodynamic factors and their specific impact on pharmacotherapies, relevant complementary and alternative medicine therapies, and interventional strategies.

Prognostic Role of Demographic, Injury and Claim Factors in Disabling Pain and Mental Health Conditions 12 Months after Compensable Injury.

Identifying who might develop disabling pain or poor mental health after injury is a high priority so that healthcare providers can provide targeted preventive interventions. This retrospective cohort study aimed to identify predictors of disabling pain or probable mental health conditions at 12 months post-injury. Participants were recruited 12-months after admission to a major trauma service for a compensable transport or workplace injury (n = 157). Injury, compensation claim, health services and medication information were obtained from the Victorian Orthopaedic Trauma Outcome Registry, Victorian State Trauma Registry and Compensation Research Database. Participants completed questionnaires about pain, and mental health (anxiety, depression, posttraumatic stress disorder) at 12 months post-injury. One third had disabling pain, one third had at least one probable mental health condition and more than one in five had both disabling pain and a mental health condition at 12 months post-injury. Multivariable logistic regression found mental health treatment 3-6 months post-injury, persistent work disability and opioid use at 6-12 months predicted disabling pain at 12 months post-injury. The presence of opioid use at 3-6 months, work disability and psychotropic medications at 6-12 months predicted a mental health condition at 12 months post-injury. These factors could be used to identify at risk of developing disabling pain who could benefit from timely interventions to better manage both pain and mental health post-injury. Implications for healthcare and compensation system are discussed.

Treatment of chronic non-malignant pain in the elderly: safety considerations.

Non-malignant pain in the elderly is frequently under-treated, with physicians appearing to be uncertain concerning how best to achieve optimum management of this common problem in individual cases. The aim of this review is to provide a brief overview and discuss the variety of interacting factors that contribute to the continuing under-treatment of chronic non-malignant pain in the older population. The central objective is to encourage safer and more effective pain management in a population that is highly vulnerable to painful conditions and to the consequences of poorly treated pain. Under-treatment of pain as experienced by the elderly is largely a consequence of uncertainties that arise within a complex environment that is underscored and exacerbated by the progressive and rapid aging of the global population. Uncertainties include the optimum management of pain in geriatric syndromes, frailty and dementia, and their impact on diagnosis, pain assessment and choices of treatment modalities. There is an inadequate evidence base for pharmacological interventions in older persons with respect to pharmacokinetic and pharmacodynamic changes that occur with aging. In this review, the prevalence of chronic pain and the incidence of adverse drug reactions are identified as factors that encourage conservatism in prescribing, as are major predictors of adverse drug reactions, i.e. aging, inappropriate combinations of medications and polypharmacy. The major classes of analgesic drugs are summarized with reference to their mechanisms of action, analgesic properties and known adverse effects. Although all medications have associated risks, the use of analgesics in managing persistent pain in elderly people is widely supported and guided on the basis of clinical experience and consensus among specialists in geriatrics and pain management. It is concluded that the absence of trial data, specific to the elderly, is substantially offset by information based on clinical experience and expert consensus statements. Used appropriately, analgesic and adjuvant treatments can and should be employed to relieve persistent pain in the expanding elderly population.

Chronic pain medication management of older populations: Key points from a national conference and innovative opportunities for pharmacy practice.

OBJECTIVE: Inappropriate use of pain medication has serious consequences for older populations. Experts in the field have noted an increase in opioid prescriptions, and opioid-related hospitalisations and deaths among this vulnerable population. In the pursuit of educating pharmacists, physicians, allied healthcare professionals, researchers, academics and the public facing the challenges of chronic pain medication management, 'The Inaugural Monash University School of Public Health and Preventive Medicine (SPHPM) Best Practice in Chronic Pain Medication Management Day Conference' was held in December 2016 at the Alfred Medical Research and Education Precinct (Melbourne, Australia). METHODS: Fifteen experts presented on aspects of chronic pain epidemiology and current analgesic use in older Australians, and discussed current practice and associated challenges. RESULTS: Presenters highlighted the dramatic increase in opioid prescribing, development of tolerance and withdrawal symptoms, problems with abuse and addiction, increased risk of death from overdose or suicide, potentiation of sedative effects with concurrent use of anxiolytics/hypnotics, and medication diversion. CONCLUSIONS: Pharmacists are very accessible to patients and are crucial members of medication management teams. They have the necessary medication expertise to review medication regimens and provide patient education. Towards addressing chronic pain medication management of older populations, pharmacists can contribute in several ways, such as being aware of relevant guidelines and completing further training, contributing to policy and guideline development, participating in multidisciplinary panels, working groups and pain management teams, collaborating on research projects, and educating the community. With regards to opioid medication management, pharmacists are in an ideal position to: monitor prescription dispensing and potential misuse, provide education about overuse, and, if appropriate, provide access to naloxone. In order to fulfil these roles and responsibilities, allied healthcare professionals should be educated and informed, and opportunities for continuing professional education should be available and utilised. Pharmacists should have the necessary knowledge and skills to optimise chronic pain management, and to both deliver and inform policies and guidelines on pharmacological management of chronic pain in older people.

Mechanisms underlying embodiment, disembodiment and loss of embodiment.

Bodily experience is a complex, mostly unconscious, process that requires the integration of multiple sensory inputs. This paper reviews the sensory systems involved in internal representations of the body--primarily the proprioceptive, motor, vestibular, and visual systems. Various neurological disorders are defined by aberrations in bodily experience--including the perceptual ablation or disembodiment of body parts, "filling in" of amputated body parts, or reduplication of body parts. These perceptual aberrations are discussed and their implications for the central and peripheral systems involved in updating and retrieving internal representations of the body are highlighted. Bodily perception and egocentric frames of reference can be experimentally manipulated through visual capture (e.g., using rubber limbs), functional adaptation and embodiment of tools and prostheses, and changes in afferent sensory feedback (e.g., through stimulation of muscle spindles). These perceptual illusions are described, and discussed for their implications for the mechanisms underlying bodily perception.

Do dyskinesia and pain share common pathophysiological mechanisms in Parkinson's disease?

Plastic changes within the striatum resulting from pulsatile dopaminergic stimulation are thought to lead to dyskinesia in patients with Parkinson's disease (PD). The basal ganglia play a role in processing pain. We hypothesized that the plastic changes that lead to dyskinesia may also mediate pain responses. Our objective was to compare the change in pain sensitivity after levodopa administration between stable responders, fluctuators without dyskinesia, and dyskinetic patients, and to compare pain sensitivity between PD and healthy subjects. Fifty patients with PD were assessed with cold water immersion after overnight withdrawal of dopaminergic medications and again after a standard levodopa challenge, and carefully classified into stable responder (n = 12), fluctuator (n = 15), and dyskinetic (n = 23) groups. Twenty age-matched controls were also tested. PD patients "off"-medication had a lower threshold (P = 0.016) and tolerance (P < 0.0001) to cold pain compared to controls. After levodopa administration, dyskinetic patients experienced a large increase in cold pain threshold (48%) and tolerance (66%) that was absent in stable responders (P = 0.038 and P = 0.015); there was no significant difference in pain sensitivity change scores between the fluctuator and either the stable responder or dyskinetic groups. Our results suggest that dyskinesia and pain may share common pathophysiological mechanisms in PD.

Central mechanisms in phantom limb perception: the past, present and future.

Phantom limbs provide valuable insight into the mechanisms underlying bodily awareness and ownership. This paper reviews the complexity of phantom limb phenomena (proprioception, form, position, posture and telescoping), and the various contributions of internal constructs of the body, or body schema, and neuromatrix theory in explaining these phenomena. Specific systems and processes that have received little attention in phantom limb research are also reviewed and highlighted as important future directions, These include prosthesis embodiment and extended physiological proprioception (i.e., the extension of the body's "area of influence" that thereby extends one's innate sense of proprioception, mirror neurons and cross-referencing of the phantom limb with the intact limb (and the related phenomena of perceiving referred sensations and mirrored movements in the phantom form the intact limb). The likely involvements of the body schema and the body-self neuromatrix, mirror neurons, and cross-callosal and ipsilateral mechanisms in phantom limb phenomena all suggest that the perception of a "normal" phantom limb (that is, a non-painful phantom that has the sensory qualities of an intact limb) is more than likely an epiphenomenon of normal functioning, action understanding and empathy, and potentially may even be evolutionarily adaptive and perhaps necessary. Phantom pain, however, may be a maladaptive failure of the neuromatrix to maintain global bodily constructs.