Kris Vissers

Pulsed radiofrequency treatment in interventional pain management: mechanisms and potential indications-a review

BackgroundThe objective of this review is to evaluate the efficacy of Pulsed Radiofrequency (PRF) treatment in chronic pain management in randomized clinical trials (RCTs) and well-designed observational studies. The physics, mechanisms of action, and biological effects are discussed to provide the scientific basis for this promising modality.MethodsWe systematically searched for clinical studies on PRF. We searched the MEDLINE (PubMed) and EMBASE database, using the free text terms: pulsed radiofrequency, radio frequency, radiation, isothermal radiofrequency, and combination of these. We classified the information in two tables, one focusing only on RCTs, and another, containing prospective studies. Date of last electronic search was 30 May 2010. The methodological quality of the presented reports was scored using the original criteria proposed by Jadad et al.FindingsWe found six RCTs that evaluated the efficacy of PRF, one against corticosteroid injection, one against sham intervention, and the rest against conventional RF thermocoagulation. Two trials were conducted in patients with lower back pain due to lumbar zygapophyseal joint pain, one in cervical radicular pain, one in lumbosacral radicular pain, one in trigeminal neuralgia, and another in chronic shoulder pain.ConclusionFrom the available evidence, the use of PRF to the dorsal root ganglion in cervical radicular pain is compelling. With regards to its lumbosacral counterpart, the use of PRF cannot be similarly advocated in view of the methodological quality of the included study. PRF application to the supracapular nerve was found to be as efficacious as intra-articular corticosteroid in patients with chronic shoulder pain. The use of PRF in lumbar facet arthropathy and trigeminal neuralgia was found to be less effective than conventional RF thermocoagulation techniques.

Changed patterns in Dutch palliative sedation practices after the introduction of a national guideline.

BACKGROUND Continuous sedation, contrary to euthanasia, has been increasingly accepted among medical professionals worldwide. In the Netherlands, a national guideline for continuous palliative sedation has been developed to contribute to the quality of palliative sedation practice. The present follow-up study investigated whether the practice of continuous sedation has changed after the introduction of this guideline. METHODS This study compared the practice of continuous sedation before and after the introduction of the guideline on December 7, 2005. A baseline measurement was performed between February 1, 2003, and May 1, 2005, with an enrollment of 492 physicians (medical specialists, general practitioners, and nursing home physicians). From January 1 to June 30, 2007, after the introduction of a national guideline for palliative sedation, a follow-up study was performed with the respondents of the baseline study. Physicians were asked to report on their last case of deep and continuous sedation in the past 12 months. RESULTS This study reports the results of the follow-up study and compares them to the results of the baseline study. The response rate was 69.3% (n = 341). Of these physicians, 160 reported a last case of continuous sedation in both the baseline and the follow-up studies. Physicians reported a significant increase in patient involvement in decision making, from 72.3% to 82.2%. Pain remained the most often reported reason to start sedation, whereas exhaustion as a reason for sedation increased. The use of benzodiazepines increased from 69.9% to 90.4%. In the first and second measurements, symptom-directed treatment during sedation was applied in 56% to 58% of the cases. In the second period, there was more often an explicit decision to not give artificial hydration during sedation (78.8% vs 56.3%). Of the physicians, 34.2% were convinced that sedation shortened the life of the patient because of dehydration. CONCLUSIONS After the introduction of the guideline, physicians reported that changes in palliative sedation practice conform to the recommendations of this guideline. For example, benzodiazepines were used for sedation more frequently than before and patient involvement in the decision-making process improved. Possible effects of dehydration and the large variation in symptom-directed treatment during sedation deserve careful attention.

Dealing With Delicate Issues in Continuous Deep Sedation Varying Practices Among Dutch Medical Specialists, General Practitioners, and Nursing Home Physicians

BACKGROUND This article examines delicate issues in continuous deep sedation (CDS) from the perspectives of different types of physicians. The following sensitive issues involved in CDS were investigated: artificial hydration, sedation for nonphysical discomfort, the relationship between CDS and euthanasia, and patient involvement in decision making for CDS. METHODS A structured retrospective questionnaire concerning the most recent case of CDS during the past 12 months was sent to a sample of medical specialists (n = 727), general practitioners (n = 626), and nursing home physicians (n = 111). RESULTS Response rates were 26.4% for medical specialists, 37.4% for general practitioners, and 59.5% for nursing home physicians. Indications for CDS differed among the types of physicians. General practitioners (25.0%) were most often confronted with a patient request for euthanasia before starting CDS compared with medical specialists (8.9%) and nursing home physicians (6.5%). A decision to forgo artificial hydration in CDS was more often made by nursing home physicians (91.3%) compared with medical specialists (53.7%) and general practitioners (51.2%). Shorter survival was found for patients sedated for nonphysical discomfort (vs other patients) by general practitioners. Among all patients, 74.5% were involved in decision making before the start of CDS. CONCLUSIONS The present study demonstrates notable differences in CDS practice among various types of physicians. To what extent this is related to different patient populations or to different expertise requires further investigation. The use of CDS for nonphysical discomfort calls for critical examination to avoid ambiguous practice.

The amygdala, a relay station for switching on and off pain

Neuropathic pain is strongly associated with mood disorders like anxiety and depression. Corticotropin‐releasing factor (CRF) plays a prominent role in these disorders as it is up‐regulated in limbic structures such as the amygdala, upon experimentally induced neuropathy. This review discusses recent literature on the role of CRF in pain processing and highlights the amygdala as a potential hot spot in supraspinal descending pain control. Many studies have demonstrated analgesic effects of CRF following local and systemic administration, but more recently also hyperalgesic effects were shown upon endogenous amygdalar CRF increase or by blocking the CRF type 1 receptor (CRFR1). On the basis of the reviewed literature, we postulate a central mechanism for pain control in which the amygdala plays a critical role by switching on and off chronic pain. In this mechanism, upon pain stimuli, CRFR1 in the amygdala is activated by CRF to induce hyperalgesia. When the activated CRFR1 is internalized (pain initiation), it triggers the translocation of the cytoplasmic CRF type 2 receptor (CRFR2) to the plasma membrane. Here, CRFR2 can be recruited by either high (pharmacological) concentrations of CRF or by endogenous CRFR2 ligands, the urocortins, leading to analgesia (pain termination). This on–off switching of pain is completed by redistribution of the CRF receptors to their initial activity state. We furthermore propose that in neuropathic pain, this mechanism is dysregulated and causes a state of permanent hyperalgesia, and present an integrative (patho)physiological model for the way disturbed CRF receptor signalling in the amygdala could initiate neuropathic pain.

The Beck Depression Inventory (BDI-II) and a single screening question as screening tools for depressive disorder in Dutch advanced cancer patients

PurposeDepression is highly prevalent in advanced cancer patients, but the diagnosis of depressive disorder in patients with advanced cancer is difficult. Screening instruments could facilitate diagnosing depressive disorder in patients with advanced cancer. The aim of this study was to determine the validity of the Beck Depression Inventory (BDI-II) and a single screening question as screening tools for depressive disorder in advanced cancer patients.MethodsPatients with advanced metastatic disease, visiting the outpatient palliative care department, were asked to fill out a self-questionnaire containing the Beck Depression Inventory (BDI-II) and a single screening question “Are you feeling depressed?” The mood section of the PRIME-MD was used as a gold standard.ResultsSixty-one patients with advanced metastatic disease were eligible to be included in the study. Complete data were obtained from 46 patients. The area under the curve of the receiver operating characteristics analysis of the BDI-II was 0.82. The optimal cut-off point of the BDI-II was 16 with a sensitivity of 90% and a specificity of 69%. The single screening question showed a sensitivity of 50% and a specificity of 94%.ConclusionsThe BDI-II seems an adequate screening tool for a depressive disorder in advanced cancer patients. The sensitivity of a single screening question is poor.

Pre-treatment with capsaicin in a rat osteoarthritis model reduces the symptoms of pain and bone damage induced by monosodium iodoacetate.

A rat model of osteoarthritis was used to investigate the effect of pre-treatment with capsaicin on the symptoms of osteoarthritis induced by the injection of monosodium iodoacetate. This model mimics both histopathology and symptoms associated of human osteoarthritis. Injection of monosodium iodoacetate, an inhibitor of glycolysis, into the femorotibial joints of rodents promotes loss of articular trabecular bone and invokes pain symptoms similar to those noted in human osteoarthritis. Twenty rats were divided in two groups either receiving placebo or monosodium iodoacetate. Each group was subdivided in two groups either receiving pre-treatment with capsaicin two weeks before monosodium iodoacetate injection or not, resulting in four groups of five rats each. The impact of a single intra-articular administration of capsaicin (0.5%) on the generation of evoked mechanical pain (hind limb weight bearing, automated von Frey monofilament and RotaRod tests) and bone lesions (micro-CT scan radiographic analyses of bone structure) following monosodium iodoacetate-induced osteoarthritis in rats was determined. Evoked mechanical pain as monitored over a period of 4 weeks after monosodium iodoacetate injection was abolished in capsaicin pre-treated animals and pain values are comparable to those of capsaicin controls. Chronic joint pathological changes such as bone erosion and trabecular damage were significantly reduced by pre-treatment with a single administration of capsaicin. Decrease of bone volume was considerably ameliorated and trabecular connectivity was substantially better in capsaicin pre-treated animals. Capsaicin, an agonist activator of the vanilloid nociceptors (TRPV1), appears to be effective in protecting bone from arthritic damage. The present results support the hypothesis that capsaicin-sensitive sensory neurons contribute to bone lesions in the monosodium iodoacetate-induced osteoarthritis rat model.

Pharmacological correlation between the formalin test and the neuropathic pain behavior in different species with chronic constriction injury

Research on mechanisms of drug action, and preclinical screening of molecules with a potential activity on neuropathic pain requires extensive animal work. The chronic constriction injury model is one of the best-characterized models of neuropathic pain behavior in rats, but requires extensive time consuming operations and animal handling. The formalin test is easier to perform, and a well validated model. The latter may serve as an effective prescreening test of molecules and may facilitate drug targeting. In the present study the activity of different pharmacological reference compounds was tested in rats and gerbils on the cold plate for animals that had undergone chronic constriction injury and in the second phase of the formalin test. In rats, a comparable outcome in both test conditions was observed for morphine, fentanyl, MK-801 and flunarizine. Clonidine had more activity in the second phase of the formalin test, whereas baclofen, tramadol, amitryptiline, ketamine and topiramate showed more activity in the cold plate. In gerbils, both test conditions yielded comparable results for fentanyl and ketoprofen. Tramadol and CP-96345 tended to have more activity in the second phase of the formalin test, whereas morphine, SR-48968, SR-142801 and R116301 demonstrated more activity in the cold plate test. This study demonstrates a good correlation between the second phase of the formalin test and the cold allodynia in the CCI model for, both for rats and gerbils. Drugs with a proven activity in humans, used as reference compounds, also showed good pharmacological activity in this animal study.

Early identification of palliative care patients in general practice: development of RADboud indicators for PAlliative Care Needs (RADPAC)

BACKGROUND According to the World Health Organization (WHO) definition, palliative care should be initiated in an early phase and not be restricted to terminal care. In the literature, no validated tools predicting the optimal timing for initiating palliative care have been determined. AIM The aim of this study was to systematically develop a tool for GPs with which they can identify patients with congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), and cancer respectively, who could benefit from proactive palliative care. DESIGN A three-step procedure, including a literature review, focus group interviews with input from the multidisciplinary field of palliative healthcare professionals, and a modified Rand Delphi process with GPs. METHOD The three-step procedure was used to develop sets of indicators for the early identification of CHF, COPD, and cancer patients who could benefit from palliative care. RESULTS Three comprehensive sets of indicators were developed to support GPs in identifying patients with CHF, COPD, and cancer in need of palliative care. For CHF, seven indicators were found: for example, frequent hospital admissions. For COPD, six indicators were found: such as, Karnofsky score ≤50%. For cancer, eight indicators were found: for example, worse prognosis of the primary tumour. CONCLUSION The RADboud indicators for PAlliative Care Needs (RADPAC) is the first tool developed from a combination of scientific evidence and practice experience that can help GPs in the identification of patients with CHF, COPD, or cancer, in need of palliative care. Applying the RADPAC facilitates the start of proactive palliative care and aims to improve the quality of palliative care in general practice.

The role of brain-derived neurotrophic factor in different animal models of neuropathic pain

Even in present day pain therapy, neuropathic pain remains a challenge for clinicians to treat and a challenge for researchers to investigate. Different animal models have been developed to mimic neuropathic pain. Neurotrophins such as nerve growth factor, brain‐derived neurotrophic factor and neurotrophin 3 have been studied extensively in these models, yet few review articles concerning brain‐derived neurotrophic factor have been published. This article reassesses the literature concerning brain‐derived neurotrophic factor expression in the sciatic nerve chronic constriction injury model, the sciatic nerve transection model, the spinal nerve ligation model and the spinal nerve transection model and discusses differences in regulation of brain‐derived neurotrophic factor between these models and their causality with neuropathic pain.

23.Pain in Patients with Cancer

Abstract:  Pain in patients with cancer can be refractory to pharmacological treatment or intolerable side effects of pharmacological treatment may seriously disturb patients’ quality of life. Specific interventional pain management techniques can be an effective alternative for those patients. The appropriate application of these interventional techniques provides better pain control, allows the reduction of analgesics and hence improves quality of life. Until recently, the majority of these techniques are considered to be a fourth consecutive step following the World Health Organization’s pain treatment ladder. However, in cancer patients, earlier application of interventional pain management techniques can be recommended even before considering the use of strong opioids.