Update on neuropathic pain treatment for trigeminal neuralgia. The pharmacological and surgical options

Navigating precision: Anatomical insights into the efficacy of masks versus stereotactic frames in icon gamma knife treatment for trigeminal neuralgia

Background

The trigeminal nerve is approximately 2 mm in thickness. Its location is critical due to the alignment of the brain stem. Hence, precise fixation during the gamma knife (GK) treatment is particularly important. This study aimed to compare the effectiveness of mask fixation compared to frame fixation during the irradiation of trigeminal neuralgia (TN) treatment.

Methods

A prospective clinical study involving 135 patients with essential TN in Baghdad, Iraq, was conducted from January to July 2024. The study used two head fixation methods: stereotactic frames and plastic masks. Patients were treated with an Icon version of the GK, with no previous radiation treatment. Patients were diagnosed with 3 Tesla magnetic resonance imaging and assessed using the Barrow Neurological Institute (BNI) score before treatment. Clinical response was assessed at 3-month intervals. Ethical consent was obtained from all patients involved.

Results

This study analyzed the socio-demographic parameters of patients with TN and found that females were more prevalent. 5.2% of patients underwent glycerol injection, while 2.9% underwent microvascular decompression surgery. The BNI score was formulated for fixation methods, with frame fixation with screws and local anesthesia reaching IV and V scores. The response of TN patients to GK treatment was assessed using the BNI score before and after three months. Most patients showed pain relief, with 17.9% having a complete response. A Chi-square statistical analysis showed no significant difference between frame and mask fixation.

Conclusion

There was no significant difference in the precision of frame fixation compared to the plastic mask fixation for TN. The mask is as efficient as the frame.

Effectiveness of Radiofrequency in Treating Pain Associated With Trigeminal Neuralgia in Oncologic Patients

Introduction In cancer patients, trigeminal neuralgia (TN) has been not only observed in its secondary form but also described as one of the common neuropathic pain syndromes related to cancer. Patients with TN experience a marked reduction in quality of life due to the nature and severity of the pain. Although the standard treatment is microvascular decompression, this approach is not always feasible in oncologic patients. Therefore, radiofrequency (RF) guided by tomography has been described as an ablative intervention that allows achieving immediate pain relief in TN. It is of interest to identify the therapeutic response to pain in oncologic patients treated by this procedure. Objective The study aimed to evaluate the effectiveness of percutaneously guided tomography-assisted RF in oncologic patients with TN. Materials and methods We conducted an observational, retrospective, longitudinal, and analytical study. Patients with cancer and TN treated at the Pain Clinic of the National Cancer Institute in Mexico, who underwent RF, were included. A non-probabilistic sampling of consecutive cases was used, and selection criteria were applied. Clinical records were reviewed to measure study variables, including pain by TN before and after the procedure, as well as patient satisfaction. Data were analyzed using descriptive and inferential statistics, employing Student's t-test for related samples, with a significant level set at p ≤ 0.05 to determine statistical significance. The recorded data were analyzed using IBM SPSS Statistics for Windows, V. 26.0 (IBM Corp., Armonk, NY, USA). Results In the sample of 76 subjects (50% women and 50% men) with a mean age of 60.6 years, a variety of oncologic diagnoses were presented, with skin and soft tissue tumors being the most frequent, mainly located at the level of the head and neck. The etiology of TN was secondary in most cases (89.5%), with similar anatomical involvement on both hemifaces (50% left, 50% right). The branches most frequently involved were the maxillary nerve (V2) and mandibular nerve (V3) (39.5%) and V3 alone (22.4%). The most common probable cause was tumor activity (53, 69.7%). Most patients were receiving anticonvulsant treatment (carbamazepine-oxcarbazepine) (58.9%), followed by gabapentinoids (31.5%). Of the 76 patients, only six received computed tomography (CT)-guided RF. No complications associated with RF application were reported. The mean baseline pre-procedure pain (3.8 ± 2.48) and mean baseline post-procedure pain (2.17 ± 1.94) were significantly different in the Wilcoxon signed-rank test (p = 0.043), as were the mean incidental pre-procedure pain (9.0 ± 1.09) and mean incidental post-procedure pain (5.8 ± 2.31) (p = 0.019).  Conclusions Our research provides relevant data on the effectiveness of RF in managing TN in oncologic patients, demonstrating a clinically and statistically significant reduction in pain intensity. These findings need to be confirmed through prospective, longitudinal, long-term studies with control groups in a larger number of patients.

Retreatment predictors after percutaneous balloon gangliolysis for trigeminal neuralgia

Percutaneous balloon ganglyolysis (PBG) for trigeminal neuralgia (TN) is an inexpensive and minimally invasive treatment modality that is effective and safe. While there are reports of its efficacy, there is still a lack of evidence of which patients are at a higher risk of treatment failures and needing retreatment. We performed a retrospective study at a major academic institution from 2012 to 2023, including TN patients who underwent PBG procedures to evaluate predictors of retreatment. Patients without imaging available from the PBG were excluded. Fifty-two patients who underwent 83 procedures in total were included in the analysis. All patients had typical TN and were primarily female (59.6%), with a median age of 61.5 years. Immediately after PBG, 42.3% had pain resolution, and 57.7% had improved but persistent pain. 30.8% underwent retreatment with PBG in a median of 32 months. From multiple factors assessed, TN disease duration ≤ 6 months and trigeminal nerve enhancement on pre-operative MRI were identified as significant retreatment predictors on univariate analysis. However, after performing logistic regression, only TN disease duration ≤ 6 months remained significant OR 3.99 (95% CI 1.59-10.0; p = 0.003). This was further confirmed in a Kaplan-Meier survival analysis, which showed that patients with TN duration ≤ 6 months require retreatment earlier (22 vs. 41 months; p = 0.01). Retreatment after PBG occurs roughly in a third of patients, and TN disease duration of ≤ 6 months is an important predictor in this study. Further studies should be performed to confirm these findings, which may impact treatment considerations in the future.

Chiari malformation and its influence on trigeminal neuralgia: a systematic review

Objective

In order to properly understand the correlation between TN and Chiari malformation type I (CMI), it is imperative to delve into the underlying processes and develop efficacious treatment strategies.

Methods

A comprehensive search was performed regarding trigeminal neuralgia (TN) in individuals diagnosed with CMI. A total of 19 cases were identified in the existing literature.

Results

The review of 19 studies showed that the most commonly affected division was V2 (31.6%), followed by V3 (10.5%) and V1 (5.3%). Radiological findings were variable. The medulla oblongata was compressed in 6 patients (31.6%), the cervical spinal cord showed abnormalities in 3 patients (15.8%) abnormalities; one cervical myelocele (5.26%), two cervical syringomyelia (10.53%) while 5 patients (26.3%) showed normal findings. The skull bones in 4 patients (21,1%) showed deformity in the form of small posterior fossa or platybasia. The surgical treatment was conducted in 14 patients (73.7%). The study suggested that posterior fossa decompression (PFD) plus microvascular decompression (MVD) dual surgical modality yielded the best results for V2 distribution (P=0.017).

Conclusion

Chiari malformation type I can directly influence the occurrence and severity of trigeminal neuralgia. Therefore, an effective management of this malformation, like neurovascular decompression, PFD or ventriculoperitoneal shunt, can act as a potential treatment for trigeminal neuralgia. While the PFD alone was effective in the V3 and V1 distribution of trigeminal neuralgia, PFD plus microvascularplus plus microvascular decompression (MVD) as a dual surgical modality yielded the best results for V2 distribution.

Exploring Carbamazepine Polymorph Crystal Growth in Water by Enhanced Sampling Simulations

In this work, the polymorphism of the active pharmaceutical ingredient carbamazepine (CBZ) was investigated by using molecular dynamics simulations with an enhanced sampling scheme. A single molecule of CBZ attaching to flat surfaces of different polymorphs was used as a model for secondary nucleation in water. A novel approach was developed to compute the free energy profile characterizing the adsorption of molecules with orientation aligned with the crystal structure of the surface. The distribution of states that showed alignment was used to rescale the adsorption free energy to include only the contribution that is consistent with crystal growth. The resulting free energy surfaces showed favorable thermodynamics for the most stable form, Form III and the second most stable form, Form I. The primary crystallization product, a dihydrate, was found to be less favorable, implying a nonclassical crystallization pathway. We suggest that a major contribution determining the energetics is the hydrophobicity of the surface. This thermodynamic ranking provides valuable information about the molecular pathways of polymorph growth and will further contribute to the understanding of the crystallization process of CBZ, which is imperative since polymorph formation can alter the physical properties of a drug significantly.

Meta-analysis and sequential analysis of acupuncture compared to carbamazepine in the treatment of trigeminal neuralgia

BACKGROUND

In this randomized controlled trial (RCT) comparing current acupuncture with carbamazepine for trigeminal neuralgia, meta- and sequential analyses were utilized.

AIM

To guide clinical decision making regarding the treatment of trigeminal neuralgia with carbamazepine.

METHODS

The RCT literature on needle comparison was searched in various Chinese biomedical databases including Chinese Biomedical Literature Database, Wanfang Data, VIP Database, as well as international databases such as Excerpt Medica Database, Cochrane Library, PubMed, and Web of Science, along with related clinical registration platforms such as World Health Organization International Clinical Trial Registry Platform, ChiCTR, and Clinical Trials up to 1 April 2020. Risk of bias was evaluated using the Cochrane Collaborative Risk Bias tool, primary outcome measures (pain reduction) were analyzed using STATA meta-analysis, outcome measures were analyzed using trial sequential analysis 0.9.5.10 Beta sequential analysis, GRADE was used to assess the evidence, and adverse reactions were documented.

RESULTS

This study analyzed 16 RCTs with a total of 1231 participants. The meta-analysis revealed a statistically significant difference in pain reduction between acupuncture and carbamazepine [standardized mean difference (SMD) = 1.47; 95% confidence interval (CI): 0.99-1.95], although the quality of evidence was deemed to be of extremely low quality. Cumulative meta-analysis based on the year of publication indicated that carbamazepine treatment first demonstrated a statistically significant difference in pain reduction in 2014 and remained relatively stable over time [SMD = 1.84; 95%CI: 0.22-3.47]. Additionally, the number of adverse events associated with acupuncture was significantly lower compared to carbamazepine.

CONCLUSION

Acupuncture for trigeminal neuralgia is better than analgesia and safer than carbamazepine; however, firm conclusions still require a high-quality, multicenter, large-sample RCT to confirm these findings.

An update on pharmacotherapy for trigeminal neuralgia

INTRODUCTION

Trigeminal neuralgia is a rare condition that can be effectively treated by carbamazepine or oxcarbazepine but these older drugs are associated with dose-dependent and potentially treatment-limiting adverse effects. Third-generation anticonvulsants, new calcitonin gene-related peptide blockers for migraine, and older drugs such as ketamine and cannabinoids may be promising adjuvants or monotherapeutic options.

AREAS COVERED

The new drugs, their presumed mechanisms of action, safety and efficacy are discussed herein. There is a paucity of robust clinical evidence in support of these drugs for trigeminal neuralgia. New migraine agents are considered as well although migraines and trigeminal neuralgia are distinct, albeit similar, conditions. No new drugs have been released to market in recent years with the specific indication of trigeminal neuralgia.

EXPERT OPINION

In real-world clinical practice, about half of trigeminal neuralgia patients take more than one agent for prevention and combination therapy may be the optimal approach. Combination therapy might allow for lower doses of carbamazepine or oxcarbazepine, thus reducing the number and severity of potential adverse events but the potential for pharmacokinetic drug-drug interactions must be considered. Drug therapy for trigeminal neuralgia involves acute or abortive treatments, often administered in hospital versus long-term preventive therapy, usually involving oral agents.

Outcomes of Different Surgical Interventions for Treating Trigeminal Neuralgia: A Review

Trigeminal neuralgia (TN) is a debilitating condition characterized by severe facial pain. Various surgical interventions are employed to manage this condition, including microvascular decompression (MVD), percutaneous radiofrequency rhizotomy (PRR), glycerol rhizotomy, percutaneous balloon compression (PBC), and stereotactic radiosurgery such as Gamma Knife radiosurgery (GKRS). This review synthesizes the outcomes of these interventions to provide an understanding of their efficacy and associated risks. MVD, known for its high initial relief rates, shows substantial long-term effectiveness, with recurrence rates varying based on patient demographics and comorbidities. GKRS offers significant pain relief with a favorable adverse event profile; however, recurrence rates increase over time, necessitating repeat procedures for sustained efficacy. PBC demonstrates high initial success, but pain recurrence is common, especially in patients with atypical TN. PRR provides immediate relief with a manageable recurrence rate and is particularly suitable for elderly patients and those with comorbidities. Glycerol rhizotomy, a cost-effective procedure, yields comparable outcomes to other interventions but requires careful patient selection. This review highlights the importance of tailored treatment approaches based on individual patient profiles, emphasizing the need for precise diagnostic criteria and careful patient selection to optimize outcomes. Long-term follow-up and the potential for repeat interventions are critical considerations in managing TN surgically.

Modern Approaches to the Treatment of Acute Facial Pain

PURPOSE OF REVIEW

Acute facial pain presents a complex challenge in medical practice, requiring a comprehensive and interdisciplinary approach to its management. This narrative review explores the contemporary landscape of treating acute facial pain, delving into pharmacological, non-pharmacological, and advanced interventions. The significance of tailored treatment strategies, rooted in the diverse etiologies of facial pain, such as dental infections, trigeminal neuralgia, temporomandibular joint disorders, sinusitis, or neurological conditions like migraines or cluster headaches, is underscored. We particularly emphasize recent advances in treating trigeminal neuralgia, elucidating current treatment concepts in managing this particular acute facial pain.

RECENT FINDINGS

Recent research sheds light on various treatment modalities for acute facial pain. Pharmacotherapy ranges from traditional NSAIDs and analgesics to anticonvulsants and antidepressants. Non-pharmacological interventions, including physical therapy and psychological approaches, play pivotal roles. Advanced interventions, such as nerve blocks and surgical procedures, are considered in cases of treatment resistance. Moreover, we explore innovative technologies like neuromodulation techniques and personalized medicine, offering promising avenues for optimizing treatment outcomes in acute facial pain management. Modern management of acute facial pain requires a nuanced and patient-centric approach. Tailoring treatment strategies to the individual's underlying condition is paramount. While pharmacotherapy remains a cornerstone, the integration of non-pharmacological interventions is essential for comprehensive care. Advanced interventions should be reserved for cases where conservative measures prove inadequate. Furthermore, leveraging innovative technologies and personalized medicine holds promise for enhancing treatment efficacy. Ultimately, a holistic approach that considers the diverse needs of patients is crucial for effectively addressing acute facial pain.

Role of HDAC5 Epigenetics in Chronic Craniofacial Neuropathic Pain

The information provided from the papers reviewed here about the role of epigenetics in chronic craniofacial neuropathic pain is critically important because epigenetic dysregulation during the development and maintenance of chronic neuropathic pain is not yet well characterized, particularly for craniofacial pain. We have noted that gene expression changes reported vary depending on the nerve injury model and the reported sample collection time point. At a truly chronic timepoint of 10 weeks in our model of chronic neuropathic pain, functional groupings of genes examined include those potentially contributing to anti-inflammation, nerve repair/regeneration, and nociception. Genes altered after treatment with the epigenetic modulator LMK235 are discussed. All of these differentials are key in working toward the development of diagnosis-targeted therapeutics and likely for the timing of when the treatment is provided. The emphasis on the relevance of time post-injury is reiterated here.

Analyzing the Effect of Intraoperative Stimulation Voltage on Facial Numbness Following Radiofrequency Thermocoagulation in the Treatment of Idiopathic Trigeminal Neuralgia

INTRODUCTION

Radiofrequency thermocoagulation (RFT) effectively alleviates idiopathic trigeminal neuralgia (ITN); however, postoperative facial numbness poses a significant challenge. This issue arises due to the close proximity of high-temperature thermocoagulation, which not only ablates pain-related nociceptive fibers but also affects tactile fibers. Intraoperative sensory stimulation voltage (SV), which reflects the distance between the RFT cannula and the target nerve, potentially possesses the ability to prevent tactile fiber injury. This study aimed to investigate the influence of SV on postoperative facial numbness and provide valuable insights to mitigate its occurrence.

METHODS

A retrospective analysis was performed on 72 ITN patients with maxillary division (V2) pain who underwent RFT between 2020 and 2022. Among them, 13 patients with SV ≤ 0.2 V constituted the low SV group. Subsequently, a matched-cohort analysis was conducted on the remaining 59 patients. The patients paired with the low SV patients were subsequently enrolled in the high SV group, adhering to a 1:1 match ratio. The primary outcome was the facial numbness scale assessment at 3 days, 3 months and 6 months post-surgery. The pain intensity and medication burden served as the secondary outcomes.

RESULTS

We successfully matched a cohort consisting of 12 patients in the low SV group and 12 patients in the high SV group. Each patient experienced various degrees of facial numbness at 3 days post-RFT. Notably, the low SV group exhibited a higher incidence of moderate numbness (66.7% vs. 16.67%, P = 0.036), whereas the high SV group had more cases of mild numbness at the 6-month follow-up (25% vs. 83.3%, P = 0.012). Both groups demonstrated significant decreases in pain intensity and medication burden compared to before the operation.

CONCLUSIONS

SV proved to be a reliable parameter for mitigating the degree of postoperative facial numbness in RFT treatment for ITN. A relatively high sensory SV ranging from 0.3 to 0.6 V during the RFT procedure results in less facial numbness in the treatment of ITN.

Trigeminal neuralgia

Trigeminal neuralgia (TN) is a facial pain disorder characterized by intense and paroxysmal pain that profoundly affects quality of life and presents complex challenges in diagnosis and treatment. TN can be categorized as classical, secondary and idiopathic. Epidemiological studies show variable incidence rates and an increased prevalence in women and in the elderly, with familial cases suggesting genetic factors. The pathophysiology of TN is multifactorial and involves genetic predisposition, anatomical changes, and neurophysiological factors, leading to hyperexcitable neuronal states, central sensitization and widespread neural plasticity changes. Neurovascular compression of the trigeminal root, which undergoes major morphological changes, and focal demyelination of primary trigeminal afferents are key aetiological factors in TN. Structural and functional brain imaging studies in patients with TN demonstrated abnormalities in brain regions responsible for pain modulation and emotional processing of pain. Treatment of TN involves a multifaceted approach that considers patient-specific factors, including the type of TN, with initial pharmacotherapy followed by surgical options if necessary. First-line pharmacological treatments include carbamazepine and oxcarbazepine. Surgical interventions, including microvascular decompression and percutaneous neuroablative procedures, can be considered at an early stage if pharmacotherapy is not sufficient for pain control or has intolerable adverse effects or contraindications.

A cost effectiveness analysis of two treatment strategies for trigeminal neuralgia in Ontario

Background

Trigeminal neuralgia (TN) is a debilitating disease with an annual incidence of approximately 4-27/100,000. In Ontario, over 2000 patients receive interventions for profound pain, including medical and surgical therapies. The global expected cost of these approaches is unknown. This study aims to analyze the cost-effectiveness of one surgical therapy, microvascular decompression (MVD), compared with the best medical therapy (carbamazepine) as first-line therapy.

Methods

Costs were gathered from the Canadian Institute for Health Information, Ontario Drug Benefit Formulary, and Ontario Ministry of Health Schedule of Benefits for Physician Services. Academic literature was used to estimate unavailable items. A cost-benefit Markov model was created for each strategy with literature-based rates for annual cycles from years 1 to 5, followed by a linear recurrent cycle from years 6 to 10. Incremental cost-effectiveness ratios (ICERs) were calculated based on the incremental cost in 2022 Canadian Dollars (CAD) per pain-free year.

Results

Base case cost per patient was $10,866 at 10 years in the "MVD first" group and $10,710 in the "carbamazepine first" group. Ten-year ICER was $1,104 for "MVD first," with strict superiority beyond this time point. One-way deterministic sensitivity analysis for multiple factors suggested the highest cost variability and ICER variability were due to surgery cost, medication failure rate, and medication cost.

Conclusion

Economic benefit is established for a "MVD first" strategy in the Ontario context with strict superiority beyond the 10-year horizon. If a cost-effectiveness threshold of $50,000 per pain-controlled year is used, the benefit is established at 4 years.

Prediction of the Need for Anticonvulsants in the Management of Orofacial Neuropathic Pain Using Machine Learning

Background and aim Orofacial neuropathic pain is a medical condition caused by a lesion or dysfunction of the nervous system and is one of the most challenging for dental clinicians to diagnose. Anticonvulsants, antidepressants, analgesics, nonsteroidal anti-inflammatory drugs, and other classes of medications are frequently used to treat this condition. Our study aimed to build a machine learning-based classifier to predict the need for anticonvulsant drugs in patients with orofacial neuropathic pain. Materials and methods A machine learning tool that was trained and tested on patients for predicting and detecting algorithms, which would in turn predict the need for anticonvulsants in the treatment of orofacial neuropathic pain, was employed in this study. Results Three machine learning algorithms successfully detected and predicted the need for anticonvulsants to treat patients with orofacial neuropathic pain. All three models showed a high accuracy, that is, 97%, 94%, and 89%, in predicting the need for anticonvulsants. Conclusion Machine learning algorithms can accurately predict the need for anticonvulsant drugs for treating orofacial neuropathic pain. Further research is needed to validate these findings using larger sample sizes and imaging modalities.

Cranial Neuralgias

OBJECTIVE

The cranial neuralgias are relatively rare, but recognizing these syndromes and distinguishing among them is critical to reducing unnecessary pain and disability for affected patients. Despite their distinctive features, cranial neuralgias may go undiagnosed or misdiagnosed for several years. A notable proportion of cranial neuralgia presentations are due to secondary causes and require targeted treatment. The purpose of this article is to review the diagnosis and management of cranial neuralgias encountered in clinical practice.

LATEST DEVELOPMENTS

In 2020, the International Classification of Orofacial Pain was released for the first time. Modeled after the International Classification of Headache Disorders, it includes updated terminology for cranial neuralgias. The underlying pathophysiology of the cranial neuralgias is currently believed to be rooted in both peripheral and central nociceptive systems. In addition, a growing number of familial cases are being identified. Recent therapeutic advancements include a better understanding of how to utilize older therapies and procedures more effectively as well as the development of newer approaches.

ESSENTIAL POINTS

Cranial neuralgia syndromes are rare but important to recognize due to their debilitating nature and greater likelihood of having potentially treatable underlying causes. While management options have remained somewhat limited, scientific inquiry is continually advancing the understanding of these syndromes and how best to address them.

Standardized Centella asiatica extract ECa 233 alleviates pain hypersensitivity by modulating P2X3 in trigeminal neuropathic pain

OBJECTIVE

During oral surgery and temporomandibular joint repositioning, pain hypersensitivity often occurs due to irritation or inflammation of the nerve endings in the orofacial region. This study aimed to investigate the effects of ECa 233, a Centella asiatica-standardized extract, on the development of mechanical hyperalgesia and allodynia induced by chronic constriction injury of the infraorbital nerve in mice.

METHODOLOGY

The right infraorbital nerves of the mice were ligated. Oral carbamazepine (20 mg/kg) or ECa 233 (30, 100, or 300 mg/kg) was administered daily for 21 days. Von Frey and air-puff tests were performed on both sides of the whisker pad on days 0, 7, 14, and 21. Thereafter, the expression of purinergic receptor subtype 3 (P2X3) and voltage-gated sodium channel 1.7 (NaV1.7), a transmembrane protein, in the trigeminal ganglion and c-fos immunoreactivity-positive neurons in the trigeminal nucleus caudalis was assessed.

RESULTS

After 21 days of infraorbital nerve ligation, the mice showed allodynia- and hyperalgesia-like behavior, P2X3 and NaV1.7 were upregulated in the trigeminal ganglion, and nociceptive activity increased in the trigeminal nucleus caudalis. However, the oral administration of carbamazepine (20 mg/kg), ECa 233 (100 mg/kg), or ECa 233 (300 mg/kg) mitigated these effects. Nevertheless, ECa 233 failed to affect NaV1.7 protein expression.

CONCLUSION

Carbamazepine and ECa 233 can prevent pain hypersensitivity in mice. Considering the side effects of the long-term use of carbamazepine, ECa 233 monotherapy or combined ECa 233 and carbamazepine therapy can be used as an alternative for regulating the development of hypersensitivity in trigeminal pain. However, further detailed clinical studies should be conducted to provide comprehensive information on the use of ECa 233.

A Pilot Study of Hypofractionated Radiosurgery for Trigeminal Neuralgia

The primary late toxicity of radiosurgery treatment for trigeminal neuralgia (TN) is facial numbness due to trigeminal nerve dysfunction. Although most patients prefer loss of facial sensation to TN, severe loss of facial sensation can be debilitating. In order to try to obtain high pain control rates while minimizing the risk of late facial numbness, we elected to treat patients on the distal trigeminal nerve with a three-fraction regimen over consecutive days instead of one fraction. Our goal was to relieve the pain while also allowing the trigeminal nerve time to repair radiation damage between treatments in an attempt to minimize the risk of permanent facial numbness. Patients in a pilot study, approved by an Institutional Review Board (IRB), received a treatment regimen of 99 Gy, administered in three consecutive daily fractions of 33 Gy each, with the dosage targeted to the 80% line. This dose was selected to approximate a biologically equivalent dose of 80 Gy maximal dose to the trigeminal nerve. Forty-eight patients were treated with CyberKnife Radiosurgery (CKRS; 99 Gy/3 fractions) for TN from 2016 to 2022, with at least one year of follow-up. The Barrow Neurological Institute (BNI) scale was used to assess facial pain, and Kaplan-Meier analysis was used to assess adequate pain relief. Thirty-eight (84%) patients experienced adequate pain relief, defined as a BNI score of I-IIIb, after a median of 1.5 months following CKRS. Treatment failure (BNI=IV-V) occurred in 12 (25%) patients after a median of 6 months following initial pain relief. The actuarial probability of pain relief at 6, 12, and 24 months post-CKRS were 87.4%, 83.7%, and 83.7%, respectively. Facial numbness was experienced in 24 (50%) cases after a median of 10 months following CKRS. Typical facial pain (p=0.034) and vascular compression (p=0.039) were the only predictors of better treatment outcomes using univariate Cox survival analysis, and vascular compression (p= 0.037) was the only predictor in multivariate Cox survival analysis. Hypofractionated treatment to the distal trigeminal nerve segment does not appear to offer an advantage in treating TN, due to similar rates of pain relief but with an unacceptably high rate of late facial numbness.

Treatment Modalities for Trigeminal Neuralgia and the Need for Vigilance in Monitoring Adverse Drug Events: A Case Report

INTRODUCTION

Trigeminal neuralgia is a rare condition characterised by paroxysms of intense pain in the distribution of the trigeminal nerve. This condition significantly diminishes the patient's quality of life, and the side effects from chronic use of medications for symptomatic relief further exacerbate their distress.

CASE DESCRIPTION

The case report discusses a patient diagnosed with Trigeminal Neuralgia who commenced carbamazepine treatment. The report tracks the disease's progression, medication adjustments, and the eventual emergence of vertigo due to long-term carbamazepine use.

CONCLUSION

The article covers fundamental information about trigeminal neuralgia and its management and also offers a comprehensive review of the basics of vertigo. It delves into carbamazepine's mechanism of action and its associated side effects. The paper also looks at prospective therapy changes that could improve patients' quality of life.

Case report: use of high-intensity laser therapy for treatment of trigeminal neuralgia

Trigeminal neuralgia represents a form of chronic facial pain that is characterized by its incapacitating nature. The current therapeutic approaches encompass pharmacological agents with carbamazepine or non-pharmacologic options including utilization of percutaneous rhizotomy, Gamma knife radiosurgery or microvascular decompression may be indicated in certain cases. While the interventions may be effective, medications have negative side effects and procedures are invasive which can pose challenges for patients with various comorbidities. High-intensity laser therapy (HILT) has demonstrated safety and efficacy for many types of chronic pain such as musculoskeletal, autoimmune and neuropathic. Herein, we demonstrate the benefits of HILT therapy in the management of trigeminal neuralgia in a 72 year-old patient with a complex history of facial surgery and radiation who had failed pharmacological treatments and denied any invasive procedures.

Surgical Interventions Targeting the Nucleus Caudalis for Craniofacial Pain: A Systematic and Historical Review

INTRODUCTION

Craniofacial pain is a prevalent group of conditions, and when refractory to conventional treatments, it poses a significant burden. The last decade has seen a renewed interest in the multimodal management of pain. Interventions targeting the nucleus caudalis (NC) of the trigeminocervical complex have been available as a treatment option since the 1930s, yet evidence for efficacy remains limited.

MATERIALS AND METHODS

We present a systematic review of the literature providing a historical perspective on interventions targeting the NC leading up to the present. We examine the various intervention techniques, clinical indications, and procedural efficacy. A novel outcome-reporting scheme was devised to enable comparison among studies owing to historically variable reporting methods.

RESULTS

A review of the literature revealed 33 retrospective studies published over the last 80 years, reporting on 827 patients. The most common technique was the open NC dorsal root entry zone nucleotomy/tractotomy; however, there has been an emergence of novel approaches such as endoscopic and spinal cord stimulation in the last ten years. Regardless of intervention technique or preoperative diagnosis, 87% of patients showed improvement with treatment.

CONCLUSIONS

The literature surrounding NC intervention techniques is reviewed. Recent advancements and the wide range of craniofacial pain syndromes for which these interventions show potential efficacy are discussed. New and less invasive techniques continue to emerge as putative therapeutic options. However, prospective studies are lacking. Furthermore, the evidence supporting even well-established techniques remains of poor quality. Future work should be prospective, use standard outcome reporting, and address efficacy comparisons between intervention type and preoperative diagnosis.

URB937 Prevents the Development of Mechanical Allodynia in Male Rats with Trigeminal Neuralgia

Cannabinoids are proposed for alleviating neuropathic pain, but their use is limited by cannabimimetic side effects. The inhibition of the fatty acid amide hydrolase (FAAH), the degrading enzyme of the endocannabinoid anandamide, has received attention as an alternative to cannabinoids in the treatment of neuropathic pain. Here, we investigated the effect of URB937, a blood-brain barrier impermeant FAAH inhibitor, on experimentally induced mechanical allodynia in an animal model of trigeminal neuralgia. Male Sprague-Dawley rats were subjected to chronic constriction injury of the infraorbital nerve (IoN-CCI); operated animals were treated sub-chronically with URB937 (1 mg/kg, i.p.) or vehicle before or after trigeminal mechanical allodynia establishment. We also assayed mRNA expression levels of the pain neuropeptide calcitonin gene-related peptide (CGRP) and cytokines in the medulla, cervical spinal cord, and trigeminal ganglion ipsilateral to IoN-CCI using rt-PCR. URB937 treatment prevented the development of mechanical allodynia and IoN-CCI-induced changes in mRNA expression levels of CGRP and cytokines in the evaluated areas. When administered after allodynia development, URB937 prevented IoN-CCI-induced changes in CGRP and cytokine gene expression; this was not associated with a significant abrogation of the mechanical allodynia. These findings suggest that URB937 may counteract, but not reverse, the development of allodynia in trigeminal neuralgia. Further research is needed to elucidate the underlying mechanisms.

Gamma Knife surgery and deep brain stimulation of the centromedian nucleus for chronic pain: A systematic review

Chronic pain has been a major problem in personal quality of life and social economy, causing psychological disorders in people and a larger amount of money loss in society. Some targets were adopted for chronic pain, but the efficacy of the CM nucleus for pain was still unclear. A systematic review was performed to summarize GK surgery and DBS of the CM nucleus for chronic pain. PubMed, Embase and Medline were searched to review all studies discussing GK surgery and DBS on the CM nucleus for chronic pain. Studies that were review, meet, conference, not English or not the therapy of pain were excluded. Demographic characteristics, surgery parameters and outcomes of pain relief were selected. In total, 101 patients across 12 studies were included. The median age of most patients ranged from 44.3 to 80 years when the duration of pain ranged from 5 months to 8 years. This review showed varied results of 30%-100% pain reduction across studies. The difference in the effect between GK surgery and DBS cannot be judged. Moreover, three retrospective articles related to GK surgery of the CM nucleus for trigeminal neuralgia presented an average pain relief rate of 34.6-82.5%. Four studies reported adverse effects in a small number of patients. GK surgery and DBS of the CM nucleus might be promising therapeutic approaches for chronic refractory pain. More rigorous studies and larger samples with longer follow-up periods are needed to support the effectiveness and safety.

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.

Clinical Effectiveness of Mirogabalin Besylate for Trigeminal Neuropathy after Skull Base Surgery: Illustrative Cases

BACKGROUND

Postoperative trigeminal neuropathy may be seen after surgery for middle and posterior cranial fossa lesions. Although neuropathic pain is a cause of reduced quality of life, global consensus on postoperative pain management is lacking. Mirogabalin besylate is a selective ligand for the α2δ subunit of voltage-gated calcium channels. Although mirogabalin has been used for patients with postherpetic neuralgia and painful diabetic peripheral neuropathy, few reports have assessed the effect on postsurgical neuropathy. In this report, we describe a clinical effectiveness of mirogabalin for trigeminal neuropathy after skull base surgery.

CASE DESCRIPTION

Case 1: A 51-year-old female with right trigeminal schwannoma was operated on via the anterior transpetrosal approach. She had tingling and numb feelings in the right face postoperatively. Mirogabalin was orally administered after the operation. Her continuous facial numbness immediately improved. Case 2: A 55-year-old female with left middle fossa base meningioma extending into the infratemporal fossa was operated on via the infratemporal fossa approach. She had a tingling feeling in the left face postoperatively. Mirogabalin was orally administered for this symptom after the operation, which gradually improved.

CONCLUSIONS

Mirogabalin may show significant pain relief for patients with trigeminal neuropathy after skull base surgery. Further studies using a larger number of patients are warranted to confirm these findings.

Percutaneous Balloon Compression for the Treatment of Trigeminal Neuralgia: A Review of 10 Years of Clinical Experience

BACKGROUND

Trigeminal neuralgia (TN) is defined as a spontaneous painful sensation in the trigeminal nerve territory. The pain intensity of TN is classified into different grades of suffering that affect a patient's quality of life. Percutaneous balloon compression of the ganglion is a neurosurgical option that is easy, reproducible, and can reduce the morbidity of TN.

METHODS

We retrospectively analyzed all patients treated with trigeminal nerve percutaneous balloon compression at the Clinical Hospital of the University of Chile between January 2012 and May 2022. Data collected from electronic records included demographic information, medical and surgical history, type of anesthesia and drugs used during surgery, balloon inflation time, surgery time, operative room time, intraoperative events, postoperative complications, duration of hospitalization, and duration of follow-up.  Results: We identified 63 patients who met our inclusion criteria. The median patient age was 62 years (interquartile range [IQR] 57-69 years). Sixty-five percent of the patients were female. The simultaneous involvement of the second and third branches of the trigeminal nerve was the most frequent symptom. Before surgery, the patients experienced an average of 6.6 years of pain (IQR 2-10 years). Right neuralgia was the most frequent laterality type (69%). Forty percent of the patients had a previous surgical procedure for neuralgia, with treatment failure being the most frequent surgical indication (63%). According to the procedure, the mean balloon insufflation volume was 0.89±0.12 mL with a median compression time of 2.5 min (IQR 2.1-4.0 min). No hemorrhagic complications were observed. Furthermore, during follow-up, there were no surgical complications among any of the patients; however, 6.4% of patients required a second intervention. The pain-free period was two years in 60% of patients and five years in 23% of patients.

CONCLUSIONS

TN is a painful condition. Although there are multiple surgical approaches, we believe that percutaneous balloon compression is an excellent alternative treatment option that offers high effectiveness, low morbidity, and low hospital stay.

Pathophysiology, Clinical Implications and Management of Orofacial Neuropathic Pain- with special attention to Trigeminal neuralgia: A Narrative Review

Background: It is a widely held belief that if the trigeminal nerve is damaged, the victim would experience agonising and unrelenting external pain. A lesion to the trigeminal nerve may have a wide-reaching effect, such as on one side of the face in particular, or it might have a more localised effect, such as on some or all of your gums. The risk of damage increases the likelihood that it will be difficult to speak and swallow. This nerve provides sensation to a part of your face that may be constantly aching or tingling for some people. However, the trigeminal nerve injury-related persistent orofacial pain might be brought on by a wide variety of unknown triggers. Aim: In this study investigate the clinical manifestations of chronic orofacial pain brought on by a damage to the trigeminal nerve, as well as the diagnostic and therapeutic approaches available to treat this condition. Methodology Through the use of search phrases such as "Trigeminal nerve injury," "Trigeminal ganglion," "Trigeminal spinal subnucleus caudalis," "Craniofacial pain," "Oral prognosis," and "treatment," the computerised databases for the last twenty years have been investigated. There are now two hundred objects in total that have been accumulated. There have been around fifty of them that are pertinent to the discussion that is going on in this work. Majority of the patients fair enough with the pharmacology treatment/drugs like the carbamazepine & oxcarbazepine which forms the first line treatment options followed by lamotrigine & baclofen encompassing the second line of drugs along with adjuvant drug support of topiramate, levetiracetam, gabapentin, pregabalin. As the field of science has explored &advanced for the latest treatment options include microvascular decompression, gamma knife radiosurgery, percutaneous rhizotomies variable based on the evidences & guidelines 54 Conclusion: New diagnostic criteria and treatment alternatives have become available for people who suffer from trigeminal neuropathy and orofacial neuropathic pain as a result of recent developments in fundamental animal research that have led to their development. Despite the results, more research needs to investigate a greater variety of distinct non-neuronal cell feature approaches.

Understanding Lamotrigine's Role in the CNS and Possible Future Evolution

The anti-epileptic drug lamotrigine (LTG) has been widely used to treat various neurological disorders, including epilepsy and bipolar disorder. However, its precise mechanism of action in the central nervous system (CNS) still needs to be determined. Recent studies have highlighted the involvement of LTG in modulating the activity of voltage-gated ion channels, particularly those related to the inhibition of neuronal excitability. Additionally, LTG has been found to have neuroprotective effects, potentially through the inhibition of glutamate release and the enhancement of GABAergic neurotransmission. LTG's unique mechanism of action compared to other anti-epileptic drugs has led to the investigation of its use in treating other CNS disorders, such as neuropathic pain, PTSD, and major depressive disorder. Furthermore, the drug has been combined with other anti-epileptic drugs and mood stabilizers, which may enhance its therapeutic effects. In conclusion, LTG's potential to modulate multiple neurotransmitters and ion channels in the CNS makes it a promising drug for treating various neurological disorders. As our understanding of its mechanism of action in the CNS continues to evolve, the potential for the drug to be used in new indications will also be explored.

Is percutaneous balloon compression better than microvascular decompression to treat trigeminal neuralgia? A systematic review and meta-analysis

BACKGROUND

Trigeminal neuralgia (TN) is a neuropathic pain that affects one or more branches of the trigeminal nerve. Surgical options after pharmacological failure are Microvascular Decompression (MVD) or percutaneous procedures, which include Balloon Compression (PBC). This study aims to describe pain outcomes and complications after PBC and MVD procedures for patients with trigeminal neuralgia.

METHODS

We performed a systematic review and meta-analysis on PubMed, EMBASE, LILACS, and Web of Science databases up to April 2022, following PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and meta-Analysis). Articles that separately describe pain outcome for MVD and PBC were included. MINORS tool was used for bias assessment. Meta-analysis results are presented in forest plot and funnel plot.

RESULTS

853 studies were assessed for screening, and 11 studies met the inclusion criteria for this review. A total of 1046 patients underwent PBC and 1324 underwent MVD. The subgroup analysis for patients without multiple sclerosis shows that MVD was associated with lower number of patients with pain than PBC, with an OR value of 0.54 (95 % CI 0.34-0.84). All other analyses evidenced a tendency for better outcomes after the MVD procedure, but with no statistically significant difference.

CONCLUSION

Considering short and long pain relief, recurrence of pain and total complications for MVD and PBC, our study found that MVD is the best surgical option available for trigeminal neuralgia.

The Influence of Radiologist Practice Setting on Identification of Vascular Compression from Magnetic Resonance Imaging in Trigeminal Neuralgia

OBJECTIVE

Preoperative magnetic resonance imaging (MRI) studies are routinely ordered for trigeminal neuralgia (TN), though with contested reliability in contemporary literature. A potential reason for this disagreement is inconsistency in MRI reading methodologies. Here, we compare the rate of reported neurovascular compression on preoperative MRI by radiologists employed in community or private practice settings and academic neuroradiologists.

METHODS

A retrospective review was conducted on patients who underwent endoscopic microvascular decompression for TN with intraoperatively visualized neurovascular compression and primary read by a non-academic or community radiologist. Patient imaging was then re-read by a board-certified neuroradiologist practicing in an academic setting, who was blinded to the initial read and the side of TN symptoms.

RESULTS

Non-academic radiologists reported vascular compression in 26.0% (20/77) of all patients, and mention was rarely made of the non-pathological side (sensitivity = 26.0%). On academic neuroradiologist re-reads, vascular compression was noted in 87.0% (67/77) of patients on the pathological side and in 57.1% (44/77) on the non-pathological side (sensitivity = 87.0%, specificity = 42.9%). Isotropic/near isotropic 3-dimensional steady state or heavily T2-weighted sequences were read with 92.3% sensitivity and 36.9% specificity, compared to 58.3% sensitivity and 66.7% specificity using routine T2 weighted sequences.

CONCLUSIONS

The frequency of vascular compression reported by non-academic radiologists is much lower than what is reported by academic neuroradiologists reading the same MRI scans. These results highlight the effect of practice setting on the predictive power of neuroimaging. Future studies are indicated to further investigate these relationships, as well as to trial newer imaging modalities.

A case of glossopharyngeal neuralgia successfully treated with levetiracetam

BACKGROUND

Glossopharyngeal neuralgia is a condition that causes severe pain in the throat during swallowing. Although carbamazepine is a viable option for treating glossopharyngeal neuralgia, there are minimal data regarding the effect of alternative agents to treat it. We report on glossopharyngeal neuralgia, which is successfully controlled by levetiracetam.

PRESENTATION

A woman in her 70s checked into our hospital with a chief complaint of neck pain lasting 5 years. She had a history of carbamazepine-induced interstitial pneumonia. As a result, we prescribed oral levetiracetam 1000 mg daily in addition to mirogabalin, which was previously prescribed. This effectively reduced the numerical rating scale from 9 to 1 with no adverse effects. Finally, she underwent microvascular decompression, and her symptoms were resolved.

CONCLUSION

Levetiracetam may be an option for patients with glossopharyngeal neuralgia who cannot receive carbamazepine. However, levetiracetam is for off-label use according to the Japanese medical system.

Ultrasound-guided dry needling of masticatory muscles in trigeminal neuralgia - A case series of 35 patients

Background

Trigeminal neuralgia (TGN) is considered a sensory neuropathy. However, reports of pain on chewing/speaking suggest a masticatory myofascial involvement.

Objective

To examine the effect of ultrasound-guided dry needling (USGDN), which deactivates myofascial trigger points in masticatory, neck, and facial muscles on TGN symptoms.

Methods

Charts of 35 patients treated for TGN were retrospectively reviewed. Treatment was USGDN alone or combined with trigeminal ganglion/mandibular nerve pulsed radiofrequency (PRF), followed by yoga mudras to stretch masticatory and facial muscles. Patients were followed for 1-8 years. Outcome parameters were reduction of medications with reduction in neuralgic attack frequency and Numeric Rating Scale (NRS) score.

Results

23 patients (65.7%) received USGDN alone, 12 patients (34.3%) received PRF treatment before USGDN. A significant reduction in the mean (SD) NRS (5.7 [1.2] vs 8.8 [1.6]; P < .001) and neuralgic attack frequency (47 [27] vs 118 [70] attacks/day; P < .001) was seen after PRF compared with baseline, respectively. Following USGDN, the mean (SD) NRS further decreased significantly to 1.0 (0.9) (P < .001). USGDN alone produced a similar improvement in the NRS (8.9 [1.5] at baseline reduced to 0.6 [0.7] post-USGDN; P < .001). Patients in both groups reported a cessation in neuralgic attacks after USGDN. Post-USGDN, 18/27 patients completely discontinued medication, with the mean (SD) carbamazepine dose significantly reducing from 716.7 (260.9) mg/day at baseline to 113.0 (250.2) mg/day post-USGDN (P < .001).

Conclusion

Decisive relief of TGN by USGDN suggests neuromyalgia involving masticatory muscles. Prospective, controlled studies could confirm these findings.

Effect of lidocaine on expression of P2X7, p-p38 and IL-Iβ in the thalamus of rats with trigeminal neuralgia

We investigated whether lidocaine can increase the pain threshold of rats with trigeminal neuralgia by affecting the expression of P2X7, p-p38 and IL-Iβ proteins in the thalamus. Thirty-three male Sprague-Dawley (SD) rats were randomly divided into three groups (n = 11): Sham group, Ion-CCI (infraorbital nerve chronic constriction injury) group and Ion-CCI+L group(Ion-CCI+lidocaine 10 mg/kg/day, i.p.). The mechanical pain threshold of rats was measured preoperatively and at 1, 3, 5, 7, 9, 11 and 14days after operation with the von Frey filament sensor tester. Fourteen days after operation, the rats were dissected to collect their whole brain, thalamus and trigeminal ganglion to detect IL-1β, P2X7, p38, and p-p38 protein expression. The pain threshold of rats in Ion-CCI+L group was lower than that in Sham group (p < 0.01) and higher than that in Ion-CCI group (p < 0.01).ELISA showed that IL-1β in the thalamus and trigeminal ganglion in Ion-CCI+L group were lower than those in ion-CCI group (p < 0.05) but higher than those in Sham group (p < 0.05). Western blot showed that the expression levels of P2X7 and p-p38 in the thalamus of rats in Ion-CCI+L group were lower than those in Ion-CCI group (p < 0.01) and higher than thaose in Sham group (p < 0.01),while the expression levels of IL-1β in the thalamus in Ion-CCI+L group were lower than those in Ion-CCI group (p < 0.05) and higher than those in Sham group (p < 0.01). Immunofluorescence showed that p-p38 in the thalamus in Ion-CCI+L group was lower than that in Ion-CCI group (p < 0.05) and higher than that in Sham group (p < 0.05). Lidocaine can reduce the inflammatory response of the central nervous system and increase the pain threshold of trigeminal neuralgia rats by inhibiting p2x7-p38-IL-1β signaling pathway.This pathway play an important role in the pathogenesis of trigeminal neuralgia, and it may be one of the targets for the treatment of trigeminal neuralgia.

Pulsed Radiofrequency for the Treatment of Trigeminal Neuralgia

PURPOSE OF REVIEW

Trigeminal neuralgia is a sudden, unilateral, stabbing pain in the distribution of one or more branches of the fifth cranial nerve, with an overall prevalence ranging between 0.03 and 0.3%. While conservative treatments may offer temporary relief, many patients experience chronic headaches associated with their neuralgia. Invasive treatments are available for patients with intractable neuralgia; however, they may cause permanent tissue damage and often do not provide relief. This article examines pulsed radiofrequency (PRF) ablation (RFA) of the trigeminal nerve as a minimally invasive procedure that offers a promising alternative to invasive procedures for relief of trigeminal neuralgia while minimizing tissue damage.

RECENT FINDINGS

Efficacy of PRF and RFA in treating trigeminal neuralgia has been studied before, but literature lacks large size studies. The results of this retrospective study indicate that PRF can be used as a safe and effective treatment for patients suffering from trigeminal neuralgia that is refractory to conservative measures.

Effectiveness, Safety, and Predictors of Response to 5% Lidocaine-Medicated Plaster for the Treatment of Patients With Trigeminal Neuralgia: A Retrospective Study

BACKGROUND

Whether 5% lidocaine-medicated plaster (LMP) is a valuable therapeutic option for the treatment of trigeminal neuralgia (TN) is worth exploring. If LMP is proven effective for TN, positive predictors of the analgesic effects of LMP warrant further investigation.

OBJECTIVE

To evaluate the efficacy and safety of LMP for the treatment of TN, and to explore the predictive factors for the treatment efficacy of LMP.

METHODS

This is a retrospective and observational study. We analyzed the efficacy of LMP for the treatment of TN between March 2019 and January 2022. The follow-up time was approximately 2 weeks, 1 month, 2 months, and 3 months after LMP treatment. The LMP response was considered the Barrow Neurological Institute (BNI) score of I to III and an improvement in BNI of at least I grade from pretreatment baseline. Univariable and multivariable logistic analyses were performed to identify the predictive factors for LMP response.

RESULTS

A total of 103 patients were included and analyzed in this study. LMP was effective in some TN patients, with an efficacy rate of 21.4%, 21.4%, 18.4%, and 16.5% after 2 weeks, 1 month, 2 months, and 3 months of LMP treatment, respectively. The overall adverse event rate associated with LMP was 5.8%, and the reported adverse events were all skin reactions. Facial trigger points (odds ratio [OR] = 0.25, 95% confidence interval [CI] = 0.07-0.86, P = 0.03) and a lower BNI score (OR = 0.37, 95% CI = 0.07-0.87, P = 0.01) were identified as potential predictors for initial efficacy (2-week follow-up) of LMP treatment.

CONCLUSIONS AND RELEVANCE

LMP has been shown to provide effective and sustained analgesia in some TN patients with minimal risk of systemic adverse reactions. Patients with facial trigger points and mild to moderate pain are more likely to benefit from LMP treatment. Our data suggest that LMP may be an effective treatment option for patients with the aforementioned characteristics of TN.

Radiofrequency thermoablation of the peripheral branches of trigeminal nerve versus the Gasserian ganglion for treating idiopathic trigeminal neuralgia: A systematic review and meta-analysis

BACKGROUND

Trigeminal neuralgia is characterized by pain at the distribution of one or more of the trigeminal nerve branches and is usually treated with anti-epileptic medication. When first line treatment fails, patients receive other treatment modalities including radiofrequency thermoablation (RFT) of the Gasserian ganglion and peripheral branches of the trigeminal nerve. The aim of this study is to compare RFT of the Gasserian ganglion and peripheral branches of trigeminal nerve in terms of efficacy and rate of complications.

METHODS

This was a systematic review and meta-analysis that searched Medline, Cochrane Central Register of Controlled Trials, and Embase using Medical Subject Headings and the references of the enrolled studies with no restriction on date. We included only RCTs that compared the RFT of the Gasserian ganglion and peripheral branches of trigeminal nerve with one of the following outcomes: pain scales, immediate effective rate, recurrence rate, and complications.

RESULTS

Five articles were eligible for our review and showed that there was no difference between RFT of the peripheral nerves and the Gasserian ganglion in terms of pain scores. There was a non-significant trend for RFT of the peripheral nerve to have higher immediate effect rates and higher recurrence rates. RFT of the Gasserian ganglion group was associated with masticatory weakness, while the other group was associated with facial swelling and numbness of V2.

CONCLUSION

RFT of the peripheral branches is a safe and effective method to treat idiopathic trigeminal neuralgia but leads to a higher recurrence rate when compared with RFT of the Gasserian ganglion.

Xper-CT combined with laser-assisted navigation radiofrequency thermocoagulation in the treatment of trigeminal neuralgia

Objective

Our objective was to study the clinical feasibility of Xper-CT combined with laser-assisted radiofrequency thermocoagulation in the treatment of trigeminal neuralgia.

Materials and methods

A retrospective analysis was made of 60 patients with trigeminal neuralgia who visited the Affiliated Hospital of Binzhou Medical University from January 2019 to May 2021. According to the different surgical methods, we were divided into C-arm X-ray group and laser navigation group. The operation time, operative complications, post-operative 24 h, post-operative 3 and 6 months Barrow Neurotics Institute (BNI) score were recorded and compared.

Results

Compared with the C-arm X-ray-guided puncture group, Xper-CT combined with laser-assisted navigation has the obvious advantages of shorter total puncture time, shorter surgical time, higher success rate of first puncture, and better surgical effect.

Conclusion

Radiofrequency therapy of trigeminal neuralgia with Xper-CT combined with laser-assisted navigation has a good clinical effect and can be promoted and applied.

Neuropathic ocular surface pain: Emerging drug targets and therapeutic implications

INTRODUCTION

Dysfunction at various levels of the somatosensory system can lead to ocular surface pain with a neuropathic component. Compared to nociceptive pain (due to noxious stimuli at the ocular surface), neuropathic pain tends to be chronic and refractory to therapies, making it an important source of morbidity in the population. An understanding of the options available for neuropathic ocular surface pain, including new and emerging therapies, is thus an important topic.

AREAS COVERED

This review will examine studies focusing on ocular surface pain, emphasizing those examining patients with a neuropathic component. Attention will be placed toward recent (after 2017) studies that have examined new and emerging therapies for neuropathic ocular surface pain.

EXPERT OPINION

Several therapies have been studied thus far, and continued research is needed to identify which individuals would benefit from specific therapies. Gaps in our understanding exist, especially with availability of in-clinic diagnostics for neuropathic pain. A focus on improving diagnostic capabilities and researching gene-modulating therapies could help us to provide more specific mechanism-based therapies for patients. In the meantime, continuing to uncover new modalities and examining which are likely to work depending on pain phenotype remains an important short-term goal.

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.

A Review of Medical and Surgical Options for the Treatment of Facial Pain

Facial pain is a common medical complaint that is easily misdiagnosed. As a result, this pain often goes mistreated. Despite this, there are a variety of pharmacologic, surgical, and neuromodulatory options for the treatment of facial pain. In this review, the authors detail the forms of facial pain and their treatment options. They discuss the common medications used in the first-line treatment of facial pain and the second-line surgical and neuromodulatory options available to patients when pharmacologic options fail.

Application of Morphological Characteristics of Radiofrequency Lesions to Individual Parameters of Thermal Rhizolysis for Trigeminal Neuralgia

Thermic rhizolysis is a reliable therapy for pharmaco-resistant trigeminal neuralgia. Temperature, duration of electrocautery and needle location can influence the efficacy and complications of the therapy. We performed experimental thermocautery on egg white with increasing parameters of time (30-120s) and temperature (60-95°C); we analyzed the shape, size and volume of the thermic lesions produced. We developed a surgical procedure to assess peroperatively the probable thermocoagulation field and its geometric relations with the trigeminal roots and other anatomical structures of Meckel's cave, and we individually adapted the parameters of rhizolysis to optimize the results. This procedure was applied on 22 patients with trigeminal neuralgia. The volume of the lesions produced by rhizolysis on egg white had a spheroidal shape and increased linearly with the level of temperature and the time of electrocautery from 1.595mm³ (SD0.38) to 54.454mm3(SD10.41); higher temperatures induced larger thermocoagulation fields than longer time periods. The calculated volumes measured at all levels of temperature and time were applied in vivo on the patient stereotactic planning during the thermocoagulation procedure in order to select the optimal parameters for rhizolysis. The median values used were 75°C(range70-85°C) and 60s(range45-60s). At 6-month follow-up, pain outcome was Barrow-Neurological-Institute class-I for 72.7%, IIIa for 22.7% and IIIb for 4.6%; the only complication due to rhizolysis was mild facial numbness in 13 subjects (59%) at 6-month follow-up. We conclude that geometric analysis of the position of the electrode before trigeminal thermocoagulation with morphometric-related individual adaptation of treatment parameters could avoid serious injuries and optimize pain control.

The State-of-the-art Pharmacotherapeutic Options for the Treatment of Chronic Non-Cancer Pain

INTRODUCTION

Pharmacotherapeutic options continue to expand for the treatment of chronic non-cancer pain. There has been an increasing emphasis on multimodal analgesia. This strategy employs use of multiple analgesic medications each with a distinct mechanism of action, which when administered concomitantly may provide profound analgesia.

AREAS COVERED

The authors describe evidence from randomized controlled trials and systematic reviews on a variety of established medications including anti-inflammatory agents, opioids, anti-convulsants, anti-depressants, N-methyl-D-aspartate receptor antagonists, sodium channel blockers, cannabinoids, and alpha-2-receptor blockers. Furthermore, they provide developing evidence on more novel pharmacotherapeutics including alpha lipoic acid, acetyl-L-carnitine, low dose naltrexone, calcitonin gene-related peptide antagonists, targeted toxin therapy, Nav1.7 inhibitors, neurotensin agonists, purinoceptor antagonists, and sigma-1 receptor antagonists. Furthermore, the authors review the safety and adverse effect profile for these agents.

EXPERT OPINION

In this era of the opioid epidemic, clinicians should first offer non-opioid analgesics and employ a multimodal analgesic strategy. Current guidelines recommend a personalized approach to the chronic pain treatment, in each case accounting for type, location, severity, and chronicity of pain. Clinicians should also carefully consider the risk-to-benefit ratio to the patient based on the drug side effect profile, patient age, and comorbidities.

Acupuncture Methods for Primary Trigeminal Neuralgia: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

Background

Primary trigeminal neuralgia (PTN) is a clinical refractory disorder characterized by excruciating pain that severely impacts the quality of life. Several studies have shown that acupuncture can improve PTN pain. However, the comparative efficacy and safety of acupuncture are unknown. Herein, a systematic review was conducted to compare the efficacy and safety of various acupuncture methods for PTN treatment.

Methods

Relevant randomized controlled trials (RCTs) published up to 1 August 2021 were obtained from PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science Core Collection, Chinese National Knowledge Infrastructure, Chinese Biomedical Literature Database, CQVIP Database, Wanfang Database, Allied and Alternative Medicine Database, and related registration platforms. Two authors independently selected the studies and obtained data. Cochrane Handbook was used to assess the methodological quality. We put the pain relief as the primary outcome and the response rate and adverse events as the secondary outcomes. Review Manager v5.3, ADDIS v1.16.8, and STATA v15.0 software were used for data analysis. The intraclass correlation coefficient was used to assess the consistency of the two investigators.

Results

A total of 58 RCTs with 4,126 participants were obtained. The meta-analysis indicated that five acupuncture methods were superior to conventional medicine (carbamazepine) in pain reduction intensity and response rate. Meanwhile, electronic acupuncture plus manual acupuncture was the most effective therapy since it reduced pain intensity in 11 methods and improved the response rate in 10 interventions. Moreover, six interventions had acceptable adverse events, and none of the included studies reported severe adverse events. However, most pieces of evidence were ranked as critically low.

Conclusion

These findings show that acupuncture methods can be effective and safe for PTN. Moreover, electronic acupuncture plus manual acupuncture maybe the best acupuncture treatment for PTN and should be administered to PTN patients. However, additional well-designed and high-quality RCTs should be conducted to verify the above findings in the future. The systematic review is registered with CRD42020221456.

Gasserian ganglion radiofrequency thermoablation in a patient with aneurysm of the anterior communicating artery -A case report

Background

Gasserian ganglion radiofrequency thermoablation is a good treatment option for the management of pain in trigeminal neuralgia. We report a case in which the patient of trigeminal neuralgia combined with anterior cerebral artery aneurysm was treated successfully by gasserian ganglion thermoablation without any complication.

Case

An 85-year-old female presenting with electric shock like sensation in the gum and molar teeth was diagnosed as trigeminal neuralgia. Carbamazepine medication and trigeminal nerve blockade relieved her pain partially, but severe side effects of carbamazepine occurred. Magnetic resonance angiography of the brain showed saccular aneurysm in inferior aspect of the anterior communicating artery. Gasserian ganglion thermoablation under sedation anesthesia using nicardipine was performed carefully without any rupture of the cerebral aneurysm.

Conclusions

Gasserian ganglion thermoablation could be performed safely in a patient with cerebral aneurysm without any inadvertent event.

Complete neuroendoscopic versus microscopical trigeminal neuralgia microvascular decompression (MVD) in primary trigeminal neuralgia (PTN)

OBJECTIVE

To compare complete neuroendoscopic and microscopic microvascular decompression (MVD) in primary trigeminal neuralgia (PTN) and their impacts on the microstructure of the trigeminal nerve.

METHODS

Eighty-seven PTN patients admitted in our hospital from July 2017 to December 2019 were selected for this prospective study and divided into the endoscopic group (n=45) (complete neuroendoscopic MVD) and the microscope group (n=42) (microscopic MVD) according to the treatment method each patient underwent. All the patients underwent MRI scanning, and the fractional anisotropy (FA) scores and the apparent diffusion coefficient (ADC) values of the neurovascular compression (NVC) sites were measured. The operation times, the treatment efficacy, the microstructural changes in the trigeminal nerve, the complications, and the recurrence and mortality rates at one year after the operations were compared.

RESULTS

The endoscopic group observed a superior therapeutic effect compared with the microscope group one year after the surgeries (P=0.046). After the surgeries, the endoscopic group observed a greater increase in their FA values and a larger decline in their ADC values than the microscope group did (P=0.014, 0.015, 0.011, 0.002). The complication rate in the endoscopic group was 11.11%, and the complication rate in the microscopic group was 30.95% (P=0.022). One year after the surgeries, we found a lower recurrence rate in the endoscopic group (P=0.001). The perforator vessels from the offending vessel to the outlet area of the durmedulla, the distances between the front edge of the bone window and the inner surfaces of the petrous part of the temporal bone ≥ the distance between the duration ≥ the duration of conventional MVD were independent risk factors for complications after MVD in the hemifacial spasm patients (P=0.001, 0.037, 0.023, 0.005).

CONCLUSION

Complete neuroendoscopic MV yields better long-term treatment outcomes than microscopic MVD, and it is more effective at improving the microstructure of the trigeminal nerve and has fewer postoperative complications.

Trigeminal Neuralgia: Current Approaches and Emerging Interventions

Trigeminal neuralgia (TN) has been described in the literature as one of the most debilitating presentations of orofacial pain. This review summarizes over 150 years of collective clinical experience in the medical and surgical treatment of TN. Fundamentally, TN remains a clinical diagnosis that must be distinguished from other types of trigeminal neuropathic pain and/or facial pain associated with other neuralgias or headache syndromes. What is increasingly clear is that there is no catch-all medical or surgical intervention that is effective for all patients with trigeminal neuralgia, likely reflective of the fact that TN is likely a heterogenous group of disorders that jointly manifests in facial pain. The first-line treatment for TN remains anticonvulsant medical therapy. Patients who fail this have a range of surgical options available to them. In general, microvascular decompression is a safe and effective procedure with immediate and durable outcomes. Patients who are unable to tolerate general anesthesia or whose medical comorbidities preclude a suboccipital craniectomy may benefit from percutaneous methodologies including glycerol or radiofrequency ablation, or both. For patients with bleeding diathesis due to blood thinning medications who are ineligible for invasive procedures, or for those who are unwilling to undergo open surgical procedures, radiosurgery may be an excellent option-provided the patient understands that maximum pain relief will take on the order of months to achieve. Finally, peripheral neurectomies continue to provide an inexpensive and resource-sparing alternative to pain relief for patients in locations with limited economic and medical resources. Ultimately, elucidation of the molecular mechanisms underlying trigeminal neuralgia will pave the way for novel, more effective and less invasive therapies.

Modulation of excitatory synaptic transmissions by TRPV1 in the spinal trigeminal subnucleus caudalis neurons of neuropathic pain rats

The present study examined contribution of the transient receptor potential vanilloid 1 channel (TRPV1) to the chronic orofacial pain. Bilateral partial nerve ligation (PNL) of the mental nerve, a branch of trigeminal nerve, was performed to induce neuropathic pain. The withdrawal threshold in response to mechanical stimulation of the lower lip skin was substantially reduced after the surgery in the PNL rats while it remained unchanged in the sham rats. This reduction in the PNL rats was alleviated by pregabalin injected intraperitoneally (10 mg/kg) and intracisternally (10, 30, 100 μg). Furthermore, an intracisternal injection of AMG9810, an antagonist of TRPV1, (1.5, 5.0 μg) attenuated the reduction of withdrawal threshold. Spontaneous and miniature excitatory postsynaptic currents (sEPSCs and mEPSCs) were recorded from the spinal trigeminal subnucleus caudalis (Vc) neurons in the brainstem slice, which receive the orofacial nociceptive signals. In the PNL rats, superfusion of capsaicin (0.03, 0.1 μM) enhanced their frequency without effect on the amplitude and the highest concentration (0.3 μM) increased both the frequency and amplitude. In the sham rats, only 0.3 μM capsaicin increased their frequency. Thus, capsaicin-induced facilitation of sEPSCs and mEPSCs in the PNL rats was significantly stronger than that in the sham rats. AMG9810 (0.1 μM) attenuated the capsaicin's effect. Capsaicin was ineffective on the trigeminal tract-evoked EPSCs in the PNL and sham rats. These results suggest that the chronic orofacial pain in the PNL model results from facilitation of the spontaneous excitatory synaptic transmission in the Vc region through TRPV1 at least partly.