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Compared to acute postsurgical pain, studies regarding the role of ketamine in persistent postsurgical pain (PPSP) are limited.
Cluster headache is characterised by attacks of excruciating unilateral headache or facial pain lasting 15 min to 3 h and is seen as one of the most intense forms of pain. Cluster headache attacks are accompanied by ipsilateral autonomic symptoms such as ptosis, miosis, redness or flushing of the face, nasal congestion, rhinorrhoea, peri-orbital swelling and/or restlessness or agitation. Cluster headache treatment entails fast-acting abortive treatment, transitional treatment and preventive treatment. The primary goal of prophylactic and transitional treatment is to achieve attack freedom, although this is not always possible. Subcutaneous sumatriptan and high-flow oxygen are the most proven abortive treatments for cluster headache attacks, but other treatment options such as intranasal triptans may be effective. Verapamil and lithium are the preventive drugs of first choice and the most widely used in first-line preventive treatment. Given its possible cardiac side effects, electrocardiogram (ECG) is recommended before treating with verapamil. Liver and kidney functioning should be evaluated before and during treatment with lithium. If verapamil and lithium are ineffective, contraindicated or discontinued because of side effects, the second choice is topiramate. If all these drugs fail, other options with lower levels of evidence are available (e.g. melatonin, clomiphene, dihydroergotamine, pizotifen). However, since the evidence level is low, we also recommend considering one of several neuromodulatory options in patients with refractory chronic cluster headache. A new addition to the preventive treatment options in episodic cluster headache is galcanezumab, although the long-term effects remain unknown. Since effective preventive treatment can take several weeks to titrate, transitional treatment can be of great importance in the treatment of cluster headache. At present, greater occipital nerve injection is the most proven transitional treatment. Other options are high-dose prednisone or frovatriptan.
There is a major unmet need to develop new therapies for migraine. We have previously demonstrated the therapeutic potential of the acid sensing ion channel (ASIC) blockade in migraine, via an ASIC1 mechanism. ASIC3 is expressed in the trigeminal ganglion and its response is potentiated by nitric oxide that can trigger migraine attacks in patients, and thus we sought to explore the potential therapeutic effect of ASIC3 blockade in migraine.
For decades, antihistamines have been the mainstay of treatment for chronic pruritus, yet they often only work by making patients drowsy and forgetful of their itch. A new era of antipruritic drugs is quickly approaching, presenting more effective treatments for patients suffering from chronic itch. Several treatments have been developed targeting specific receptors in the nervous system, such as the transient receptor potential channels, sodium channels, neurokinin-1 receptors, opioid receptors, and many more. Additionally, antipruritic therapies developed to work on the immune system have become more targeted, leading to greater safety and efficacy measures. These include crisaborole, several interleukin antagonists, and janus kinase inhibitors. The promising results presented with these new antipruritic therapies allow physicians to be better equipped to treat their itchy patients.
Increasing numbers survive cancers in childhood and adolescence. Long-term survivors of cancers in adulthood have increased prevalence of pain and consumption of analgesics. It is not established whether long-term survivors of cancers in childhood and adolescence also have an increased use of analgesics. However, based on increased use of antidepressants and anxiolytics in long-term survivors of cancers in childhood and adolescence, we hypothesized that this group also had increased use of analgesics. Based on data from the two nationwide registers the Cancer Registry of Norway and the Norwegian Prescription Database a cohort of 5585 (52% males) long-term survivors of cancers in childhood, adolescence and early adult life was established. Age and gender adjusted comparisons were made to the general population. The age adjusted one-year periodic prevalence of receiving prescriptions of opioids, benzodiazepines and benzodiazepine-related hypnotics in the study population was increased by 20-50% and the one-year periodic prevalence of receiving prescriptions of gabapentinoids was approximately increased two-fold compared to the general population. For paracetamol and NSAIDs no difference was found. For those survivors, who were persistent or high-dose users of opioids, co-medication with high doses of benzodiazepines and/or benzodiazepine-related hypnotics was far more common than among persistent and high-dose opioid users in the general population. The high prevalence of gabapentinoids may indicate increased prevalence of neuropathic pain in this group. The high degree of co-medication with benzodiazepines and/or benzodiazepine-related hypnotics in survivors on persistent and high-dose opioids might be an indication of problematic opioid use or addiction.
Improvements in the survival of breast cancer patients have led to the emergence of bone health and pain management as key aspects of patient's quality of life. Here, we used a female rat MRMT-1 model of breast cancer-induced bone pain to compare the effects of three drugs used clinically morphine, nabilone and zoledronate on tumor progression, bone remodeling and pain relief. We found that chronic morphine reduced the mechanical hypersensitivity induced by the proliferation of the luminal B aggressive breast cancer cells in the tumor-bearing femur and prevented spinal neuronal and astrocyte activation. Using MTT cell viability assay and MRI coupled to FDG PET imaging followed by ex vivo 3D µCT, we further demonstrated that morphine did not directly exert tumor growth promoting or inhibiting effects on MRMT-1 cancer cells but induced detrimental effects on bone healing by disturbing the balance between bone formation and breakdown. In sharp contrast, both the FDA-approved bisphosphonate zoledronate and the synthetic cannabinoid nabilone prescribed as antiemetics to patients receiving chemotherapy were effective in limiting the osteolytic bone destruction, thus preserving the bone architecture. The protective effect of nabilone on bone metabolism was further accompanied by a direct inhibition of tumor growth. As opposed to zoledronate, nabilone was however not able to manage bone tumor-induced pain and reactive gliosis. Altogether, our results revealed that morphine, nabilone and zoledronate exert disparate effects on tumor growth, bone metabolism and pain control. These findings also support the use of nabilone as an adjuvant therapy for bone metastases.
Analgesia induced by stressful and painful stimuli is an adaptive response during life-threatening situations. There is no evidence linking the mechanisms underlying them, while the former depends on the activation of stress-related brain pathways, the second depends on opioidergic mechanisms in the nucleus accumbens and on nicotinic cholinergic mechanisms in the rostral ventromedial medulla. In this study, we hypothesized that stress-induced analgesia is also dependent on opioidergic mechanisms in the nucleus accumbens and on nicotinic cholinergic mechanisms in the rostral ventromedial medulla. We used immobilization, a classical procedure to induce acute stress, and evaluated its ability to decrease the nociceptive responses induced either by carrageenan or by formalin in rats. Immobilization stress significantly decreased either carrageenan-induced hyperalgesia or formalin-induced tonic nociception in a time-dependent manner. This stress-induced analgesia is similar to pain-induced analgesia, as revealed by contrasting the antinociceptive effect induced by immobilization and by a forepaw injection of capsaicin. The administration of a µ-opioid receptor antagonist (CTOP, 0.5 µg) into the nucleus accumbens, as well as that of a nicotinic cholinergic receptor antagonist (mecamylamine, 0.6 µg) into the rostral ventromedial medulla, blocked immobilization stress-induced analgesia in both pain models. These results demonstrate that supraspinal mechanisms which are known to mediate pain-induced analgesia also mediate stress-induced analgesia. Therefore both forms of analgesia have overlapping mechanisms, probably recruited in response to the perception of danger.
Intrathecal drug delivery appeared in the early eighties and allows to administer high concentrate analgesic medications in the cerebrospinal fluid with higher efficacy and a limited incidence of systemic side effects. Opioids are still the first line treatment with high-quality evidence for chronic cancer pain, and limited evidence for chronic non-cancer pain, being often considered as a last resort therapy. Device implantation requires a strict patient's selection with a close follow-up in order to adapt therapy, refill the reservoir and detect and prevent potential severe complications.
Electroconvulsive therapy (ECT) has been applied for chronic pain for decades. The amounts of opioids to treat pain are sometimes reduced after a series of ECT. The effect of ECT on morphine-induced analgesia and its mechanism underlying the reduction of morphine requirement has yet to be clarified. Therefore, we administered electroconvulsive shocks (ECS) to mice and investigated the antinociceptive effect of morphine in a hot plate test. We examined the expression level of µ-opioid receptor in the thalami of mice 25 h after administration of ECS compared to the thalami of mice without ECS administration using western blotting. ECS disturbed the development of a decrease in the percentage of maximal possible effect (%MPE), which was observed 24 h after a morphine injection, when ECS was applied 25, 23, 21, and 12 h before the second administration of morphine. We also examined the effect of ECS on the dose-response curve of %MPE to morphine-antinociception. Twenty-five hours after ECS, the dose-response curve was shifted to the left, and the EC of morphine given to ECS-pretreated mice decreased by 30.1% compared to the mice that were not pretreated with ECS. We also found that the expression level of µ-opioid receptors was significantly increased after ECS administration. These results confirm previous clinical reports showing that ECT decreased the required dose of opioids in neuropathic pain patients and suggest the hypothesis that this effect of ECT works through the thalamus.
Chronic low back pain (CLBP) is one of the most common chronic pain conditions in pain practice.