Intraoral administration of botulinum toxin for trigeminal neuropathic pain

Pharmacological Management of Orofacial Pain

Orofacial pain is a category of complex disorders, including musculoskeletal, neuropathic and neurovascular disorders, that greatly affect the quality of life of the patient. These disorders are within the fields of dentistry and medicine and management can be challenging, requiring a referral to an orofacial pain specialist, essential for adequate evaluation, diagnosis, and care. Management is specific to the diagnosis and a treatment plan is developed with diverse pharmacological and non-pharmacological modalities. The pharmacological management of orofacial pain encompasses a vast array of medication classes and approaches. This includes anti-inflammatory drugs, muscle relaxants, anticonvulsants, antidepressants, and anesthetics. In addition, as adjunct therapy, different injections can be integrated into the management plan depending on the diagnosis and needs. These include trigger point injections, temporomandibular joint (TMJ) injections, and neurotoxin injections with botulinum toxin and nerve blocks. Multidisciplinary management is key for optimal care. New and safer therapeutic targets exclusively for the management of orofacial pain disorders are needed to offer better care for this patient population.

The Utility of Capsicum annuum L. in Internal Medicine and In Dentistry: A Comprehensive Review

Capsaicin is a chili peppers extract, genus Capsicum, commonly used as a food spice. Since ancient times, Capsaicin has been used as a "homeopathic remedy" for treating a wild range of pathological conditions but without any scientific knowledge about its action. Several studies have demonstrated its potentiality in cardiovascular, nephrological, nutritional, and other medical fields. Capsaicin exerts its actions thanks to the bond with transient receptor potential vanilloid subtype 1 (TRPV1). TRPV1 is a nociceptive receptor, and its activation starts with a neurosensitive impulse, responsible for a burning pain sensation. However, constant local application of Capsaicin desensitized neuronal cells and leads to relief from neuropathic pain. In this review, we analyze the potential adjuvant role of Capsaicin in the treatment of different pathological conditions either in internal medicine or dentistry. Moreover, we present our experience in five patients affected by oro-facial pain consequent to post-traumatic trigeminal neuropathy, not responsive to any remedy, and successfully treated with topical application of Capsaicin. The topical application of Capsaicin is safe, effective, and quite tolerated by patients. For these reasons, in addition to the already-proven beneficial actions in the internal field, it represents a promising method for the treatment of neuropathic oral diseases.

Botulinum toxin A for management of refractory concurrent buccal and inferior alveolar nerve post-traumatic neuropathies: a case report

Painful post-traumatic trigeminal neuropathy (PPTTN) can result from iatrogenic injury to one or more branches of the trigeminal nerve during oral surgical procedures such as tooth extractions. Like other chronic neuropathic pain conditions, PPTTN can significantly alter the patient’s quality of life, especially when pharmacological treatment is ineffective or not tolerated. As such, new treatment options have been investigated, including local injections of botulinum toxin type A (BTX-A). A 29-year-old woman presented to our tertiary orofacial pain clinic for evaluation of chronic electric shock-like pain attacks and severe allodynia in the territory of the right inferior alveolar nerve and buccal nerve following right mandibular third molar extraction 3 years prior. Following several failed attempts at classic pharmacological management (including carbamazepine, venlafaxine, duloxetine, pregabalin, clonazepam, and amitriptyline), BTX-A injections were administered in the vicinity of the right mental nerve. This treatment provided significant improvement in the patient’s condition and overall quality of life with no significant adverse effects. Because both neuropathies were significantly improved by remote BTX-A injections, this case report provides preliminary clinical evidence supporting spinopetal transport of BTX-A, as shown in animal models, as an underlying pathophysiological mechanism of BTX-A-mediated analgesia.

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].

Pharmacologic Management of Neuropathic Pain

This article aims to provide the practitioner with therapeutic options to treat a broad spectrum of acute and chronic orofacial pain syndromes. The focus will be nonsurgical that the oral health care physician can implement to treat this population of patients. The World Health Organization estimated that more than 1 in every 3 people suffers from acute or chronic pain. This article is primarily devoted to medication management once the diagnosis of neuropathic pain, a true trigeminal neuralgia, or a variant of trigeminal neuralgia often referred to as traumatic neuropathic pain or traumatic trigeminal neuralgia.

Acute and Chronic Pain from Facial Skin and Oral Mucosa: Unique Neurobiology and Challenging Treatment

The oral cavity is a portal into the digestive system, which exhibits unique sensory properties. Like facial skin, the oral mucosa needs to be exquisitely sensitive and selective, in order to detect harmful toxins versus edible food. Chemosensation and somatosensation by multiple receptors, including transient receptor potential channels, are well-developed to meet these needs. In contrast to facial skin, however, the oral mucosa rarely exhibits itch responses. Like the gut, the oral cavity performs mechanical and chemical digestion. Therefore, the oral mucosa needs to be insensitive, to some degree, in order to endure noxious irritation. Persistent pain from the oral mucosa is often due to ulcers, involving both tissue injury and infection. Trigeminal nerve injury and trigeminal neuralgia produce intractable pain in the orofacial skin and the oral mucosa, through mechanisms distinct from those seen in the spinal area, which is particularly difficult to predict or treat. The diagnosis and treatment of idiopathic chronic pain, such as atypical odontalgia (idiopathic painful trigeminal neuropathy or post-traumatic trigeminal neuropathy) and burning mouth syndrome, remain especially challenging. The central integration of gustatory inputs might modulate chronic oral and facial pain. A lack of pain in chronic inflammation inside the oral cavity, such as chronic periodontitis, involves the specialized functioning of oral bacteria. A more detailed understanding of the unique neurobiology of pain from the orofacial skin and the oral mucosa should help us develop novel methods for better treating persistent orofacial pain.

Botulinum Neurotoxin for the Treatment of Neuropathic Pain

Botulinum neurotoxin is widely used for the treatment of central and peripherical neurological conditions. Initially used to treat strabismus, over the years its use has been expanded also to spasticity and other neurological disorders. This review summarizes the evidence from the published literature regarding its effect on neuropathic pain. Almost all investigations were performed using onabotulinum toxin type A (BoNT/A). Most studies provided positive results, even though toxin formulation, dose, dilution, injection techniques, and sites are heterogeneous across studies. Future larger, high-quality, specifically designed clinical trials are warranted to confirm botulinum neurotoxin efficacy in neuropathic pain.

The Use of Botulinum Toxin A in the Management of Trigeminal Neuralgia: a Systematic Literature Review

OBJECTIVES

The purpose of this article is to systematically review the use, efficacy, differences between botulinum toxin type A doses and side effects of botulinum toxin type A therapy in patients with trigeminal neuralgia.

MATERIAL AND METHODS

The search for the performed reviews was done in PubMed and Cochrane library in English language from January 2010 up to February 2020. Inclusion criteria: full-text studies in English language, in which visual assessment scale (VAS) was present, in which patients with trigeminal neuralgia (TN) were participated and the comparison between botulinum toxin type A (BT-A) and saline was done.

RESULTS

The review included 4 randomized, double-blind, placebo-controlled trials with 8 to 12 weeks follow-up to observe changes in VAS and in frequency of TN attacks, differences between dosages of BT-A in therapy and side effects. Mean VAS of BT-A group decreased by approximately 68% and of palcebo group decreased by approximately 21.6% after the therapy. Mean frequency of TN attacks in 3 studies of BT-A group decreased by 85%, while in palcebo by only 15.9%.

CONCLUSIONS

Botulinum toxin type A injection therapy is a safe and effective method in management of trigeminal neuralgia. No differences between dosages of botulinum toxin type A were found. Maximum efficacy was noticed between 6 weeks and 3 months after the procedure. Side effects were mostly facial asymmetry after injection, headaches, haematoma, which disappeared in one week.

Botulinum neurotoxin injections for muscle-based (dystonia and spasticity) and non-muscle-based (neuropathic pain) pain disorders: a meta-analytic study

Apart from the known efficacy of Botulinum Neurotoxin Type A (BoNT/A) in hyperactive striated and smooth muscles, different pain states have become potential targets of toxin effects. This present study determined the comparative toxin effectiveness in pain reduction among those patients injected with BoNT/A in muscle-based and in non-muscle-based conditions. Randomized controlled trials (RCTs) on the effect of BoNT/A on selected pain conditions were included. The conditions were spasticity and dystonia for muscle-based pain. For non-muscle-based pain, conditions included were painful diabetic neuropathy (PDN), post-herpetic neuralgia (PHN), trigeminal neuralgia (TN), complex regional pain syndrome (CRPS), and spinal cord injury (SCI). In view of possibly differing pathophysiology, myofascial pain, temporomandibular joint (TMJ), other joint or tendon pains, cervicogenic and lumbar pains, migraine and visceral pain syndromes were excluded. Standardized mean difference was used as the effect measure and computed with STATA. 25 RCTs were analyzed. Pooled estimates showed significantly lower pain score in the Treatment group (z = 5.23, p < 0.01, 95% CI = - 0.75, - 0.34). Subgroup analyses showed that BoNT/A significantly reduced both muscle-based (z = 3.78, p < 0.01, 95% CI = - 0.72, - 0.23) and non-muscle-based (z = 3.37, p = 0.001, 95% CI = - 1.00, - 0.27) pain. Meta-regression using four covariates namely dosage, route, frequency and duration was done which revealed that dosage significantly affects standardized mean differences, while the other three covariates were insignificant. The joint F-test was found to be insignificant (p value = 0.1182). The application of the model with these covariates does not significantly explain the derived heterogeneity of standardized mean differences. In conclusion, BoNT/A can be effectively used in muscle-based and non-muscle-based pain disorders. We detected no difference between the presence and magnitude of pain relief favoring muscle-based compared to non-muscle-based pain. Thus, we cannot say whether or not there might be independent mechanisms of toxin-induced pain relief for pain generated from either muscle or nerve hyperactivity.

In silico mutagenesis: decreasing the immunogenicity of botulinum toxin type A

Botulinum toxin serotype A is a prominent therapeutic enzyme, for both clinical and cosmetic uses. Since this protein is produced by bacteria, it exhibits an allergenic effect when subjected to human therapy. Protein mutagenesis is one method to improve the characteristics of protein. However, in silico study is needed to give suggestion of which amino acid should be mutated. Hence, a lot of money and time can be saved. This study initially screened which residue of the Botulinum toxin serotype A is B-cell epitopes both linearly and conformationally. By overlapping the B-cell epitopes with the excluded conserve sequence, seven residues were allowed to be mutated. There were two proposed muteins showing a reduction in the antigenicity probability: ΔE147, E510F, T1062F, ΔE1080, N1089M and ΔQ1090; and ΔE147, E510F, T1062F, E1080W, N1089M and ΔQ1090. Molecular dynamics simulation of the 3D proposed muteins indicated an increase of flexibility in both muteins compared to that in the native protein. Both muteins have lower antigenicity. In addition, they are similar in structure, stability and functionality compared to the native protein.

OnabotulinumtoxinA injections for atypical odontalgia: an open-label study on nine patients

Background

Atypical odontalgia (AO) manifests as continuous pain in the region of one or several teeth, in the absence of signs of dental pathology. Currently, there is insufficient evidence to establish treatment guidelines for AO. The aim of this study was to describe the effectiveness and safety of treatment with OnabotulinumtoxinA (OnabotA) on a series of patients with AO.

Methods

Nine patients with AO (four males and five females, aged between 31 and 77 years) received injections of OnabotA in the region of pain. The dosage used in each procedure ranged between 10 and 30 U, spread between 4 and 12 injection sites along the gums (n=9), the lips (n=3), and the hard palate (n=1). The median follow-up time was 27 months (interquartile range, IQR 20–40) and the median number of injection sessions per patient was seven (IQR 4.5–9). The assessment variables included the change in the maximal intensity of pain on a 0–10 numerical rating scale (NRS), the response latency, and the duration of the effect.

Results

All patients experienced a significant improvement, with ≥50% of reduction in the intensity of the maximal pain. The median of reduction of maximal pain after treatment was six points on the NRS (IQR 5–8.5). The response latency was 2–15 days and the duration of the effect was 2–6 months. No significant adverse reactions were registered.

Conclusion

OnabotA may be a safe and effective option for the treatment of AO.

Neuropathic Pain Due to Iatrogenic Lingual Nerve Lesion: Nerve Grafting to Reduce Otherwise Untreatable Pain

Iatrogenic lingual nerve lesion is a well-known and unfortunate complication after mandibular third molar removal. Occasionally, the nerve injury can cause severe neuropathic pain.Here, the authors present the history of 2 patients with lingual nerve injury due to mandibular third molar removal, and with severe neuropathic pain in the craniomandibular region. Pharmacotherapy and physiotherapy did not reduce the pain, and ultimately, the lingual nerve was surgically explored. Scar tissue and a lingual nerve neuroma were observed and resected in both patients.In the first patient, the gap between the nerve stumps was bridged with an autologous sural nerve graft. In the second patient, some continuity of the lingual nerve was preserved and the resected part was substituted with an autologous sural nerve graft. Significant pain reduction was achieved in both patients and no further medical treatment was necessary at the end of follow-up.These reports show that lingual nerve reconstruction can be a successful therapy in patients experiencing severe neuropathic pain after iatrogenic lingual nerve injury. Different treatment options for neuropathic pain due to lingual nerve injury are discussed.