Hypervigilance for innocuous tactile stimuli in patients with fibromyalgia: an experimental approach.

BACKGROUND: Hypervigilance, i.e., excessive attention, is often invoked as a potential explanation for the observation that many individuals with fibromyalgia show a heightened sensitivity to stimulation in various sensory modalities, such as touch and hearing. Compelling evidence for this assumption is, however, lacking. The aim of the present study was to investigate the presence of somatosensory hypervigilance in patients with fibromyalgia. METHODS: Fibromyalgia patients (n = 41) and a matched control group (n = 40) performed a tactile change detection task in which they had to detect whether there was a change between two consecutively presented patterns of tactile stimuli presented to various body locations. The task was performed under two conditions: in the unpredictable condition, tactile changes occurred equally often at all possible body locations; in the predictable condition, the majority of tactile changes occurred at one specific body location. RESULTS: It was hypothesized that the fibromyalgia group would show better tactile change detection in the unpredictable condition and when changes ocurred at unexpected locations in the predictable condition. The results did not support this hypothesis. In neither condition was the fibromyalgia group better than the control group in detecting tactile changes. CONCLUSIONS: No evidence was found to support the claim that patients with fibromyalgia display somatosensory hypervigilance. This finding challenges the idea of hypervigilance as a static feature of fibromyalgia and urges for a more dynamic view in which hypervigilance emerges in situations when bodily threat is experienced.

Fibromyalgia patients and controls are equally accurate in detecting tactile stimuli while observing another in pain: an experimental study.

This study investigated the effects of observing pain in others upon vicarious somatosensory experiences and the detection of somatosensory stimuli in both fibromyalgia (FM) patients and controls. The putative modulatory role of dispositional empathy, hypervigilance to pain, and central sensitization was examined. FM patients (n = 39) and controls (n = 38) saw videos depicting pain-related (hands being pricked) and non-pain-related scenes, while occasionally experiencing vibrotactile stimuli themselves on the left, right, or both hands. Participants reported the location at which they felt a somatosensory stimulus. Tactile and visual scenes were presented in the same spatial location (congruent; e.g., left-left) or from opposite locations (incongruent; e.g., left-right). We calculated the proportion of correct responses, vicarious somatosensory experiences (i.e., trials on which an illusory somatosensory experience was reported while observing pain-related scenes), and neglect errors (i.e., reporting only the site congruent to the visual pain-related information when both hands had been stimulated). Observing another in pain resulted in an equal numbers of vicarious somatosensory experiences in both groups and facilitated the detection of tactile stimuli, especially during spatially congruent trials. Counter to our expectations, this facilitation was not moderated by group. FM patients made fewer neglect errors. Hypervigilance for pain, dispositional empathy, and central sensitization did not exert a modulatory role. Observing pain facilitates the detection of tactile stimuli in FM patients and controls. Overall, a low incidence of vicarious experiences was observed. Further research is needed to understand the role of attentional body focus in the elicitation of vicarious experiences.

Personality traits in chronic pain patients are associated with low acceptance and catastrophizing about pain.

OBJECTIVE: Pain acceptance is considered important for mental well-being with better functional outcomes for chronic pain patients. The present study explored whether pain-related variables (pain severity, pain interference, pain duration, and pain catastrophizing) and non-pain-related variables (personality traits) influence acceptance and additionally examined the interrelationship between the influencing variables and acceptance. METHODS: One hundred patients with chronic pain from a multidisciplinary pain centre completed self-report questionnaires on acceptance, pain severity, interference of life, pain duration, pain catastrophizing, and personality. RESULTS: Pain severity, pain interference, and pain duration had no significant correlations with acceptance. Pain catastrophizing and most personality traits were significantly and negatively related to acceptance. Regression analyses revealed that of all personality traits, the avoidant personality trait explains most variance of acceptance. Subsequent mediation analysis indicated that catastrophizing about pain mediated the relationship between the avoidant personality trait and acceptance. CONCLUSION: The findings indicate that acceptance is influenced by catastrophizing and avoidant personality traits. The clinical implication might be that acceptance-oriented treatments may prove less successful in chronic pain patients with more pronounced avoidant personality traits. Extra focus on a reduction of the frequency of pain catastrophizing might be helpful.

Opioid rotation in the management of chronic pain: where is the evidence?

The management of chronic pain remains a challenge because of its complexity and unpredictable response to pharmacological treatment. In addition, accurate pain management may be hindered by the prejudice of physicians and patients that strong opioids, classified as step 3 medications in the World Health Organization ladder for cancer pain management, are reserved for the end stage of life. Recent information indicates the potential value of strong opioids in the treatment of chronic nonmalignant pain. There are, up until now, insufficient data to provide indications about which opioid to use to initiate treatment or the dose to be used for any specific pain syndrome. The strong inter-patient variability in opioid receptor response and in the pharmacokinetic and pharmacodynamic behavior of strong opioids justifies an individual selection of the appropriate opioid and stepwise dose titration. Clinical experience shows that switching from one opioid to another may optimize pain control while maintaining an acceptable side effect profile or even improving the side effects. This treatment strategy, described as opioid rotation or switch, requires a dose calculation for the newly started opioid. Currently, conversion tables and equianalgesic doses are available. However, those recommendations are often based on data derived from studies designed to evaluate acute pain relief, and sometimes on single dose studies, which reduces this information to the level of an indication. In daily practice, the clinician needs to titrate the optimal dose during the opioid rotation from a reduced calculated dose, based on the clinical response of the patient. Further research and studies are needed to optimize the equianalgesic dosing tables.

Impact of opioid rescue medication for breakthrough pain on the efficacy and tolerability of long-acting opioids in patients with chronic non-malignant pain.

BACKGROUND: There is little evidence that short-acting opioids as rescue medication for breakthrough pain is an optimal long-term treatment strategy in chronic non-malignant pain. We compared clinical studies of long-acting opioids that allowed short-acting opioid rescue medication with those that did not, to determine the impact of opioid rescue medication use on the analgesic efficacy and tolerability of chronic opioid therapy in patients with chronic non-malignant pain. METHODS: We searched MEDLINE (1950 to July 2006) and EMBASE (1974 to July 2006) using terms for chronic non-malignant pain and long-acting opioids. Independent review of the search results identified 48 studies that met the study selection criteria. The effect of opioid rescue medication on analgesic efficacy and the incidence of common opioid-related side-effects were analysed using meta-regression. RESULTS: After adjusting for potentially confounding variables (study design and type of opioid), the difference in analgesic efficacy between the 'rescue' and the 'no rescue' studies was not significant, with regression coefficients close to 0 and 95% confidence intervals that excluded an effect of more than 18 points on a 0-100 scale in each case. There was also no significant difference between the 'rescue' and the 'no rescue' studies for the incidence of nausea, constipation, or somnolence in both the unadjusted and the adjusted analyses. CONCLUSIONS: We found no evidence that rescue medication with short-acting opioids for breakthrough pain affects analgesic efficacy of long-acting opioids or the incidence of common opioid-related side-effects among chronic non-malignant pain patients.

Clinical pharmacy in a multidisciplinar team for chronic pain in adults.

The aim of this study was to evaluate the role and the impact of a clinical pharmacist as a member of a multidisciplinary pain team. Although physicians have a good knowledge of pharmacotherapy in the field of pain medication, pharmacy interventions were necessary to enhance the quality of prescribing. On a population of 93 patients, a total of 120 interventions were recorded. The different types of interventions included: provision of information (10.0%), clinical intervention (89.2%) and the provision of a specific product (0.8%). Out of the 107 clinical interventions, a total of 95.3 % interventions were accepted by the physicians. The results highlight the clinical importance of the pharmacy in optimizing drug therapy for adult patients with chronic pain.

Impact of long-term use of opioids on quality of life in patients with chronic, non-malignant pain.

OBJECTIVE: The use of opioids in the management of non-malignant pain remains controversial. For many physicians, pain relief stemming from opioid use is not enough unless there is also a noticeable change in quality of life (QoL) and patient functioning. The impact of long-term opioid treatment on patients' QoL has been investigated in a limited number of trials, and these studies differ considerably with respect to their design and principal findings. This systematic review presents the results of these studies. DESIGN AND METHODS: MEDLINE (1966 to November/December 2004), EMBASE (1974 to November/December 2004), the Oxford Pain Relief Database (Bandolier; 1954-1994) and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched for relevant papers by combining search terms for function with terms for opioid analgesia, non-malignant and pain. Studies were eligible for inclusion if they met all of the pre-defined criteria specifying study design, population, intervention and outcome measures. RESULTS: Eleven studies evaluated long-term treatment with opioids in patients with chronic, non-malignant pain and assessed QoL (N = 2877). Six studies were randomised trials and the remaining five were observational studies. In general, the former had higher Jadad rating scores for the quality of the paper than the latter. Of the four randomised studies in which baseline QoL was reported, three showed an improvement in QoL. Similarly, of the five observational studies, a significant improvement in QoL was reported in four. CONCLUSIONS: There is both moderate/high- and low-quality evidence suggesting that long-term treatment with opioids can lead to significant improvements in functional outcomes, including QoL, in patients with chronic, non-malignant pain. However, further methodologically rigorous investigations are required to confirm the long-term QoL benefit of opioid treatment in these patients, and to elucidate the effect of physical tolerance, withdrawal and addiction, which are all associated with long-term use of opioids, on patients' functional status.

Systematic overview of the pharmacological management of postherpetic neuralgia. An evaluation of the clinical value of critically selected drug treatments based on efficacy and safety outcomes from randomized controlled studies.

OBJECTIVE: This study systematically reviews current evidence on drug treatments commonly used in postherpetic neuralgia. METHODS: Randomized controlled trials were critically selected using predefined search criteria. Efficacy was evaluated as percentage of improvement in pain intensity between baseline and endpoint, tolerability by number of study discontinuations because of adverse events and incidence of adverse events. RESULTS: Currently published trials enrolled different patient populations and small patient numbers. The great variability in doses, titration schemes, designs and washout periods together with other design flaws made comparison between different studies scientifically impossible. CONCLUSIONS: There is a real need for well-performed clinical trials with standardization in design and reporting. Development of adequate and validated questionnaires for evaluation and comparison of efficacy and safety of treatments is also needed. Based on the evaluation of individual studies, it is concluded that only gabapentin is studied in large (over 200 patients), placebo-controlled studies showing good efficacy and safety.

Chronic pain therapy: an evolution from solo-interventions to a holistic interdisciplinary patient approach.

The treatment of chronic pain patients has changed over years. Anaesthesiologists treat pain patients, their skills in locoregional anaesthesia techniques and their pharmacological knowledge being a unique resource to reduce pain. However, the International Association for the Study of Pain provides more and more scientific evidence that chronic pain is a biopsychosocial event and that its diagnosis and treatment should be considered in a multidisciplinary frame. Nevertheless, in practice we can't deny the fact that there are several steps in the process in which the patient himself decides if he wants such an approach or not. The 'motivating' phase is a very important pretherapy and basic condition to start up a holistic pain treatment. Therefore, at the Ghent University Hospital Pain Clinic, we focused in a first step how to motivate our pain patients to take part in a multidisciplinary diagnostic examination, the second step is motivate them for an interdisciplinary treatment when it is indicated. We diagnose the four most important pain components: the sensory, myofacial, autonomic and psychosocial problems. The patient who is initially examined by the anaesthesiologist, will also be evaluated by the psychologist and the physician in rehabilitation medicine. By this way each component is mapped and a final (holistic) diagnosis can be made. In a weekly half-a-day meeting, the different specialists discuss the patients and put forward an interdisciplinary treatment plan. On several moments, the patients' treatment progress will be discussed and redirected if necessary. So, we hope to obtain an optimal result and avoid overtreatment and too invasive pain treatment.

Postherpetic ophthalmic neuralgia.

Postherpetic ophthalmic neuralgia is the final stage of a varicella zoster infection. Many years after chickenpox infection, patients can develop herpes zoster in one or more specific dermatomal regions. The ophthalmic branch of the trigeminal nerve and the thoracic nerves are most commonly affected. Younger patients are less prone to postherpetic neuralgia than the older. Patients with a depression in cell-mediated immunity are more susceptible to develop postherpetic pain. Postherpetic ophthalmic neuralgia is a neuropathic pain and can be treated by anticonvulsants and tricyclic antidepressants. Neurodestructive procedures are not recommended as they enhance destruction and neuropathic pain. Sympathetic nerve blocks can be helpful. Neurostimulation is the last therapeutic resort.

Gabapentin for pain control in cancer patients' wound dressing care.

A patient with mycosis fungoides illustrates the problem of pain management during wound care and suggests the utility of a novel treatment, gabapentin. Skin lesions, be they induced through necrosis of tumor, therapy (e.g., radiotherapy), or by pressure ulceration, are often the cause of continuous pain or acute wound dressing pain. Optimizing the analgesic treatment in those patients is thus of major importance. Anti-inflammatory drugs and opioids are the cornerstones in the treatment of cancer pain but are rarely sufficient to control wound pain. Different adjuvant techniques can be used, including topical analgesics, psychological distraction techniques, anxiolytics, and co-analgesics. There is growing evidence that anticonvulsants, and sodium channel blockers in particular, are effective not only in neuropathic but also in inflammatory pain. Gabapentin, a voltage sensitive sodium and calcium channel blocker, was used as a co-analgesic to supplement morphine in this case of cancer wound dressing pain.

The pain cycle: implications for the diagnosis and treatment of pelvic pain syndromes.

The aim of the study was to report our results of sacral nerve stimulation in patients with pelvic pain after failed conservative treatment. From 1992 to August 1998 we treated 111 patients (40 males, 71 females, ages 46 +/- 16 years) with chronic pelvic pain. All patients with causal treatment were excluded from this study. Pelvic floor training, transcutaneous electrical nerve stimulation (TENS) and intrarectal or intravaginal electrostimulation were applied and sacral nerve stimulation was used for therapy-resistant pain. The outcome of conservative treatment and sacral nerve stimulation (VAS <3/10; >50% pain relief) was related to symptoms of voiding dysfunction and dyschezia, and urodynamic proof of dysfunctional voiding, not to the pain localization or treatment modality. Outcome was inversely related to neuropathic pain. When conservative treatment failed, a test stimulation of the S3 root was effective in 16/26 patients, and 11 patients were implanted successfully with a follow-up of 36 +/- 8 months. So far no late failures have been seen. A longer test stimulation is needed in patients with pelvic pain because of a higher incidence of initial false positive tests. Our conclusion is that sacral nerve stimulation is effective in the treatment of therapy-resistant pelvic pain syndromes linked to pelvic floor dysfunction.

Lamotrigine in the treatment of chronic refractory neuropathic pain.

Many patients suffer from chronic, intractable neuropathic pain. Despite similar diagnoses and presumed pathophysiologies, symptoms and response to treatment can differ. Monotherapy is only occasionally successful. In this prospective survey, 20 patients with chronic, neuropathic pain not responding to interventional therapy received lamotrigine, sometimes as monotherapy and sometimes combined with oral morphine. The latter occurred in patients who lost pain relief from morphine after time. Ten patients did not respond to the drug; 4 were temporary responders and 6 patients obtained sustained pain relief. It is interesting that 5 patients regained opioid responsiveness and that the drug combination produced excellent pain relief for more than 5 months. We hypothesize an additive effect between morphine and lamotrigine.

Nerve root sleeve injections in patients with failed back surgery syndrome: a comparison of three solutions.

OBJECTIVE: To evaluate outcome in patients with failed back surgery syndrome treated with nerve root sleeve injections. DESIGN AND PATIENTS: An open, nonblinded, randomized study on 60 patients with documented fibrosis in fewer than three nerve roots. INTERVENTIONS: After random selection, 20 patients were injected with 1 ml bupivacaine 0.5% combined with 1500 units hyaluronidase and 1 ml saline per nerve root sleeve (group A), another 20 were treated with 1 ml bupivacaine 0.5% combined with 40 mg methylprednisolone solution (Depo Medrol) per nerve root (group B), and a third group was treated with bupivacaine 0.5% combined with 1500 units hyaluronidase and 40 mg methylprednisolone solution (group C). The volume of each injection was 2 ml. The injections were given twice at an interval of 1 week. OUTCOME MEASURES: The patients were evaluated on a verbal pain rating scale 1, 3, and 6 months after the second injection. The Kruskal-Wallis test was used to detect statistically significant differences among the three groups, and the analysis was refined with the Friedman test. RESULTS AND CONCLUSIONS: Overall, although injections induced analgesia at 1 month, these effects were reduced at 3- and 6-month follow-ups. No statistical differences were found between the three treatment groups (after 1 month, p = 0.71; after 3 months, p = 0.69; after 6 months, p = 0.66. The Friedman test showed a significant decrease in treatment score as a function of time in groups B and C (p = 0.015) but not in group A (p = 0.074). Corticosteroids seem responsible for the last phenomenon.

Persisting misconceptions of Belgian physicians and nurses about cancer pain treatment.

In Belgium palliative hospices, palliative support teams in hospitals and palliative home care are well-developed. The author gave a lecture about pain treatment in palliative care and inquired after the knowledge and attitudes of 28 nurses and 45 physicians. A questionnaire containing questions about morphine and cancer pain treatment was completed by the attendees before and after the session. In the initial questionnaire the care-providers' attitudes towards palliative care and symptom control were included also. The Wilcoxon test revealed a significant difference in knowledge between the physicians and nurses before the session (p = 0.007). Afterwards knowledge had improved in both groups (p = 0.007) but a difference still remained (p = 0.007). This study reveals that continued education is mandatory. An oral presentation seems not ideal; interactive training with practical exercises might be more appropriate.

Dual channel electrostimulation in pain.

Spinal cord stimulation is an accepted treatment for neuropathic pain. Technical advances in electrode design and better patient selection have led to better and sustained pain control by these devices. Multilead electrical stimulation is the latest innovation in implantable electrostimulation (Mattrix, Medtronic Minneapolis, USA). Two combined multipolar leads connected to a radiofrequency--coupled system can deliver electrical pulses of various amplitudes and pulse widths at different dermatome levels. Single stimulation is applied with different electrode configurations using both electrodes with identical stimulation parameters. In dual stimulation, the amplitude and the pulse width can vary between the electrode configurations. Dual channel stimulation helps steering stimulation paresthesias. Three patients illustrate the technical advantages of dual channel electrostimulation in the pain relief at multiple sites. Two patients with failed back surgery syndrome obtained more easily stimulation-induced paresthesias in the back and the legs. Dual channel stimulation is cost saving in patients implanted with two electrodes. This is presented in a third patient with an electrode in the thalamus--as pain treatment for cervicobrachialgia and a second in the epidural space--as treatment for the failed back surgery syndrome. These electrodes were connected to the Mattrix stimulator.