Old Friends With New Faces: Are Sodium Channel Blockers the Future of Adjunct Pain Medication Management?

Beyond Amitriptyline: A Pediatric and Adolescent Oriented Narrative Review of the Analgesic Properties of Psychotropic Medications for the Treatment of Complex Pain and Headache Disorders

Children and adolescents with recurrent or chronic pain and headache are a complex and heterogenous population. Patients are best served by multi-specialty, multidisciplinary teams to assess and create tailored, individualized pain treatment and rehabilitation plans. Due to the complex nature of pain, generalizing pharmacologic treatment recommendations in children with recurrent or chronic pains is challenging. This is particularly true of complicated patients with co-existing painful and psychiatric conditions. There is an unfortunate dearth of evidence to support many pharmacologic therapies to treat children with chronic pain and headache. This narrative review hopes to supplement the available treatment options for this complex population by reviewing the pediatric and adult literature for analgesic properties of medications that also have psychiatric indication. The medications reviewed belong to medication classes typically described as antidepressants, alpha 2 delta ligands, mood stabilizers, anti-psychotics, anti-sympathetic agents, and stimulants.

Palliation, end-of-life care and burns; practical issues, spiritual care and care of the family - A narrative review II

Palliative care is the turn from cure as the priority of care to symptom relief and comfort care. Although very little is published in the burn literature on palliative care, guidelines can be gleaned from the general literature on palliative care, particularly for acute surgical and critical care patients. This second article discusses practical issues around palliative care for burn patients, such as pain and fluid management, withdrawal of ventilator support and wound care, as well as spiritual and family issues. This paper forms part two, of two narrative reviews on the topic of palliation, end-of-life care and burns. The first part considered concepts, decision-making and communication. It was published in volume 10, issue 2, June 2020, pages 95–98.

•

Mortality of burns presented to a burns unit in Africa is about 10%.

•

Resources in Africa to manage burn patients are scarce and patients with massive burns may not be offered curative burn care.

•

There are no guidelines for palliative care in burn patients.

Pharmacological Management of Adults with Chronic Non-Cancer Pain in General Practice

Chronic pain is a public health priority that affects about 20% of the general population, causing disability and impacting productivity and quality of life. It is often managed in the primary care setting. Chronic pain management is most effective when the pain mechanism has been identified and addressed by appropriate therapy. This document provides an overview of pharmacological therapy for chronic non-cancer pain in the primary care setting, with the aim of improving treatment decisions based on the underlying pain mechanisms and pain neuroscience.

Guideline "diagnosis and non interventional therapy of neuropathic pain" of the German Society of Neurology (deutsche Gesellschaft für Neurologie)

2019 the DGN (Deutsche Gesellschaft für Neurology) published a new guideline on the diagnosis and non-interventional therapy of neuropathic pain of any etiology excluding trigeminal neuralgia and CRPS (complex regional pain syndrome). Neuropathic pain occurs after lesion or damage of the somatosensory system. Besides clinical examination several diagnostic procedures are recommended to assess the function of nociceptive A-delta and C-Fibers (skin biopsy, quantitative sensory testing, Laser-evoked potentials, Pain-evoked potentials, corneal confocal microscopy, axon reflex testing). First line treatment in neuropathic pain is pregabalin, gabapentin, duloxetine and amitriptyline. Second choice drugs are topical capsaicin and lidocaine, which can also be considered as primary treatment in focal neuropathic pain. Opioids are considered as third choice treatment. Botulinum toxin can be considered as a third choice drug for focal limited pain in specialized centers only. Carbamazepine and oxcarbazepine cannot be generally  recommended, but might be helpful in single cases. In Germany, cannabinoids can be prescribed, but only after approval of reimbursement. However, the use is not recommended, and can only be considered as off-label therapy within a multimodal therapy concept.

Neuropathic pain: preclinical and early clinical progress with voltage-gated sodium channel blockers

Introduction: Neuropathic pain is a chronic condition that significantly affects the quality of life of millions of people globally. Most of the pharmacologic treatments currently in use demonstrate modest efficacy and over half of all patients do not respond to medical management. Hence, there is a need for new, efficacious drugs. Evidence points toward voltage-gated sodium channels as a key target for novel analgesics.Area covered: The role of voltage-gated sodium channels in pain pathophysiology is illuminated and the preclinical and clinical data for new sodium channel blockers and toxin-derived lead compounds are examined. The expansion of approved sodium channel blockers is discussed along with the limitations of current research, trends in drug development, and the potential of personalized medicine.Expert opinion: The transition from preclinical to clinical studies can be difficult because of the inherent inability of animal models to express the complexities of pain states. Pain pathways are notoriously intricate and may be pharmacologically modulated at a variety of targets; it is unlikely that action at a single target could completely abolish a pain response because pain is rarely unifactorial. Combination therapy may be necessary and this could further confound the discovery of novel agents.

Bromelain reversed electrolyte imbalance in the chronically constricted sciatic nerve of Wistar rats

Derangement of electrolyte in the sensory nervous system has been attributed to the development and maintenance of hyperalgesic and allodynic symptoms in painful neuropathy. This study investigated the effect of bromelain on electrolyte imbalance in chronically constricted sciatic nerve of rats (a model of neuropathic pain). Forty Wistar rats, divided into five groups of eight animals each were used for this study. von Frey filaments, tail immersion and acetone spray tests were used to assessed allodynic and thermal hyperalgesic symptoms in the Wistar rats. Sodium ion (Na⁺), potassium ion (K⁺), calcium ion (Ca²⁺) and chloride ion (Cl^-) concentrations as well as sodium-potassium and calcium electrogenic pump (Na-K ATPase and Ca ATPase, respectively) activities were estimated using spectrophotometry techniques. Bromelain significantly (p < 0.05) reversed elevation of Na⁺ and Ca²⁺ concentration compared with sciatic nerve chronic constriction injury (snCCI) group (35.68 ± 1.71 vs 44.46 ± 1.24 mg/ml/mg protein and 1.06 ± 0.19 vs 6.66 ± 0.03 mg/ml/mg protein, respectively). There were also significant (p < 0.05) increases in the level of K⁺ (0.84 ± 0.02 vs 0.36 ± 0.05 mg/ml/mg protein) and Cl^- (18.51 ± 0.29 vs 15.82 ± 0.21 mg/ml/mg protein). Bromelain reduced the activities of Ca²⁺ electrogenic pumps significantly compared with snCCI. This study therefore suggests that bromelain mitigated electrolyte imbalance in chronic constricted injury of the sciatic nerve implying that this may be an important mechanism for the anti-nociceptive effect of bromelain.

Human Dorsal Root Ganglia

Sensory neurons with cell bodies situated in dorsal root ganglia convey information from external or internal sites of the body such as actual or potential harm, temperature or muscle length to the central nervous system. In recent years, large investigative efforts have worked toward an understanding of different types of DRG neurons at transcriptional, translational, and functional levels. These studies most commonly rely on data obtained from laboratory animals. Human DRG, however, have received far less investigative focus over the last 30 years. Nevertheless, knowledge about human sensory neurons is critical for a translational research approach and future therapeutic development. This review aims to summarize both historical and emerging information about the size and location of human DRG, and highlight advances in the understanding of the neurochemical characteristics of human DRG neurons, in particular nociceptive neurons.

PRERECORDED HYPNOTIC PERI-SURGICAL INTERVENTION TO ALLEVIATE RISK OF CHRONIC POSTSURGICAL PAIN IN TOTAL KNEE REPLACEMENT: A RANDOMIZED CONTROLLED PILOT STUDY

This pilot study evaluated the effect sizes associated with prerecorded hypnotic interventions provided during the perisurgical period for reducing risk factors associated with chronic postsurgical pain, including acute postsurgical pain, anxiety, depression, and pain catastrophizing. A total of 25 participants (N = -25) were randomly assigned to receive a hypnotic intervention (n = 8), minimal-effect treatment (n = 8), or treatment as usual (n = 9) during their hospital stay for total knee replacement (TKR). Participants were followed for 6 months after hospital discharge. Results indicate that prerecorded hypnotic intervention exerted medium effects for reducing acute postsurgical pain and large effects for reducing perisurgical anxiety and pain catastrophizing. The findings indicate that a fully powered clinical trial to evaluate the beneficial effects of prerecorded hypnosis to manage pain and psychological distress in patients undergoing TKR is warranted.

A novel gain-of-function Nav1.7 mutation in a carbamazepine-responsive patient with adult-onset painful peripheral neuropathy

Voltage-gated sodium channel Nav1.7 is a threshold channel in peripheral dorsal root ganglion (DRG), trigeminal ganglion, and sympathetic ganglion neurons. Gain-of-function mutations in Nav1.7 have been shown to increase excitability in DRG neurons and have been linked to rare Mendelian and more common pain disorders. Discovery of Nav1.7 variants in patients with pain disorders may expand the spectrum of painful peripheral neuropathies associated with a well-defined molecular target, thereby providing a basis for more targeted approaches for treatment. We screened the genome of a patient with adult-onset painful peripheral neuropathy characterized by severe burning pain and report here the new Nav1.7-V810M variant. Voltage-clamp recordings were used to assess the effects of the mutation on biophysical properties of Nav1.7 and the response of the mutant channel to treatment with carbamazepine (CBZ), and multi-electrode array (MEA) recordings were used to assess the effects of the mutation on the excitability of neonatal rat pup DRG neurons. The V810M variant increases current density, shifts activation in a hyperpolarizing direction, and slows kinetics of deactivation, all gain-of-function attributes. We also show that DRG neurons that express the V810M variant become hyperexcitable. The patient responded to treatment with CBZ. Although CBZ did not depolarize activation of the mutant channel, it enhanced use-dependent inhibition. Our results demonstrate the presence of a novel gain-of-function variant of Nav1.7 in a patient with adult-onset painful peripheral neuropathy and the responsiveness of that patient to treatment with CBZ, which is likely due to the classical mechanism of use-dependent inhibition.