Botulinum Toxin for the Treatment of Neuropathic Pain

Development and characterization of a novel neutralizing scFv vectored immunoprophylaxis against botulinum toxin type A

Botulinum toxin is a protein toxin secreted by Clostridium botulinum that is strongly neurotoxic. Due to its characteristics of being super toxic, quick acting, and difficult to prevent, the currently reported antiviral studies focusing on monoclonal antibodies have limited effectiveness. Therefore, for the sake of effectively prevention and treatment of botulism and to maintain country biosecurity as well as the health of the population, in this study, we intend to establish a single chain antibody (scFv) targeting the carboxyl terminal binding functional domain of the botulinum neurotoxin heavy chain (BONT/AHc) of botulinum neurotoxin type A, and explore the value of a new passive immune method in antiviral research which based on adeno-associated virus (AAV) mediated vector immunoprophylaxis (VIP) strategy. The scFv small-molecular single-chain antibody sequenced, designed, constructed, expressed and purified by hybridoma has high neutralising activity and affinity level, which can lay a good foundation for the modification and development of antibody engineering drugs. In vivo experiments, AAV-mediated scFv engineering drug has good anti-BONT/A toxin neutralisation ability, has advantages of simple operation, stable expression and good efficacy, and may be one of the effective treatment strategies for long-term prevention and protection of BONT/A botulinum neurotoxin.

Analgesic effect of Botulinum toxin in neuropathic pain is sodium channel independent

Botulinum neurotoxin type A BoNT/A is used off-label as a third line therapy for neuropathic pain. However, the mechanism of action remains unclear. In recent years, the role of voltage-gated sodium channels (Nav) in neuropathic pain became evident and it was suggested that block of sodium channels by BoNT/A would contribute to its analgesic effect. We assessed sodium channel function in the presence of BoNT/A in heterologously expressed Nav1.7, Nav1.3, and the neuronal cell line ND7/23 by high throughput automated and manual patch-clamp. We used both the full protein and the isolated catalytic light chain LC/A for acute or long-term extracellular or intracellular exposure. To assess the toxin's effect in a human cellular system, we differentiated induced pluripotent stem cells (iPSC) into sensory neurons from a healthy control and a patient suffering from a hereditary neuropathic pain syndrome (inherited erythromelalgia) carrying the Nav1.7/p.Q875E-mutation and carried out multielectrode-array measurements. Both BoNT/A and the isolated catalytic light chain LC/A showed limited effects in heterologous expression systems and the neuronal cell line ND7/23. Spontaneous activity in iPSC derived sensory neurons remained unaltered upon BoNT/A exposure both in neurons from the healthy control and the mutation carrying patient. BoNT/A may not specifically be beneficial in pain syndromes linked to sodium channel variants. The favorable effects of BoNT/A in neuropathic pain are likely based on mechanisms other than sodium channel blockage and new approaches to understand BoNT/A's therapeutic effects are necessary.

Peripheral and central neurobiological effects of botulinum toxin A (BoNT/A) in neuropathic pain: a systematic review

ABSTRACT

Botulinum toxin (BoNT), a presynaptic inhibitor of acetylcholine (Ach) release at the neuromuscular junction (NMJ), is a successful and safe drug for the treatment of several neurological disorders. However, a wide and recent literature review has demonstrated that BoNT exerts its effects not only at the "periphery" but also within the central nervous system (CNS). Studies from animal models, in fact, have shown a retrograde transport to the CNS, thus modulating synaptic function. The increasing number of articles reporting efficacy of BoNT on chronic neuropathic pain (CNP), a complex disease of the CNS, demonstrates that the central mechanisms of BoNT are far from being completely elucidated. In this new light, BoNT might interfere with the activity of spinal, brain stem, and cortical circuitry, modulating excitability and the functional organization of CNS in healthy conditions. Botulinum toxins efficacy on CNP is the result of a wide and complex action on many and diverse mechanisms at the basis of the maladaptive plasticity, the core of the pathogenesis of CNP. This systematic review aims to discuss in detail the BoNT's mechanisms and effects on peripheral and central neuroplasticity, at the basis for the clinical efficacy in CNP syndromes.

Evaluation of the Effect of Botulinum Toxin A on the Lymphatic Endothelial Cells

INTRODUCTION

Botulinum toxin A (BoTA) is a neurotoxin formed by Clostridium botulinum, with a broad medical application spectrum. While the primary effect of BoTA is on the muscles, the effects of BoTA in other systems including the blood vasculature have already been examined, revealing unexpected actions. However, no studies exist to the best of our knowledge regarding the potential effects of BoTA on the lymphatic vascular system, possessing a critical role in health and disease. Isolated human lymphatic endothelial cells (LECs) were cultured in dedicated in vitro culture systems. The analysis including imaging and cell culture approaches as well as molecular biology techniques is performed to examine the LEC alterations occurring upon exposure to different concentrations of BoTA.

MATERIALS AND METHODS

Human LECs were cultured and expanded on collagen-coated petri dishes using endothelial basal medium and the commercial product Botox from Allergan as used for all our experiments. Harvested cells were used in various in vitro functional tests to assess the morphologic and functional properties of the BoTA-treated LECs. Gene expression analysis was performed to assess the most important lymphatic system-related genes and pathways.

RESULTS

Concentrations of 1, 5 or 10 U of BoTA did not demonstrate a significant effect regarding the proliferation and migration capacity of the LECs versus untreated controls. Interestingly, even the smallest BoTA dose was found to significantly decrease the cord-like-structure formation capacity of the seeded LECs. Gene expression analysis was used to underpin possible molecular alterations, suggesting no significant effect of BoTA in the modification of gene expression versus the starvation medium control.

CONCLUSION

LECs appear largely unaffected to BoTA treatment, with an isolated effect on the cord-like-structure formation capacity. Further work needs to assess the effect of BoTA on the smooth-muscle-cell-covered collecting lymphatic vessels and the possible aesthetic implications of such an effect, due to edema formation.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Evaluation of Botox treatment in patients with chronic scrotal pain: Protocol for a randomized double-blinded control trial

Background

Chronic scrotal pain is a common condition with a prevalence of 2.5-4.8% in male outpatients. Up to 40% of these patients report depressive symptoms and many feel isolated. Minimal invasive treatment is lacking, while spermatic cord injections of Botox® (BTX) have been proposed to offer long-term pain relief.

Study Design

This research protocol comprises a prospective multicentre, randomized, double-blinded clinical trial drawing patients from other urological departments in the region of Southern Denmark.

End Points

The primary end point will be reduction in pain evaluated by visual analogue score for pain at 3 months. Secondary end point will be length of effect of BTX injections along with changes in quality of life.

Patients and Methods

The study will include 50 patients for randomization to either spermatic cord block with 100 IE BTX or sterile saline. All patients will prior to randomization undergo physical examination and will be asked to fulfil multiple questionnaires regarding pain and impact in daily life, that is, (1) visual analogue score for pain, (2) quality of life (EQ-5D-5L), (3) Chronic Prostatitis Symptom Index (NIH-CPSI), (4) ICD-10 depression questionnaire (MDI), (5) Likert global assessment scale, and (6) International Index of Erectile Function questionnaire. Physical examination and fulfilment of the questionnaires will be repeated multiple times throughout the study period of 12 weeks. After this time point, patients will be unblinded, and the control arm will be given the opportunity of cross-over.

Treating neuropathic pain and comorbid affective disorders: Preclinical and clinical evidence

INTRODUCTION

Neuropathic pain (NP) significantly impacts quality of life and often coexists with affective disorders such as anxiety and depression. Addressing both NP and its psychiatric manifestations requires a comprehensive understanding of therapeutic options. This study aimed to review the main pharmacological and non-pharmacological treatments for NP and comorbid affective disorders to describe their mechanisms of action and how they are commonly used in clinical practice.

METHODS

A review was conducted across five electronic databases, focusing on pharmacological and non-pharmacological treatments for NP and its associated affective disorders. The following combination of MeSH and title/abstract keywords were used: "neuropathic pain," "affective disorders," "depression," "anxiety," "treatment," and "therapy." Both animal and human studies were included to discuss the underlying therapeutic mechanisms of these interventions.

RESULTS

Pharmacological interventions, including antidepressants, anticonvulsants, and opioids, modulate neural synaptic transmission to alleviate NP. Topical agents, such as capsaicin, lidocaine patches, and botulinum toxin A, offer localized relief by desensitizing pain pathways. Some of these drugs, especially antidepressants, also treat comorbid affective disorders. Non-pharmacological techniques, including repetitive transcranial magnetic stimulation, transcranial direct current stimulation, and photobiomodulation therapy, modulate cortical activity and have shown promise for NP and mood disorders.

CONCLUSIONS

The interconnection between NP and comorbid affective disorders necessitates holistic therapeutic strategies. Some pharmacological treatments can be used for both conditions, and non-pharmacological interventions have emerged as promising complementary approaches. Future research should explore novel molecular pathways to enhance treatment options for these interrelated conditions.

Recent Developments in Engineering Non-Paralytic Botulinum Molecules for Therapeutic Applications

This review discusses the expanding application of botulinum neurotoxin in treating neurological conditions. The article specifically explores novel approaches to using non-paralytic botulinum molecules. These new molecules, such as BiTox or el-iBoNT, offer an alternative for patients who face limitations in using paralytic forms of botulinum neurotoxin due to concerns about muscle function loss. We highlight the research findings that confirm not only the effectiveness of these molecules but also their reduced paralytic effect. We also discuss a potential cause for the diminished paralytic action of these molecules, specifically changes in the spatial parameters of the new botulinum molecules. In summary, this article reviews the current research that enhances our understanding of the application of new botulinum neurotoxins in the context of common conditions and suggests new avenues for developing more efficient molecules.

Cellular and molecular mechanisms involved in the analgesic effects of botulinum neurotoxin: A literature review

Botulinum neurotoxins (BoNTs), derived from Clostridium botulinum, have been employed to treat a range of central and peripheral neurological disease. Some studies indicate that BoNT may be beneficial for pain conditions as well. It has been hypothesized that BoNTs may exert their analgesic effects by preventing the release of pain-related neurotransmitters and neuroinflammatory agents from sensory nerve endings, suppressing glial activation, and inhibiting the transmission of pain-related receptors to the neuronal cell membrane. In addition, there is evidence to suggest that the central analgesic effects of BoNTs are mediated through their retrograde axonal transport. The purpose of this review is to summarize the experimental evidence of the analgesic functions of BoNTs and discuss the cellular and molecular mechanisms by which they can act on pain conditions. Most of the studies reviewed in this article were conducted using BoNT/A. The PubMed database was searched from 1995 to December 2022 to identify relevant literature.

Evaluation of therapeutic benefits of botulinum toxin for foot dystonia associated with Parkinson's disease

BACKGROUND

Foot dystonia occurs in patients with Parkinson's disease (PD) and leads to pain, malformation, and difficulty with walking. Botulinum toxin injections may be effective for foot dystonia, but the extent of improvement and effects on motor function are unclear.

METHODS

In this study, we performed botulinum toxin injections for foot dystonia in 25 patients with PD. At 3 weeks and 3 months post-infection, we assessed changes in plantar pressure distribution utilizing the Pressure Plate system; dystonia using the Modified Ashworth Spasm score; pain using the visual analog scale (VAS) score; and lower extremity function using the Calf-raise Senior (CRS) test, Timed Up and Go (TUG) test, and gait parameters (eg, stride length, step length).

RESULTS

We found improved Modified Ashworth Spasm score (p < 0.01) and VAS score (p < 0.01) post-injection. CRS test score (3 weeks, p = 0.006; 3 months, p = 0.068), stride length (3 weeks, p = 0.012; 3 months, p = 0.715), and step length (3 weeks, p = 0.011; 3 months, p = 0.803) also improved. Plantar pressure distribution improved after botulinum toxin injection (metatarsal 1, 3 weeks, p = 0.031; 3 months, p = 0.144; metatarsal 2, 3 weeks, p = 0.049; 3 months, p = 0.065; metatarsal 3, 3 weeks, p = 0.002; 3 months, p = 0.017; metatarsal 4, 3 weeks, p = 0.017; 3 months, p = 0.144; medial heel, 3 weeks, p = 0.01; 3 months, p = 0.395; lateral heel, 3 weeks, p = 0.035; 3 months, p = 0.109).

CONCLUSION

Botulinum toxin injection for foot dystonia in patients with PD can reduce spasms and pain and normalize plantar pressure distribution, which improves balance and lower extremity function.

A Pathophysiological Approach for Selecting Medications to Treat Nociceptive and Neuropathic Pain in Servicemembers

INTRODUCTION

The prevalence of chronic pain of service members (SMs) in the U.S. is estimated to be higher (roughly 31-44%) compared to that of civilian population (26%). This higher prevalence is likely due to the high physical demands related combat and training injuries that are not immediately resolved and worsen over time. Mental Health America reports that chronic pain can lead to other mental health conditions such as severe anxiety, depression, bipolar disorder, and post-traumatic stress disorder. Such mental health conditions can negatively affect job performance, reduce readiness for military duties, and often lead to patterns of misuse of opioid after SMs entering civilian life. The primary objective of this narrative review is to present a summarized guideline for the treatment of two types of pain that likely affect SMs, namely nociceptive somatic pain and neuropathic pain. This review focused on a stepwise approach starting with nonopioid interventions prior to opioid therapy. The secondary objective of this review is to elucidate the primary mechanisms of action and pathways associated with these two types of pain.

METHODS

We followed the Scale for Assessment of Narrative Review Articles when transcribing this narrative review article to enhance the quality and brevity of this review. This Scale has 0.77% an intra-class coefficient of correlation, 95% confidence interval and 0.88 inter-rater reliability. We searched PubMed, Google Scholar, WorldCAT, and the Cochrane Library for the primary and secondary articles that targeted mechanisms of action, pathways, and pharmacological modalities for nociceptive somatic and neuropathic pain that were published from 2011 to 2022. We excluded articles related to pediatric, some specific pain conditions such as cancer-related pain, palliative care, end-of-life care, and articles that were not written in English language. For pharmacologic selection, we adopted the guidelines from the Policy for Implementation of a Comprehensive Policy on Pain Management by the Military Health Care system for the Fiscal Year 2021; the Clinical Practice Guidance for Opioid Therapy for Chronic Pain by the Department of Defense/Veterans Health Administration (2022); the (2021) Implementation of a Comprehensive Policy on Pain Management by the Military Health Care System; and the (2022) Guideline for Prescribing Opioids for Chronic Painby the Centers for Disease Control.

DISCUSSION

From the knowledge of the mechanisms of action and pathways, we can be more likely to identify the causative origins of pain. As a result, we can correctly diagnose the type of pain, properly develop an efficient and personalized treatment plan, minimize adverse effects, and optimize clinical outcomes. The guideline, however, does not serve as a substitute for clinical judgment in patient-centered decision-making. Medication choices should be individualized judiciously based on the patient's comorbid conditions, available social and economic resources, and the patient's preferences to balance the benefits and risks associated with various pain medications and to achieve optimal pain relief and improve the patient's quality of life.

Biopsychosocial approach to male chronic pelvic pain syndrome: recent treatments and trials

INTRODUCTION

Chronic pelvic pain syndrome (CPPS) is a common urologic condition that can cause significant disability in affected individuals. Physiologic explanations of chronic pain are often incomplete; appropriate management of CPPS includes recognition of biological, psychological, and social elements, known as the biopsychosocial model.

OBJECTIVE

The aim of this narrative review is to investigate treatments for men with CPPS, with a special focus on those utilizing the biopsychosocial model of care.

METHODS

A comprehensive literature search was conducted on the electronic databases PubMed, Embase, and Cochrane Library, using relevant Medical Subject Heading terms and keywords related to CPPS treatments. The search was limited to studies published in English from inception to January 2023. Additionally, reference lists of selected studies were manually reviewed to find studies not identified by the initial search. Studies were included if they investigated pharmacologic or nonpharmacologic treatments for men with CPPS.

RESULTS

A total of 30 studies met the inclusion criteria. Antibiotics, α-blockers, nonsteroidal anti-inflammatory drugs, gabapentinoids, antidepressants, and phosphodiesterase type 5 inhibitors were among the pharmacologic agents included in trials attempting to reduce symptoms of male CPPS. Studies that focused on treating CPPS without medication included interventions such as shockwave therapy, acupuncture, physical therapy, botulinum toxin, cryotherapy, electrotherapy, exercise, and cognitive behavioral therapy.

CONCLUSION

α-Blockers and nonsteroidal anti-inflammatory drugs have shown promising results in treating CPPS in men, while the effectiveness of antibiotics remains controversial. Antidepressants and phosphodiesterase type 5 inhibitors may also be useful in decreasing symptoms in patients with CPPS. Treatments such as pelvic floor muscle therapy, acupuncture, shockwave therapy, and cognitive behavioral therapy must be considered effective complements to medical management in men with CPPS. While these interventions demonstrate benefits as monotherapies, the individualization and combination of treatment modalities are likely to result in reduced pain and improved quality of life.

The analgesic effects of dezocine in rats with chronic constriction injuries

Neuropathic pain (NP) is caused by diseases or dysfunction of nervous system and has a considerable negative impact on patients' quality of life. Opioid analgesics can be used for NP treatment. However, the effect of dezocine on NC remains unknown. In this study, we aimed to investigate the analgesic and intestinal effects of various doses of dezocine in rats with chronic constriction injuries (CCI). 100 rats were equally divided into 5 groups: the low (D1 group), medium (D2 group), and high (D3 group) doses of dezocine, and sham operation and model groups. The effects of dezocine on pain, analgesic effect, pain response, and tension and contraction frequencies of intestinal smooth muscles were assessed. With an increase in the dezocine dosage, the cumulative pain scores of rats decreased and analgesic effect significantly increased; mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) improved in varying degrees. The expression of the NP-related proteins glial fibrillary acidic protein (GFAP) and connexin 43 (Cx43) was also improved by dezocine treatment. The results of western blot and ELISA showed that IL-6, and monocyte chemotactic protein-1 (MCP-1) levels also decreased significantly with an increase in the dezocine dose, indicated that dezocine alleviated the inflammatory microenvironment. The dezocine exhibited no significant effect on the tension or contraction frequencies of intestinal smooth muscles of rats. In conclusion, the analgesic effect of dezocine on rats with CCI is dose-dependent and has little effect on the tension or contraction frequencies of intestinal smooth muscles. Our research proved the analgesic effect of dezocine in rats with CCI, and provided further insights into new therapies for NP treatment.

Botulinum Toxin Type a for Treating Rest Pain in Chronic Limb-threatening Ischemia: A Case Report

Botulinum toxin type A (BoNT/A) is a potent neurotoxin with widely use range, for the good outcomes in the treatment of pain, it was considered as an unique analgesic drugs with the feature of sustained efficacy after a single application, but up to now, treating chronic limb-threatening ischemia (CLTI) with BoNT/A was rarely reported. We present a 91-year-old man with CLTI, the main clinical manifestations were left foot rest pain, intermittent claudication and toe necrosis, the patient refused invasive treatments, and the pain failure to respond to conventional analgesic drugs, the subcutaneous injections of BoNT/A was performed to the patient. The pain score on the visual analog scale (VAS), decreased from 5-6 (before treatment) to 1 within days after infiltration, and keep in 1-2 of VAS during follow-up. Our case report demonstrated that BoNT/A may be an unique minimally invasive solution for treating rest pain in CLTI.

Neuropathic pain: From actual pharmacological treatments to new therapeutic horizons

Neuropathic pain, caused by a lesion or disease affecting the somatosensory system, affects between 3 and 17% of the general population. The treatment of neuropathic pain is challenging due to its heterogeneous etiologies, lack of objective diagnostic tools and resistance to classical analgesic drugs. First-line treatments recommended by the Special Interest Group on Neuropathic Pain (NeuPSIG) and European Federation of Neurological Societies (EFNS) include gabapentinoids, tricyclic antidepressants (TCAs) and selective serotonin noradrenaline reuptake inhibitors (SNRIs). Nevertheless these treatments have modest efficacy or dose limiting side effects. There is therefore a growing number of preclinical and clinical studies aim at developing new treatment strategies to treat neuropathic pain with better efficacy, selectivity, and less side effects. In this review, after a brief description of the mechanisms of action, efficacy, and limitations of current therapeutic drugs, we reviewed new preclinical and clinical targets currently under investigation, as well as promising non-pharmacological alternatives and their potential co-use with pharmacological treatments.

Botulinum Toxin Injections as a Treatment of Refractory Vulvodynia in Adolescents: A Case Series

BACKGROUND

Vulvodynia involves vulvar discomfort that occurs in the absence of an identifiable cause. Because vulvodynia is often accompanied by myofascial pain and pelvic floor tension, transvaginal botulinum toxin (BT) injection into the pelvic floor has been proposed as a possible treatment.

METHODS

Retrospective case series RESULTS: Three adolescents with vulvodynia had a suboptimal response to treatment with several interventions, including neuromodulators (oral and topical), tricyclic antidepressants (oral and topical), and pelvic floor physical therapy. Subsequently, these patients underwent BT injections to the pelvic floor as treatment with varying responses.

CONCLUSION

In select adolescent patients with vulvodynia, transvaginal BT injection into the pelvic floor can be an effective treatment. Further studies are needed to assess the optimal dosing, frequency, and sites of BT injections in the treatment of vulvodynia in pediatric and adolescent patients.

Intrathecal Injection of Botulinum Toxin Type A has an Analgesic Effect in Male Rats CCI Model by Inhibiting the Activation of Spinal P2X4R

Purinergic receptor P2X4 (P2X4R) plays an essential role in neuropathic pain. However, the specific mechanism needs to be clarified. Botulinum toxin type A is a neurotoxin produced by Clostridium botulinum type A. This study found that intrathecal injection of botulinum toxin type A produced an excellent analgesic effect in a rat model of chronic constriction sciatic nerve injury and inhibited the activation of P2X4R, microglia, and astrocytes. The administration of a P2X4R activator can up-regulate the expression of P2X4R and eliminate the analgesic effect of intrathecal injection of botulinum toxin type A. In addition, we found that microglia and astrocytes in the spinal cord of rats injected with botulinum toxin type A were reactivated after administration of the P2X4R activator. Our results suggest that intrathecal injection of botulinum toxin type A has an analgesic effect in a rat model of chronic constriction sciatic nerve injury by inhibiting the activation of P2X4R in the spinal cord.

Non-Surgical Treatments of Trigeminal Neuralgia from the Perspective of a Pain Physician: A Narrative Review

Trigeminal neuralgia (TN) is a unilateral disorder characterized by electric shock-like pain, abrupt onset and termination, and limited to one or more branches of the trigeminal nerve. Various therapeutic modalities for TN have been introduced. We searched for literature indexed in PubMed, Medline, and the National Library of Medicine and reviewed all relevant articles on non-surgical treatments for TN. Published studies were reviewed with no restrictions on date; reviews, clinical trials, animal studies, retrospective studies, and cases were included. Carbamazepine and oxcarbazepine are the recommended first-line pharmacotherapies. Interventional treatments should be considered when pharmacotherapy is insufficient or withdrawn because of adverse effects.

Treatment and Improvement of Healing after Surgical Intervention

The development of abnormal scars has a great impact on people's well-being, and improving scarring outcomes after surgery is a field that currently lacks consensus. This review aims to identify newly researched approaches to improving the quality of surgical scars. A systematic search of PubMed, Scopus, Web of Science, and ScienceDirect was conducted between 13 May 2023 and 17 May 2023, in accordance with the recommendations of the PRISMA Statement. Study selection and analysis of methodological quality were performed in parts, independently and blindly, based on eligibility criteria. The 21 prospective, comparative, and randomized studies reviewed included 1057 subjects and studied approaches such as topical applications of creams with herbal extracts and silicone gels, growth factors, negative pressure dressings, oligonucleotides, intralesional injection of compounds such as botulinum toxin, skin closure techniques such as suturing and tissue adhesive, and laser treatments. There are recent research techniques that generate good results and are really promising to improve the results of surgical scars; however, the available evidence is extremely limited in some cases, and it is necessary to deepen its analysis to obtain reliable action protocols in each type of surgery.

Dolichoectasia of vertebrobasilar artery presenting as facial pain: a case report

Dolichoectasia of the intracranial arteries is a rare condition characterized by elongated and tortuous arteries due to progressive destruction of the vessel walls. Although most patients present with cerebrovascular accidents, our patient presented with intractable facial pain along the distribution of the trigeminal nerve. Clinical examination revealed involvement of the 5th, 7th, and 8th cranial nerves, and subsequent MRI showed dolichoectasia of the left basilar artery. The patient experienced symptomatic relief after a trial of carbamazepine along with botulinum toxin injections.

Bruxism and Botulinum Injection: Challenges and Insights

Botulinum toxin (BTA) is a bacterial-derived extract that can inhibit muscle contraction, acting directly on the absorption of acetylcholine. Thanks to this property, botulinum has been used in aesthetic and general medicine for several years. Nowadays, the use of botulinum toxin is being deepened to address the problem of bruxism. In this scoping review, the results of the studies in the literature of the last 10 years were analyzed. Indeed, 12 reports (found on PubMed, Web of Science, and Scopus, entering the keywords "BRUXISM" and "BOTULINUM TOXIN") were deemed eligible for inclusion in this review. In the studies reviewed, BTA was injected into different muscle groups: masseters, masseter and temporalis or masseter, temporalis, and medial pterygoid. Botulinum toxin injection is a viable therapeutic solution, especially in patients with poor compliance or without improvement in conventional treatment.

Botulinum toxin type A for genitofemoral neuralgia: A case report

Genitofemoral neuralgia is an uncommon pain disorder that could be resistant to conventional treatment. A 78-year-old woman with refractory right genitofemoral neuralgia was treated with BoNT/A subcutaneous injections; the treatment was performed three times with significant pain improvement, although temporary, and without adverse events. BoNT/A may be a promising alternative intervention in the setting of genitofemoral neuralgia refractory to oral and/or topical treatment.

Botulinum Toxins and Zinc: From Theory to Practice-A Systematic Review

OBJECTIVE

The aims of this study were to determine whether zinc supplementation affects botulinum toxin's effect and longevity and to establish a transition from the molecular to the clinical aspect.

METHODS

We conducted a systematic review in which we included all published studies on PubMed and Embase using the combination of the following terms: "zinc" AND (botox OR botulinum OR onabotulinumtoxinA OR abobotulinumtoxinA OR incobotulinumtoxinA).

RESULTS

From the 260 yielded articles, 3 randomized control trials and 1 case report were retained. Three of them found a significant improvement with zinc supplementation in the toxin's effect and longevity. This was observed in neurological conditions and cosmetic uses.

CONCLUSIONS

Zinc supplementation could be an interesting asset in the potentialization of botulinum neurotoxin effect and longevity. Larger clinical trials and objective measurement tools should be used to further defining the role of zinc in maximizing botulinum neurotoxin effect.

Efficacy and safety of botulinum toxin for treating motor dysfunction in patients with Parkinson's disease: a systematic review and meta-analysis

OBJECTIVE

To evaluate the efficacy and safety of botulinum toxin (BTX) for motor dysfunction in Parkinson's disease (PD).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Searches of PubMed, EMBASE and the Cochrane Library, from database inception to 20 October 2022.

ELIGIBILITY CRITERIA

Studies reported in English with adult PD patients treated with BTX.

DATA EXTRACTION AND SYNTHESIS

Primary outcomes were United Parkinson's Disease Rate Scale Section (UPDRS) III (or its items) and Visual Analogue Scale (VAS). Secondary outcomes were UPDRS-II (or its items), Freezing of Gait Questionnaire (FOG-Q), Timed Up and Go test (TUG) and treatment-related adverse events (TRAEs). Mean difference (MD) or standardised MD (SMD) before and after treatment with 95% CIs were used for continuous variables and risk ratios (RRs) with 95% CIs was used for TRAEs.

RESULTS

Six randomised controlled trials (RCTs) and six non-RCTs (case series) were included (ntotal=224 participants, nRCT=165). No significant difference was found in pooled results of UPDRS-III (available in four RCTs and two non-RCTs, SMD=-0.19, 95% CI -0.98 to 0.60), UPDRS-II (four RCTs and one non-RCT, SMD=-0.55, 95% CI -1.22 to 0.13), FOG-Q (one RCT and one non-RCT, SMD=0.53, 95% CI -1.93 to 2.98) or the risk of TRAEs (five RCTs, RR 0.87, 95% CI 0.37 to 2.01). Significant decreases were found in pooled VAS score (three RCTs and five non-RCTs, MD=-2.14, 95% CI -3.05 to -1.23) and TUG (MD=-2.06, 95% CI -2.91 to -1.20) after BTX treatment.

CONCLUSIONS

BTX may not be associated with motor symptoms alleviation, although it benefits pain alleviation and functional mobility improvement.

Botulinum Toxin Type A for the Treatment of Auriculotemporal Neuralgia-A Case Series

Auriculotemporal neuralgia is a rare pain disorder in which anesthetic nerve blockade is usually effective but not always resolutive. Botulinum toxin type A has proven to be effective in treating neuropathic pain, and patients with auriculotemporal neuralgia could also benefit from this treatment. We described nine patients with auriculotemporal neuralgia treated with botulinum toxin type A in the territory of auriculotemporal nerve innervation. We compared the basal NRS and Penn facial pain scale scores with those obtained 1 month after BoNT/A injections. Both Penn facial pain scale (96.67 ± 24.61 vs. 45.11 ± 36.70, p 0.004; mean reduction 52.57 ± 36.50) and NRS scores (8.11 ± 1.27 vs. 4.22 ± 2.95, p 0.009; mean reduction 3.89 ± 2.52) improved significantly at one month after treatment. The mean duration of the effect of BoNT/A on pain was 95.00 ± 53.03 days and no adverse effects were reported.

[Thermal radiofrequency as an alternative in the treatment of persistent localized neuropathic pain due to entrapment of a collateral nerve of the hand]

Localized neuropathic pain (LNP) is a relatively common cause of musculoskeletal pain, which can be present in up to 60% of neuropathic pain conditions. Its appearance can be associated with numerous pathologies (herpes, diabetes, etc.). A less common cause would be the direct compression of a peripheral nerve branch. Its diagnosis is usually clinical since complementary tests such as neurophysiological tests do not provide definitive data. As therapeutic measures we have oral analgesics, anticonvulsants, analgesic skin patches and interventional actions, including radiofrequency (RF). Thermal RF consists in the transmission of an electric impulse through a needle reaching a controlled increase in temperature with which a nerve ablative injury is achieved. We present a clinical case where thermal RF of the collateral nerve of the hand is proposed as a therapeutic alternative, whose entrapment is the cause of pain, obtaining a satisfactory clinical improvement.

Temporomandibular Disorder Treated With Chiropractic Therapy

Temporomandibular disorders (TMDs) are common and affect the temporomandibular joint (TMJ) and surrounding musculoskeletal tissues. Although traditional rehabilitative treatments such as physiotherapy, occlusal splints, orthodontics, and electrotherapy effectively manage TMDs, chiropractic therapy is emerging as a promising non-invasive treatment option. We report a 39-year-old female patient with TMD who underwent chiropractic therapy, including spinal adjustments, soft tissue therapy, and exercise rehabilitation. After four weeks of treatment, the patient reported a complete resolution of symptoms and an improved quality of life score. Thereafter, the patient continued chiropractic treatment monthly for six months, during which she reported no symptoms and demonstrated improvements in her spinal range of motion, open-mouth anatomy, and cervical lordosis. This case study highlights the efficacy of applying an interdisciplinary approach to treating TMD and the potential of chiropractic therapy as a valuable treatment option for managing TMD.

Botulinum toxin for refractory Raynaud's phenomenon: A "how to" guide for pediatric patients

Raynaud's phenomenon describes symptoms caused by digital vascular spasm and is classically induced by cold exposure. Severe cases can result in ulceration, necrosis, and digital autoamputation. When standard and adjunctive medical therapies fail or are contraindicated, botulinum toxin A (BTX-A) is an effective treatment option that can be added to existing regimens and should be considered before utilizing rescue therapies associated with higher risk and often higher cost. This report describes our technique, highlights considerations relevant to pediatric patients, and provides photos and videos of the procedure performed on a 16-year-old girl.

Case report: Peripheral nerve stimulation relieves post-traumatic trigeminal neuropathic pain and secondary hemifacial dystonia

Post-traumatic trigeminal neuropathic pain (PTNP) combined with secondary dystonia are rare sequelae of orofacial injury and often do not respond to conservative treatment. The consensus on treatment for both symptoms is yet to be standardized. This study reports the case of a 57-year-old male patient with left orbital trauma who developed PTNP immediately after the injury and secondary hemifacial dystonia 7 months thereafter. To treat his neuropathic pain, we performed peripheral nerve stimulation (PNS) using a percutaneously implanted electrode to the ipsilateral supraorbital notch along the brow arch, which instantly resolved the patient's pain and dystonia. PTNP was relieved in a satisfactory manner until 18 months after the surgery, despite a gradual recurrence of the dystonia since 6 months after the surgery. To the best of our knowledge, this is the first reported case of PNS used for the treatment of PTNP combined with dystonia. This case report highlights the potential benefits of PNS in relieving neuropathic pain and dystonia and discusses the underlying therapeutic mechanism. Moreover, this study suggests that secondary dystonia occurs due to the uncoordinated integration of afferent sensory and efferent motor information. The findings of the present study indicate that PNS should be considered for patients with PTNP following the failure of conservative treatment. Secondary hemifacial dystonia may benefit from PNS upon further research and long-term assessment.

Preliminary Findings of the Efficacy of Botulinum Toxin in Temporomandibular Disorders: Uncontrolled Pilot Study

Temporomandibular disorders are a common pathology affecting up to 70% of the population, with a maximum incidence in young patients. We used a sample of twenty patients recruited in the Maxillofacial Surgery Service of the University Hospital of Salamanca (Spain), who met the inclusion criteria, with unilateral painful symptomatology of more than three months' duration. All patients were randomly treated by intramuscular and intra-articular injections of botulinum toxin (100 U) in eight predetermined points. Pain symptomatology was assessed by the visual analog scale (VAS) at the different locations, together with joint symptomatology, at baseline and six weeks after treatment. Adverse effects were also evaluated. In 85% of the patients, pain upon oral opening improved and 90% showed improvement in pain upon mastication. A total of 75% of the patients reported improvement in joint clicking/noise. Headaches improved or disappeared in 70% of the patients treated. Despite the limitations of the study and the preliminary results, intramuscular and intra-articular infiltrations with botulinum toxin were effective in the treatment of symptoms associated with temporomandibular disorders (TMDs), with minimal adverse effects.

Myofascial Pelvic Pain: Best Orientation and Clinical Practice. Position of the European Association of Urology Guidelines Panel on Chronic Pelvic Pain

CONTEXT

Despite the high prevalence of a myofascial pain component in chronic pelvic pain (CPP) syndromes, awareness and management of this component are lacking among health care providers.

OBJECTIVE

To summarize the current state of the art for the management of myofascial pain in chronic primary pelvic pain syndromes (CPPPS) according to scientific research and input from experts from the European Association of Urology (EAU) guidelines panel on CPP.

EVIDENCE ACQUISITION

A narrative review was undertaken using three sources: (1) information in the EAU guidelines on CPP; (2) information retrieved from the literature on research published in the past 3 yr on myofascial pelvic pain; and (3) expert opinion from panel members.

EVIDENCE SYNTHESIS

Studies confirm a high prevalence of a myofascial pain component in CPPPS. Examination of the pelvic floor muscles should follow published recommendations to standardize findings and disseminate the procedure. Treatment of pelvic floor muscle dysfunction and pain in the context of CPP was found to contribute to CPP control and is feasible via different physiotherapy techniques. A multidisciplinary approach is the most effective.

CONCLUSIONS

Despite its high prevalence, the myofascial component of CPP has been underevaluated and undertreated to date. Myofascial pain must be assessed in all patients with CPPPS. Treatment of the myofascial pain component is relevant for global treatment success. Further studies are imperative to reinforce and better define the role of each physiotherapy technique in CPPPS.

PATIENT SUMMARY

Pain and inflammation of the body's muscle and soft tissues (myofascial pain) frequently occurs in pelvic pain syndromes. Its presence must be evaluated to optimize management for each patient. If diagnosed, myofascial pain should be treated.

Clinical efficacy of botulinum toxin type A in patients with traumatic brain injury, spinal cord injury, or multiple sclerosis: An observational longitudinal study

Botulinum toxin type A (BoNT-A) is the treatment of choice for focal spasticity, with a concomitant effect on pain reduction and improvement of quality of life (QoL). Current evidence of its efficacy is based mainly on post stroke spasticity. This study aims to clarify the role of BoNT-A in the context of non-stroke spasticity (NSS). We enrolled 86 patients affected by multiple sclerosis, spinal cord injury, and traumatic brain injury with clinical indication to perform BoNT-A treatment. Subjects were evaluated before injection and after 1, 3, and 6 months. At every visit, spasticity severity using the modified Ashworth scale, pain using the numeric rating scale, QoL using the Euro Qol Group EQ-5D-5L, and the perceived treatment effect using the Global Assessment of Efficacy scale were recorded. In our population BoNT-A demonstrated to have a significant effect in improving all the outcome variables, with different effect persistence over time in relation to the diagnosis and the number of treated sites. Our results support BoNT-A as a modifier of the disability condition and suggest its implementation in the treatment of NSS, delivering a possible starting point to generate diagnosis-specific follow-up programs.

Clinical trial identifier

NCT04673240.

Neurotoxins Acting at Synaptic Sites: A Brief Review on Mechanisms and Clinical Applications

Neurotoxins generally inhibit or promote the release of neurotransmitters or bind to receptors that are located in the pre- or post-synaptic membranes, thereby affecting physiological functions of synapses and affecting biological processes. With more and more research on the toxins of various origins, many neurotoxins are now widely used in clinical treatment and have demonstrated good therapeutic outcomes. This review summarizes the structural properties and potential pharmacological effects of neurotoxins acting on different components of the synapse, as well as their important clinical applications, thus could be a useful reference for researchers and clinicians in the study of neurotoxins.

A Double-Blind, Split-Face, Randomized Study on the Effects and Safety of Intradermal Injection of Botulinum Toxin A (Incobotulinum Toxin A) in the Cheek

BACKGROUND

Intradermal injection of botulinum toxin A (BTXA) is used for cosmetic purposes without strong evidence for clinical use, as opposed to intramuscular injection.

OBJECTIVE

To evaluate the efficacy and safety of intradermal injection of incobotulinum toxin A (iBTXA) in the cheeks.

METHODS

We conducted a study with 18 volunteers who received intradermal injection of iBTXA into one cheek and normal saline into the contralateral side as a control. Volunteers visited the clinic at weeks 2, 4, 8, and 12 after injection. At each visit, pores and wrinkles were evaluated by a facial analyzer, sebum secretion by a sebumeter, skin texture by both volunteers and clinicians, and wrinkles of the nasolabial fold were graded with photographic reviews.

RESULTS

There were no significant effects on the wrinkles of the infraorbital area and sebum secretion. However, there were significant improvements in the wrinkles of the nasolabial fold and skin texture on the iBTXA injected side. The effects on the wrinkles of the nasolabial fold lasted 12 weeks, and those on skin texture lasted 8 weeks. Improvement in the pore size was observed only at week 2. No serious adverse events were reported except one volunteer who complained of facial palsy after the injection of 30 units of iBTXA in one cheek. However, injection of 20 units of iBTXA in one cheek was not associated with any adverse events.

CONCLUSION

Intradermal injection of iBTXA, could provide clinical benefits for skin texture and wrinkles overcoming the skin prick effect without obvious side effects.

A prospective study of intrapyloric botulinum toxin and EndoFLIP in children with nausea and vomiting

BACKGROUND

Intrapyloric botulinum toxin injection (IPBI) is used to treat nausea and vomiting in children, but no prospective pediatric studies exist. The aims of the current study were to assess the efficacy of IPBI in children with refractory nausea or vomiting and to use EndoFLIP as a biomarker of IPBI response.

METHODS

This was a prospective observational cohort study of pediatric patients undergoing IPBI for refractory nausea, vomiting, or feeding difficulties at a tertiary center. Patients completed validated questionnaires at baseline and 1, 2, and 3 months after IPBI. A subset of patients >10 years old underwent pyloric EndoFLIP at the time of IPBI. Symptoms were compared pre- and post-IPBI, and EndoFLIP measurements were assessed in relation to baseline characteristics and response to IPBI.

KEY RESULTS

Forty-five patients (mean age 14.2 ± 6.0 years) received IPBI, and 23 of those patients underwent EndoFLIP. Twenty-nine patients (64%) had symptomatic improvement at 1-month follow-up, including improvements in overall GI symptoms (p = 0.003), nausea and vomiting (p = 0.009), and discomfort when eating (p = 0.006). Symptomatic improvements lasted up to 3 months. There was a trend towards lower pyloric distensibility in patients with delayed versus normal gastric emptying (4.5 ± 3.8 mm2 /mmHg in delayed vs. 8.9 ± 6.6 mm2 /mmHg in normal, p = 0.09), though there were no differences in EndoFLIP measurements between IPBI responders and non-responders (p > 0.05).

CONCLUSIONS AND INFERENCES

The majority of patients responded to IPBI, with significant improvements seen in nausea, vomiting, and discomfort. Pyloric EndoFLIP tended to distinguish baseline delays in gastric emptying, but it did not predict IPBI response in this patient cohort.

Novel botulinum neurotoxin-A tibial nerve perineural injection to alleviate overactive bladder symptoms in male rats

Although tibial nerve modulation has shown to induce positive changes in the overactive bladder (OAB), prolonged therapeutic effects using percutaneous stimulation have not yet been achieved. Intradetrusor onabotulinum toxin A injection can provide prolonged therapeutic effects; however, its delivery requires invasive measures. By applying local relief of tibial nerve neural entrapment with onabotulinum toxin A injection, this study investigated the feasibility and efficacy of combining the abovementioned two therapeutic strategies. An OAB animal model was developed using 12 adult Sprague-Dawley rats with cyclophosphamide intraperitoneal injection. A perineural injection site comparable to the tibial nerve perineural injection site and corresponding to that in humans was identified and developed in rats. The toxin was injected five days after establishing the OAB. The incision was made in the skin on the lateral surface of the thigh. The biceps femoris muscle was cut across, exposing the sciatic nerve and its three terminal branches: the sural, common peroneal, and tibial nerves, and 100 units of onabotulinum toxin A was injected into the surrounding tissue. Five days following injection, cystometry was performed. Inter-contraction time, contraction pressure, and interval of the disease state improved with statistical significance. The OAB animal model showed significant improvement with the tibial nerve perineural injection of botulinum toxin, thereby suggesting the possibility of a comparable treatment adaptation in humans.

Reasons and Determinants of BoNT-A Treatment Discontinuation in Patients Living with Spasticity: A 10-Year Retrospective Analysis

BACKGROUND

The present study aimed to evaluate the reasons and determinants of BoNT-A discontinuation in patients with stroke, multiple sclerosis, spinal cord injury, and traumatic brain injury.

METHODS

It is a retrospective study of 56 discontinuer patients treated with botulinum toxin between January 2011 and December 2021. Discontinuation rates and their predictors were estimated using Kaplan-Meier, Log rank test, and Cox's regression method of analyses.

RESULTS

The mean age was 56.54 years, 53.57% were affected by post-stroke spasticity, 17.86% by spinal cord injury, 12.5% and 16.07% by traumatic brain injury and multiple sclerosis, respectively. The median discontinuation time was 5 months. The main reason for discontinuation were logistic problems (37%) and orthopedic surgeries or intrathecal baclofen (27%). Discontinuers were more likely to have severe spasticity (R = 1.785), have no pain (HR = 1.320), no access to rehabilitation services (HR = 1.402), and have cognitive impairment (HR = 1.403).

CONCLUSIONS

The main reasons for discontinuation are related to logistic issues (due to distance or the absence of an adequate caregiver) and surgical interventions for spasticity, including intrathecal baclofen. It is crucial to identify possible predictors of discontinuation to improve the effectiveness of a multidisciplinary management. The study confirms the crucial role of rehabilitation and caregivers in achieving better long-term outcomes.

Botulinum Toxin, a Drug with Potential Interest for Dentists—An Introduction

The review is an introduction to medical, non-cosmetic treatments with botulinum neurotoxin (BoNT) in the orofacial region. It focuses on the current most common, best-documented and safest indications of interest for dentists in terms of dystonia and sialorrhea. These conditions are recommended to start with and suitable to gain better skill and experience with BoNT. The introduction also stresses the importance of correct diagnostics based on interdisciplinary cooperation, precise targeting of the injections, measurements of treatment effect, and control of the oral health with regard to side effects.

Bacterial AB toxins and host-microbe interactions

AB toxins are protein virulence factors secreted by many bacterial pathogens, contributing to the pathogenicity of the cognate bacteria. AB toxins consist of two functionally distinct components: the enzymatic "A" component for pathogenicity and the receptor-binding "B" component for toxin delivery. Consistently, unlike other virulence factors such as effectors, AB toxins do not require additional systems to deliver them to the target host cells. Target host cells are located in the infection site and/or located distantly from infected host cells. The first part of this review discusses the structural and functional features of single-peptide and multiprotein AB toxins in the context of host-microbe interactions, using several well-characterized examples. The second part of this review discusses toxin neutralization strategies, as well as applications of AB toxins relevant to developing intervention strategies against diseases.

Therapeutic Efficacy of Botulinum Toxin in Trigeminal Neuralgia

Trigeminal neuralgia (TN) is a unilateral, paroxysmal, sharp, shooting, or jabbing pain that occurs in the trigeminal nerve divisions, including the ophthalmic (V1), maxillary (V2), and mandibular (V3) nerves. Typically, an episode is triggered by anything touching the face or teeth. TN is a clinical diagnosis with no specific diagnostic test; it is determined by the patient's medical history and pain description. Imaging is necessary to exclude secondary causes. The precise reason for TN is uncertain, but it is commonly believed to result from vascular compression of the trigeminal nerve root, typically near its origin in the pons. There are numerous surgical and medical treatment options available. The most frequently applied medical treatment therapies are carbamazepine and oxcarbazepine. Surgical alternatives are reserved for patients who do not respond to medical treatment. Botulinum toxin A (BTX-A) has emerged as a novel and promising alternative to surgery for individuals whose pain is unresponsive to medication. Multiple studies have established the safety and usefulness of BTX-A in treating TN, with the most significant benefits occurring between six weeks and three months after the surgery. This article reviews various studies published in the last 10 years regarding the therapeutic use of BTX-A in TN. These studies include various observational, clinical, pilot, and animal studies.

Increased Stiffness of the Superficial Cervical Extensor Muscles in Patients With Cervicogenic Headache: A Study Using Shear Wave Elastography

Background

Cervicogenic headache (CEH) is a secondary headache caused by lesions of the cervical spine and surrounding soft tissues. Cervical muscle dysfunction may be related to the onset of CEH. However, whether cervical muscle stiffness changes in patients with CEH has not been well studied. The purpose of this study was to explore changes in superficial cervical extensor muscle stiffness in patients with CEH using shear wave elastography (SWE).

Methods

In this study, 19 patients with CEH and 20 healthy controls were recruited. Superficial cervical extensor muscle stiffness was obtained from SWE, and the SuperLinear SL10-2 MHz linear array probe in the musculoskeletal muscle mode was chosen as the transducer. Regions of interest in the trapezius (TRAP), splenius capitis (SPL), semispinalis capitis (SCap), and semispinalis cervicis (SCer) were manually segmented. Correlations between superficial cervical extensor muscle stiffness and visual analog scale (VAS) scores, age, and body mass index (BMI) were analyzed using Pearson's correlation. Receiver operating characteristic (ROC) curve was used to investigate the diagnostic ability of superficial cervical extensor stiffness for CEH.

Results

Superficial cervical extensor muscle stiffness on the headache side of patients with CEH was higher than that on the non-headache side and in healthy controls (p < 0.05). Increased stiffness was also observed in SCer on the non-headache side of patients with CEH compared to healthy controls (p < 0.01). In patients with CEH, SCer stiffness was positively correlated with VAS scores (r = 0.481, p = 0.037), but no correlation was found between other muscles and VAS scores (p > 0.05). The areas under the curve of TRAP, SPL, SCap, and SCer in diagnosing CEH were 0.766, 0.759, 0.964, and 1.000, respectively.

Conclusions

Increased stiffness was observed in the superficial cervical extensor muscles on the headache side of patients with CEH. SCer stiffness was correlated with headache intensity in patients with CEH and may provide clues for the diagnosis of CEH.

Evaluation of Recombinant Botulinum Neurotoxin Type A1 Efficacy in Peripheral Inflammatory Pain in Mice

Well-established efficacy of botulinum neurotoxin type A (BoNT/A) in aesthetic dermatology and neuromuscular hyperactivity disorders relies on canonical interruption of acetylcholine neurotransmission at the neuromuscular junction at the site of the injection. The mechanisms and the site of activity of BoNT/A in pain, on the other hand, remain elusive. Here, we explored analgesic activity of recombinant BoNT/A1 (rBoNT/A1; IPN10260) in a mouse model of inflammatory pain to investigate the potential role of peripheral sensory afferents in this activity. After confirming analgesic efficacy of rBoNT/A1 on CFA-induced mechanical hypersensitivity in C57Bl6J mice, we used GCaMP6s to perform in vivo calcium imaging in the ipsilateral dorsal root ganglion (DRG) neurons in rBoNT/A1 vs. vehicle-treated mice at baseline and following administration of a range of mechanical and thermal stimuli. Additionally, immunohisochemical studies were performed to detect cleaved SNAP25 in the skin, DRGs and the spinal cord. Injection of CFA resulted in reduced mechanical sensitivity threshold and increased calcium fluctuations in the DRG neurons. While rBoNT/A1 reduced mechanical hypersensitivity, calcium fluctuations in the DRG of rBoNT/A1- and vehicle-treated animals were similar. Cleaved SNAP25 was largely absent in the skin and the DRG but present in the lumbar spinal cord of rBoNT/A1-treated animals. Taken together, rBoNT/A1 ameliorates mechanical hypersensitivity related to inflammation, while the signal transmission from the peripheral sensory afferents to the DRG remained unchanged. This strengthens the possibility that spinal, rather than peripheral, mechanisms play a role in the mediation of analgesic efficacy of BoNT/A in inflammatory pain.

Amyotrophic Lateral Sclerosis as an Adverse Drug Reaction: A Disproportionality Analysis of the Food and Drug Administration Adverse Event Reporting System

INTRODUCTION

Amyotrophic lateral sclerosis is a fatal progressive disease with a still unclear multi-factorial etiology. This study focused on the potential relationship between drug exposure and the development of amyotrophic lateral sclerosis by performing a detailed analysis of events reported in the FDA Adverse Event Reporting System database.

METHODS

The FDA Adverse Event Reporting System quarterly data (January 2004-June 2020) were downloaded and deduplicated. The reporting odds ratios and their 95% confidence intervals were calculated as a disproportionality measure. The robustness of the disproportion was assessed accounting for major confounders (i.e., using a broader query, restricting to suspect drugs, and excluding reports with amyotrophic lateral sclerosis as an indication). Disproportionality signals were prioritized based on their consistency across analyses (reporting odds ratio stability).

RESULTS

We retained 1188 amyotrophic lateral sclerosis cases. Sixty-two drugs showed significant disproportionality for amyotrophic lateral sclerosis onset in at least one analysis, and 31 had consistent reporting odds ratio stability, including tumor necrosis factor-alpha inhibitors and statins. Disproportionality signals from ustekinumab, an immunomodulator against interleukins 12-23 used in autoimmune diseases, and the anti-IgE omalizumab were consistent among analyses and unexpected.

CONCLUSIONS

For each drug emerging as possibly associated with amyotrophic lateral sclerosis onset, biological plausibility, underlying disease, and reverse causality could be argued. Our findings strengthened the plausibility of a precipitating role of drugs primarily through immunomodulation (e.g., tumor necrosis factor-alpha, ustekinumab, and omalizumab), but also by impacting metabolism and the musculoskeletal integrity (e.g., statins and bisphosphonates). Complement and NF-kB dysregulation could represent interesting topics for planning translational mechanistic studies on amyotrophic lateral sclerosis as an adverse drug effect.

Multidimensional Effectiveness of Botulinum Toxin in Neuropathic Pain: A Systematic Review of Randomized Clinical Trials

Although botulinum toxin (BoNT) has been suggested as a treatment to counter neuropathic pain, no previous systematic reviews investigated the multidimensional effects of BoNT on pain relief and Health-Related Quality of Life (HR-QoL). The aim of this systematic review is to summarize the current evidence on the effectiveness of BoNT treatment for neuropathic pain, and to characterize its multidimensional effectiveness in order to guide physicians in clinical practice. Five databases were systematically searched up to 4 April 2022, to identify randomized controlled trials satisfying the following criteria: adults suffering from neuropathic pain, BoNT administration, any comparator, multidimensional assessment of pain as primary outcome, HR-QoL, physical function, anxiety and depression, and sleep quality as secondary outcomes. Twelve studies were included. The multidimensional pain scales used were short-form McGill Pain Questionnaire, Neuropathic pain scale, Neuropathic Pain Symptom Inventory, International SCI Pain Basic Data Set, West Haven-Yale Multidimensional Pain Inventory, Brief Pain Inventory, and Douleur Neuropathique 4. These scales highlighted the positive effects of BoNT administration. According to the Jadad scale, all the RCTs included were high-quality studies. BoNT administration might be effectively introduced in the comprehensive management of neuropathic pain. Further research should focus on optimal and cost-effective therapeutic protocols.

Preclinical Evidence for the Role of Botulinum Neurotoxin A (BoNT/A) in the Treatment of Peripheral Nerve Injury

Traumatic peripheral nerve injuries tend to be more common in younger, working age populations and can lead to long-lasting disability. Peripheral nerves have an impressive capacity to regenerate; however, successful recovery after injury depends on a number of factors including the mechanism and severity of the trauma, the distance from injury to the reinnervation target, connective tissue sheath integrity, and delay between injury and treatment. Even though modern surgical procedures have greatly improved the success rate, many peripheral nerve injuries still culminate in persistent neuropathic pain and incomplete functional recovery. Recent studies in animals suggest that botulinum neurotoxin A (BoNT/A) can accelerate nerve regeneration and improve functional recovery after injury to peripheral nerves. Possible mechanisms of BoNT/A action include activation or proliferation of support cells (Schwann cells, mast cells, and macrophages), increased angiogenesis, and improvement of blood flow to regenerating nerves.

Comparative Efficacy and Safety of 11 Drugs as Therapies for Adults With Neuropathic Pain After Spinal Cord Injury: A Bayesian Network Analysis Based on 20 Randomized Controlled Trials

Objective

To provide an updated analysis of the efficacy and safety of drugs for the management of neuropathic pain (NP) after spinal cord injury (SCI) based on Bayesian network analysis.

Methods

A Bayesian network meta-analysis of literature searches within PubMed, Cochrane Library, Embase, and Web of Science databases from their inception to February 21 2021 was conducted without language restrictions. Paired and network meta-analyses of random effects were used to estimate the total standardized mean deviations (SMDs) and odds ratios (ORs).

Results

A total of 1,133 citations were identified and 20 RCTs (including 1,198 patients) involving 11 drugs and placebos for post-SCI NP selected. The 5 outcomes from all 11 drugs and placebos had no inconsistencies after Bayesian network analysis. BTX-A gave the most effective pain relief for the 4 weeks, following a primary outcome. No significant differences were found among drugs with regard to adverse events of the primary outcome. Gabapentin, BTX-A, and pregabalin were found to be the most helpful in relieving secondary outcomes of mental or sleep-related symptoms with differences in SMDs, ranging from −0.63 to −0.86. Tramadol triggered more serious adverse events than any of the other drugs with differences in ORs ranging from 0.09 to 0.11.

Conclusion

BTX-A, gabapentin, pregabalin, amitriptyline, ketamine, lamotrigine, and duloxetine were all effective for NP management following SCI. Lamotrigine and gabapentin caused fewer side effects and had better efficacy in relieving mental or sleep-related symptoms caused by SCI-related NP. Tramadol, levetiracetam, carbamazepine, and cannabinoids could not be recommended due to inferior safety or efficacy.

Systematic Review Registration

[https://inplasy.com/inplasy-2020-7-0061/], identifier [INPLASY202070061].

Neuropathic Pain in Neurologic Disorders: A Narrative Review

Neuropathic pain is defined as a painful condition caused by neurological lesions or diseases. Sometimes, neurological disorders may also be associated with neuropathic pain, which can be challenging to manage. For example, multiple sclerosis (MS) may cause chronic centralized painful symptoms due to nerve damage. Other chronic neuropathic pain syndromes may occur in the form of post-stroke pain, spinal cord injury pain, and other central pain syndromes. Chronic neuropathic pain is associated with dysfunction, disability, depression, disturbed sleep, and reduced quality of life. Early diagnosis may help improve outcomes, and pain control can be an important factor in restoring function. There are more than 100 different types of peripheral neuropathy and those involving sensory neurons can provoke painful symptoms. Accurate diagnosis of peripheral neuropathy is essential for pain control. Further examples are represented by gluten neuropathy, which is an extraintestinal manifestation of gluten sensitivity and presents as a form of peripheral neuropathy; in these unusual cases, neuropathy may be managed with diet. Neuropathic pain has been linked to CoronaVirus Disease (COVID) infection both during acute infection and as a post-viral syndrome known as long COVID. In this last case, neuropathic pain relates to the host’s response to the virus. However, neuropathic pain may occur after any critical illness and has been observed as part of a syndrome following intensive care unit hospitalization.

Advances in Interventional Therapies for Painful Diabetic Neuropathy: A Systematic Review

BACKGROUND

Painful diabetic neuropathy (PDN) is one of the major complications of diabetes mellitus. It is often debilitating and refractory to pharmaceutical therapies. Our goal was to systematically review and evaluate the strength of evidence of interventional management options for PDN and make evidence-based recommendations for clinical practice.

METHODS

We searched PubMed, Scopus, Google Scholar, and Cochrane Llibrary and systematically reviewed all types of clinical studies on interventional management modalities for PDN.

RESULTS

We identified and analyzed 10 relevant randomized clinical trials (RCTs), 8 systematic reviews/meta-analyses, and 5 observational studies of interventional modalities for PDN using pain as primary outcome. We assessed the risk of bias in grading of evidence and found that there is moderate to strong evidence to support the use of dorsal column spinal cord stimulation (SCS) in treating PDN in the lower extremities (evidence level: 1B+), while studies investigating its efficacy in the upper extremities are lacking. Evidence exists that acupuncture and injection of botulinum toxin-A provide relief in pain or muscle cramps due to PDN with minimal side effects (2B+/1B+). Similar level of evidence supports surgical decompression of lower limb peripheral nerves in patients with intractable PDN and superimposed nerve compression (2B±/1B+). Evidence for sympathetic blocks or neurolysis and dorsal root ganglion (DRG) stimulation is limited to case series (2C+).

CONCLUSIONS

Moderate to strong evidence exists to support the use of SCS in managing lower extremity pain in patients who have failed conventional medical management for PDN. Acupuncture or injection of botulinum toxin-A can be considered as an adjunctive therapy for PDN. Surgical decompression of peripheral nerves may be considered in patients with PDN superimposed with nerve compression. High-quality studies are warranted to further evaluate the safety, efficacy, and cost-effectiveness of interventional therapies for PDN.