Pulsed radiofrequency (PRF) fields applied by an electrode to neural structures, such as the peripheral sensory nociceptor axons and dorsal root ganglion, are clinically effective in reducing pain ...and other neuropathic syndromes. However, a full understanding of the underlying mechanisms by which this occurs has not yet been clarified. In this study, PRF is applied to the afferent axons of the sciatic nerves of rats. A standard radiofrequency (RF) electrode and RF generator is used to apply the RF signal output to the sciatic nerve using standard PRF parameters that have been successfully used in clinical practice. The ultrastructure of the treated axons is observed after 10 days by electron microscopy. A control, sham application is simultaneously applied to the contralateral sciatic nerve to provide a statistical differential comparison. It is found that the internal ultrastructural components of the axons show microscopic damage after PRF exposure, including: abnormal membranes and morphology of mitochondria, and disruption and disorganization of microfilaments and microtubules. The damage appears to be more pronounced for C‐fibers than for A‐delta and A‐beta fibers. The results are discussed in terms of internal electric field strengths and thermodynamic parameters.
Lesioning using radiofrequency (RF) current has been increasingly used in clinical practice for the treatment of pain syndromes. Although formation of heat causing “thermocoagulation” of the nervous ...tissues is thought to be responsible of the clinical outcome, a more recent modality of RF application named pulsed radiofrequency (PRF) delivers the RF current without producing destructive levels of heat. In our study, we compared the effects of conventional RF (CRF) and PRF on rabbit dorsal root ganglion (DRG) morphology, including also control and sham operated groups. The setting of the experiment and the RF parameters used were similar to those used in current clinical practice. The specimens were analyzed both with light microscopy and electron microscopy, two weeks after the procedure. At the light microscopic level, all groups had preserved the normal DRG morphology and no differences were observed between them. In the electron microscopic analysis there were no pathological findings in the control and sham operated groups. But the ganglion cells in the RF groups had enlarged endoplasmic reticulum cisterns and increased number of cytoplasmic vacuoles which were more evident in the CRF group. Some of the ganglion cells in the CRF group had mitochondrial degeneration, nuclear membrane disorders or loss of nuclear membrane and neurolemma integrity. The myelinated and unmyelinated nerve fibers were of normal morphology in all groups. Our results suggest that PRF application is less destructive of cellular morphology than CRF at clinically used “doses”. Before making certain judgements, more experimental and clinical studies should be planned.
Percutaneous epidural neuroplasty (lysis of epidural adhesions, epidural application of hypertonic saline) is an interventional technique for the management of pain due to spinal disorders. Epidural ...neuroplasty is found to be effective in removing fibrous tissue occurring in the epidural space for various reasons, however, the procedure may be prone to serious complications. We present here our retrospectively collected complications and precautions of complications of epidural neuroplasty in 250 patients. Neuroplasty, as per the technique of Racz et al., was only considered in patients suffering from low back and cervical pain after conservative treatments had been tried and had failed. Possible known complications include bending of the tip of the introducer needle, shearing/tearing of the catheter, misplacement of the catheter, inadvertent blockage of the catheter or catheter tip, migration of the catheter, hypotension, respiratory depression, urinary and/or fecal incontinence, urinary hesitancy, sexual dysfunction, paresthesia, epidural abscess, and meningitis. We found the following complications in our series: the tips of the introducer needle were bent in 12 patients; catheter sheaths were torn during withdrawal through the needle in three patients; 39 patients had bleeding or aspiration of blood from the epidural space; eight patients had their catheters migrate into an epidural vein; one patient's catheter migrated into the prevertebral space during the procedure; there were dural punctures in 11 patients; there were catheter blockages in six patients during consecutive applications of neuroplasty; hypotension was seen during and after drug injections in 12 patients, there was hypotension in one patient; three patients had migration and penetration of their catheters into the dura after placement and in consecutive days; 25 patients experienced numbness in dermatomal areas of the upper and lower extremities depending the level of the procedure; and there were eight infections at the entry site of the catheter, three epidural abscesses, and two patients with meningitis. In order to prevent complications such as those seen, epidural neuroplasty procedures must be performed in well‐equipped centers by experienced hands.
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Summary of consensus:
1. The use of opioids in cancer pain: The criteria for selecting analgesics for pain treatment in the elderly include, but are not limited to, overall efficacy, overall ...side‐effect profile, onset of action, drug interactions, abuse potential, and practical issues, such as cost and availability of the drug, as well as the severity and type of pain (nociceptive, acute/chronic, etc.). At any given time, the order of choice in the decision‐making process can change.
This consensus is based on evidence‐based literature (extended data are not included and chronic, extended‐release opioids are not covered). There are various driving factors relating to prescribing medication, including availability of the compound and cost, which may, at times, be the main driving factor.
The transdermal formulation of buprenorphine is available in most European countries, particularly those with high opioid usage, with the exception of France; however, the availability of the sublingual formulation of buprenorphine in Europe is limited, as it is marketed in only a few countries, including Germany and Belgium. The opioid patch is experimental at present in U.S.A. and the sublingual formulation has dispensing restrictions, therefore, its use is limited.
It is evident that the population pyramid is upturned. Globally, there is going to be an older population that needs to be cared for in the future. This older population has expectations in life, in that a retiree is no longer an individual who decreases their lifestyle activities. The “baby‐boomers” in their 60s and 70s are “baby zoomers”; they want to have a functional active lifestyle. They are willing to make trade‐offs regarding treatment choices and understand that they may experience pain, providing that can have increased quality of life and functionality. Therefore, comorbidities—including cancer and noncancer pain, osteoarthritis, rheumatoid arthritis, and postherpetic neuralgia—and patient functional status need to be taken carefully into account when addressing pain in the elderly.
World Health Organization step III opioids are the mainstay of pain treatment for cancer patients and morphine has been the most commonly used for decades. In general, high level evidence data (Ib or IIb) exist, although many studies have included only few patients. Based on these studies, all opioids are considered effective in cancer pain management (although parts of cancer pain are not or only partially opioid sensitive), but no well‐designed specific studies in the elderly cancer patient are available. Of the 2 opioids that are available in transdermal formulation—fentanyl and buprenorphine—fentanyl is the most investigated, but based on the published data both seem to be effective, with low toxicity and good tolerability profiles, especially at low doses.
2. The use of opioids in noncancer‐related pain: Evidence is growing that opioids are efficacious in noncancer pain (treatment data mostly level Ib or IIb), but need individual dose titration and consideration of the respective tolerability profiles. Again no specific studies in the elderly have been performed, but it can be concluded that opioids have shown efficacy in noncancer pain, which is often due to diseases typical for an elderly population. When it is not clear which drugs and which regimes are superior in terms of maintaining analgesic efficacy, the appropriate drug should be chosen based on safety and tolerability considerations. Evidence‐based medicine, which has been incorporated into best clinical practice guidelines, should serve as a foundation for the decision‐making processes in patient care; however, in practice, the art of medicine is realized when we individualize care to the patient. This strikes a balance between the evidence‐based medicine and anecdotal experience. Factual recommendations and expert opinion both have a value when applying guidelines in clinical practice.
3. The use of opioids in neuropathic pain: The role of opioids in neuropathic pain has been under debate in the past but is nowadays more and more accepted; however, higher opioid doses are often needed for neuropathic pain than for nociceptive pain. Most of the treatment data are level II or III, and suggest that incorporation of opioids earlier on might be beneficial. Buprenorphine shows a distinct benefit in improving neuropathic pain symptoms, which is considered a result of its specific pharmacological profile.
4. The use of opioids in elderly patients with impaired hepatic and renal function: Functional impairment of excretory organs is common in the elderly, especially with respect to renal function. For all opioids except buprenorphine, half‐life of the active drug and metabolites is increased in the elderly and in patients with renal dysfunction. It is, therefore, recommended that—except for buprenorphine—doses be reduced, a longer time interval be used between doses, and creatinine clearance be monitored. Thus, buprenorphine appears to be the top‐line choice for opioid treatment in the elderly.
5. Opioids and respiratory depression: Respiratory depression is a significant threat for opioid‐treated patients with underlying pulmonary condition or receiving concomitant central nervous system (CNS) drugs associated with hypoventilation. Not all opioids show equal effects on respiratory depression: buprenorphine is the only opioid demonstrating a ceiling for respiratory depression when used without other CNS depressants. The different features of opioids regarding respiratory effects should be considered when treating patients at risk for respiratory problems, therefore careful dosing must be maintained.
6. Opioids and immunosuppression: Age is related to a gradual decline in the immune system: immunosenescence, which is associated with increased morbidity and mortality from infectious diseases, autoimmune diseases, and cancer, and decreased efficacy of immunotherapy, such as vaccination. The clinical relevance of the immunosuppressant effects of opioids in the elderly is not fully understood, and pain itself may also cause immunosuppression.
Providing adequate analgesia can be achieved without significant adverse events, opioids with minimal immunosuppressive characteristics should be used in the elderly. The immunosuppressive effects of most opioids are poorly described and this is one of the problems in assessing true effect of the opioid spectrum, but there is some indication that higher doses of opioids correlate with increased immunosuppressant effects. Taking into consideration all the very limited available evidence from preclinical and clinical work, buprenorphine can be recommended, while morphine and fentanyl cannot.
7. Safety and tolerability profile of opioids: The adverse event profile varies greatly between opioids. As the consequences of adverse events in the elderly can be serious, agents should be used that have a good tolerability profile (especially regarding CNS and gastrointestinal effects) and that are as safe as possible in overdose especially regarding effects on respiration. Slow dose titration helps to reduce the incidence of typical initial adverse events such as nausea and vomiting. Sustained release preparations, including transdermal formulations, increase patient compliance. ▪
Abstract The aim of this prospective, randomized, double-blinded study was to evaluate the effect of pulsed radiofrequency (PRF) in comparison with conventional radiofrequency (CRF) in the treatment ...of idiopathic trigeminal neuralgia. A total of 40 patients with idiopathic trigeminal neuralgia were included. The 20 patients in each group were randomly assigned to one of the two treatment groups. Each patient in the Group 1 was treated with CRF, whereas each patient in the Group 2 was treated by PRF. Evaluation parameters were: pain intensity using a Visual Analogue Scale (VAS), patient satisfaction using a Patient Satisfaction Scale (PSS), additional pharmacological treatment, side effects, and complications related to the technique. The VAS scores decreased significantly ( p < 0.001) and PSS improved significantly after the procedure in Group 1. The VAS score decreased in only 2 of 20 patients from the PRF group (Group 2) and pain recurrence occurred 3 months after the procedure. At the end of 3 months, we decided to perform CRF in Group 2, because all patients in this group still had intractable pain. After the CRF treatment, the median VAS score decreased ( p < 0.001) and PSS improved ( p < 0.001) significantly. In conclusion, the results of our study demonstrate that unlike CRF, PRF is not an effective method of pain treatment for idiopathic trigeminal neuralgia.
Interventional techniques are divided into two categories: neuroablative and neuromodulatory procedures. Neuroablation is the physical interruption of pain pathways either surgically, chemically or ...thermally. Neuromodulation is the dynamic and functional inhibition of pain pathways either by administration of opioids and other drugs intraspinally or intraventricularly or by stimulation. Neuroablative techniques for cancer pain treatment have been used for more than a century. With the development of imaging facilities such as fluoroscopy, neuroablative techniques can be performed more precisely and efficiently.
The percutaneus blockade of the celiac plexus is being performed nearly for a century. The aim of performing celiac plexus and splancnic nerve blocks was surgical anesthesia at the beginning. But ...because of the technical demands and variable results of celiac plexus and splanchnic nerve blocks as a surgical anesthetic, over time, these techniques were supplanted by spinal anesthesia and segmental blockade of the somatic paravertebral nerves. As celiac plexus and splanchnic nerve blocks were falling into disuse for surgical anesthesia, the clinical utility of these techniques was becoming apparent in the new specialty of pain management. Celiac plexus and splancnic nerve blocks are effective in relieving chronic abdominal pain, especially originating from the malignancies of the pancreas, liver, gallbladder, omentum, mesentery, and alimentary tract from the stomach to the transverse portion of the large colon. The relevant anatomy, indications, cotraindications, different application techniques and results of celiac blockade is reviewed in this paper.
