Prevalence of trigeminal neuralgia and persistent idiopathic facial pain: a population-based study

Efficacy and safety of microvascular decompression with or without partial sensory rhizotomy: a comprehensive meta-analysis and systematic review in treating trigeminal neuralgia

Classical trigeminal neuralgia (TN), caused by vascular compression of the nerve root, is a severe cause of pain with a considerable impact on a patient's quality of life. While microvascular decompression (MVD) has lower recurrence rates when compared with partial sensory rhizotomy (PSR) alone, refractoriness can still be as high as 47%. We aimed to assess the efficacy and safety profile of MVD + PSR when compared to standalone MVD for TN. We searched Medline, Embase, and Web of Science following PRISMA guidelines. Eligible studies included those with ≥ 4 patients, in English, published between January 1980 and December 2023, comparing MVD vs. MVD + PSR for TN. Endpoints were pain cure, immediate post-operative pain improvement, long-term effectiveness, long-term recurrence, and complications (facial numbness, hearing loss, and intracranial bleeding). We pooled odds ratios (OR) with 95% confidence intervals with a random-effects model. I2 was used to assess heterogeneity, and sensitivity and Baujat analysis were conducted to address high heterogeneity. Eight studies were included, comprising a total of 1,338 patients, of whom 1,011 were treated with MVD and 327 with MVD + PSR. Pain cure analysis revealed a lower likelihood of pain cure in patients treated with MVD when compared to patients treated with MVD + PSR (OR = 0.30, 95% CI: 0.13 to 0.72). Immediate postoperative pain improvement assessment revealed a lower likelihood of improvement in the MVD group when compared with the MVD + PSR group (OR = 0.31, 95% CI: 0.10 to 0.95). Facial numbness assessment revealed a lower likelihood of occurrence in MVD alone when compared to MVD + PSR (OR = 0.08, 95% CI: 0.04 to 0.15). Long-term effectiveness, long-term recurrence, hearing loss, and intracranial bleeding analyses revealed no difference between both approaches. Our meta-analysis identified that MVD + PSR was superior to MVD for pain cure and immediate postoperative pain improvement for treating TN. However, MVD + PSR demonstrated a higher likelihood of facial numbness complications. Furthermore, identified that hearing loss and intracranial bleeding complications appear comparable between the two treatments, and no difference between long-term effectiveness and recurrence.

Other Secondary Headaches: Odontogenic Pain and Other Painful Orofacial Conditions

This article discusses extremely common odontogenic pain conditions, which may occasionally present to the neurology clinic mimicking headache, and other uncommon orofacial pain conditions, which may do the same. Typical presentations, investigative strategies, and management are discussed, as well as highlighting key diagnostic criteria and the importance of involving oral or dental specialists where diagnostic uncertainty exists.

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.

Exploring biomarkers in trigeminal neuralgia patients operated with microvascular decompression: A comparison with multiple sclerosis patients and non-neurological controls

BACKGROUND

Trigeminal neuralgia (TN) is a severe facial pain condition often associated with a neurovascular conflict. However, neuroinflammation has also been implicated in TN, as it frequently co-occurs with multiple sclerosis (MS).

METHODS

We analysed protein expression levels of TN patients compared to MS patients and controls. Proximity Extension Assay technology was used to analyse the levels of 92 proteins with the Multiplex Neuro-Exploratory panel provided by SciLifeLab, Uppsala, Sweden. Serum and CSF samples were collected from TN patients before (n = 33 and n = 27, respectively) and after (n = 28 and n = 8, respectively) microvascular decompression surgery. Additionally, we included samples from MS patients (n = 20) and controls (n = 20) for comparison.

RESULTS

In both serum and CSF, several proteins were found increased in TN patients compared to either MS patients, controls, or both, including EIF4B, PTPN1, EREG, TBCB, PMVK, FKBP5, CD63, CRADD, BST2, CD302, CRIP2, CCL27, PPP3R1, WWP2, KLB, PLA2G10, TDGF1, SMOC1, RBKS, LTBP3, CLSTN1, NXPH1, SFRP1, HMOX2, and GGT5. The overall expression of the 92 proteins in postoperative TN samples seems to shift towards the levels of MS patients and controls in both serum and CSF, as compared to preoperative samples. Interestingly, there was no difference in protein levels between MS patients and controls.

CONCLUSIONS

We conclude that TN patients showed increased serum and CSF levels of specific proteins and that successful surgery normalizes these protein levels, highlighting its potential as an effective treatment. However, the similarity between MS and controls challenges the idea of shared pathophysiology with TN, suggesting distinct underlying mechanisms in these conditions.

SIGNIFICANCE

This study advances our understanding of trigeminal neuralgia (TN) and its association with multiple sclerosis (MS). By analysing 92 protein biomarkers, we identified distinctive molecular profiles in TN patients, shedding light on potential pathophysiological mechanisms. The observation that successful surgery normalizes many protein levels suggests a promising avenue for TN treatment. Furthermore, the contrasting protein patterns between TN and MS challenge prevailing assumptions of similarity between the two conditions and point to distinct pathophysiological mechanisms.

The Therapeutic Effect of Botulinum Toxin Type A on Trigeminal Neuralgia: Are There Any Differences between Type 1 versus Type 2 Trigeminal Neuralgia?

BACKGROUND

Botulinum toxin type A is an effective treatment for trigeminal neuralgia. Moreover, its efficacy in type 2 trigeminal neuralgia and comparative studies between type 1 and type 2 trigeminal neuralgia (TN) still need to be improved.

METHODS

We treated 40 TN patients with onabotulinumtoxinA; 18 had type 1 TN, and 22 had type 2 TN. We compared the baseline pain score with the Visual Analogue Scale (VAS) and paroxysm frequency (number per week) at the baseline with those obtained at 1-month and 3-month follow-ups. Nonetheless, we compared the baseline Penn Facial Pain Scale with the scores obtained at the 1-month follow-up.

RESULTS

BoNT/A effectively reduced pain intensity and frequency at the 1-month and 3-month follow-ups. Moreover, the type 1 TN and type 2 TN groups had baseline pain scores of 7.8 ± 1.65 and 8.4 ± 1.1, respectively. Pain significantly improved (p < 0.001) in both groups to 3.1 ± 2.3 (type 1 TN) and 3.5 ± 2.3 (type 2 TN) at the 1-month follow-up and to 3.2 ± 2.5 (type 1 TN) and 3.6 ± 2.5 (type 2 TN) at the 3-month follow-up. There was no difference between the two groups (p 0.345). The baseline paroxysm frequencies (number per week) were 86.7 ± 69.3 and 88.9 ± 62.2 for the type 1 and type 2 TN groups, respectively; they were significantly reduced in both groups at the 1-month and 3-month follow-ups without significant differences between the two groups (p 0.902). The Pain Facial Pain Scale improved at the 1-month follow-up, and no significant differences were found between the two groups. There was a strong correlation between background pain and paroxysm pain intensity (r 0.8, p < 0.001).

CONCLUSIONS

Botulinum toxin type A effectively reduced the pain, paroxysm frequency, and PFPS scores of type 1 and type 2 trigeminal neuralgia patients without statistically significant differences. Facial asymmetry was the only adverse event.

Progress in animal models of trigeminal neuralgia

OBJECTIVE

This review aims to systematically summarize the methods of establishing various models of trigeminal neuralgia (TN), the scope of application, and current animals used in TN research and the corresponding pain measurements, hoping to provide valuable reference for researchers to select appropriate TN animal models and make contributions to the research of pathophysiology and management of the disease.

DESIGN

The related literatures of TN were searched through PubMed database using different combinations of the following terms and keywords including but not limited: animal models, trigeminal neuralgia, orofacial neuropathic pain. To find the maximum number of eligible articles, no filters were used in the search. The references of eligible studies were analyzed and reviewed comprehensively.

RESULTS

This study summarized the current animal models of TN, categorized them into the following groups: chemical induction, photochemical induction, surgery and genetic engineering, and introduced various measurement methods to evaluate animal pain behaviors.

CONCLUSIONS

Although a variety of methods are used to establish disease models, there is no ideal TN model that can reflect all the characteristics of the disease. Therefore, there is still a need to develop more novel animal models in order to further study the etiology, pathological mechanism and potential treatment of TN.

Transcriptome-wide analysis of trigeminal ganglion and subnucleus caudalis in a mouse model of chronic constriction injury-induced trigeminal neuralgia

Trigeminal neuropathic pain (TNP) induces mechanical allodynia and hyperalgesia, which are known to alter gene expression in injured dorsal root ganglia primary sensory neurons. Non-coding RNAs (ncRNAs) have been linked to TNP. However, the functional mechanism underlying TNP and the expression profile of ncRNAs in the trigeminal ganglion (TG) and trigeminal subnucleus caudalis (Sp5C) are still unknown. We used RNA sequencing and bioinformatics analysis to examine the TG and Sp5C transcriptomes after infraorbital nerve chronic constrictive injury (IoN-CCI). The robust changes in the gene expression of lncRNAs, circRNAs, and mRNAs were observed within the TG and Sp5C from mice that underwent IoN-CCI and the sham-operated mice (day 7). In total, 111,003 lncRNAs were found in TG and 107,157 in Sp5C; 369 lncRNAs were differentially expressed in TG, and 279 lncRNAs were differentially expressed in Sp5C. In addition, 13,216 circRNAs in TG and 21,658 circRNAs in Sp5C were identified, with 1,155 circRNAs and 2,097 circRNAs differentially expressed in TG and Sp5C, respectively. Furthermore, 5,205 DE mRNAs in TG and 3,934 DE mRNAs in Sp5C were differentially expressed between IoN-CCI and sham groups. The study revealed a high correlation of pain-related differentially expressed genes in the TG and Sp5C to anxiety, depression, inflammation, neuroinflammation, and apoptosis. Gene Ontology analysis revealed that binding-related molecular functions and membrane-related cell components were significantly enriched. Kyoto Encyclopedia of Genes and Genomes analysis shows the most significant enrichments in neurogenesis, nervous system development, neuron differentiation, adrenergic signaling, cAMP signaling, MAPK signaling, and PI3K-Akt signaling pathways. Furthermore, protein-protein interaction analysis showed that hub genes were implicated in neuropeptide signaling pathways. Functional analysis of DE ncRNA-targeting genes was mostly enriched with nociception-related signaling pathways underpinning TNP. Our findings suggest that ncRNAs are involved in TNP development and open new avenues for research and treatment.

The Consistency Between the Preoperative 3D-Reconstructed Meckel's Cave and the Intraoperative Balloon Results in Percutaneous Balloon Compression

Objective

To predict the volume and shape of the balloon before PBC by reconstructing the Meckel's cave (MC) and establishing a volumetric measurement model, supporting preoperative preparation and intraoperative decisions.

Methods

The clinical data of 31 patients with good therapeutic effects who underwent PBC are retrospectively collected, including preoperative MRI, the volume of contrast agent injected into the balloon, and intraoperative lateral X-ray images. The MC on the affected side of the 31 patients is reconstructed based on MRI using 3D Slicer, while the volume of the MC is calculated to compare with the volume of contrast agent. The width (W) and length (L) of the model of the MC in lateral view are measured and used to classify the shape of the MC based on W/L. The consistency between the W/L of the model of the MC and the W/L of the intraoperative balloon is evaluated.

Results

For volume, the mean value of the models of the MC (V1) in 31 patients is 399.77±155.13 mm³, while the mean value of the contrast agent injected during PBC (V2) is 539.03±111.93 mm³. The formula obtained by linear regression is V2= 392.1 + 0.3676×V1. Based on the value of W/L, the shape of the MC is classified into thin "pear" in 5 patients (16.13%), standard "pear" in 22 patients (70.97%), and square "pear" in 4 patients (12.90%). There is no significant difference in W/L between the models of the MC and the intraoperative balloons in 31 patients (P=0.221).

Conclusion

In 31 patients with good efficacy, it is verified that the prediction of the MC before PBC by 3D Slicer is consistent with the actual situation of the intraoperative balloon. This method can provide certain basis for preoperative preparation and intraoperative judgment.

Improvement in persistent idiopathic facial pain with comorbid ADHD using the combination of a dopamine system stabilizer and psychostimulant: A case report

Key Clinical Message

Persistent idiopathic facial pain (PIFP) and attention-deficit/hyperactivity disorder (ADHD) may coexist and can be improved with ADHD medications. Thus, clinicians should screen for ADHD by a multidisciplinary approach when treating PIFP and differentiate between other odontogenic disorders.

Abstract

We report a case of a woman with persistent idiopathic facial pain (PIFP) and attention-deficit/hyperactivity disorder (ADHD) that markedly improved with the administration of a combination of aripiprazole (APZ) and methylphenidate (MP) treatment. Screening for ADHD and administration of APZ and/or MP may be considered in treating PIFP.

Diagnosis and treatment of intractable idiopathic orofacial pain with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) has been reported to be associated with primary chronic pain syndromes, such as fibromyalgia, migraine, and chronic low back pain. Although idiopathic orofacial pain (IOP) is classified as burning mouth syndrome or persistent idiopathic facial or dentoalveolar pain and as a primary chronic pain, the association between IOP and ADHD has not been investigated. This retrospective cohort study investigated the severity of ADHD symptoms measured using the ADHD scale and the effects of treatment using ADHD drugs and the dopamine system stabilizer aripiprazole. The participants were 25 consecutive patients with refractory IOP referred to a psychiatrist and diagnosed with coexisting ADHD according to the Diagnostic and Statistical Manual of Mental Disorders-5. The ADHD scale scores were higher in patients with intractable IOP than those in the general population. Pharmacotherapy used in this study led to clinically significant improvements in pain, anxiety/depression, and pain catastrophizing. Intractable IOP and ADHD were shown to be associated. In the future, screening and pharmacotherapy for ADHD should be considered in the treatment of intractable IOP.

A preliminary study of diffusion tensor imaging in root entry zone of primary trigeminal neuralgia

Objective

Primary Trigeminal Neuralgia (PTN) is a common and refractory neurological disease. Conventional vascular compression theory could not completely explain the etiology and pathogenesis of PTN. This study used diffusion tensor imaging (DTI) to demonstrate the microstructural changes of root entry zone (REZ) region in PTN patients.

Materials and methods

DTI sequences was performed on PTN patients and healthy controls (HCs). Clinical data included affected side, disease course and visual analogue scale (VAS) were collected. Quantitative DTI variables such as FA, MD, AD and RD of the root entry/Exit zone (REZ) were measured and compared in PTN/HCs, affected/unaffected side, and pre/post operation groups. The PCoA was established to conduct overall differences between PTN group and the HCs.

Results

A total of 17 patients with PTN (mean age 59.29 ± 8.53; 5 men) and 34 HCs (mean age 57.70 ± 6.37; 10 men) were included. Lower FA value of the affected side of PTN group was observed compared to the unaffected side and the HCs (p = 0.001), whereas the values of MD, AD and RD were significantly increased (p < 0.001). Moreover, the decrease of FA value was recovered post operation. PCoA results of the comprehensive indexes can significantly distinguish PTN group from HCs (r = 0.500, p < 0.001).

Conclusion

Quantitative variables derived from DTI in REZ had significantly different profiles between PTN patients and HCs, which were associated with VAS situation and the disease course of PTN. The comprehensive index established on DTI variables were of great potential to reveal the microstructure changes in PTN patients and predict the therapeutic effect.

Cerebral perfusion alterations in patients with trigeminal neuralgia as measured by pseudo-continuous arterial spin labeling

Background

Accumulating evidence suggests that trigeminal neuralgia (TN) causes structural and functional alterations in the brain. However, only a few studies have focused on cerebral blood flow (CBF) changes in patients with TN. This study aimed to explore whether altered cerebral perfusion patterns exist in patients with TN and investigate the relationship between abnormal regional CBF (rCBF) and clinical characteristics of TN.

Materials and methods

This study included 28 patients with TN and 30 age- and sex-matched healthy controls (HCs) who underwent perfusion functional MRI (fMRI) of the brain using pseudo-continuous arterial spin labeling (pCASL) in the resting state. The regions of significantly altered CBF in patients with TN were detected using group comparison analyses. Then, the relationships between the clinical characteristics and abnormal rCBF were further investigated.

Results

Compared to the control group, patients with TN exhibited increased rCBF, primarily in the thalamus, middle frontal gyrus (MFG), and left insula. Furthermore, the CBF values of the thalamus were negatively correlated with the pain intensity of TN and positively correlated with pain duration in patients with TN.

Conclusion

Primary alterations in rCBF in patients with TN occurred in different brain regions related to pain, which are involved in cognitive-affective interaction, pain perception, and pain modulation. These results indicate that non-invasive resting cerebral perfusion imaging may contribute complementary information to further understanding the neuropathological mechanism underlying TN.

Multimodal pain therapy for persistent idiopathic facial pain - a pilot study

OBJECTIVE

Persistent Idiopathic Facial Pain (PIFP) is a pain syndrome with missing evidence-based therapy recommendations. According to the biopsychosocial pain model, multidisciplinary pain treatment (MPT) offers a promising therapeutic option for chronic pain syndromes. MPT is an interprofessional treatment procedure, consisting of medical, physiotherapeutic and psychotherapeutic treatment units, which has not yet been studied in PIFP.

METHODS

This retrospective study included 25 patients with PIFP, who had been treated with MPT. Pain intensity on the numerical rating scale (NRS), perceived disability, habitual well-being, as well as anxiety/depression and stress scales were recorded. Moreover, the patients evaluated the efficacy of each type of the single therapeutic interventions.

RESULTS

There was a highly significant decrease in the characteristic pain intensity. Also habitual well-being improved significantly, as did anxiety and depression. The perceived disability and stress also improved, but without statistical significance. Physiotherapy was rated as the most effective therapeutic unit. Among the medical measures, consultations took first place (40% of the participants). Nearly three-fourths of the patients (72%) would recommend MPT.

CONCLUSION

The present study shows beneficial outcomes in patients with PIFP following MPT. Patients evaluate physiotherapeutic treatment as particularly efficacious. Therefore, MPT can be considered as a therapeutic option in patients with PIFP.

Effect of neuropathic pain on sphenopalatine ganglion block responses in persistent idiopathic facial pain

OBJECTIVES

Management of persistent idiopathic facial pain (PIFP) can be challenging. Sphenopalatine ganglion (SPG) has been the target for the interventional treatment of many facial pain syndromes. However, possible factors that may affect SPG block success are unknown. It was aimed to investigate the effect of neuropathic pain on SPG block outcomes in PIFP, which includes a heterogeneous patient group.

METHODS

All of the patients underwent fluoroscopy-guided SPG block with an injection of 40 mg of 2% lidocaine and 8 mg of dexamethasone. The patients were assigned to 2 groups according to existence of neuropathic pain determined with the DN4 questionnaire score: 19 patients with neuropathic pain (Group 1) and 15 patients without neuropathic pain (Group 2). Preprocedural and postprocedural Visual Analog Scale (VAS) scores were compared between the 2 groups.

RESULTS

The mean age of the patients was 47.65 ± 6.50 years. The average pain duration was 52.95 ± 34.81 weeks. A significantly greater decrease was detected in the VAS scores at 1 week (p = 0.036) and 1 month (p < 0.001) in Group 1 when compared to Group 2. Moreover, the proportion of patients with >50% improvement in the VAS scores at 1 week (p = 0.012) and 1 month (P = 0.017) was significantly lower in Group 1 than in Group 2.

DISCUSSION

SPG block appears as a safe, effective, and rapid method to treat PIFP, especially in cases with neuropathic pain. Neuropathic pain may be a predictor for pain relief in interventional procedures targeting SPG in the treatment of PIFP.

Microvascular decompression: Diversified of imaging uses, advantages of treating trigeminal neuralgia and improvement after the application of endoscopic technology

Classical trigeminal neuralgia (CTN) is a unilateral and severe facial pain disease, which seriously affects the patient's quality of life. Microvascular decompression (MVD) is currently the most effective surgical method, and it is the only treatment for the etiology of CTN. Imaging for MVD has been increasingly used, and the advantages and disadvantages of endoscopy-assisted vascular decompression surgery have been controversially debated. In this review, we aimed to discuss the advantages of MVD in the treatment of patients with CTN, the importance of using imaging in disease management, and the improvements of vascular decompression surgery through the application and maturity of endoscopic techniques. Compared with other surgical methods, MVD has more prominent short- and long-term treatment effects. Its selection depends on the accurate discovery of neurovascular compression by preoperative imaging. Moreover, magnetic resonance imaging plays a diverse role in MVD, not only in identifying the responsible vessels but also in determining the prognosis and as a tool for scientific research. The use of endoscopic techniques provides improved visualization of the MVD and additional benefits for vascular decompression surgery.

Incidence of repeat procedures and healthcare utilization following surgery, radiosurgery, and percutaneous procedures in elderly patients with trigeminal neuralgia

OBJECTIVE

Management of trigeminal neuralgia (TN) in elderly patients poses significant challenges. The impact of different treatment modalities (surgery, radiosurgery [RS], and percutaneous techniques [PTs]) on healthcare utilization is not well defined in the management of TN in elderly patients. The aim of this study was to compare the long-term healthcare utilization metrics of different interventions in the management of elderly patients with TN.

METHODS

The MarketScan database was queried using the International Classification of Diseases, Ninth Revision and Current Procedural Terminology, from 2000 to 2016. TN patients ≥ 65 years of age managed using surgery, RS, and PTs with at least 5 years of follow-up after the index procedure were included. Outcomes analyzed were hospital admissions, outpatient services, and medication refills.

RESULTS

Of 993 patients, 43% (n = 430) underwent RS, 44% (n = 432) had PTs, and only 13% (n = 131) underwent surgery for TN. Overall, the median age of patients was 74 years old, 64% were females, 90% had Medicare insurance, and 17% had an Elixhauser index ≥ 3. Patients in the surgery group were younger (median age 71 years) with a higher comorbidity index (≥ 3; 24%) compared with patients undergoing RS and PTs (13% and 17%, respectively). At 1, 2, and 5 years after the index procedure, 41%, 48%, and 57% of patients in the PT cohort underwent any repeat procedure compared with 11%, 18%, and 29% for the RS cohort, and 6%, 9%, and 11% for the surgical cohort, respectively. Also, patients in the PT cohort incurred 1.8, 1.9, and 2.0 times the combined payment at 1, 2, and 5 years, respectively, compared with the surgery cohort. Similarly, patients who underwent RS for TN incurred 1.4, 1.5, and 1.5 times the combined payment at 1, 2, and 5 years, respectively, compared with the surgery cohort. At 5 years after the index procedure, combined payments for the PT cohort were $79,753 (IQR $46,013, $144,064) compared with $61,016 (IQR $27,114, $117,097) for the RS cohort and $41,074 (IQR $25,392, $87,952) for the surgery cohort (p < 0.0001).

CONCLUSIONS

PTs followed by RS were the common procedures used in the majority of elderly patients with TN. However, surgery for TN resulted in durable control with the least need for reoperations up to 5 years after the index procedure, followed by RS and PTs. PTs for TN resulted in the highest utilization of healthcare resources and need for reoperations at all time points. These findings should be considered in clinical decision-making when selecting appropriate treatment modalities in elderly patients with TN.

The Effectiveness of High-Frequency Repetitive Transcranial Magnetic Stimulation on Patients with Neuropathic Orofacial Pain: A Systematic Review of Randomized Controlled Trials

Background

Repetitive transcranial magnetic stimulation (rTMS) has been widely used in the treatment of neuropathic orofacial pain (NOP). The consistency of its therapeutic efficacy with the optimal protocol is highly debatable.

Objective

To assess the effectiveness of rTMS on pain intensity, psychological conditions, and quality of life (QOL) in individuals with NOP based on randomized controlled trials (RCTs).

Methods

We carefully screened and browsed 5 medical databases from inception to January 1, 2022. The study will be included that use of rTMS as the intervention for patients with NOP. Two researchers independently completed record retrieval, data processing, and evaluation of methodological quality. Quality and evidence were assessed using the PEDro scores and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system.

Results

Six RCTs with 214 participants were included in this systematic review: 2 studies were considered level 1 evidence, and 4 were considered level 2 evidence. Six studies found that high-frequency rTMS had a pain-relieving effect, while 4 studies found no improvement in psychological conditions and QOL. Quality of evidence (GRADE system) ranged from moderate to high. No significant side effects were found.

Conclusions

There is moderate-to-high evidence to prove that high-frequency rTMS is effective in reducing pain in individuals with NOP, but it has no significant positive effect on psychological conditions and QOL. High-frequency rTMS can be used as an alternative treatment for pain in individuals with NOP, but further studies will be conducted to unify treatment parameters, and the sample size will be expanded to explore its influence on psychological conditions and QOL.

Rich-club reorganization and related network disruptions are associated with the symptoms and severity in classic trigeminal neuralgia patients

BACKGROUND

Alterations in white matter microstructure and functional activity have been demonstrated to be involved in the central nervous system mechanism of classic trigeminal neuralgia (CTN). However, the rich-club organization and related topological alterations in the CTN brain networks remain unclear.

METHODS

We simultaneously collected diffusion-tensor imaging (DTI) and resting state functional magnetic resonance imaging (rs-fMRI) data from 29 patients with CTN (9 males, mean age = 54.59 years) and 34 matched healthy controls (HCs) (12 males, mean age = 54.97 years) to construct structural networks (SNs) and functional networks (FNs). Rich-club organization was determined separately based on each group's SN and different kinds of connections. For both network types, we calculated the basic connectivity properties (network density and strength) and topological properties (global/local/nodal efficiency and small worldness). Moreover, SN-FN coupling was obtained. The relationships between all those properties and clinical measures were evaluated.

RESULTS

Compared to their FN, the SN of CTN patients was disrupted more severely, including its topological properties (reduced network efficiency and small-worldness), and a decrease in network density and strength was observed. Patients showed reorganization of the rich-club architecture, wherein the nodes with decreased nodal efficiency in the SN were mainly non-hub regions, and the local connections were closely related to altered global efficiency and whole brain coupling. While the cortical-subcortical connections of feeder were found to be strengthened in the SN of patients, the coupling between networks increased in all types of connections. Finally, disease severity (duration, pain intensity, and affective alterations) was negatively correlated with coupling (rich-club, feeder, and whole brain) and network strength (the rich-club of the SN and local connections of the FN). A positive correlation was only found between pain intensity and the coupling of local connections.

CONCLUSIONS

The SN of patients with CTN may be more vulnerable. Accompanied by the reorganization of the rich-club, the less efficient network communication and the impaired functional dynamics were largely attributable to the dysfunction of non-hub regions. As compensation, the pain transmission pathway of feeder connections involving in pain processing and emotional regulation may strengthen. The local and feeder sub-networks may serve as potential biomarkers for diagnosis or prognosis.

Persistent Idiopathic Facial Pain (PIFP) in Patients Referred to a Multidisciplinary Centre in Italy: A Retrospective Observational Study

Background: Persistent Idiopathic Facial Pain (PIFP), previously named Atypical Facial Pain (AFP) is a poorly understood condition, often diagnosed after several inconclusive investigations. The aim of this retrospective study was to evaluate the demographic and clinical characteristics of patients with PIFP referred to a Facial Pain Center. Methods: Between May 2011 and September 2014, data on 41 PIFP patients were analyzed regarding temporal, topographical and descriptive pain features, including onset, localization, pain descriptors and intensity. Pharmacological pain treatments were also registered. Finally, the presence and type of previous minor oro-surgery procedures in the painful area were investigated. Results: Demographic and clinical characterization were similar to PIFP patients reported in literature. The presence of previous minor oro-surgery procedures in the painful area was reported in most of these patients, in particular endodontic treatments and tooth extractions. Conclusions: This retrospective analysis showed a high prevalence of minor oro-surgery procedures in our population, while its role in PIFP pathophysiology remains unknown. A new classification of PIFP built around the main discriminant factor of presence of these procedures in the painful area could be considered while available data were still insufficient to define specific diagnostic criteria.

Cervical Spinal Cord Stimulation for Trigeminal Neuralgia: a Narrative Review

BACKGROUND

Trigeminal neuralgia (TN) is a chronic neuropathic pain condition affecting one or more divisions of the fifth cranial (trigeminal) nerve. TN is defined by recurrent unilateral electric shock-like pain that is abrupt in both onset and termination. The pain is triggered by innocuous sensory stimuli and is classified as either classic TN, related to vascular compression; secondary TN, due to a tumor along the trigeminal nerve or an underlying disease like multiple sclerosis; or idiopathic TN. Among the various therapies available for TN, carbamazepine remains the first-line treatment. Newer medications have demonstrated efficacy in patients who do not respond to or cannot tolerate carbamazepine. When medical management and neuroablative procedures fail, spinal cord stimulation (SCS) serves as a promising and popular option, with an estimated 34,000 SCS procedures performed annually worldwide. SCS employs the implantation of electrical leads in the epidural space to manage pain.

PURPOSE OF REVIEW

A review of literature was conducted to explore the use of cervical spinal cord stimulation (SCS) for the treatment of trigeminal neuralgia.

METHODS

A MEDLINE/PubMed search using the search terms "spinal cord stimulation" and "trigeminal neuralgia" was employed to find any case reports and research studies (retrospective studies, double-blinded studies, observational studies) on the topic. No date limiters were used for the search. The initial search resulted in 76 non-duplicate entries from the database. After application of the search criteria, 58 studies were excluded because they were not relevant to the study. A further detailed review of the included articles was conducted by all the reviewers. During this phase of the review, additional 6 studies were excluded. A total of 11 studies were included: 7 case reports and 4 retrospective review studies.

RECENT FINDINGS

In the review, we discuss 7 different case reports on the use of cervical SCS for trigeminal neuralgia and an additional 4 retrospective studies reviewing outcomes and pain relief in patients who underwent treatment. The case reports and retrospective studies reviewed demonstrated that TN patients realized > 50% pain relief following permanent electrode implantation. In all the cases discussed, complications from SCS were rare and/or not reported. Additionally, most of the cases report that patients who had adequate pain relief from SCS were able to wean off, or significantly reduce, oral medications given the vast improvement in pain reduction.

CONCLUSIONS

Cervical spinal cord stimulation (SCS) is a safe and effective procedure for patients with trigeminal neuralgia (TN) who have refractory pain despite the use of medications. In many cases, the procedure provides an adequate level of pain relief with very few complications or side effects. The vast majority of current research on the use of cervical SCS for TN currently consists of case reports and retrospective analysis. In order to further evaluate the efficacy of SCS for treatment, large-scale randomized controlled studies or observational studies need to be conducted to properly evaluate SCS as a treatment modality for trigeminal neuralgia.

Prevention of Superior Petrosal Vein Injury during Microvascular Decompression for Trigeminal Neuralgia: Operative Nuances

Background The superior petrosal vein (SPV) often obscures the surgical field or bleeds during microvascular decompression (MVD) for the treatment of trigeminal neuralgia. Although SPV sacrifice has been proposed, it is associated with multiple complications. We have performed more than 4,500 MVDs, including approximately 400 cases involving trigeminal neuralgia. We aimed to describe our operative technique and nuances to avoid SPV injury.

Methods We have provided a detailed description of our institutional protocol, including the anesthesia technique, neurophysiologic monitoring, patient positioning, surgical approach, and SPV management. The surgical outcomes and treatment-related complications were retrospectively analyzed.

Results No SPVs were sacrificed intentionally or accidentally during our MVD protocol for trigeminal neuralgia. In the 344 operations performed during 2006 to 2020, 269 (78.2%) patients did not require medication postoperatively, 58 (16.9%) tolerated the procedure with adequate medication, and 17 (4.9%) did not respond to MVD. Postoperatively, 35 (10.2%), 1 (0.3%), and 0 patients showed permanent trigeminal, facial, or vestibulocochlear nerve dysfunction, respectively. Wound infection occurred in five (1.5%) patients, while cerebrospinal fluid leaks occurred in three (0.9%) patients. Hemorrhagic complications appeared in four (1.2%) patients but these were unrelated to SPV injury. No surgery-related mortalities were reported.

Conclusion MVD for the treatment of trigeminal neuralgia can be achieved safely without sacrificing the SPV. A key step is positioning the patient's vertex at a 10-degree elevation from the floor, which can ease venous return and loosen the SPV, making it less fragile to manipulation and providing a wider surgical corridor.

The impact of needle location on clinical outcome of radiofrequency rhizotomy for trigeminal neuralgia

BACKGROUND

Radiofrequency thermocoagulation trigeminal rhizotomy (RT-TR) through the foramen ovale is a minimally invasive treatment for trigeminal neuralgia. Navigation of magnetic resonance imaging (MRI) and CT fusion imaging is a well-established method for cannulation of the Gasserian ganglion. In this study, we use the inline measurements from fusion image to analyze the anatomical parameters between the actual and simulation trajectories and compare the short- and intermediate-term outcomes according to determinable factors.

METHODS

The study included thirty-six idiopathic neuralgia patients who had undergone RT-TR with MRI and CT fusion image as a primary modality or repeated procedures.

RESULTS

Among thirty-six treated patients, the inline length of the trigeminal cistern was longer for the simulated trajectory (8.4 ± 2.4 versus 6.5 ± 2.8 mm; p < 0.05), and the predominant structure at risk extrapolated from the inline trajectory was the brainstem, which signified a more medially directed route, in contrast with the equal weighting of temporal lobe and brainstem for the actual trajectory. The preoperative visual analogue scale (VAS) was 9.3 ± 1.0, which decreased to 2.5 ± 2.6 and 2.9 ± 3.1 at first (mean, 3 months) and second (mean, 14 months) postoperative follow-up, respectively. The postoperative VAS scores at the two follow-ups were not statistically significant without a covariate analysis. After adjustment for covariate risk factors, the second follow-up sustained therapeutic benefit was evident in patients with no prior history of related treatment, an ablation temperature greater than 70 °C, and needle location within or adjacent to the trigeminal cistern.

CONCLUSIONS

This preliminary study demonstrated that the needle location between cistern and ganglion also plays a significant role in better intermediate-term results.

Orofacial pain disorders: An overview and diagnostic approach

Background:

Non-dental orofacial pain disorders are not uncommon, but idiopathic or primary facial pain syndromes are rare. Inadequate recognition of these disorders usually leads to unsatisfactory and unmet treatment needs.

Methods:

We conducted a narrative review with a literature search in PubMed until December 2021, focusing on current guidelines and the recently published International Classification of Orofacial Pain (ICOP).

Results:

In this paper, we provide an updated overview of the common orofacial pain disorders following the ICOP, covering the classification, epidemiology, pathophysiology, clinical approaches, and treatment options. Additionally, we propose a pragmatic approach focusing on the attack duration to improve distinguishing orofacial disorders.

Conclusion:

The introduction of ICOP offers the opportunity to better coordinate and concentrate scientific efforts, which lays the foundation for the identification of the disease mechanism of facial pain disorders and the optimization of the currently still insufficient therapeutic strategies.

Cerebrospinal Fluid in Classical Trigeminal Neuralgia: An Exploratory Study on Candidate Biomarkers

Trigeminal neuralgia (TN) is a severe type of facial pain. A neurovascular conflict between cranial nerve V and a nearby vessel is the main pathophysiological mechanism, but additional factors are likely necessary to elicit TN. In this study, the primary aim was to explore differences in protein expression in the cerebrospinal fluid (CSF) of TN patients in relation to controls. Methods: Sixteen TN patients treated with microvascular decompression and 16 control patients undergoing spinal anesthesia for urological conditions were included. Lumbar CSF was collected preoperatively for the TN patients and before spinal anesthesia for the controls. A multiplexed proximity extension analysis of 91 CSF proteins was conducted using Proseek Multiplex Development 96, including biomarkers of cell communication, cell death, neurogenesis, and inflammation Results: The TN patients and the controls were of similar age, sex, and burden of co-morbidities. The TN patients exhibited higher concentrations of Clec11a, LGMN, MFG-E8, and ANGPTL-4 in CSF than the controls (q < 0.05). Conclusions: TN patients exhibited increased CSF biomarkers indicative of peripheral demyelinating injury (Clec11a), immune tolerance and destruction of myelin (LGMN), neuronal cell death (MFG-E8), and disturbances in myelin clearance (ANGPTL-8). Our findings are hypothesis-generating for candidate biomarkers and pathophysiological processes in classical TN.

Cardiovascular response to Gasserian ganglion ablation on trigeminal neuralgia under local anesthesia: a retrospective single-blind case-control study

Objective

Radiofrequency thermocoagulation of Gasserian ganglion brings with it the difficult problem of how to provide adequate acesodyne therapy for patients in order to make the treatment more comfortable. In our study, we assess the safety and efficacy of lidocaine local anesthesia in the treatment of trigeminal neuralgia.

Methods

From January, 2017 to December, 2020, 80 patients in our hospital who were suffering from trigeminal neuralgia were treated with radiofrequency thermocoagulation through oval foramen. They were all enrolled in our study and randomly divided into a study group and a placebo group. In the study group an appropriate concentration of lidocaine was given outside and inside of the oval foramen after puncturing in place, while in the placebo group the same dose of normal saline was given in the same way. We then recorded the mean arterial pressure (MAP), heart rate (HR) and visual analogue scale (VAS) at different treatment temperatures.

Results

The values of MAP and HR in the study group were generally lower than those in the placebo group, and the difference was statistically significant. Additionally, the two groups showed a significant difference in MAP, HR, and VAS at different treatment temperatures. There were significant differences in MAP and VAS between the study group at the baseline as well as each time point thereafter, and the range of MAP and HR in the study group were lower than those in the placebo group.

Conclusion

Reasonable lidocaine local anesthesia can provide analgesic effects and prevent hypertension and arrhythmia during Gasserian ganglion radiofrequency thermocoagulation for the treatment of trigeminal neuralgia.

Thinking Outside the Tooth: Diagnosis and Management of Patients with Neuropathic Orofacial Pain

Nonodontogenic orofacial pain exists, and diagnosis and management of those conditions can be challenging. This article highlights and discusses how to take a complete and systematic pain history and the important red flags to recognize in patients presenting with perplexing nonodontogenic orofacial pain. Cause and epidemiology, clinical presentation, clinical evaluation and diagnosis, and management options for common neuropathic pain conditions are included. Neuralgia and neuropathic pain conditions and red flags as secondary cause of orofacial pain are more common in older-aged patients.

The Molecular Basis and Pathophysiology of Trigeminal Neuralgia

Trigeminal neuralgia (TN) is a complex orofacial pain syndrome characterized by the paroxysmal onset of pain attacks in the trigeminal distribution. The underlying mechanism for this debilitating condition is still not clearly understood. Decades of basic and clinical evidence support the demyelination hypothesis, where demyelination along the trigeminal afferent pathway is a major driver for TN pathogenesis and pathophysiology. Such pathological demyelination can be triggered by physical compression of the trigeminal ganglion or another primary demyelinating disease, such as multiple sclerosis. Further examination of TN patients and animal models has revealed significant molecular changes, channelopathies, and electrophysiological abnormalities in the affected trigeminal nerve. Interestingly, recent electrophysiological recordings and advanced functional neuroimaging data have shed new light on the global structural changes and the altered connectivity in the central pain-related circuits in TN patients. The current article aims to review the latest findings on the pathophysiology of TN and cross-examining them with the current surgical and pharmacologic management for TN patients. Understanding the underlying biology of TN could help scientists and clinicians to identify novel targets and improve treatments for this complex, debilitating disease.

Characteristics of headache disorders, according to ICHD-III in an outpatient headache clinic in Sohag Governorate, Egypt

Background

Headache disorders are rated among the ten most disabling conditions around the world. The primary headache disorders are more common that of secondary headache. The third edition of the International Classification of Headache Disorders (ICHD-III) is considered as a helpful tool for classification and diagnosis of different headache disorders.

Methods

This is a cross-sectional study that included 500 patients who attended to the headache clinic, between May 2018 and April 2019. Arabic version of headache questionnaire was used to characterize headache, according to ICHD-III.

Results

Primary headache disorders were found in 89% (most of them is episodic in nature 76.2%), secondary headache disorders in about 10%, and painful cranial neuropathy was present in 0.8%. Primary headache associated with sexual activity was present in 1% of the total number of headache patients, and episodic cluster headache was found in 0.8%. Medication overuse headache (MOH) was the most frequent secondary headache with 2.8% of the total number of headache patients, and when overlaps with chronic migraine or chronic tension type of headache (TTH), the percent was 12.8% and 8.8% respectively. Male to female ratio was 1:3, 3:5, and 1:1 in primary headache, secondary headache, and painful cranial neuropathy respectively. Simple analgesia was the most common abortive therapy (44.8%) while the antidepressants were the most common preventive treatment (17%).

Conclusion

This study estimates the frequency and characterizes different headache disorders, according to ICHD-III in an outpatient headache clinic at Sohag Governorate, Egypt.

A Prospective Study to Examine the Association of the Foramen Ovale Size with Intraluminal Pressure of Pear-Shaped Balloon in Percutaneous Balloon Compression for Trigeminal Neuralgia

INTRODUCTION

Percutaneous balloon compression (PBC) is an effective and safe option for patients with trigeminal neuralgia. A pear-shaped balloon can be used to identify the proper compression of the Gasserian ganglion during the PBC procedure. The aim of this study was to evaluate the relationship between the foramen ovale (FO) size and intraluminal pressure of the pear-shaped balloon.

METHODS

Thirteen patients that presented with classical trigeminal neuralgia were scheduled to undertake PBC surgery at the Pain Department of the Third Xiangya Hospital, Central South University, from November 2020 to April 2021. Three-dimensional computed tomography reconstruction of the skull base was performed to capture the feature of FO preoperatively. The intraluminal pressure was continuously recorded when a pear-shaped balloon was obtained during the procedure. Correlation analysis was calculated to determine the association of the intraluminal balloon pressure with FO parameter.

RESULTS

All participants reported complete relief of pain at discharge. The enduring analgesic effect of PBC was maintained in all patients with a median follow-up up to 5.5 months (range, 3-8 months). The average intraluminal balloon pressure was 161.5 ± 29.4 kPa at the initial compression (P1), and 134.8 ± 21.5 kPa at the ending of compression (P2), respectively. P1 was significantly correlated with the length (r = 0.61, P = 0.024) of FO. Similarly, a significant and positive correlation was observed between P2 and the length (r = 0.63, P = 0.022) of FO.

CONCLUSIONS

Preoperative assessment of FO may be a potential predictor of intraluminal pressure to reach a pear-shaped balloon during PBC treatment. Narrow FO is associated lower intraluminal balloon pressure.

Pharmacologic Management of Neuropathic Pain

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

White matter integrity in patients with classic trigeminal neuralgia: a multi-node automated fiber tract quantification study

OBJECTIVE

To study the characteristics of point-by-point destruction of white matter tracts in patients using automated fiber tract quantification (AFQ).

METHODS

Thirty-four classic trigeminal neuralgia (CTN) patients and 34 healthy control (HC) subjects underwent 3.0 T diffusion tensor magnetic resonance imaging and T1-weighted imaging. The fractional anisotropy (FA) and mean diffusivity (MD) of 100 nodes of 20 fiber tracts were analyzed by AFQ, and the correlations of the FA and MD with the visual analogue scale (VAS) pain score were assessed.

RESULTS

The FA values of the left thalamic radiation (middle segment), left corticospinal tract, callosum forceps minor, and right uncinate fasciculus were significantly lower in CTN patients than in the HC group. The MD of the left thalamic tract (middle segment), left corticospinal tract, right superior longitudinal fasciculus, and left superior longitudinal fasciculus (anterior segment) were significantly higher in the CTN group. Additionally, the VAS pain score in CTN patients was positively correlated with FA and negatively correlated with MD.

CONCLUSION

Specific fiber tract nodes were damaged in CTN patients, which was related to the VAS pain score. Multi-node quantitative studies of fiber tract damage are valuable for understanding the white matter tract damage pattern in CTN patients.

Characteristics and natural disease history of persistent idiopathic facial pain, trigeminal neuralgia, and neuropathic facial pain

OBJECTIVE

This study aimed to characterize key features, and to assess the clinical development of common nondental facial pain syndromes such as persistent idiopathic facial pain (PIFP), trigeminal neuralgia (TN), and neuropathic facial pain (NEUROP).

METHODS

This is a longitudinal study in which prospective questionnaire data of patients presenting to a specialized outpatient clinic were collected from 2009 to 2019. A telephone interview was conducted with the same patients in 2020 to assess the natural disease history.

RESULTS

n = 411 data sets of patients with chronic facial pain were compiled. Among these were n = 150 patients with PIFP, n = 111 patients with TN, and n = 86 patients with NEUROP. Guideline therapy had not been initiated in 38.7% (58/150; PIFP), 19.8% (22/111; TN), and 33.7% (29/86; NEUROP) patients. Of the patients with PIFP, 99.3% (149/150) had primarily consulted a dentist due to their pain syndrome. The additional telephone interview was completed by 236 out of the 411 patients (57.4%). Dental interventions in healthy teeth had been performed with the intention to treat the pain in many patients (78/94 [83.0%] PIFP; 34/62 [54.8%] TN; 19/43 [44.2%] NEUROP), including dental extractions. 11.3% (7/43) of the patients with TN had never profited from any therapy. In contrast, 29.8% (28/94) of the patients with PIFP had never profited from any therapy. Furthermore, the primary pharmaceutical therapy options suggested by national guidelines were, depending on the substance class, only considered to be effective by 13.8% (13/94; antidepressants) and 14.9% (14/94; anticonvulsants) of the patients with PIFP.

CONCLUSIONS

Facial pain syndromes pose a considerable disease burden. Although treatment of TN seems to be effective in most patients, patients with PIFP and NEUROP report poor effectiveness even when following guideline therapy suggestions. In addition, unwarranted dental interventions are common in facial pain syndromes.

Trigeminal neuralgia: a practical guide

Trigeminal neuralgia (TN) is a highly disabling disorder characterised by very severe, brief and electric shock like recurrent episodes of facial pain. New diagnostic criteria, which subclassify TN on the basis of presence of trigeminal neurovascular conflict or an underlying neurological disorder, should be used as they allow better characterisation of patients and help in decision-making regarding medical and surgical treatments. MR imaging, including high-resolution trigeminal sequences, should be performed as part of the diagnostic work-up. Carbamazepine and oxcarbazepine are drugs of first choice. Lamotrigine, gabapentin, pregabalin, botulinum toxin type A and baclofen can be used either alone or as add-on therapy. Surgery should be considered if the pain is poorly controlled or the medical treatments are poorly tolerated. Trigeminal microvascular decompression is the first-line surgery in patients with trigeminal neurovascular conflict while neuroablative surgical treatments can be offered if MR imaging does not show any neurovascular contact or where patients are considered too frail for microvascular decompression or do not wish to take the risk.

Management of chronic idiopathic pain in patients with dental implant without a clear pathological lesion: A retrospective study

Non-nociceptive, persistent idiopathic facial pain (PIFP) is a poorly localized, continuous dull pain that occurs even in the absence of apparent pathological lesions or clinical neurologic deficiency. This study aimed to investigate the disease characteristics of PIFP that developed after dental implant treatments. The clinical characteristics of pain as well as treatment method and outcomes were retrospectively analyzed in 20 patients diagnosed with PIFP. The patients developed pain either after implant fixation or prosthetic treatment. In most of the patients, the pain persisted not only around the implant region but also at a distant site from the related implant (13/20, 65%). Many patients desired removal of the implants to manage the pain although the pain was not considered to be related to the implant treatment itself. In 12 patients, the related implants were removed but 67% (n = 8/12) of the patients still experienced chronic pain after implant removal. Medication helped decrease the pain in most patients (n = 17). Pregabalin and clonazepam showed relatively higher efficiency than other medications for controlling the pain. The results showed that although the onset of PIFP was related to dental implant treatment, implant removal could not be considered a reliable option for the management of PIFP. Although medication controls the pain at least partially, complete pain control with medication should not be expected. These results demonstrate that an accurate diagnosis of PIFP is important for the selection of appropriate treatment.

Down-regulation of MAPK pathway alleviates TRPV4-mediated trigeminal neuralgia by inhibiting the activation of histone acetylation

Our objective of this study is to determine the molecular mechanism of MAPKs (mitogen activated protein kinase systems) on TRPV4 (transient receptor potential vanilloid 4)-mediated trigeminal neuralgia (TN). Partial chronic constriction injury of the infraorbital nerve (CCI-ION) ligation model was used in this research. When treated with antagonists of p38, JNK or ERK, the mechanical hyperalgesia threshold, nerve fiber disorder, myelinoclasis, and Schwann cells proliferation could be reversed. RT-PCR (real-time quantitative polymerase chain reaction), Western blot and IHC (immunohistochemistry) showed that TRPV4 mRNA and protein levels, TRPV4-positive cells and small positive neurons decreased remarkably in TN group treated with antagonists of p38, JNK or ERK. ELISA (enzyme-linked immunosorbent assay) was performed to discover inhibition of MAPK pathway can down-regulate the expression of HATs (histone acetyltransferases), and up-regulate the expression of HDACs (histone deacetylases) in TN, thus inhibiting histone acetylation. Finally, Western blot was performed to identify the phosphorylation status of p38, JNK and ERK, finding decreased phosphorylation forms in antagonists treated TN groups compared with TN groups. Based on the above investigation method, on a whole, our study showed that down-regulation of MAPK pathway could alleviate TRPV4-mediated trigeminal neuralgia, via inhibiting the activation of histone acetylation.

Polymorphisms of Nav1.6 sodium channel, Brain-derived Neurotrophic Factor, Catechol-O-methyltransferase and Guanosine Triphosphate Cyclohydrolase 1 genes in trigeminal neuralgia

SUBJECTS

Trigeminal neuralgia is a neuropathic pain characterized by episodes of severe shock-like pain within the distribution of one or more divisions of the trigeminal nerve. Pain can be influenced by ethnicity, environment, gender, psychological traits, and genetics. Molecules Nav1.6 sodium channel, Brain-derived Neurotrophic Factor, Catechol-O-methyltransferase and Guanosine Triphosphate Cyclohydrolase 1 have been involved in mechanisms that underlie pain and neurological conditions.

OBJECTIVE

The aim of this case-control study was to investigate the occurrence of genetic polymorphisms in Nav1.6 sodium channel (SCN8A/rs303810), Brain-derived Neurotrophic Factor (BDNF/rs6265/Val66Met), Catechol-O-methyltransferase (COMT/rs4680/Val158Met), and Guanosine Triphosphate Cyclohydrolase 1 (GCH1/rs8007267) genes in trigeminal neuralgia patients.

METHODS

Ninety-six subjects were divided into two groups: 48 with trigeminal neuralgia diagnosis and 48 controls. Pain was evaluated by visual analog scale and genomic DNA was obtained from oral swabs and analyzed by real-time polymerase chain reaction.

RESULTS

No association was observed among SCN8A, BDNF, COMT or GCH1 polymorphisms and the presence of trigeminal neuralgia. Genotype distribution and allele frequencies did not correlate to pain severity.

CONCLUSIONS

Although no association of evaluated polymorphisms and trigeminal neuralgia or pain was observed, our data contributes to the knowledge of genetic susceptibility to trigeminal neuralgia, which is very scarce. Further studies may focus on other polymorphisms and mutations, as well as on epigenetics and transcriptional regulation of these genes, in order to clarify or definitively exclude the role of Nav1.6, BDNF, COMT or GCH1 in trigeminal neuralgia susceptibility and pathophysiology.

Cortical thickness, gyrification and sulcal depth in trigeminal neuralgia

Neuroimaging studies have documented brain structural alterations induced by chronic pain, particularly in gray matter volume. However, the effects of trigeminal neuralgia (TN), a severe paroxysmal pain disorder, on cortical morphology are not yet known. In this study, we recruited 30 TN patients and 30 age-, and gender-matched healthy controls (HCs). Using Computational Anatomy Toolbox (CAT12), we calculated and compared group differences in cortical thickness, gyrification, and sulcal depth with two-sample t tests (p < 0.05, multiple comparison corrected). Relationships between altered cortical characteristics and pain intensity were investigated with correlation analysis. Compared to HCs, TN patients exhibited significantly decreased cortical thickness in the left inferior frontal, and left medial orbitofrontal cortex; decreased gyrification in the left superior frontal cortex; and decreased sulcal depth in the bilateral superior frontal (extending to anterior cingulate) cortex. In addition, we found significantly negative correlations between the mean cortical thickness in left medial orbitofrontal cortex and pain intensity, and between the mean gyrification in left superior frontal cortex and pain intensity. Chronic pain may be associated with abnormal cortical thickness, gyrification and sulcal depth in trigeminal neuralgia. These morphological changes might contribute to understand the underlying neurobiological mechanism of trigeminal neuralgia.

Is this really trigeminal neuralgia? Diagnostic re-evaluation of patients referred for neurosurgery

OBJECTIVES

Patients with facial pain are sometimes referred for neurosurgical treatment with a poorly documented diagnosis of trigeminal neuralgia. In such cases, neurosurgery will usually not be helpful. We conducted a re-evaluation of the diagnosis in patients referred for neurosurgical treatment of presumed trigeminal neuralgia. Our objective was to find out why and how often misdiagnosis occurred.

METHODS

A retrospective study was done in consecutive first-time patients referred for trigeminal neuralgia to our outpatient clinic in 2019. We used five ICHD-3-based clinical criteria to verify or exclude the diagnosis. In patients where trigeminal neuralgia was excluded, we established a diagnosis for their facial pain based upon medical history and a physical examination by a neurosurgeon - often supplemented with examination by an oral surgeon.

RESULTS

Thirty-eight patients were referred for presumed trigeminal neuralgia. Only 17 of them fulfilled the five criteria and were diagnosed with trigeminal neuralgia. In 20 of the remaining 21 patients trigeminal neuralgia could be clearly excluded, while one of the patients had a periodontitis closely mimicking trigeminal neuralgia. In 14 of the 21 patients we diagnosed temporomandibular dysfunction or dental conditions. MRI scans had detected low-grade neurovascular contacts in 13 of the 21 patients, a finding that was clearly overestimated by the referring neurologists in seven patients.

CONCLUSIONS

Overdiagnosis of trigeminal neuralgia was common in patients referred for neurosurgery, mostly due to insufficient clinical evaluation combined with an overestimation of MRI-detected NVCs. The clinical diagnosis should be critically re-evaluated before recommending neurosurgery to patients referred for presumed trigeminal neuralgia.

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.

Medical Management of Trigeminal Neuralgia

Background

Trigeminal neuralgia (TN) is a painful condition, often leading to poor quality of life.

Objective

The aim of this review was to discuss the various treatment modalities for the medical management of TN.

Materials and Methods

We reviewed the available literature on TN in clinical databases including PubMed, Google Scholar, and the Cochrane Database of Systematic Reviews, with a specific focus on the pharmacological treatment and newer drugs under development for the treatment of TN.

Results

Carbamazepine (CBZ) is the gold standard of treatment for TN. The first-line drugs for the treatment of TN are CBZ and oxcarbazepine (OXC). A proportion of cases (30%) are initially resistant to the first-line drugs. Alternative drugs need to be considered if the first-line drugs are not well tolerated or become ineffective with prolonged therapy. The second-line drugs comprise lamotrigine, baclofen, gabapentin, and pregabalin used as monotherapy or in combination with CBZ/OXC. Botulinum toxin A may be a promising presurgical option. Newer drug like vixotrigine has shown good results in phase two randomized control trials. About 50% of cases develop treatment resistance to oral drugs over the subsequent years of therapy and require surgical options.

Conclusion

The first-line drugs for the treatment of TN (irrespective of the age group or type) are CBZ and OXC. Combination therapy with second-line or other drugs may become necessary with poor response to CBZ/OXC, or if adverse events occur. Patients should be offered surgical options if there is poor response or tolerance to the medical therapy.

Altered trigeminal pain processing on brainstem level in persistent idiopathic facial pain

ABSTRACT

Persistent idiopathic facial pain (PIFP) is a poorly understood chronic pain syndrome of the face, formerly known as atypical facial pain. It is characterized by a constant painful sensation without neurological abnormalities and without clinically objectifiable cause. Similarities to neuropathic pain conditions have been discussed and are currently thought to be relevant for the pathophysiology of this disease. In this study, we aim to characterize the trigeminal pain processing in PIFP using functional magnetic resonance imaging of the brainstem. Twenty-five patients suffering from PIFP and 25 healthy controls underwent a standardized and well-established paradigm of painful stimulation of the trigeminal nerve using gaseous ammonia. Functional images were acquired within a 3T magnetic resonance imaging scanner using an optimized protocol for high-resolution echo planar brainstem imaging. Patients with PIFP show exclusively a stronger activation to painful stimulation in the spinal trigeminal nucleus when contrasted against healthy controls. Our data suggest that abnormal central pain processing plays a role in the pathophysiology of PIFP. An integration of these findings into neuropathic pain models might help to gain a better general understanding of the pathophysiology of PIFP.

The Integrity of the Substructure of the Corpus Callosum in Patients With Right Classic Trigeminal Neuralgia

OBJECTIVE

Patients with classic trigeminal neuralgia (CTN) have abnormalities in white matter integrity of the corpus callosum (CC). However, in CTN patients, it is unclear whether the CC substructure region is affected to varying degrees.

MATERIAL AND METHODS

A total of 22 patients with CTN and 22 healthy controls (HC) with matching age, gender, and education were selected. All subjects underwent 3.0 T magnetic resonance diffusion tensor imaging and high resolution T1-weighted imaging. The CC was reconstructed by DTI technology, which was divided into three substructure regions: genu, body, and splenium. Group differences in multiple diffusion metrics, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD), were compared between CTN patients and HC, and correlations between the white matter change and disease duration and VAS in CTN patients were assessed.

RESULTS

Compared with HC group, CTN patients had extensive damage to the CC white matter. The FA of the genu (P = 0.04) and body (P = 001) parts decreased, while RD (P = 0.003; P = 0.02) and MD (P = 0.002; P = 0.04) increased. In addition, the authors observed that the disease duration and VAS of CTN patients were negatively correlated with FA.

CONCLUSION

The corpus callosum substructure region has extensive damage in chronic pain, and the selective microstructural integrity damage was particularly manifested by changes in axons and myelin sheath in the genu and body of corpus callosum.

Facial pain beyond trigeminal neuralgia

PURPOSE OF REVIEW

Trigeminal neuralgia is a well-known facial pain syndrome with several treatment options. In contrast, non-neuralgiform idiopathic facial pain syndromes are relatively rare, reflected by the fact that, until 2020, no internationally accepted diagnostic classification existed. Like trigeminal neuralgia, these non-dental facial pain syndromes need to be managed by neurologists and pain specialists, but the lack of pathophysiological understanding has resulted in an underrepresented and undertreated patient group.

RECENT FINDINGS

This work provides a brief overview of the most common primary facial pain syndromes, namely, the facial attack-like facial pain, which corresponds to attack-like headache, the persistent idiopathic facial pain (formerly 'atypical facial pain'), and trigeminal neuropathy. What these disorders have in common is that they should all be treated conservatively.

SUMMARY

On the basis of pragmatic classifications, permanent and attack-like primary facial pain can be relatively easily differentiated from one another. The introduction of the new International Classification of Orofacial Pain offers the opportunity to better coordinate and concentrate scientific efforts, so that in the future the therapy strategies that are still inadequate, can be optimized.

Idiopathic Facial Pain Syndromes–An Overview and Clinical Implications

BACKGROUND

Idiopathic facial pain syndromes are relatively rare. A uniform classification system for facial pain became available only recently, and many physicians and dentists are still unfamiliar with these conditions. As a result, patients frequently do not receive appropriate treatment.

METHODS

This article is based on pertinent publications retrieved by a selective search in PubMed, focusing on current international guidelines and the International Classification of Orofacial Pain (ICOP).

RESULTS

The ICOP subdivides orofacial pain syndromes into six major groups, the first three of which consist of diseases of the teeth, the periodontium, and the temporomandibular joint. The remaining three groups (non-dental facial pain) are discussed in the present review. Attack-like facial pain syndromes most closely resemble the well-known primary headache syndromes, such as migraine, but with pain located below the orbitomeatal line. These syndromes are treated in accordance with the guidelines for the corresponding types of headache. Persistent idiopathic facial pain (PIFP) is a chronic pain disorder with persistent, undulating pain in the face and/or teeth, without any structural correlate. Since this type of pain tends to become chronified after invasive procedures, no dental procedures should be performed to treat it if the teeth are healthy; rather, the treatmentis similar to that of neuropathic pain, e.g., with antidepressant and anticonvulsive drugs. Neuropathic facial pain is also undulating and persistent. It is often described as a burning sensation, and neuralgiform attacks may additionally be present. Trigeminal neuralgia is a distinct condition involving short-lasting, lancinating pain of high intensity with a maximum duration of two minutes. The first line of treatment is with medications; invasive treatment options should be considered only if pharmacotherapy is ineffective or poorly tolerated.

CONCLUSION

With the aid of this pragmatic classification system, the clinician can distinguish persistent and attack-like primary facial pain syndromes rather easily and treat each syndrome appropriately.

Evaluation of circulating microRNA expression in patients with trigeminal neuralgia: An observational study

Trigeminal neuralgia (TN) is a chronic neuropathic pain that seriously affects the daily life of patients. There is increasing evidence that microRNAs (miRNAs) play an important role in the development of neuropathic pain.In this study, the TaqMan Low Density Array (TLDA) was used to analyze the serum miRNA levels of 28 TN patients, and 31 healthy people without any neuropathic pain were used as controls.The results showed that the expression profile of serum miRNA in TN patients was different from that in healthy controls. Compared with the control group, 13 miRNAs in the serum of TN patients were up-regulated and 115 miRNAs were down-regulated by >2 times. Quantitative reverse transcription PCR (RT-qPCR) analysis and receiver operating characteristic (ROC) curve were performed. The analysis further confirmed that the expression levels of 4 miRNAs, including miR-132-3p, miR-146b-5p, miR-155-5p, and miR-384, were significantly higher than those of healthy controls, and the difference was statistically significant.This study preliminarily confirmed the changes of serum miRNA expression profile in TN patients. Among them, 4 kinds of serum miRNA are likely to be related to the occurrence and development of TN.

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.

Repetitive percutaneous radiofrequency thermocoagulation for persistent idiopathic facial pain and central neuropathic pain attributed to multiple sclerosis-a retrospective monocentric analysis

BACKGROUND

Persistent idiopathic facial pain (PIFP) is a debilitating chronic pain condition with pain radiating to trigeminal dermatomes. Typically, there are no pathological findings that can be identified during workup and therapy is symptomatic. Facial pain is common in patients with multiple sclerosis (central neuropathic pain attributed to MS). Our aim was to evaluate the effectiveness of percutaneous radiofrequency thermocoagulation (PRTC) of the gasserian ganglion and the duration of pain relief, as well as the identification of factors associated with its outcome.

METHODS

Data on all the above-mentioned patients that have been treated with PRTC between 2009 and 2019 were included into the study. The outcome was assessed with a six-tiered score from 1 (complete remission) to 6 (no benefit). Univariate and multivariate analyses were performed in order to obtain factors associated with the outcome.

RESULTS

A total of 52 patients were included. The total number of procedures performed was 114. 61.5% of patients who experienced temporary pain relief that lasted for a median of 60 days (range 3-1490 days). In patients with recurrence, the fraction of successful interventions was higher, and also transient, with successful pain amelioration in over 80% of patients. Successful responses to PRTC were observed in 27.9% after 1 year, 19.4% after 2 years, and 8.3% after 3 years. The only independent variable predicting pain relief was a repeat intervention with a history of ≥ 2 interventions (OR: 4.36, 95%-CI: 1.34-14.34, p = 0.015). No severe complications occurred.

CONCLUSIONS

Our data showed good and immediate pain relief after PRTC in the majority of our patients. PRTC is a low-risk procedure that can be discussed as an option in case of failure of medical treatment even in critically ill patients and can be repeated with good results when necessary. Long-term pain amelioration, even with repeated procedures, was not possible and no patient was permanently cured.