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

The Ganglia of the Head and Neck: Clinical Relevance for the Interventional Pain Physician

PURPOSE OF REVIEW

The purpose of this article is to provide a comprehensive review of the ganglia of the head and neck and their role in the interventional management of chronic headaches and facial pain disorders.

RECENT FINDINGS

Interventions targeting the sphenopalatine, stellate and gasserian ganglia are well described in the literature for headaches and facial pain disorders. There is a growing body of evidence supporting use of these techniques for clinical conditions outside of pain such as post-traumatic stress disorder and Long COVID symptoms. These findings increase the potential applications of such procedures, making them more relevant to the interventional physician tasked with managing symptoms in difficult to treat medical conditions. Nerve blocks of the head and neck are used for diagnostic and therapeutic purposes in the management of headaches and facial pain disorders. Headaches, whether acute or chronic, are common pain conditions with a wide-range of etiologies and are often difficult to treat. Chronic facial pain can have a variety of underlying causes, including direct or indirect nerve damage, infection, inflammation, and muscle dysfunction. Traditional pain management strategies such as medications and physical therapy often fail or are associated with significant adverse effects. Interventions such as nerve blocks and neuroablative procedures have shown promise in managing headaches and facial pain by directly targeting the underlying causes. This review article summarizes the most recent evidence regarding the efficacy, safety, applications and limitations of these interventional pain management techniques.

Efficacy and safety of lacosamide in patients with trigeminal neuralgia: an 8-week pilot dose-escalation study

BACKGROUND

Trigeminal neuralgia (TN) is a severe neuropathic pain condition in the orofacial region, with carbamazepine recommended as the first-line treatment. Nonetheless, its application is constrained by unfavorable drug responses and side effects. The objective of this research was to assess the effectiveness and safety of lacosamide, a third-generation anticonvulsant, in individuals with TN, and to juxtapose the findings with observational records from recently diagnosed TN patients who underwent carbamazepine monotherapy within the corresponding timeframe.

METHODS

An 8-week flexible dose titration of lacosamide was performed on newly diagnosed 12 TN patients who were divided into two groups: 200 mg/day (n = 5), and 400 mg/day (n = 7). Outcome measures included average pain score, Brief Pain Inventory-facial scores, and side effects. Patients were followed-up at 2, 4 and 8 weeks after baseline.

RESULTS

The percentage change of pain score at 4-week visit was compared between both lacosamide groups and patients receiving carbamazepine (n = 6) for four weeks during concurrent period. Both lacosamide groups experienced a decrease in pain score at 2-week follow-up, and differences in average pain score reduction were not observed between the two groups across all visits (p > 0.05). The mean Brief Pain Inventory-facial score in the lacosamide 200 mg/day group was higher than that in the 400 mg/day group at the 2-week follow-up (p = 0.03). Interestingly, the 4-week follow-up revealed that there were no significant variances in pain intensity between the lacosamide and the contemporaneous carbamazepine cohorts (p > 0.05). Frequently noted adverse events were mild somnolence (n = 9), slight vertigo (n = 5), and emotional lability (n = 2) without instances of severe adverse drug responses.

CONCLUSIONS

Lacosamide demonstrates potential as a therapeutic option for patients suffering from trigeminal neuralgia.

CLINICAL TRIAL REGISTRATION

TCTR20210811002.

Microvascular Decompression for Trigeminal Neuralgia Using Autologous Muscle Grafting: A Retrospective Analysis in a Resource-Limited Setting

Background Trigeminal neuralgia (TN) is a rare and painful condition that offers various treatment options. Despite the availability of multiple modalities, their comparative efficacy is still debated due to inconsistent study outcomes. Microvascular decompression (MVD) using autologous muscle grafts has recently gained attention as a treatment option. While muscle grafts were previously employed extensively, this approach is only now being introduced in Yemen, where documented outcomes related to MVD for TN are scarce. This study aims to present the outcomes of MVD for TN utilizing autologous muscle grafts in a resource-limited environment. Patients and methods This study employs a retrospective cross-sectional design involving 324 patients diagnosed with TN who underwent MVD using autologous muscle grafts between April 1, 2006, and March 25, 2020. Data regarding demographic and clinical factors, outcomes, and complications were systematically collected and analyzed. Results The mean age of the patients was 48.8±11.6 years, with the majority being female patients (n=180, 55.6%), with a significant proportion of patients exhibiting left-sided involvement (n=204; 63%). Significant nerve compression was the primary operative finding in the study population (n=251; 77.5%). In most cases, a single vessel contributed to the compression of the nerve, primarily the superior cerebellar artery (n=303; 93.5%). No major surgical complications were reported, with temporary nasal cerebrospinal fluid (CSF) leakage (n=1; 0.3%), transient facial numbness (n=16; 4.9%) that resolved within one week to one month, hyperacusis (n=5; 1.5%), and hyperesthesia (n=3; 0.9%) being the common ones. Follow-up over an average of 52.7±8.0 months indicated that the majority of patients (n=302; 93.2%) achieved favorable outcomes, as reflected in Barrow Neurological Institute (BNI) scores I and II. The BNI pain intensity score improved from V preoperatively to I and II and was statistically significant (P=0.006). The remaining patients (n=22; 6.8%) exhibited fair to poor BNI scores (III, IV, and V). Sixteen patients obtained effective pain relief through medication, while six required radiofrequency thermocoagulation. Conclusion  The findings suggest that MVD utilizing autologous muscle grafts may serve as an effective long-term surgical intervention for TN, even in resource-limited settings. Effective management of TN necessitates a comprehensive preoperative assessment, careful candidate selection, appropriate imaging techniques, and proficient surgical execution.

Different Scale, Different Pain? Discordant Pain Measurements After Surgery for Trigeminal Neuralgia

OBJECTIVE

Trigeminal neuralgia (TN) has been described as one of the worst pains known to humankind. However, pain severity in TN has been measured using several different scales, resulting in difficulty comparing illness burden and response to TN surgery across studies. We examined the degree of concordance between standardized scales evaluating pain severity in a cohort of patients undergoing surgery for TN.

METHODS

In this cross-sectional study, we evaluated 39 surgical TN patients with 3 pain measurement instruments: a Visual Analog Pain Scale, the Brief Pain Inventory-Facial (BPI-F) Pain, and the Barrow Neurological Institute (BNI) Pain Intensity Score. Scores were transformed into a 0-10 scale, and grouped into 5 severity categories (none, mild, moderate, severe, and worst). Discordant patients were those classified in different severity categories by at least 2 pain measurement instruments. Level of agreement was assessed with the intraclass correlation coefficient.

RESULTS

Almost 50% of patients (18/39) had at least 1 categorical discordance when comparing all 3 scores. We found 30% discordance between visual analog scale (VAS) and BPI-F, 33% discordance between BPI-F and BNI, and 35% discordance between VAS and BNI. The highest degree of discordance between BNI and either VAS or BPI-F occurred in patients with moderate pain (BNI IIIb). The degree of agreement across all 3 scores was moderate (intraclass correlation coefficient = 0.72).

CONCLUSIONS

TN patients with residual mild-moderate pain after surgery are often discordantly classified by different pain measurement scales. These findings argue for a more standardized method of reporting postoperative pain outcomes in the TN literature.

Trigeminal Neuralgia: Disease Characterization and Prediction of Response to Surgical Intervention

PURPOSE OF REVIEW

Trigeminal neuralgia (TN) is a highly heterogeneous condition with a wide choice of successful treatment options. However, differences between subtypes are poorly understood and it remains unknown which patients will respond to different treatments. This review aims to summarize the current state of the TN field and explore the problem of predicting surgical outcomes.

RECENT FINDINGS

Attempts have been made to standardize classification, outcome reporting, and treatment guidelines. Identification of risk factors for poor surgical treatment outcomes has led to the development of prognostic scoring systems to predict outcomes and guide management. Advances in imaging techniques including diffusion tensor imaging show promise in better understanding the underlying pathophysiology and predicting surgical outcomes. Progress is hampered by lack of understanding of the pathophysiology in TN and differences between disease subtypes. Further work needs to be done to create accurate prediction tools for widespread use, including use of advanced imaging and computing tools, multicenter collaboration, and prospective validation.

Synthesis of temporomandibular disorders management intervention outcomes for development of core outcome sets: A systematic review

INTRODUCTION

The selection of appropriate outcomes in clinical trials and systematic reviews is a crucial factor in determining the results that are useful, reliable, and relevant for both patients and healthcare professionals. Clinicians and researchers have been encouraged to develop and apply core outcome sets (COS) to minimise the discrepancy between studies.

AIM

This systematic review is the first phase of the COS development project for clinical trials in temporomandibular disorders (COS-TMD). It aims to identify and synthesise the outcomes used in the randomised controlled trials (RCT) that evaluated the effectiveness of interventions used in TMD management.

MATERIALS AND METHODS

An electronic search was performed in several databases: MEDLINE (via PubMed), Scopus, Web of Science, Cochrane Library and EMBASE. The eligibility criteria comprised RCT that applied any intervention to treat temporomandibular joint disorders or masticatory muscle disorders. The identified outcomes were categorised according to domains of the Initiative on Methods, Measurement and Pain Assessment in Clinical Trials (IMMPACT).

RESULTS

The electronic search resulted in 1606 studies. After removing duplicates and applying the eligibility criteria, 106 RCT were included. A total of 43 studies evaluated masticatory muscle disorders, 27 evaluated temporomandibular joint disorders, and 36 analysed mixed TMD.

CONCLUSIONS

The evaluation showed significant variability in the types of outcomes and their measurement instruments. In addition, some domains such as physical and emotional functioning, participant ratings of global improvement and adverse events have been neglected when determining the effectiveness of treatments for TMD.

Comparison of microvascular decompression, percutaneous radiofrequency rhizotomy, and stereotactic radiosurgery in the treatment of trigeminal neuralgia: A long term quasi-experimental study

BACKGROUND

Microvascular decompression (MVD), radiofrequency rhizotomy (RFR), and stereotactic radiosurgery (SRS) are surgical techniques frequently used in the treatment of idiopathic trigeminal neuralgia (TN), although the results reported for each of these are diverse.

OBJECTIVE

This study aimed to compare long-term pain control obtained by MVD, SRS, and RFR in patients with idiopathic TN.

METHODS

To compare the results obtained by MVD, SRS, and RFR we chose a quasi-experimental, ambispective design with control groups but no pretest. A total of 52 participants (MVD n = 33, RFR n = 10, SRS n = 9) were included. Using standardized outcome measures, pain intensity, pain relief, quality of life, and satisfaction with treatment were assessed by an independent investigator. The TREND statement for reporting non-randomized evaluations was applied. Clinical outcomes were evaluated at the initial postoperative period and at 6 months, 1, 2, 3, 4, and 5 years postoperatively.

RESULTS

MVD has shown better results in pain scales compared to ablative procedures. Significant differences between groups were found regarding pain intensity and pain relief at the initial postoperative period (p < 0.001) and 6 months (p = 0.022), 1 year (p < 0.001), 2 years (p = 0.002), and 3 years (p = 0.004) after the intervention. Those differences exceeded the thresholds of the minimal clinically important difference. A higher percentage of patients free of pain was observed in the group of patients treated by MVD, with significant differences at the initial postoperative period (p < 0.001) and 6 months (p = 0.02), 1 year (p = 0.001), and 2 years (p = 0.04) after the procedure. Also, a higher risk of pain recurrence was observed in the RFR and SRS groups (HR 3.15, 95% CI 1.33-7.46; p = 0.009; and HR 4.26, 95% CI 1.77-10.2; p = 0.001, respectively) compared to the MVD group. No significant differences were found in terms of quality of life and satisfaction with treatment. A higher incidence of complications was observed in the MVD group.

CONCLUSION

Concerning pain control and risk of pain recurrence, MVD is superior to RFR and SRS, but not in terms of quality of life, satisfaction with treatment, and safety profile.

Trigeminal neuralgia and trigeminal neuropathic pain

It is very important that the dental team are aware of the varied presentations of pain in the mouth, face and other parts of the trigeminal region which are not directly caused by teeth or oral structures. Our understanding of underlying causes in this complex area is evolving. Ultimately, patients who present with what may at first seem to be oral or dental problems will require specialist input in secondary care with potential for use of systemic medications. This article reviews the common non-dental pains encountered in the orofacial region related to dysfunction of the trigeminal nerve.

Microvascular Decompression and Trigeminal Neuralgia: Patient Sentiment Analysis Using Natural Language Processing

OBJECTIVE

Microvascular decompression (MVD) as a treatment for trigeminal neuralgia (TGN) has high success rate but is associated with risks of complication. This study analyzes Twitter to provide insights into discussions surrounding MVD for patients with TGN.

METHODS

A Twitter search performed in April 2022 yielded 491 tweets from 426 accounts. Tweets and accounts were classified thematically, and descriptive statistics were used for various social media metrics. Using a natural language processing machine learning algorithm, sentiment analysis (SA) was performed to evaluate patient perspectives before and after surgery, and a multivariate regression model was used to identify predictors of higher engagement metrics (likes, retweets, quote tweets, replies).

RESULTS

Most accounts were patients, caregivers, and other members of the public (70%). The most encountered themes were research (47%) and personal experiences (33.4%). SA of tweets about patient experiences showed that 40.2% of tweets were positive, 31.1% were neutral and 28.7% were negative. Negative tweets decreased significantly in postoperative tweets and mostly discussed complications or failure of surgery (63%). On multivariate analysis, only inclusion of media (photo or video) in a Tweet was associated with higher engagement metrics.

CONCLUSIONS

This study provides a comprehensive review of Twitter use discussing MVD in TGN and is the first to assess patient satisfaction after treatment using SA. The data presented on patient perspectives on social media could help physicians establish direct lines of communication with patients, fostering a more patient-focused care.

An international Delphi survey and consensus meeting to define the core outcome set for trigeminal neuralgia clinical trials

BACKGROUND

Trigeminal neuralgia (TN) is an excruciating unilateral facial pain, which negatively affects patient's quality of life. Historically, it has been difficult to compare treatment efficacy due to the lack of standardized outcomes. In addition, patients' perspective has seldomly been acknowledged. The aim of this study was to reach consensus on what outcomes of treatment are important to different TN stakeholders (patients, clinicians and researchers), to identify the TN Core Outcome Set (TRINCOS).

METHODS

A list of outcomes identified through a systematic review and focus group work was used to develop the survey questionnaire. A three-round Delphi was conducted. Participants were asked to score the outcomes on scale from 1 to 9 (1-3 not important;4-6 important but not critical;7-9 critical). Outcomes scored as critical by ≥70% and not important by <15% were retained, and those for which no consensus was reached were discussed at a consensus meeting.

RESULTS

Of the 70 participants who completed the Delphi, 26 were patients, 38 were clinicians and six were researchers. Of the 40 outcomes presented, 17 were scored as critical and no consensus was met for 23 outcomes. Agreement was reached during a consensus meeting on 10 outcomes across six domains (pain, side effects, social impact, quality of life, global improvement, and satisfaction with treatment).

CONCLUSION

Implementation of TRINCOS in future clinical trials will improve homogeneity of studies' results, reduce the redundancy in the outcome assessment and effectively allow comparison of different treatments to better inform researchers, clinicians and most importantly patients, about the efficacy of the different treatments.

SIGNIFICANCE

Implementation of a 10-item core outcome set in trigeminal neuralgia will improve comparability between studies allowing patients to have faster access to better treatments.

Effects of microvascular decompression on quality-of-life in trigeminal neuralgia patients aged 70 years and older

Background

Trigeminal neuralgia (TN) occasionally affects older adults, frequently worsens, and becomes refractory to medication. Older adult patients with TN may consider microvascular decompression (MVD) for their treatment. No study examines MVD effects on older adult TN patients' health-related quality of life (HRQoL). The present study evaluates the HRQoL of TN patients aged 70 years and older before and after MVD.

Methods

Adult TN patients who underwent MVD evaluated their HRQoL using the 36-Item Short-form (SF-36) Health Survey before and 6 months after MVD. The patients were divided into four groups according to their decade of age. The clinical parameters and operative outcomes were analyzed statistically. The SF-36 physical, mental, and role social component summary scores and eight domain scale scores were analyzed using a twoway repeated-measures analysis of variance (ANOVA) to compare the effects of age group and preoperative and postoperative time points.

Results

Among 57 adult patients (34 women, 23 men; mean age, 69 years; range, 30-89 years), 21 patients were in their seventies, and 11 were in their eighties. The SF-36 scores of patients in all age groups improved after MVD. Two-way repeated-measures ANOVA demonstrated a significant age group effect on the physical component summary and its physical functioning domain. A time point effect was significant on all component summaries and domains. There was a significant interaction between age group and time point effects on the bodily pain domain. These results suggested that patients 70 years and older had significant postoperative HRQoL improvement, but their improvement of physical-related HRQoL and multiple physical pain issues were limited.

Conclusion

Impaired HRQoL in TN patients aged 70 years and older can improve after MVD. Careful management of multiple comorbidities and surgical risks enables MVD to be an appropriate treatment for older adult patients with refractory TN.

Long term evaluation of a multidisciplinary trigeminal neuralgia service

BACKGROUND

Trigeminal neuralgia is an episodic severe neuralgic pain and can be managed both medically and surgically. If possible, this should be directed by a Multidisciplinary Team (MDT) of specialised surgeons, physicians, dentists, psychologists and specialist nurses with access to all treatment modalities, which enables patients to make an informed decision about their future management.

OBJECTIVE

The aim of this study was to review the outcomes of patients managed by an MDT clinic, in a single institute over an eleven-year period.

METHODS

A prospective database was used to identify patients with trigeminal neuralgia or its variants who had attended a joint MDT clinic. The electronic notes were examined for demographics, onset and duration of trigeminal neuralgia, medications history, pain scores and details of surgical procedures if any by two independent assessors.

RESULTS

Three hundred thirty-four patients attended the MDT between 2008-2019. Forty-nine of them had surgery before being referred to the service and were included but analysed as a subgroup. Of the remaining patients, 54% opted to have surgery following the MDT either immediately or at a later date. At the last reported visit 55% of patients who opted to have surgery were pain free and off medications, compared to 15.5% of medically managed patients. Surgical complications were mostly attributable to numbness and in the majority of cases this was temporary. All patients who were not pain free, had complications after surgery or opted to remain on medical therapy were followed up in a facial pain clinic which has access to pain physicians, clinical nurse specialists and a tailored pain management program. Regular patient related outcome measures are collected to evaluate outcomes.

CONCLUSION

An MDT clinic offers an opportunity for shared decision making with patients deciding on their personal care pathway which is valued by patients. Not all patients opt for surgery, and some continue to attend a multidisciplinary follow up program. Providing a full range of services including psychological support, improves outcomes.

Development of core outcome sets for clinical trials in temporomandibular disorders: A study protocol

Background

Temporomandibular Disorder (TMD) is a generic term applied to describe musculoskeletal disorders that affect the temporomandibular joint (TMJ), the masticatory muscles and the related structures. TMD comprises two groups of disorders, namely intra-articular TMD and masticatory muscle disorders. There is still difficulty in establishing the effectiveness of different therapeutic modalities for TMD with robust evidence, despite the large volume of publications in the area. The lack of outcomes standardization may represent a limiting factor in the search for scientific evidence.

Objective

This study aims to develop a core outcome sets (COS) for clinical trials in intra-articular TMD and masticatory muscle disorders.

Methods

The protocol for determining the COS-TMD will consist of three phases: 1. Synthesis of TMD Management Intervention Outcomes. The identification of outcomes will be carried out through a systematic review, which will include randomized clinical trials that evaluated the effectiveness of interventions used in TMD management. 2. Through a two-round international Delphi survey, the list of outcomes will be scored by three panels of stakeholders. 3. A representative sample of key stakeholders will be invited to participate in a face-to-face meeting where they can discuss the results of the Delphi survey and determine the final core set.

Conclusions

The implementation of this protocol will determine the COS-TMD, which will be made available for use in all TMD clinical studies. The use of COS when planning and reporting TMD clinical trials will reduce the risk of publication bias and enable proper comparison of results found by different studies.

Multidata Analysis Based on an Artificial Neural Network Model for Long-Term Pain Outcome and Key Predictors of Microvascular Decompression in Trigeminal Neuralgia

OBJECTIVE

To investigate use of multidata analysis based on an artificial neural network (ANN) to predict long-term pain outcomes after microvascular decompression (MVD) in patients with trigeminal neuralgia (TN) and to explore key predictors.

METHODS

Perioperative and long-term follow-up multidata of 1041 patients with TN who received MVD surgery at Hangzhou First People's Hospital from March 2013 to May 2018 were collected to construct an ANN model for prediction. The prediction results were compared with the actual follow-up outcomes, and the variables in each input layer were changed to test the effectiveness of ANN and explore the factors that had the greatest impact on prediction accuracy.

RESULTS

The ANN model could predict the long-term pain outcomes after MVD in patients with TN with an accuracy rate of 95.2% and area under the curve of 0.862. Four factors contributed the most to the predictive performance of the ANN: whether the neurovascular offending site of the trigeminal nerve corresponded the region of facial pain, immediate postoperative pain remission after MVD, degree of nerve compression by culprit vessels, and the type of culprit vessels. After these factors were sequentially removed, the accuracy of the ANN model decreased to 74.5%, 78.6%, 87.2%, and 90.1%, while the area under the curve was 0.705, 0.761, 0.793, and 0.810.

CONCLUSIONS

The ANN model, constructed using multiple data, predicted long-term pain prognosis after MVD in patients with TN objectively and accurately. The model was able to assess the importance of each factor in the prediction of pain outcome.

Long-term Recurrence-free Survival and Complications of Percutaneous Balloon Compression and Radiofrequency Thermocoagulation of Gasserian Ganglion for Trigeminal Neuralgia:A Retrospective Study of 1313 Cases

OBJECTIVE

To estimate long-term recurrence, complications after percutaneous balloon compression (PBC) and radiofrequency thermocoagulation (RFT) of gasserian ganglion among a large sample of patients with trigeminal neuralgia (TN) during a long-term follow-up.

METHODS

A retrospective analysis of 1313 patients undergoing PBC or RFT for the treatment of TN was conducted from 2006 to 2020. Recurrence-free survival (RFS) was assessed by Kaplan-Meier method. Complications including facial numbness, corneal reflex decrease and masseter weakness were also estimated.

RESULTS

For patients who received first initial PBC and RFT, the median RFS was 130.1 months (95%CI: 124.4, 135.9) and 123.3 months (95%CI: 117.6, 128.9) in PBC and RFT group with log-rank p=0.108. The RFS rate was respectively 90.6% (95%CI: 88.1%-93.3%) and 91.4% (95%CI: 89.1%-93.7%) at 1 year, 84.6% (95%CI: 81.4%-87.8%) and 83.3% (95%CI: 80.3%-86.3%) at 3 years, 81.5% (95%CI: 78.1%-85.0%) and 78.6 % (95%CI: 75.2%-81.9%) at 5 years, 71.5% (95%CI: 67.5%-75.5%) and 64.8% (95%CI: 61.0%-68.7%) at 10 years in two groups. No significant difference was observed in facial numbness degree between two groups after procedure. Compared with PBC group, ophthalmic complication prevalence was higher in RFT group (9.6%) (p=0.001). However, masseter weakness incidence was lower (10.7%) than that in PBC group (24.0%) with p<0.001.

CONCLUSIONS

Patients with TN seemed to attain similar long-term benefit from PBC and RFT, especially in elderly. However, in order to reduce postoperative complications, PBC provided a safer and alternative for treating TN involving ophthalmic division, whereas RFT could be employed as a preferred regimen for maxillary and mandibular TN.

A Narrative Review of Therapeutic Peripheral Nerve Blocks for Chronic Orofacial Pain Conditions

AIMS

To provide an analysis of the different therapeutic peripheral nerve blocks (PNBs), as well as their limitations and the related evidence base for their use in chronic orofacial pain (OFP) conditions, excluding migraine and other headache conditions.

METHODS/RESULTS

The evidence base for therapeutic PNBs for chronic OFP is poor and highlights the need for improved research in this area. The diagnostic criteria and interventional PNB definitions and techniques varied between studies. In addition, the placebo effect of a peripheral injection and its resultant bias was rarely considered. Most of the PNB interventions for temporomandibular disorders were for arthrogenous disorders (arthritis and disc entrapment with pain). However, there is emerging evidence for the use of onabotulinum toxin (BTX-A) in trigeminal neuralgia, with four prospective randomized controlled trials (pRCTs), and for postherpetic neuralgia. However, despite high-level evidence for BTX-A in posttraumatic neuropathic pain outside the trigeminal system, there is no evidence for its use for PTNP within the trigeminal system.

CONCLUSION

There may be emerging evidence for treating trigeminal neuralgia with BTX-A injections; however, there is a need for future clinical studies of therapeutic PNBs in orofacial pain conditions.

Trigeminal neuropathic pain causes changes in affective processing of pain in rats

Trigeminal neuropathic pain has been modeled in rodents through the constriction of the infraorbital nerve (CCI-ION). Sensory alterations, including spontaneous pain, and thermal and mechanical hyperalgesia are well characterized, but there is a notable lack of evidence about the affective pain component in this model. Evaluation of the emotional component of pain in rats has been proposed as a way to optimize potential translational value of non-clinical studies. In rats, 22 and 50 kHz ultrasonic vocalizations (USVs) are considered well-established measures of negative and positive emotional states, respectively. Thus, this study tested the hypothesis that trigeminal neuropathic pain would result, in addition to the sensory alterations, in a decrease of 50 kHz USV, which may be related to altered function of brain areas involved in emotional pain processing. CCI-ION surgery was performed on 60-day-old male Wistar rats. 15 days after surgery, von Frey filaments were applied to detect mechanical hyperalgesia, and USV was recorded. At the same timepoint, systemic treatment with d,l-amphetamine (1 mg/kg) allowed investigation of the involvement of the dopaminergic system in USV emission. Finally, brain tissue was collected to assess the change in tyrosine hydroxylase (TH) expression in the nucleus accumbens (NAc) and c-Fos expression in brain areas involved in emotional pain processing, including the prefrontal cortex (PFC), amygdala, and NAc. The results showed that CCI-ION rats presented mechanical hyperalgesia and a significant reduction of environmental-induced 50 kHz USV. Amphetamine caused a marked increase in 50 kHz USV emission in CCI-ION rats. In addition, TH expression was lower in constricted animals and c-Fos analysis revealed an increase in neuronal activation. Taken together, these data indicate that CCI-ION causes a reduction in the emission of environmental-induced appetitive calls concomitantly with facial mechanical hyperalgesia and that both changes may be related to a reduction in the mesolimbic dopaminergic activity.

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.

The journeys of patients with trigeminal neuralgia on a background of multiple sclerosis

Aim: Multiple sclerosis (MS) is well recognized as a secondary cause for trigeminal neuralgia (TN). In this case series, we detail the management of all the patients with TN and MS (pwTNMS) presenting to a specialist unit. Materials & methods: A prospective patient database was used to extract key clinical data on pharmacological, psychometric and surgical management of 20 pwTNMS. Results: 65% of pwTNMS underwent surgical interventions for management of their pain.12/20 achieved remission periods, through surgery and/or medication. Significant improvement was noted on the global impression of change illustrated by a p < 0.001. Conclusion: pwTNMS require a multifaceted approach combining polypharmacy, surgical interventions and psychological support. Developing self-management skills is crucial if patients are to live well with pain.

Patient reported outcome measures in trigeminal neuralgia - A systematic review of psychometric performance

BACKGROUND

Trigeminal neuralgia (TN) is a rare condition for which there are multiple treatment options available. To date, there has been difficulty in comparing the outcomes of treatment due to the variety of patient-reported outcome measures (PROMs) and their inadequate psychometric testing. The aim of this review was to assess the psychometric properties of PROMs used to date in TN and make recommendations for their use in future studies.

METHODS

Five electronic databases (MEDLINE, EMBASE, CINAHL Plus, PsycINFO, Health and Psychosocial Instruments) were searched for studies assessing the development of PROMs or their psychometric properties in TN studies. The records obtained were assessed independently by two reviewers for their methodological quality, following guidance from the Consensus-based Standards for the selection of Health Measurement Instruments (COSMIN).

RESULTS

Six studies were identified and information on five PROMs (Brief Pain Inventory Facial (BPI-F), Visual Analogue Scale (VAS), Barrow Neurology Institute Pain Scale (BNI-PS), Penn Facial Pain Scale-Revised (Penn-FPS-R) and Trigeminal Neuralgia Quality of Life Score) were retrieved. The Penn-FPS-R demonstrated moderate quality evidence for sufficient content validity. The BPI-F showed moderate evidence for sufficient internal consistency and structural validity but low evidence for inconsistent content validity. The Trigeminal Neuralgia Quality of Life score showed very low-quality evidence for insufficient content validity, structure validity and responsiveness. No evidence was found on the assessment of any psychometric properties of the VAS and BNI-PS in TN.

CONCLUSION

There is limited evidence of the psychometric performance of patient-reported outcomes for TN and recommendations for their inclusion in future studies cannot be made. The validation of PROMs in TN studies should be a priority in this field of research.

SIGNIFICANCE

This review highlights the knowledge gap in the field of psychometrics of patient reported outcomes measures in the field of TN. Given the unavailability of an objective outcome measure for pain or health related quality of life, psychometrically sound PROMs are essential for assessing medical and surgical treatment outcomes in TN.

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.

Operative findings and outcome of microvascular decompression/adhesiolysis for trigeminal neuralgia in multiple sclerosis without demyelinating brain stem lesions

OBJECTIVE

Trigeminal neuralgia (TN) in multiple sclerosis (MS) poses several challenges for treatment. Although these patients often have typical attacks, they may not be considered as candidates for microvascular decompression (MVD). Here we report on surgical findings and long term follow-up of MVD/ adhesiolysis in a series of patients with multiple sclerosis but without demyelinating brain stem lesions.

METHODS

Fifteen patients with MS-related TN underwent MVD/ adhesiolysis. Demyelinating brain stem lesions were excluded radiologically. Outcome of the intervention was assessed according to the Barrow Neurological Institute (BNI) pain intensity score at 3, 12, 24 months follow-up and at the last available follow-up (mean 88.2 months, range 38-146).

RESULTS

All 15 patients benefited from MVD/adhesiolysis and were pain free on the first day of surgery. Intraoperative findings included arterial contact in 7/15 (47 %) patients, venous contact in 9/15 (60 %), and prominent arachnoid thickening in 12/15 (80 %). The distribution of the BNI pain intensity scores showed marked improvement at all follow-up evaluations. Five patients underwent repeat MVD/adhesiolysis for pain recurrence at a mean of 43 months after the first surgery. Long term evaluation at the last available follow-up demonstrated favorable outcome in 13/15 patients (BNI I-IIIa) (87 %), while 2/15 patients had limited benefit (BNI IV).

CONCLUSIONS

MS-related TN in patients without demyelinating brain stem lesions may be related either to vascular conflicts or to focal arachnoiditis at the trigeminal nerve entry zone. MVD/ adhesiolysis may be considered as a useful treatment option in this subgroup of patients with regard to long term outcome.

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.

Efficacy and safety of acupuncture for trigeminal neuralgia: A protocol for systematic review and meta-analysis

BACKGROUND

Trigeminal neuralgia (TN) is a disease accompanied by severe facial pain, which seriously affects the daily life of patients. Acupuncture is widely used by Traditional Chinese Medicine doctors to treat various painful diseases. Acupuncture combined with the treatment of trigeminal neuralgia can increase the analgesic effect and reduce side effects. However, there is still a lack of more quality multi-center clinical controlled trials and comprehensive meta-analysis, and a lack of more comprehensive and stronger evidence-based medical evidence.

METHODS

The 2 reviewers used the same search strategy to search CNKI, PubMed, Web of Science, Cochrane Library, Scopus, EBSCO, and the search date is until July 19, 2020. Two people read the retrieved literatures independently, and then delete duplications. Then, use the "risk of bias" tool in Cochrane Handbook 5.2 to score. Only documents with a score greater than 5 can be included. Make a table of literature characteristics, extract baseline patient data, research methods and possible risks of bias in the literature, interventions in treatment and control groups, outcome evaluation indicators (BNI, VAS, ER and AE), and research funding support. Use Review Manager 5.3.5 for meta-analysis, use Stata 15 for regression analysis to find the source of heterogeneity, and then perform subgroup analysis to resolve the heterogeneity based on the corresponding source.

RESULTS

The analysis of BNI, VAS, ER and AE data can provide high-quality evidence for high-quality synthesis and/or descriptive analysis of the effectiveness and safety of acupuncture treatment of various causes of urinary retention.

CONCLUSION

This study can provide more comprehensive and strong evidence to prove whether acupuncture is effective and safe in the treatment of TN patients.

REGISTRATION

The research has been registered and approved on the PROSPERO website. The registration number is CRD42019119606.

The role of connexins and pannexins in orofacial pain

Trigeminal neuralgia is characterized by extensive spreading of pain, referred to as ectopic pain, which describes the phenomenon of the pain passing from the injured regions to uninjured regions. Patients with orofacial pain often show no response to commonly used analgesics, and the exact mechanism of ectopic pain remains unclear, which restricts the development of specific drugs. The present review aims to summarize the contribution of the two families of transmembrane proteins, connexins (Cxs) and pannexins (Panxs), to the induction and spreading of orofacial pain and to provide potential targets for orofacial pain treatment. Cxs and Panxs have recently been shown to play essential roles in intercellular signal propagation in sensory ganglia, and previous studies have provided evidence for the contribution of several subtypes of Cxs and Panxs in various orofacial pain models. Upregulation of the expression of Cxs and Panxs in the trigeminal ganglia is observed in most cases after trigeminal injury, and regulating their expression or activity can improve pain-like behaviors in animals. It is speculated that after trigeminal injury, pain-related signals are transmitted to adjacent neurons and satellite glial cells in the trigeminal ganglia directly through gap junctions and simultaneously through hemichannels and pannexons through both autocrine and paracrine mechanisms. This review highlights recent discoveries in the regulation of Cxs and Panxs in different orofacial pain models and presents a hypothetical mechanism of ectopic pain in trigeminal neuralgia. In addition, the existing problems in current research are discussed.

Craniofacial neuralgias

While non-headache, non-oral craniofacial neuralgia is relatively rare in incidence and prevalence, it can result in debilitating pain. Understanding the relevant anatomy of peripheral branches of nerves, natural history, clinical presentation, and management strategies will help the clinician better diagnose and treat craniofacial neuralgias. This article will review the nerves responsible for neuropathic pain in periorbital, periauricular, and occipital regions, distinct from idiopathic trigeminal neuralgia. The infratrochlear, supratrochlear, supraorbital, lacrimal, and infraorbital nerves mediate periorbital neuralgia. Periauricular neuralgia may involve the auriculotemporal nerve, the great auricular nerve, and the nervus intermedius. The greater occipital nerve, lesser occipital nerve, and third occipital nerve transmit occipital neuralgias. A wide range of treatment options exist, from modalities to surgery, and the evidence behind each is reviewed.

Chronic Facial Pain: Trigeminal Neuralgia, Persistent Idiopathic Facial Pain, and Myofascial Pain Syndrome-An Evidence-Based Narrative Review and Etiological Hypothesis

Trigeminal neuralgia (TN), the most common form of severe facial pain, may be confused with an ill-defined persistent idiopathic facial pain (PIFP). Facial pain is reviewed and a detailed discussion of TN and PIFP is presented. A possible cause for PIFP is proposed. (1) Methods: Databases were searched for articles related to facial pain, TN, and PIFP. Relevant articles were selected, and all systematic reviews and meta-analyses were included. (2) Discussion: The lifetime prevalence for TN is approximately 0.3% and for PIFP approximately 0.03%. TN is 15-20 times more common in persons with multiple sclerosis. Most cases of TN are caused by neurovascular compression, but a significant number are secondary to inflammation, tumor or trauma. The cause of PIFP remains unknown. Well-established TN treatment protocols include pharmacotherapy, neurotoxin denervation, peripheral nerve ablation, focused radiation, and microvascular decompression, with high rates of relief and varying degrees of adverse outcomes. No such protocols exist for PIFP. (3) Conclusion: PIFP may be confused with TN, but treatment possibilities differ greatly. Head and neck muscle myofascial pain syndrome is suggested as a possible cause of PIFP, a consideration that could open new approaches to treatment.