Natural history and outcome of 200 outpatients with classical trigeminal neuralgia treated with carbamazepine or oxcarbazepine in a tertiary centre for neuropathic pain

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.

Electroacupuncture and carbamazepine for patients with trigeminal neuralgia: a randomized, controlled, 2 × 2 factorial trial

BACKGROUND

Trigeminal neuralgia (TN) is difficult to treat due to its severe pain intensity and recurring episodes, which significantly impact quality of life.

OBJECTIVES

We aimed to assess the effectiveness of electroacupuncture (EA) in alleviating the pain intensity in TN, and to determine whether EA combined with low-dosage carbamazepine (CBZ) has a synergistic effect.

METHODS

A multi-centre, randomized, 2 × 2 factorial trial was conducted. Participants who met the inclusion criteria received active EA or sham EA for 60 min, three times a week for four weeks; CBZ (300 mg per day) or placebo for four weeks. The primary outcome was the change in visual analog scale (VAS) score from baseline to weeks 2, 4, 16, and 28. Secondary outcomes included quality of life and adverse events.

RESULTS

A total of 120 participants (75 females and 45 males; mean (SD) age, 58.5 (15.3) years) were included. The main effects of EA and CBZ were significant (P < 0.001), and there was a significant interaction was identified between the interventions (P = 0.041). Participants who received EA (mean difference [MD], -0.3 [95% CI, -0.40 to -0.20] at week 2; -1.6 [-1.70 to -1.50] at week 4; -1.1 [-1.31 to -0.89] at week 16; -0.8 [-1.01 to -0.59] at week 28), CBZ (MD, -0.6 [95% CI, -0.70 to -0.50] at week 2; -0.9 [-1.03 to -0.77] at week 4, -0.2 [-0.41 to 0.01] at week 16, 0.2 [-0.01 to 0.41] at week 28), and the combination of both (MD, -1.8 [95% CI, -1.90 to -1.70] at week 2; -3.7 [-3.83 to -3.57] at week 4, -3.4 [-3.61 to -3.19] at week 16, -2.9 [-3.11 to -2.69] at week 28) had a greater reduction in VAS score over the treatment phase than their respective control groups (sham EA, placebo, and sham EA plus placebo). EA-related adverse events (6/59, 10.17%) were lower than that of CBZ (15/59, 25.42%) during the whole phases.

CONCLUSIONS

EA or CBZ alone are effective treatments for TN, while the combination of EA and low-dosage CBZ exerts a greater benefit. These findings in this trial demonstrate that the combination of EA and low-dosage CBZ may be clinically effective under certain circumstances.

TRIAL REGISTRATION

NCT03580317.

Radiological characteristics predicting early poor drug response in patients with hemifacial spasm

OBJECTIVES

Patients with hemifacial spasm (HFS) often resort to botulinum toxin injections or microvascular decompression surgery when medication exhibits limited effectiveness. This study aimed to identify MRI and demographic factors associated with poor drug response at an early stage in patients with HFS.

METHODS

We retrospectively included patients with HFS who underwent pre-therapeutic MRI examination. The presence, location, severity, and the offending vessels of neurovascular compression were blindly evaluated using MRI. Drug responses and clinical data were obtained from the medical notes or phone follow-ups. Logistic regression analysis was performed to identify potential factors.

RESULTS

A total of 116 patients were included, with an average age at the time of first examination of 50.4 years and a median duration of onset of 18 months. Forty-nine (42.2%) patients reported no symptom relief. Thirty-seven (31.9%) patients reported poor symptom relief. Twenty-two (19.0%) patients reported partial symptom relief. Eight (6.9%) patients achieved complete symptom relief. The factors that were statistically significant associated with poor drug responses were contact in the attach segment of the facial nerve and aged 70 and above, with an odds ratio of 7.772 (p = 0.002) and 0.160 (p = 0.028), respectively.

CONCLUSIONS

This study revealed that mild compression in the attach segment of the facial nerve in pre-therapeutic MRI increases the risk of poor drug responses in patients with HFS, while patients aged 70 and above showed a decreased risk. These findings may assist clinician to choose optimal treatment at an early stage.

The Challenges in Clinical Diagnosis of Trigeminal Neuralgia: A Review

The lack of established laboratory tests or biomarkers for trigeminal neuralgia (TN) makes diagnosing this relatively rare condition extremely challenging. Trigeminal nerve compression observable on magnetic resonance imaging may indicate TN, but many patients do not have visible lesions or compression. In particular, TN may be confused with migraine, cluster headache, temporomandibular disorder, and other types of headache. An accurate diagnosis is imperative for proper treatment since these conditions do not respond to the same treatment. Many symptoms of these headaches can be vague or overlap, and clinicians depend in large measure on the subjective reports of their patients. Nevertheless, it is imperative to diagnose TN better, which can cause excruciating pain, reduce the quality of life, and even result in disability. It is possible that TN is underestimated.

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.

Compared to oxcarbazepine and carbamazepine, botulinum toxin type A is a useful therapeutic option for trigeminal neuralgia symptoms: A systematic review

OBJECTIVES

This review aimed to compare the effectiveness of three treatments: BTX A, CBZ, and OXB, in managing trigeminal neuralgia (TN).

MATERIAL AND METHODS

We conducted a thorough search for research articles related to our issue using specific keywords on several databases, including Cochrane Central Register of Controlled Trials, Science Direct, Scopus, PubMed, Elsevier, Springer Journals, Ovid Medline, EBSCO, and Web of Science. Our focus was on publications from 1965 to 2023.

RESULTS

We retrieved 46 articles from the search and reviewed them carefully. Out of these, we selected 29 articles that met the inclusion criteria. Among the selected articles, 11 investigated the effects of CBZ and OXB, while 18 explored the impact of BTX A on the improvement of TN symptoms. The response rate ranged between 56% and 90.5% for CBZ and between 90.9% and 94% for OXB. The response rate for BTX A ranged between 51.4% and 100%. All these three treatments had a remarkable effect on the improvement of TN. Importantly, findings highlighted that side effects of CBZ and OXB could lead to treatment discontinuation in some cases, whereas BTX A's side effects have been minimal and less frequent.

CONCLUSIONS

Consequently, BTX A emerges as a promising alternative for TN treatment. However, additional clinical trials are necessary to validate this finding, and further research is required to establish a standardized protocol for administering BTX A in TN.

Microvascular decompression for trigeminal neuralgia: A retrospective analysis of long-term outcomes and prognostic factors

INTRODUCTION

Microvascular decompression is considered to be the most effective and only etiological surgical treatment for classical trigeminal neuralgia, relieving the neurovascular compression found in up to 95% of cases. This study aims to report the long-term outcomes and to identify prognostic factors in a series of patients with trigeminal neuralgia treated by microvascular decompression.

METHODS

A retrospective observational study of 152 consecutive patients operated by microvascular decompression with at least six months of follow-up. The surgical results, including pain relief according to the Barrow Neurological Institute pain scale, complications and the medical treatment during the follow-up period were reviewed. Binary regression analysis was performed to identify factors associated with a good long-term outcome.

RESULTS

A total of 152 patients with a mean age of 60 years and a mean follow-up of 43 months were included. At the final follow-up visit, 83% of the patients had achieved significant relief of the pain and 63% could reduce the absolute drug doses by 50% or more. The most frequent complications were wound infection (4.5%) and CSF fistula (7%). Being over 70 years of age and having paroxysmal pain were associated with a long-term pain relief.

CONCLUSIONS

Our results support the notion that microvascular decompression is an effective and safe therapy in patients with trigeminal neuralgia. A multidisciplinary approach with an early referral to a neurosurgical unit many be beneficial in patients who are refractory to pharmacological treatment.

Considerations When Using Gabapentinoids to Treat Trigeminal Neuralgia: A Review

Despite the exemplary efficacy of voltage-gated sodium channel blockers as a first-line treatment of trigeminal neuralgia, the pharmacological management of this excruciating facial pain condition remains a major issue, as these first-line drugs produce intolerable side effects in a significant portion of patients. In addition, in patients with concomitant continuous pain, the efficacy of these drugs may drop, thus suggesting the opportunity to test the efficacy of different drug categories. The aim of this review is to provide current, evidence-based, knowledge about the use of gabapentin and other α2δ ligands in patients with trigeminal neuralgia. We searched for relevant papers within PubMed, EMBASE, the Cochrane Database of Systematic Reviews and the Clinical Trials database (ClinicalTrials.gov), considering publications up to April 2023. Two authors independently selected studies for inclusion and data extraction. The efficacy of α2δ ligands, gabapentin and pregabalin, has been assessed in seven controlled or open-label studies. Despite the low quality of evidence, the favorable tolerability profile and the possible action on concomitant continuous pain make this drug category of interest for future trials in trigeminal neuralgia.

Brain imaging signatures of neuropathic facial pain derived by artificial intelligence

Advances in neuroimaging have permitted the non-invasive examination of the human brain in pain. However, a persisting challenge is in the objective differentiation of neuropathic facial pain subtypes, as diagnosis is based on patients' symptom descriptions. We use artificial intelligence (AI) models with neuroimaging data to distinguish subtypes of neuropathic facial pain and differentiate them from healthy controls. We conducted a retrospective analysis of diffusion tensor and T1-weighted imaging data using random forest and logistic regression AI models on 371 adults with trigeminal pain (265 classical trigeminal neuralgia (CTN), 106 trigeminal neuropathic pain (TNP)) and 108 healthy controls (HC). These models distinguished CTN from HC with up to 95% accuracy, and TNP from HC with up to 91% accuracy. Both classifiers identified gray and white matter-based predictive metrics (gray matter thickness, surface area, and volume; white matter diffusivity metrics) that significantly differed across groups. Classification of TNP and CTN did not show significant accuracy (51%) but highlighted two structures that differed between pain groups-the insula and orbitofrontal cortex. Our work demonstrates that AI models with brain imaging data alone can differentiate neuropathic facial pain subtypes from healthy data and identify regional structural indicates of pain.

Predictive value of preoperative magnetic resonance imaging structural and diffusion indices for the results of trigeminal neuralgia microvascular decompression surgery

PURPOSE

To explore the predictive value of preoperative magnetic resonance imaging structural and diffusion indices of the spinal trigeminal tract (SpTV) on the results of microvascular decompression (MVD) in patients with trigeminal neuralgia (TN).

METHODS

This retrospective study included patients diagnosed with TN and treated with MVD in the Jining First People's Hospital between January 2020 and January 2021. The patients were divided into good and poor results groups according to postoperative pain relief. Logistic regression analysis was performed to explore independent risk factors for poor results of MVD, and their predictive value was examined using receiver operating characteristic (ROC) curves.

RESULTS

A total of 97 TN cases were included, 24 cases with a poor result and 73 with a good result. They were comparable in demographic characteristics. Fractional anisotropy (FA) was lower (P < 0.001), and radial diffusivity (RD) was higher (P < 0.001) in the poor result group compared to the good result group. Patients in the good result group showed a higher proportion of grade 3 neurovascular contact (NVC) (39.7% vs. 16.7%, P = 0.001) and a lower RD (P < 0.001). The multivariate analysis showed that the RD of SpTV (OR = 0.000016, 95% CI: 0.000-0.004, P < 0.001) and NVC (OR = 8.07, 95% CI: 1.67-38.93, P = 0.009) were independently associated with poor results. The area under the curve (AUC) of RD and NVC were 0.848 and 0.710, and their combination achieved an AUC of 0.880.

CONCLUSION

NVC and RD of SpTV are independent risk factors for poor results after MVD surgery, and combining the NVC and RD might achieve relatively high predictive value for poor results.

The Pharmacological Treatment of Chronic Pain: From Guidelines to Daily Clinical Practice

In agreement with the International Association for the Study of Pain, chronic pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage. To date, there are several types of pain: nociceptive, neuropathic, and nociplastic. In the present narrative review, we evaluated the characteristics of the drugs used for each type of pain, according to guidelines, and their effects in people with comorbidity to reduce the development of severe adverse events.

Treatment of multiple sclerosis-related trigeminal neuralgia with onabotulinumtoxinA

BACKGROUND

The effectiveness of onabotulinumtoxinA (BTX-A) has been established in primary trigeminal neuralgia (TN). However, to the best of our knowledge, the efficacy of BTX-A in secondary TN has not yet been studied.

OBJECTIVE

This study aimed to investigate the efficacy of BTX-A treatment in patients with multiple sclerosis-related trigeminal neuralgia (TN-MS) and compare the efficacy of BTX-A treatment between patients with primary trigeminal neuralgia (TN-P) and patients with TN-MS.

METHODS

This was a retrospective medical record-review study. Demographic and clinical features and severity and frequency of pain before and 2 weeks after the BTX-A administration were extracted from the patient files. BTX-A was injected into the painful area subcutaneously and/or submucosally. BTX-A injections were performed by the same physician using the same methods. A reduction in severity and/or frequency of pain ≥50% was considered therapeutic efficacy.

RESULTS

Fifty-three patients were included in this study. We classified 22 (42%) as TN-P and 31 (58%) as TN-MS. Treatment with BTX-A was effective in 16 of 31 (52%) patients with TN-MS and 10 of 22 (45%) with TN-P. BTX-A treatment was less effective in patients with a history of interventional treatments and more effective in patients with concomitant continuous pain (p = 0.007; odds ratio [OR]: 0.020-0.53 and p = 0.047; OR: 0.046-0.98, respectively).

CONCLUSION

The BTX-A treatment was found to be effective in at least half of our cohort with TN-MS. Concomitant continuous pain and history of interventional treatments to the trigeminal nerve or ganglion might be predictive factors for the efficacy of BTX-A treatment.

Pharmacotherapeutic management of trigeminal neuropathic pain: an update

INTRODUCTION

Guidelines recommend a number of pharmacotherapeutic options used as monotherapy or in combination with others for treating the pain of trigeminal neuropathy.

AREAS COVERED

The authors examine the pharmacotherapeutic options for treating trigeminal neuralgia and supporting evidence in the literature. Guidelines reported the most effective treatment for trigeminal neuropathy, in particular trigeminal neuralgia, appears to be carbamazepine or oxcabazepine, but side effects can be treatment limiting. Lamotrigine and gabapentin are also recommended in guidance. In real-world clinical practice, baclofen, cannabinoids, eslicarbazepine, levetiracetam, brivaracetam, lidocaine, misoprostol, opioids, phenytoin, fosphenytoin, pimozide, sodium valproate, sumatriptan, tizanidine, tocainide, tricyclic antidepressants, and vixotrigine are sometimes used, either as monotherapy or in combination. The relatively small patient population has limited the number of large-scale studies and there is limited evidence on which to base prescribing choices.

EXPERT OPINION

While there is no optimal pharmacotherapy for treating trigeminal neuropathy, advancements in our understanding of the underlying mechanisms of this condition and drug development indicate promise for NaV inhibitors, despite the fact that not all patients respond to them and they may have potentially treatment-limiting side effects. Nevertheless, better understanding of NaV channels may be important avenues for future drug development for trigeminal neuropathy.

Efficacy and complications of microvascular decompression in patients over 70 years with trigeminal neuralgia

OBJECTIVE

Treatment of choice for trigeminal neuralgia (TN) by neurovascular conflict in case of failure of medical treatment is microvascular decompression (MVD). It is a safe and effective technique in the short and long term. But what about older patients who are considered more fragile anesthetically and surgically? Our Objective is to demonstrate the efficacy and complication rate of microvascular decompression (MVD) for older and younger patients with trigeminal neuralgia (TN) due to neurovascular conflict.

METHODS

102 patients with TN due to neurovascular conflict were included (June 2005-December 2016) in a single Regional hospital. 25 were included in the group composed of ≥ 70-year-old patients (G1), while 77 were included in the < 70-year-old group (G2). The patients were operated on by the same surgical team using a retro-sigmoid approach to access the neurovascular conflict. The epidemiologic, clinical, anesthetic, and surgical data were extracted.

RESULTS

The immediate efficacy of surgical treatment (BNI pain intensity = I) was 96% in G1 and 96.10% in the G2 group (p = 0.71). At 3-year follow-up, the efficacy rate was 89% and 86%, respectively (p = 0.93). At 5 years, it was 92% and 92% (p = 0.98). Complication rates were comparable between the two groups (20% versus 27%; p = 0.47) and no deaths occurred despite the fact that G1 group had worst preoperative anesthetic score (ASA-NYHA).

CONCLUSION

MVD is a durable procedure in patients over 70 years of age diagnosed with essential TN. The complication rate and immediate-, medium-, and long-term efficacy were similar to those of younger patients.

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.

Exploring patient satisfaction of a joint-consultation clinic for trigeminal neuralgia: Enabling improved decision-making

Background

Trigeminal neuralgia (TN) is a relatively rare condition which has a profound impact not only on the patient but also on those around them. There is no cure for TN, and the management of the condition is complex. The most effective forms of treatment are either through medication, neurosurgery, or combination of the two. Each option has risks and implications for the patient. As with all clinical decisions, it is important for patients to understand and be fully informed of the treatments available to them. A London UK unit adopted a joint-consultation clinic approach where the patient meets with both physician and neurosurgeon at the same time to discuss treatment options. The purpose of this evaluation is to understand patients’ level of satisfaction with the joint-consultation clinic and evaluate utilisation of a clinical decision-making tool.

Method

Patients who had attended the joint-consultation clinic over a period of 12 months were invited to participate in a telephone or paper survey (N = 55). Responses were analysed using descriptive statistics and thematic analysis.

Results

Forty-one patients (77% response rate) participated in the survey, and the results were overwhelmingly positive for the joint-consultation clinic regarding satisfaction. The benefits were broad ranging including increased understanding, collaboration and confidence in decision-making.

Conclusions

A joint-consultation clinic comprising a neurosurgeon and a physician for the treatment of TN is valued by patients who become better informed and able to make decisions about their care. Positive application of clinical decision-making aids in this situation offers potential across specialities.

Efficacy of microsurgical vascular decompression in trigeminal neuralgia

OBJECTIVES

Analysis of the long-term efficacy of microvascular decompression surgery in trigeminal neuralgia.

MATERIAL AND METHODS

A single-center retrospective study included patients undergoing microvascular decompression surgery for trigeminal neuralgia after failure of well-conducted medical or complementary therapy, with visualization of nerve compression syndrome on MRI.

RESULTS

Eighty-seven patients were included. Nerve compression was alleviated without interposition of polytetrafluoroethylene in 79.3% of cases. Postoperative efficacy on pain was immediate in 97.7% of cases. There were no postoperative deaths, and the rate of severe complications was low (2.3%). The efficacy of microvascular decompression surgery was total at 2 years in 90.8% of cases and at 10 years in 92.3%, without resumption of medical treatment. The failure rate was 10.3%; 26.3% of these patients had been previously treated by a lesional technique (P: 0.043) and 33.3% by interposition of polytetrafluoroethylene (P: 0.003).

CONCLUSIONS

With confirmed clinical and radiological diagnosis, microvascular decompression surgery for trigeminal nerve compression was safe, with total effectiveness in the immediate, short and long terms. It should be considered in first line in case of failure or intolerance of well-conducted medical treatment.

[Neuropathic pain syndromes in patients with multiple sclerosis]

Among the numerous pain syndromes (PS) of various localizations and types, observed in patients with multiple sclerosis (MS), the greatest attention of researchers is attracted by neuropathic PS. Neuropathic PS are often present already in the early stage of MS, significantly reduce the quality of life, hinder the social adaptation of patients, poorly respond to therapy. Central neuropathic PS, which pathogenesis is closely related with plaques in the central nervous system, are most common in patients with MS. Diagnostics of neuropathic PS in MS is based mainly on typical clinical symptoms; MRI and neurophysiological methods data are of secondary importance. This review focuses on modern concepts of three main neuropathic PS in MS: ongoing extremity pain, trigeminal neuralgia and Lhermitte's sign. Clinical symptoms of neuropathic PS, current ideas about their pathogenetic mechanisms, MRI and neurophysiological techniques data and the existing approaches to conservative therapy and surgical treatment based on randomized trials data are presented.

Inhibitory Effects of Palmatine on P2X7 Receptor Expression in Trigeminal Ganglion and Facial Pain in Trigeminal Neuralgia Rats

Trigeminal Neuralgia (TN) refers to recurrent severe paroxysmal pain in the distribution area of the trigeminal nerve, which seriously affects the quality of life of patients. This research applied the chronic constriction injury of the infraorbital nerve (CCI—ION) approach to induce an animal model of TN in rats. The mechanical pain threshold of each group of rats was determined postoperatively; the expression of P2X7 receptor in trigeminal ganglion (TG) was assessed by qRT-PCR, immunofluorescence and Western blot; and the changes of the proinflammatory cytokines IL-1β and TNF-α in serum of rats were detected by ELISA. The results showed that the administration of palmatine in the TN rats could reduce the mechanical pain threshold, significantly decrease the expression of P2X7 receptor in TG, and lower the serum concentrations of IL-1β and TNF-α, compared to the sham group. In addition, the phosphorylation level of p38 in TG of TN rats was significantly decreased after treatment with palmatine. Likewise, inhibition of P2X7 expression by shRNA treatment could effectively counteract the adversary changes of pain sensitivity, IL-1β and TNF-α production, and p38 phosphorylation in TN rats. Our data suggest that palmatine may alleviate mechanical facial pain in TN rats possibly by reducing the expression of P2X7 receptor in TG of TN rats, which may be attributable to inhibiting p38 phosphorylation and reducing the release of IL-1β and TNF-α.

The changing face of trigeminal neuralgia-A narrative review

OBJECTIVE

This narrative review aims to update the reader on the new classification of trigeminal neuralgia (TN), clinical signs, pathophysiologic evidence, and their implications on management. This review is based on the authors' collective experience and knowledge of the literature in addition to a literature search.

BACKGROUND

In recent years, the phenotype of TN has been intensively studied leading to discrete groups of patients. These include patients with TN with additional continuous pain, and patients with and without neurovascular compression of the trigeminal dorsal root entry zone. A number of associated clinical signs such as tearing and sensory changes need further research.

METHODS

The literature on TN was searched in PubMed with the aims of providing evidence for the recently published third edition of the International Classification of Headache Disorders (ICHD) and update the clinical phenotype and management of the TN subcategories.

RESULTS

The ICHD's new classification for TN is based on reliable clinical data, imaging, and neurophysiologic studies. The TN classification reflects current knowledge and has improved the possibility for clinicians to choose adequate management options. However, there is a lack of effective, safe drugs for the management of TN and sparse, robust data on neurosurgical options.

CONCLUSION

Research into all aspects of TN-diagnosis, pharmacotherapy, surgery, long-term management prognosis, and natural history-is needed. Research should adhere to the ICHD's schema for TN. Improved drugs are needed along with rigorous research into surgical options and their efficacy for different subtypes of TN.

Epidemiology of trigeminal neuralgia: an electronic population health data study in Korea

BACKGROUND

Trigeminal neuralgia (TN) is one of the most painful disorder in the orofacial region, and many patients have suffered from this disease. For the effective management of TN, fundamental epidemiologic data related to the target population group are essential. Thus, this study was performed to clarify the epidemiological characteristics of TN in the Korean population. This is the first national study to investigate the prevalence of TN in Korean patients.

METHODS

From 2014 to 2018, population-based medical data for 51,276,314 subscribers to the National Health Insurance Service of Korea were used for this study.

RESULTS

The incidence of TN was 100.21 per 100,000 person-years in the year of 2018 in Korea, and the male to female ratio was 1:2.14. The age group of 51-59 years had the highest prevalence of TN. Constant increases in medical cost, regional imbalance, and differences in prescription patterns by the medical specialties were showed in the management of TN.

CONCLUSIONS

The results in this study will not only help to study the characteristics of TN, but also serve as an important basis for the effective management of TN in Korea.

Cranial Neuralgias

PURPOSE OF REVIEW

This article discusses the differential diagnosis, evaluation, and management of trigeminal neuralgia and reviews other neuralgias of the head and neck, including those that contribute to neuralgic ear pain.

RECENT FINDINGS

Most cases of trigeminal neuralgia are related to vascular compression, a demyelinating plaque, or a compressive mass affecting the trigeminal nerve. However, recent studies have shown that up to 11% of patients have a family history of trigeminal neuralgia, suggesting that some patients may have a genetic predisposition to demyelination or nerve hyperexcitability. In these patients, trigeminal neuralgia may occur at a younger age, on both sides of the face, or in combination with other neuralgias.

SUMMARY

When a patient presents with neuralgic pain, the diagnosis is made by careful history and neurologic examination, with attention to the dermatome involved, the triggers, and the presence of any associated sensory deficit. All patients with new neuralgia or neuropathic facial pain warrant a careful evaluation for a secondary cause. The presence of sensory deficit on bedside examination is particularly concerning for an underlying secondary etiology.

Microvascular decompression for trigeminal neuralgia: A retrospective analysis of long-term outcomes and prognostic factors

INTRODUCTION

Microvascular decompression is considered to be the most effective and only etiological surgical treatment for classical trigeminal neuralgia, relieving the neurovascular compression found in up to 95% of cases. This study aims to report the long-term outcomes and to identify prognostic factors in a series of patients with trigeminal neuralgia treated by microvascular decompression.

METHODS

A retrospective observational study of 152 consecutive patients operated by microvascular decompression with at least six months of follow-up. The surgical results, including pain relief according to the Barrow Neurological Institute pain scale, complications and the medical treatment during the follow-up period were reviewed. Binary regression analysis was performed to identify factors associated with a good long-term outcome.

RESULTS

A total of 152 patients with a mean age of 60 years and a mean follow-up of 43 months were included. At the final follow-up visit, 83% of the patients had achieved significant relief of the pain and 63% could reduce the absolute drug doses by 50% or more. The most frequent complications were wound infection (4.5%) and CSF fistula (7%). Being over 70 years of age and having paroxysmal pain were associated with a long-term pain relief.

CONCLUSIONS

Our results support the notion that microvascular decompression is an effective and safe therapy in patients with trigeminal neuralgia. A multidisciplinary approach with an early referral to a neurosurgical unit many be beneficial in patients who are refractory to pharmacological treatment.

P2X3 receptor upregulation in trigeminal ganglion neurons through TNFα production in macrophages contributes to trigeminal neuropathic pain in rats

BACKGROUND

Trigeminal neuralgia is a characteristic disease that manifests as orofacial phasic or continuous severe pain triggered by innocuous orofacial stimulation; its mechanisms are not fully understood. In this study, we established a new animal model of trigeminal neuralgia and investigated the role of P2X₃ receptor (P2X₃R) alteration in the trigeminal ganglion (TG) via tumor necrosis factor alpha (TNFα) signaling in persistent orofacial pain.

METHODS

Trigeminal nerve root compression (TNC) was performed in male Sprague-Dawley rats. Changes in the mechanical sensitivity of whisker pad skin, amount of TNFα in the TG, and number of P2X₃R and TNF receptor-2 (TNFR2)-positive TG neurons were assessed following TNC. The effects of TNFR2 antagonism in TG and subcutaneous P2X₃R antagonism on mechanical hypersensitivity following TNC were examined.

RESULTS

TNC induced unilateral continuous orofacial mechanical allodynia, which was depressed by carbamazepine. The accumulation of macrophages showing amoeboid-like morphological changes and expression of TNFα in the TG was remarkably increased following TNC treatment. The number of P2X₃R- and TNFR2-positive TG neurons innervating the orofacial skin was significantly increased following TNC. TNFα was released from activated macrophages that occurred in the TG following TNC, and TNFR2 antagonism in the TG significantly diminished the TNC-induced increase in P2X₃R-immunoreactive TG neurons. Moreover, subcutaneous P2X₃R antagonism in the whisker pad skin significantly depressed TNC-induced mechanical allodynia.

CONCLUSIONS

Therefore, it can be concluded that the signaling of TNFα released from activated macrophages in the TG induces the upregulation of P2X₃R expression in TG neurons innervating the orofacial region, resulting in orofacial mechanical allodynia following TNC.

Effects of Preoperative Carbamazepine Treatment on Microvascular Decompression for Classical Trigeminal Neuralgia

BACKGROUND

Carbamazepine (CBZ) is the first-line therapy for trigeminal neuralgia (TN), and microvascular decompression (MVD) is considered to be an effective surgical treatment for TN. However, the effect of preoperative CBZ treatment on MVD outcome is not clear.

METHODS

From 2013 to 2019, 63 patients with classical TN underwent MVD at the First Affiliated Hospital of Zhengzhou University, China. Data were collected through telephone follow-up and electronic medical records in April 2020. Short-term surgical outcome and long-term follow-up data were estimated by univariate and multivariate analysis.

RESULTS

Multivariate analysis indicated that preoperative CBZ treatment was not a significant predictor for short-term outcomes of MVD (P > 0.05). Multivariate analysis for the long-term outcome of MVD indicated that preoperative CBZ treatment could predict postoperative recurrence of TN (P < 0.05).

CONCLUSIONS

For patients with classical TN, a longer preoperative medication history of CBZ treatment had no significant effect on short-term outcome of MVD, but CBZ treatment was associated with a poor long-term outcome following MVD.

Trigeminal neuralgia: An overview from pathophysiology to pharmacological treatments

The trigeminal nerve (V) is the fifth and largest of all cranial nerves, and it is responsible for detecting sensory stimuli that arise from the craniofacial area. The nerve is divided into three branches: ophthalmic (V1), maxillary (V2), and mandibular (V3); their cell bodies are located in the trigeminal ganglia and they make connections with second-order neurons in the trigeminal brainstem sensory nuclear complex. Ascending projections via the trigeminothalamic tract transmit information to the thalamus and other brain regions responsible for interpreting sensory information. One of the most common forms of craniofacial pain is trigeminal neuralgia. Trigeminal neuralgia is characterized by sudden, brief, and excruciating facial pain attacks in one or more of the V branches, leading to a severe reduction in the quality of life of affected patients. Trigeminal neuralgia etiology can be classified into idiopathic, classic, and secondary. Classic trigeminal neuralgia is associated with neurovascular compression in the trigeminal root entry zone, which can lead to demyelination and a dysregulation of voltage-gated sodium channel expression in the membrane. These alterations may be responsible for pain attacks in trigeminal neuralgia patients. The antiepileptic drugs carbamazepine and oxcarbazepine are the first-line pharmacological treatment for trigeminal neuralgia. Their mechanism of action is a modulation of voltage-gated sodium channels, leading to a decrease in neuronal activity. Although carbamazepine and oxcarbazepine are the first-line treatment, other drugs may be useful for pain control in trigeminal neuralgia. Among them, the anticonvulsants gabapentin, pregabalin, lamotrigine and phenytoin, baclofen, and botulinum toxin type A can be coadministered with carbamazepine or oxcarbazepine for a synergistic approach. New pharmacological alternatives are being explored such as the active metabolite of oxcarbazepine, eslicarbazepine, and the new Nav1.7 blocker vixotrigine. The pharmacological profiles of these drugs are addressed in this review.

Real-world effectiveness and tolerability of carbamazepine and oxcarbazepine in 354 patients with trigeminal neuralgia

BACKGROUND

It is widely agreed that carbamazepine and oxcarbazepine are highly effective in the long-term treatment of trigeminal neuralgia. However, the tolerability of these drugs across the different aetiologies of trigeminal neuralgia is still undetermined.

METHODS

In this retrospective, real-world study, we assessed the effectiveness and tolerability of carbamazepine and oxcarbazepine in a large cohort of patients with classical (254 patients), secondary (60 patients) and idiopathic (40 patients) trigeminal neuralgia. We analysed data using a propensity score analysis to account for selection bias; frequencies of side effects associated with carbamazepine and oxcarbazepine were calculated by adjusting data with the inverse probability of treatment weighting.

RESULTS

The initial proportion of responders was 88.3% with carbamazepine, and 90.9% with oxcarbazepine. The number of refractory patients was significantly higher in idiopathic (15%) and secondary forms (27%) than in classical trigeminal neuralgia (6%; p < .05). In 53 patients treated with carbamazepine (29.6%) and in 22 treated with oxcarbazepine (12.6%), major side effects caused treatment interruption or dosage reduction to an unsatisfactory level. Side effects occurred more frequently in patients treated with carbamazepine (43.6%) than with oxcarbazepine (30.3%, p < .0001). The frequency of treatment discontinuation was higher in patients with secondary and idiopathic forms than in those with classical trigeminal neuralgia (p < .05).

CONCLUSIONS

Our real-world study shows that carbamazepine and oxcarbazepine are effective in most patients with trigeminal neuralgia; nevertheless, side effects are still a major issue, particularly in patients with secondary and idiopathic trigeminal neuralgia.

SIGNIFICANCE

Although carbamazepine and oxcarbazepine are effective in most patients with trigeminal neuralgia, their side effects are still a major issue, thus necessitating the development of better-tolerated drugs.

Invasive and Non-Invasive Electrical Neuromodulation in Trigeminal Nerve Neuralgia: A Systematic Review and Meta-Analysis

BACKGROUND

Trigeminal neuralgia is a chronic disease characterized by intense facial pain that is caused by trigeminal nerve affectation. It usually affects adults from 50 years of age, and is more frequent in women. Additionally, it presents serious psychological effects that often lead to depression, which is why it is considered highly disabling. The therapeutic approach is based on the modification of nerve activity through electrical, surgical or chemical stimulation in specific regions of the nervous system.

OBJECTIVE

To perform a meta-analysis of the scientific literature related to invasive and non-invasive electrical neuromodulation of trigeminal neuralgia, in order to assess their effects over pain and adverse effects.

METHODS

A literature search was conducted in 4 databases, followed by a manual search of articles on invasive or non-invasive electrical neuromodulation to control the pain of trigeminal neuralgia, including the last 15 years.

RESULTS

Regarding non-invasive methods, clinical trials did not present enough results in order to perform a meta-analysis. Regarding invasive methods, clinical trials meta-analysis showed no statistical differences between different treatment methods. In all cases, improvements in patients' pain were reported, although results regarding adverse effects were variable.

CONCLUSION

In the treatment of trigeminal neuralgia, the continuous radiofrequency provides better short and medium-term results, but pulsed radiofrequency shows less adverse effects after treatment, and has better results in the long-term.

Five-year result of Microvascular decompression using video endoscopy in the treatment of classic trigeminal neuralgia with paroxysmal pain syndrome

Background. The incidence of trigeminal neuralgia (TN) is 15 per 100,000 people per year. The effectiveness of the existing conservative methods of therapy does not exceed 50%. At the same time, the use of carbamazepine doubles the frequency of depressive conditions, and by 40% increases the incidence of suicidal thoughts. Microvascular decompression (MVD) of the trigeminal root is a"gold standard" treatment for patients with facial pain, however, due to the lack of awareness of the disease, not all the patients receive the adequate therapy timely. Aims: to evaluate the long-term results of video endoscopy-assisted microvascular decompression in the treatment of patients with classical trigeminal neuralgia (cNTN) with paroxysmal facial pain. Methods. In the period from 2014 to 2019, 62 patients were operated for classic NTN and paroxysmal facial pain. The average period from the onset of pain syndrome to surgery was 5 years (from 2 months to 15 years). All the patients in the preoperative period underwent conservative therapy (carbamazepine, gabapentin, pregabalin), which was not accompanied by significant pain reduction. Two (3%) patients had previously undergone a radiosurgical treatment using the Gamma Knife device, and 7 (11%) patients had an analgesic blockade without an effect at other hospitals. The maximum pain intensity upon the admission to the hospital, according to the visual analogue scale (VAS,) was 10 points, according to the BNI (Barrow Neurological Institute) pain syndrome scale V. All the patients underwent MVD of the trigeminal nerve root using Teflon, and video endoscopic assistance during surgery was used in 9 patients . The average follow-up period after the surgery was 3.4 1.7 years (from 1 to 5 years). Results. In all (100%) the patients, the pain was completely relieved after the surgery (BNI I). Excellent and good results after MVD within 5 years were achieved in 97% of patients (BNI III). Facial hypesthesia, not causing discomfort and anxiety (BNI II), developed in 5 (8.1%) patients. The use of video endoscopy made it possible to identify the vessels compressing the trigeminal nerve root with a minimal traction of the cerebellum and cranial nerves. The development of cerebellar edema and ischemia occurred in one (1.6%) patient operated without the application of video endoscopy. Conclusion. The MVD method with video endoscopy is effective in the treatment of patients with cNTN with paroxysmal pain syndrome.

Photobiomodulation on trigeminal neuralgia: systematic review

Trigeminal neuralgia is a recurrent episode of facial pain, that may be associated with other conditions such as multiple sclerosis, neoplasms, and nerve compromises or may occur due to an unknown cause. The available treatments are pharmacotherapy or surgery; however, both are susceptible to develop side effects. Photobiomodulation could be a promising alternative therapy for trigeminal neuralgia. A systematic review of literature was carried out using the PRISMA protocol, in the PubMed/MEDLINE, Embase, and Web of Science databases. Risk of bias by ROB 2.0 protocol was performed in included studies. Initially, 20 identified articles were collected varying between the years of 1983-2018, from which 6 were included. A total of 193 patients were evaluated; photobiomodulation was compared to conventional therapies, TENS, and therapy combinations with pharmacotherapy. The overall risk of bias was low, with some concerns in the randomization and double-blinding process; moreover, there are few reports in the literature. Photobiomodulation appears to be as effective as conventional therapies, being a coadjutant therapeutic opportunity for the treatment of trigeminal neuralgia.

Burden of illness of trigeminal neuralgia among patients managed in a specialist center in England

Background

Trigeminal neuralgia (TN) causes severe episodic, unilateral facial pain and is initially treated with antiepileptic medications. For patients not responding or intolerant to medications, surgery is an option.

Methods

In order to expand understanding of the pain-related burden of illness associated with TN, a cross-sectional survey was conducted of patients at a specialist center that utilizes a multidisciplinary care pathway. Participants provided information regarding their pain experience and treatment history, and completed several patient-reported outcome (PRO) measures.

Results

Of 129 respondents, 69/128 (54%; 1 missing) reported no pain in the past 4 weeks. However, 84 (65%) respondents were on medications, including 49 (38%) on monotherapy and 35 (27%) on polytherapy. A proportion of patients had discontinued at least one medication in the past, mostly due to lack of efficacy (n = 62, 48%) and side effects (n = 51, 40%). A total of 52 (40%) patients had undergone surgery, of whom 30 had microvascular decompression (MVD). Although surgery, especially MVD, provided satisfactory pain control in many patients, 29% of post-surgical patients reported complications, 19% had pain worsen or stay the same, 48% were still taking pain medications for TN, and 33% reported new and different facial pain.

Conclusions

In most PRO measures, respondents with current pain interference had poorer scores than those without pain interference. In the Patient Global Impression of Change, 79% expressed improvement since beginning of treatment at this clinic. These results indicate that while the multidisciplinary approach can substantially alleviate the impact of TN, there remains an unmet medical need for additional treatment options.

Advances in diagnosis, classification, pathophysiology, and management of trigeminal neuralgia

Trigeminal neuralgia is a very painful neurological condition with severe, stimulus-evoked, short-lasting stabbing pain attacks in the face. The past decade has offered new insights into trigeminal neuralgia symptomatology, pathophysiology, and treatment, leading to a change in the classification of the condition. An accurate diagnosis is crucial because neuroimaging interpretation and clinical management differ among the various forms of facial pain. MRI using specific sequences should be a part of the diagnostic workup to detect a possible neurovascular contact and exclude secondary causes. Demonstration of a neurovascular contact should not be used to confirm a diagnosis but rather to facilitate surgical decision making. Carbamazepine and oxcarbazepine are drugs of first choice for long-term treatment, whereas microvascular decompression is the first-line surgery in medically refractory patients. Advances in neuroimaging techniques and animal models will provide further insight into the causes of trigeminal neuralgia and its pathophysiology. Development of more efficacious treatment options is highly warranted.

Evaluation of the Potential Pharmacokinetic Interactions Between Vixotrigine and an Oral Contraceptive

BACKGROUND AND OBJECTIVE

Vixotrigine is a voltage- and use-dependent sodium channel blocker in development for neuropathic pain management. This study evaluated the effect of coadministration of vixotrigine (metabolized primarily via uridine diphosphate-glucuronosyltransferases) and an oral contraceptive containing ethinyl estradiol (uridine diphosphate-glucuronosyltransferase inducer) and levonorgestrel on the pharmacokinetics and safety of all three compounds.

METHODS

In this phase I, open-label, fixed-sequence, multiple-dose study, 36 healthy women received oral vixotrigine 150 mg three times daily for 6 days and once on day 7. This was followed by a washout period, days 8-11. The oral contraceptive was administered alone on days 12-25 and with vixotrigine 150 mg three times daily on days 26-32. Serial blood samples were collected for pharmacokinetic analysis. Safety was assessed.

RESULTS

The geometric least-squares mean ratios (90% confidence intervals) for the area under the concentration-time curve over 8 h and maximum concentration of vixotrigine co-administered with an oral contraceptive vs vixotrigine alone were 0.85 (0.82-0.89) and 0.91 (0.87-0.96), respectively. The geometric least-squares mean ratios (90% confidence interval) for area under the concentration-time curve over 24 h and maximum concentration of ethinyl estradiol with vixotrigine vs ethinyl estradiol alone were 0.94 (0.91-0.97) and 0.89 (0.84-0.94), respectively; the ratios for levonorgestrel with vixotrigine vs levonorgestrel alone were 1.06 (0.98-1.16) and 1.05 (0.98-1.13), respectively. No adverse events occurring with vixotrigine alone were deemed related to the study drug by the investigators.

CONCLUSIONS

Coadministration of vixotrigine and an oral contraceptive containing ethinyl estradiol and levonorgestrel had no clinically relevant effect on exposure of all three compounds.

TRIAL REGISTRATION

ClinicalTrials.gov registration number: NCT03324685 (registered 25 October, 2017).

Cognitive and sensorimotor function in participants being treated for trigeminal neuralgia pain

BACKGROUND

Trigeminal neuralgia (TN) is an orofacial condition defined by reoccurring, spontaneous, short-lived but excruciating stabbing pain. Pharmacological interventions constitute the first-line treatment for TN, with antiepileptic drugs commonly prescribed. People treated for TN pain with antiepileptic drugs describe cognitive and motor difficulties affecting activities of daily living, and report poorer quality of life. We undertook the first comprehensive objective evaluation of sensorimotor and cognitive performance in participants being treated for TN pain with antiepileptic drugs relative to age-matched controls.

METHODS

Participants (43 TN, 41 control) completed a battery of sensorimotor (steering, aiming and tracking) and cognitive (working memory, processing speed, inhibition) tasks.

RESULTS

The TN group performed significantly worse than controls on the sensorimotor tracking and aiming tasks and across all cognitive measures.

CONCLUSIONS

The data explain why patients treated with antiepileptic drugs report impairment when conducting activities of daily living (given the need for cognitive and motor capability within most of these). The study is an important first step in: (i) ensuring there is adequate information on the impact of pharmacological treatment; (ii) identifying measures to determine optimal medication dosage and track change over time; (iii) creating an evidence base that could allow scientific justification of alternative pain treatment options for TN (e.g. the costs/benefits of surgery).

Design of Phase 3 Studies Evaluating Vixotrigine for Treatment of Trigeminal Neuralgia

Purpose

Vixotrigine (BIIB074) is a voltage- and use-dependent sodium channel blocker. These studies will evaluate the efficacy and safety of vixotrigine in treating pain experienced by patients with trigeminal neuralgia (TN) using enriched enrollment randomized withdrawal trial designs.

Patients and Methods

Two double-blind randomized withdrawal studies are planned to evaluate the efficacy and safety of vixotrigine compared with placebo in participants with TN (NCT03070132 and NCT03637387). Participant criteria include ≥18 years old who have classical, purely paroxysmal TN diagnosed ≥3 months prior to study entry, who experience ≥3 paroxysms of pain/day. The two studies will include a screening period, 7-day run-in period, a 4- or 6-week single-dose-blind dose-optimization period (Study 1) or 4-week open-label period (Study 2), and 14-week double-blind period. Participants will receive vixotrigine 150 mg orally three times daily in the dose-optimization and open-label periods. The primary endpoint of both studies is the proportion of participants classified as responders at Week 12 of the double-blind period. Secondary endpoints include safety measures, quality of life, and evaluation of vixotrigine population pharmacokinetics.

Conclusion

There is a need for an effective, well-tolerated, noninvasive treatment for the neuropathic pain associated with TN. The proposed studies will evaluate the efficacy and safety of vixotrigine in treating pain experienced by patients with TN.

Diabetes mellitus contributes to carbamazepine resistance in patient with trigeminal neuralgia

OBJECTIVE

To determine whether diabetes mellitus (DM) contributes to the drug resistance of carbamazepine (CBZ), we investigated the correlation between the blood glucose status and the CBZ resistance condition in patients with trigeminal neuralgia (TN).

PATIENTS AND METHODS

A total of 155 TN patients treated with the CBZ monotherapy were selected at Shanghai General Hospital and Shanghai Xinhua Hospital from September 2018 to January 2020. Among them, 15 were diagnosed with DM. Patients' CBZ resistance levels were evaluated according to progression-free survival. We utilized ordered multiple classification logistic regression to determine the dominant factors leading to CBZ resistance. We analyzed the correlation between hemoglobin A1c (HbA1c) and progression-free survival using the Pearson correlation analysis.

RESULTS

The regression analysis showed that DM was the only factor affecting CBZ resistance (p = 0.035; OR = 0.327; 95% CI, 0.115-0.926). Progression-free survival was 28.5 ± 21.2 months in the DM group and 66.0 ± 33.2 months in the non-DM group. The concentration of HbA1c in the blood was negatively correlated with progression-free survival (r = - 0.197; p = 0.014).

CONCLUSIONS

This study shows that blood glucose status is a significant factor contributing to the CBZ resistance in the treatment of TN. The progression-free survival of patients is affected by the status of DM and blood HbAlc levels.

Treatment Outcomes in Trigeminal Neuralgia-A Systematic Review of Domains, Dimensions and Measures

BACKGROUND

Trigeminal neuralgia (TN) is a painful disorder characterized by sudden electric shock-like pain. It is a rare condition for which multiple treatments are available, including medical and surgical. The best treatment option is yet to be defined, and this is related to the lack of definition in the treatment outcomes and outcome measures. The aim of this systematic review was to summarize all the outcomes and outcomes measures that have been published to date and highlight variability in their use.

METHODS

We have conducted a literature search using a wide range of databases (1946-2019 for medical and 2008-2019 for surgical treatment), for all intervention studies in TN. Four hundred and sixty-seven studies were selected for data extraction on TN classification, data collection method, intervention, and treatment outcomes mapped to the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT guidelines).

RESULTS

Most studies collected data on pain (n = 459) and side effects (n = 386) domains; however, very few collected data on the impact of treatment on physical (n = 46) and emotional functioning (n = 17) and on patient satisfaction (n = 35). There was high variability on outcome measures used for pain relief (n = 10), pain intensity (n = 9), and frequency of pain episodes (n = 3).

CONCLUSIONS

A clear definition of what are the important outcomes for patients with TN is essential. The choice of standardized outcome measures allowing for consistent reporting in TN treatment will allow for comparison of studies and facilitate treatment choice for patients and clinicians thus, improving health outcomes and reducing health care cost.

Natural history of trigeminal neuralgia-A hospital-based retrospective study

OBJECTIVE

The objective of this study was to assess the natural history of trigeminal neuralgia (TN) and pretrigeminal neuralgia (PTN) in a hospital-based sample using a retrospective and descriptive study design.

METHODS

This study followed a retrospective study design, which yielded a sample size of 216 patients who were reclassified as per the new classification and diagnostic grading for practice and research proposed by the American Academy of Neurology. Based on an in-depth analysis of patient history and the treatments administered, a possible state of PTN prior to TN development was determined.

RESULTS

TN shows a female predilection with predominantly unilateral involvement. A total of 45.83% of patients had left-side involvement with V3 primarily affected. Additionally, 11.11% of patients did not have any clinically apparent trigger zone, while 68.05% had a single trigger zone. Twenty-one patients were found to have suspected PTN prior to TN. The time interval between PTN onset and TN development ranged from 6 months to 6 years. The PTN pain varied, and the clinical overlap between the site of PTN and the site of future TN was 100%.

CONCLUSION

An in-depth patient history can serve as a reliable modality for TN diagnosis. PTN should be considered as a differential diagnosis for pain of orofacial origin because of its overlapping features with other painful conditions.

Familial trigeminal neuralgia - a systematic clinical study with a genomic screen of the neuronal electrogenisome

Objective

This cross-sectional study examined, for the first time, a large cohort of patients with trigeminal neuralgia, to ascertain the occurrence of familial cases, providing a systematic description of clinical features of familial disease. Since there is evidence linking hyperexcitability of trigeminal ganglion neurons to trigeminal neuralgia, we also carried out an exploratory genetic analysis of the neuronal electrogenisome in these patients.

Methods

We recorded familial occurrence by systematically interviewing all patients with a definite diagnosis of classical or idiopathic trigeminal neuralgia. We found 12 occurrences of trigeminal neuralgia with positive family history out of 88 enrolled patients. Whole-exome sequencing was carried out in 11 patients. We concentrated on the genetic variants within a 173-gene panel, comprising channel genes encoding sodium, potassium, calcium, chloride, transient receptor potential channels, and gap junction channels. Gene expression profiles were based on published RNA sequencing datasets of rodent/human trigeminal ganglia tissues, with a focus on genes related to neuronal excitability.

Results

In patients with familial trigeminal neuralgia, pain was more often located in the right, second division. All patients reported triggers. Four patients experienced concomitant continuous pain. Whole-exome sequencing analysis within the trigeminal ganglion electrogenisome identified 41 rare variants in ion channels, consisting of variants in sodium channels (6), potassium channels (10), chloride channels (5), calcium channels (7), transient receptor potential channels (12), and gap junction channels (1). In one patient, a previously profiled gain-of-function mutation in SCN10A (Nav1.8 p.Ala1304Thr), previously reported in painful neuropathy, was found; this variant was not present in unaffected siblings.

Conclusions

Our results suggest that familial occurrence of trigeminal neuralgia is more common than previously considered. Although our results demonstrate variants in genes encoding voltage-gated ion channels and transient receptor potential channels within these patients, further study will be needed to determine their roles in the pathogenesis of trigeminal neuralgia.

Trigeminal Neuralgia: Basic and Clinical Aspects

The trigeminal nerve is the largest of all cranial nerves. It has three branches that provide the main sensory innervation of the anterior two-thirds of the head and face. Trigeminal neuralgia (TN) is characterized by sudden, severe, brief, and stabbing recurrent episodes of facial pain in one or more branches of the trigeminal nerve. Pain attacks can occur spontaneously or can be triggered by non-noxious stimuli, such as talking, eating, washing the face, brushing teeth, shaving, a light touch or even a cool breeze. In addition to pain attacks, a proportion of the patients also experience persistent background pain, which along with autonomic signs and prolonged disease duration, represent predictors of worse treatment outcomes. It is now widely accepted that the presence of a neurovascular compression at the trigeminal root entry zone is an anatomic abnormality with a high correlation with classical TN. However, TN may be related to other etiologies, thus presenting different and/or additional features. Since the 1960s, the anticonvulsant carbamazepine is the drug of choice for TN treatment. Although anti-epileptic drugs are commonly used to treat neuropathic pain in general, the efficacy of carbamazepine has been largely limited to TN. Carbamazepine, however, is associated with dose-limiting side-effects, particularly with prolonged usage. Thus, a better understanding and new treatment options are urgently warranted for this rare, but excruciating disease.

Microvascular decompression for treating classical trigeminal neuralgia: can we offer the gold standard therapy to older patients?

PURPOSE

Microvascular decompression is the most successful procedure for treating classic trigeminal neuralgia. However, due to the risks of surgery and anesthesia, the procedure is performed less frequently in older patients. The aim of the study is to investigate the intraoperative and perioperative morbidity in older patients who underwent this surgical treatment.

METHODS

Patients who underwent microvascular decompression in our department between 2004 and 2016 were divided into two age groups (A: < 69 years old, n = 114; B: ≥ 70 years old, n = 47). Retrospectively, the pre-, intra- and postoperative data were analyzed.

RESULTS

Older patients showed a statistically significant prolonged duration of symptoms until surgery (mean 127 months vs. 70 months; p < 0.001). They also showed a significantly increased necessity for duroplasty (p = 0.015), but with no increased incidence of postoperative cerebrospinal fluid leakage or rhinoliquorrhea. A comparable postoperative course was found in both groups. Over 90% in both groups had a significantly postoperative improvement. There were no cardiopulmonary complications or infections in either group. In the 3-month follow-up, there was a comparable success of pain reduction and no increased incidence of sensory disturbances.

CONCLUSIONS

Based on the high chances of success and low morbidity, microvascular decompression should also be offered to older patients with anesthesiologic agreement.

Patterns of opioid use in patients with trigeminal neuralgia undergoing neurosurgery

OBJECTIVE

First-line treatment for trigeminal neuralgia (TN) is pharmacological management using antiepileptic drugs (AEDs), e.g., carbamazepine (CBZ) and oxcarbazepine (OCBZ). Surgical intervention has been shown to be an effective and durable treatment for TN that is refractory to medical therapy. Despite the lack of evidence for efficacy in patients with TN, the authors hypothesized that patients with neuropathic facial pain are prescribed opioids at high rates, and that neurosurgical intervention may lead to a reduction in opioid use.

METHODS

This is a retrospective study of patients with facial pain seen by a single neurosurgeon. All patients completed a survey on pain medications, medical comorbidities, prior interventions for facial pain, and a validated pain outcome tool (the Penn Facial Pain Scale). Patients subsequently undergoing neurosurgical intervention completed a survey at the 1-month follow-up in the office, in addition to telephone interviews using a standardized script between 1 and 6 years after intervention. Univariate and multivariate logistic regression were used to predict opioid use.

RESULTS

The study cohort consisted of 309 patients (70% Burchiel type 1 TN [TN1], 18% Burchiel type 2 [TN2], 6% atypical facial pain [AFP], and 6% TN secondary to multiple sclerosis [TN-MS]). At initial presentation, 20% of patients were taking opioids. Of these patients, 55% were receiving concurrent opioid therapy with CBZ/OCBZ, and 84% were receiving concurrent therapy with at least one type of AED. Facial pain diagnosis (for diagnoses other than TN1, odds ratio [OR] 2.5, p = 0.01) and facial pain intensity at its worst (for each unit increase, OR 1.4, p = 0.005) were predictors of opioid use at baseline. Neurosurgical intervention led to a reduction in opioid use to 8% at long-term follow-up (p < 0.01, Fisher's exact test; n = 154). Diagnosis (for diagnoses other than TN1, OR 4.7, p = 0.002) and postintervention reduction in pain at its worst (for each unit reduction, OR 0.8, p < 10-3) were predictors of opioid use at long-term follow-up. On subgroup analysis, patients with TN1 demonstrated a decrease in opioid use to 5% at long-term follow-up (p < 0.05, Fisher's exact test), whereas patients with non-TN1 facial pain did not. In the nonsurgical group, there was no statistically significant decrease in opioid use at long-term follow-up (n = 81).

CONCLUSIONS

In spite of its high potential for abuse, opioid use, mostly as an adjunct to AEDs, is prevalent in patients with facial pain. Opportunities to curb opioid use in TN1 include earlier neurosurgical intervention.

Evaluation of the Pharmacokinetic Interaction Between the Voltage- and Use-Dependent Nav1.7 Channel Blocker Vixotrigine and Carbamazepine in Healthy Volunteers

Vixotrigine is a voltage- and use-dependent Nav1.7 channel blocker under investigation for the treatment of peripheral neuropathic pain conditions, including trigeminal neuralgia. Vixotrigine is metabolized primarily via uridine diphosphate-glucuronosyltransferases (UGTs). Carbamazepine, a UGT and cytochrome P450 3A4 inducer, is a first-line treatment for trigeminal neuralgia. We conducted a double-blind, randomized, placebo-controlled, parallel-group, single-center phase 1 study to investigate the impact of coadministering vixotrigine and carbamazepine on their respective pharmacokinetics (PK) in healthy volunteers, the safety and tolerability of combined treatment, and PK recovery of vixotrigine following carbamazepine discontinuation. Randomly assigned treatments were carbamazepine (100 mg twice a day, days 1-3 and 200 mg twice a day, days 4-21) or placebo on days 1 to 21. All volunteers received vixotrigine 150 mg 3 times a day on days 16 to 28. At prespecified times, whole-blood samples were collected for PK assessment. Statistical analyses were performed on the log-transformed PK parameters area under the concentration-time curve within a dosing interval (AUC_0-tau ) and maximum observed concentration (C_max ) for vixotrigine, carbamazepine, and metabolites. Vixotrigine AUC_0-tau and C_max were reduced by 31.6% and 26.3%, respectively, when coadministered with carbamazepine compared with placebo. Seven days after carbamazepine discontinuation, vixotrigine AUC_0-tau and C_max remained 24.5% and 21.4% lower compared with placebo. Carbamazepine AUC_0-tau and C_max were <10% lower when coadministered with vixotrigine compared on days 15 and 21. Vixotrigine/carbamazepine coadministration was well tolerated. These results suggest that vixotrigine does not have an effect on carbamazepine PK, and although carbamazepine has an effect on the exposure of vixotrigine, the effect is not considered clinically relevant.

The Mechanistic Differences in HLA-Associated Carbamazepine Hypersensitivity

Drug hypersensitivity reactions that resemble acute immune reactions are linked to certain human leucocyte antigen (HLA) alleles. Severe and life-threatening Stevens Johnson Syndrome and Toxic Epidermal Necrolysis following treatment with the antiepileptic and psychotropic drug Carbamazepine are associated with HLA-B*15:02; whereas carriers of HLA-A*31:01 develop milder symptoms. It is not understood how these immunogenic differences emerge genotype-specific. For HLA-B*15:02 an altered peptide presentation has been described following exposure to the main metabolite of carbamazepine that is binding to certain amino acids in the F pocket of the HLA molecule. The difference in the molecular mechanism of these diseases has not been comprehensively analyzed, yet; and is addressed in this study. Soluble HLA-technology was utilized to examine peptide presentation of HLA-A*31:01 in presence and absence of carbamazepine and its main metabolite and to examine the mode of peptide loading. Proteome analysis of drug-treated and untreated cells was performed. Alterations in sA*31:01-presented peptides after treatment with carbamazepine revealed different half-life times of peptide-HLA- or peptide-drug-HLA complexes. Together with observed changes in the proteome elicited through carbamazepine or its metabolite these results illustrate the mechanistic differences in carbamazepine hypersensitivity for HLA-A*31:01 or B*15:02 patients and constitute the bridge between pharmacology and pharmacogenetics for personalized therapeutics.

Characterizing Treatment Utilization Patterns for Trigeminal Neuralgia in the United States

BACKGROUND AND AIM

Trigeminal neuralgia (TN) is a rare orofacial disorder characterized by severe unilateral paroxysmal pain in the region of the fifth cranial nerve. Clinical guidelines recommend carbamazepine (only US Food and Drug Administration-approved drug for TN) and oxcarbazepine as first-line therapies. We utilized the US Truven Health MarketScan database to examine treatment patterns among patients with TN.

METHODS

Included patients were aged 18 years and above, newly diagnosed with TN (≥2 TN diagnoses ≥14 days apart; no diagnosis in the previous year), continuously enrolled 1 year before index, with ≥3 years' follow-up postindex. We assessed utilization of selected pharmacotherapies (carbamazepine, oxcarbazepine, pregabalin, gabapentin, baclofen, duloxetine, topiramate), surgery (posterior fossa, radiosurgery), and injections (peripheral anesthetic injections, Gasserian ganglion procedures) for TN.

RESULTS

In total, 3685 patients were included (2425 commercial, 1260 Medicare; 71.8% female; age, mean [SD], 59 [15] y). Overall, 72.5% of patients received at least 1 studied medication, most commonly carbamazepine (51.7%) or gabapentin (48.6%). In total, 65% of pharmacologically treated patients had ≥2 treatment episodes; 41.6% had ≥3 (defined by a change in pharmacotherapy [monotherapy/combination] regimen). Overall, 12.3% had surgery and 7.3% injections; 42.9% received opioids for TN.

CONCLUSIONS

In the 3 years after diagnosis, patients with TN in the United States receive a variety of pharmacological treatments, including opioids, despite carbamazepine being the only approved medication. A notable proportion utilize surgeries/injections. A high proportion of pharmacologically treated patients receive multiple treatment episodes, suggesting frequent therapy switching, perhaps because of suboptimal efficacy/tolerability. Our data suggest a high burden of illness associated with TN.