Trigeminal Neuralgia

Posterior Fossa Volume and Dimensions: Relation to Pathophysiology and Surgical Outcomes in Classic Trigeminal Neuralgia

OBJECTIVE

A small posterior fossa (PF) has been hypothesized to explain the increased incidence of trigeminal neuralgia (TN) in females and could make microvascular decompression (MVD) more challenging. The aim of this study was to investigate the association between the PF volume and dimensions in relation to biological sex, type of neurovascular conflict (NVC), and outcome after MVD in classic TN.

METHODS

In this observational study, 84 patients with TN operated on with MVD with a preoperative head computed tomography(CT) scan were included. Eighty-two adults without TN who had undergone head CT for other reasons were included as controls. PF volume and dimensions (x-axis, y-axis, and z-axis) were evaluated on the CT scans. For the patients with TN, Barrow Neurological Institute (BNI) grade was evaluated 6 months after MVD.

RESULTS

There was no difference in PF volume or dimensions between the patients with TN and controls. Women showed a smaller volume and narrower (x-axis) PF than men, but these differences did not manifest when comparing patients with TN and controls within each sex. Patients with an NVC involving the superior cerebellar artery had a narrower (x-axis) and shorter (y-axis) PF than did patients with an NVC resulting from other arteries. PF volume or dimensions were not associated with BNI grade after MVD.

CONCLUSIONS

PF anatomy was related to the NVC type but did not differ between patients with TN and controls and was not related to the surgical outcome after MVD.

Fully endoscopic microvascular decompression for trigeminal neuralgia: technical note and early outcomes

Microscopic microvascular decompression (MVD) has been considered a curative and reliable method for treating classical trigeminal neuralgia (TN) for decades. Endoscopy can provide bright illumination and a panoramic view, which enhances the visualization of the posterior fossa. In view of the above advantages of endoscopy, it gradually became an option for MVD for treating TN. This study was performed to evaluate the advantages of fully endoscopic MVD for treating TN and is presented with a description of our operative technique. From January 2020 to January 2022, 95 classical TN patients underwent fully endoscopic MVD performed by the same surgeon and assistant in our department. The assistant held the endoscope, and the surgeon operated. Brain stem auditory evoked potentials (BEMPs) were routinely monitored. For every patient, the neurovascular conflict was identified, and complete decompression was achieved. The Barrow Neurological Institute (BNI) pain intensity score was used to evaluate the degree of facial pain. The intraoperative findings, postoperative outcomes, and complications were analyzed. Immediately after the operation, 93 patients (97.9%) achieved complete pain relief (BNI score of I). Two patients (2.1%) still had some pain, but it could be adequately controlled with medicine (BNI score of III). During the 12-36 months of follow-up, recurrence was found in 3 patients (3.2%), including one patient (1.1%) with a BNI score of II and 2 patients (2.1%) with a BNI score of III. Complications were found in 5 patients (5.3%), including facial numbness in 3 patients (3.2%), vertigo in one patient (1.1%), and headache in one patient (1.1%). There were no cases of mortality, stroke, hearing impairment, facial paralysis, or other complications. Fully endoscopic MVD is a safe and effective method for treating TN. It provides bright illumination and a panoramic view for surgeons to better observe neurovascular conflicts in deep areas of the cerebellopontine angle (CPA).

Endoscopic microvascular decompression versus microscopic microvascular decompression for trigeminal neuralgia: A systematic review and meta-analysis

BACKGROUND

To compare the efficacy and safety of full endoscopic or endoscope-assisted microvascular decompression (E-MVD) and microscopic microvascular decompression (M-MVD) for primary trigeminal neuralgia (TN).

METHODS

We systematically searched the online database, including PubMed, Embase and Cochrane Library. The search terms used included, but were not limited to, "Trigeminal Neuralgia", "Microvascular Decompression Surgery" and "Endoscope". Postoperative facial pain relief and postoperative complications were considered for meta-analysis. All the outcomes were calculated as odds ratios (ORs) with 95% confidence intervals using R language.

RESULTS

A total of three studies involving 442 (E-MVD [218] versus M-MVD [224]) patients were included for analysis in our study. Postoperative facial pain relief (very much improved or much improved) was no difference between the two groups (OR, 0.95;95% CI, 0.57-1.58; I2 = 0%; p = 0.83). In addition, the occurrence of some postoperative complications was not statistically different between the two groups, including CSFleak (OR, 1.35;95% CI, 0.16-11.13; I2 = 0%; p = 0.94), facial paralysis (OR, 0.26;95% CI, 0.03-2.54; I2 = 0%; p = 0.67), hearing loss (OR, 0.87;95% CI, 0.30-2.55; I2 = 32%; p = 0.22), facial numbness (OR, 1.03;95% CI, 0.56-1.87; I2 = 62%; p = 0.10).

CONCLUSIONS

Both endoscopic microvascular decompression and microscopic microvascular decompression for trigeminal neuralgia appear to provide patients with equivalent facial pain relief outcomes. Complication rates were also similar between the groups.

BMP7 alleviates trigeminal neuralgia by reducing oligodendrocyte apoptosis and demyelination

BACKGROUND

BMP7 has been shown to have neuroprotective effects and to alleviate demyelination. However, its role in trigeminal neuralgia (TN) has not been well investigated. The current study aims to determine whether BMP7 plays a role in demyelination, its effects on pain behaviors and mechanism of action in rats with TN.

METHODS

We used an infraorbital-nerve chronic-constriction injury (ION-CCI) to establish a rat model of TN. Adeno-associated viruses (AAVs) were injected into the rats to upregulate or downregulate BMP7. The mechanical withdrawal thresholds (MWT) of the injured rats were detected using Von Frey filaments. The changes in expression levels of BMP7 and oligodendrocyte (OL) markers were examined by western blotting, quantitative real-time PCR, immunofluorescence, and transmission electron microscopy.

RESULTS

The ION-CCI induced mechanical allodynia, demyelination, and loss of OLs with a reduction of BMP7. Short-hairpin RNA (shRNA)-BMP7 that inhibited BMP7 expression also caused mechanical allodynia, demyelination, and loss of OLs, and its mechanism may be OL apoptosis. Overexpressing BMP7 in the trigeminal spinal subnucleus caudalis(VC) with AAV-BMP7 relieved all three phenotypes induced by the CCI, and its mechanism may be alleviating OLs apoptosis. Two signal pathways associated with apoptosis, STAT3 and p65, were significantly downregulated in the VC after CCI and rescued by BMP7 overexpression.

CONCLUSION

BMP7 can alleviate TN by reducing OLs apoptosis and subsequent demyelination. The mechanism behind this protection could be BMP7-mediated activation of the STAT3 and NF-κB/p65 signaling pathway and subsequent decrease in OL apoptosis. Importantly, our study presents clear evidence in support of BMP7 as a possible therapeutic target for the treatment of TN.

Development and validation of radiomics models for the prediction of diagnosis of classic trigeminal neuralgia

The study aims to develop a magnetic resonance imaging (MRI)-based radiomics model for the diagnosis of classic trigeminal neuralgia (cTN). This study involved 350 patients with cTN and 100 control participants. MRI data were collected retrospectively for all the enrolled subjects. The symptomatic side trigeminal nerve regions of patients and both sides of the trigeminal nerve regions of control participants were manually labeled on MRI images. Radiomics features of the areas labeled were extracted. Principle component analysis (PCA) and least absolute shrinkage and selection operator (LASSO) regression were utilized as the preliminary feature reduction methods to decrease the high dimensionality of radiomics features. Machine learning methods were established, including LASSO logistic regression, support vector machine (SVM), and Adaboost methods, evaluating each model's diagnostic abilities using 10-fold cross-validation. All the models showed excellent diagnostic ability in predicting trigeminal neuralgia. A prospective study was conducted, 20 cTN patients and 20 control subjects were enrolled to validate the clinical utility of all models. Results showed that the radiomics models based on MRI can predict trigeminal neuralgia with high accuracy, which could be used as a diagnostic tool for this disorder.

Intraoperative Mapping of the Sensory Root of the Trigeminal Nerve in Patients with Pontocerebellar Angle Pathology

OBJECTIVE

The aim of the present study was to determine the position of the 3 sensory branches of the trigeminal nerve in the preganglionic tract using intraoperative neurophysiological mapping.

METHODS

We included consecutive adult patients who underwent neurosurgical treatment of cerebellopontine angle lesions. The trigeminal nerve was antidromically stimulated at 3 sites along its circumference with different stimulus intensities at a distance of ≤1 cm from the brainstem. The sensory nerve action potentials (SNAPs) were recorded from each main trigeminal branch (V1 [ophthalmic branch], V2 [maxillary branch], and V3 [mandibular branch]).

RESULTS

We analyzed 13 patients. The stimulation points at which we obtained the greatest number of congruous and exclusive SNAPs (SNAPs only on the stimulated branch) was the stimulation point for V3 (20.7%). The stimulation intensity at which we obtained the highest number of congruent and exclusive SNAPs with the stimulated branch was 0.5 mA.

CONCLUSIONS

Using our recording conditions, trigeminal stimulation is a reliable technique for mapping the V3 and V1 branches using an intensity not exceeding 0.5. However, reliable identification of the fibers of V2 is more difficult. Stimulation of the trigeminal nerve can be a reliable technique to identify the V3 and V1 branches if rhizotomy of these branches is necessary.

A Case Series of Stereotactic Radiosurgery First for Trigeminal Neuralgia: A History of Stereotactic Radiosurgery Does Not Complicate Microvascular Decompression

BACKGROUND AND OBJECTIVES

The influence of prior stereotactic radiosurgery (SRS) on outcomes of subsequent microvascular decompression (MVD) for patients with trigeminal neuralgia (TN) is not well understood. To directly compare pain outcomes in patients undergoing primary MVD vs those undergoing MVD with a history of 1 prior SRS procedure.

METHODS

We retrospectively reviewed all patients undergoing MVD at our institution from 2007 to 2020. Patients were included if they underwent primary MVD or had a history of SRS alone before MVD. Barrow Neurological Institute (BNI) pain scores were assigned at preoperative and immediate postoperative time points and at every follow-up appointment. Evidence of pain recurrence was recorded and compared via Kaplan-Meier analysis. Multivariate Cox proportional hazards regression was used to identify factors associated with worse pain outcomes.

RESULTS

Of patients reviewed, 833 met our inclusion criteria. Thirty-seven patients were in the SRS alone before MVD group, and 796 patients were in the primary MVD group. Both groups demonstrated similar preoperative and immediate postoperative BNI pain scores. There were no significant differences between average BNI at final follow-up between the groups. Multiple sclerosis (hazard ratio (HR) = 1.95), age (HR = 0.99), and female sex (HR = 1.43) independently predicted increased likelihood of pain recurrence on Cox proportional hazards analysis. SRS alone before MVD did not predict increased likelihood of pain recurrence. Furthermore, Kaplan-Meier survival analysis demonstrated no relationship between a history of SRS alone and pain recurrence after MVD ( P = .58).

CONCLUSION

SRS is an effective intervention for TN that may not worsen outcomes for subsequent MVD in patients with TN.

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.

The Value of a Headless Pear Shape in Percutaneous Balloon Compression for Trigeminal Neuralgia

BACKGROUND AND OBJECTIVES

Percutaneous balloon compression (PBC) has been regarded as a simple and effective remedy for trigeminal neuralgia. This study aims to retrospectively analyze the correlation between intraoperative balloon shapes and postoperative outcomes.

METHOD

Those consecutive PBC cases performed in our department between 2019 and 2022 were reviewed. According to the intraoperative balloon figures, they were cataloged as headless pear, slim pear, bottle gourd, and winter melon groups. The degree of pain or numbness was quantified using the visual analog scale. Those pain-free or pain score <3 and satisfied by the patient were called effective, and those numb score >3 were taken into account of numbness incidence.

RESULTS

Except for missing cases, 160 were finally recruited in this study with a mean follow-up for 23.6 ± 12.8 months. Postoperatively, the pain score plunged from 8.8 ± 1.0 to 0.8 ± 2.0 immediately, which rose slightly over time and maintained at 2.4 ± 3.1. The maximal pain score drop occurred in the headless pear group ( P < .001) and the minimal in the winter melon group ( P < .001). The early efficacy of PBC was 100%, 84.1%, 91.4%, and 50.0%, respectively. However, the long-term efficacy was 88.2%, 75.0%, 82.1% and 25.0%. The ipsilateral numbness occurred in most of the cases immediately after PBC with a score of 3.5 ± 2.3, which decreased significantly within 3 months to 2.3 ± 2.0 and turned to 1.7 ± 1.8 finally ( P < .05). The highest and lowest numb score appeared in bottle gourd and winter melon groups, respectively ( P < .05).

CONCLUSION

A headless pear shape emerged in lateral fluoroscopy as the balloon was fully inflated indicates that the entire Meckel cave is suffused, and hence, the anterior semilunar ganglion has been solidly compressed, which may lead to a successful outcome.

A Patient with Refractory Trigeminal Neuralgia was Referred for Suspected Odontogenic Pain

Chronic pain of the face with a sudden, unilateral, and electric shock-like pain in the distribution of the trigeminal nerve is known as Trigeminal neuralgia (TN). This case report presents a patient with TN symptoms, along with concomitant tooth pain. The diagnostic process and management of the patient are discussed, emphasizing the importance of interdisciplinary collaboration for optimal patient care.

Trigeminal neuralgia caused by vertebrobasilar dolichoectasia: efficacy of stepwise decompression technique

OBJECTIVE

To explore and analyze the clinical efficacy of a stepwise decompression technique in the treatment of trigeminal neuralgia (TN) caused by vertebrobasilar dolichoectasia (VBD).

METHODS

A total of 918 patients with TN admitted to our hospital from June 2015 to May 2020 were divided into the VBD group (n = 61) and the conventional group (n = 857). The VBD group underwent stepwise decompression, while the conventional group received traditional microvascular decompression (MVD) surgery. Patients associated with the VBD were divided into direct compression (n = 14) and indirect compression group (n = 47) who had compression by other vessels in the presence of the VBD. Thereafter, the clinical data, intraoperative findings, efficacy, and complications were analyzed.

RESULTS

The curative ratio, efficacy, and recurrence rate for the VBD and conventional group were 83.6% and 89.6%, 93.4% and 95.3%, and 8.2% and 5.3%, respectively. The curative ratio, efficacy, and recurrence rate for the direct compression and indirect compression group were 85.7% and 83.0%, 92.9% and 93.6%, and 7.1% and 8.5%, separately. There were no significant differences in the curative ratio, efficacy, recurrence rate, and the incidence of complications between the two series (P > 0.05).

CONCLUSION

For TN caused by VBD, stepwise decompression not only reduces the direct compression of the trigeminal nerve by VBA but also allows identification and decompression of the actual vessels responsible for the compression. It has a good curative ratio, efficacy, and long-term pain relief rate, and it does not significantly increase the incidences of complications after surgery.

Considerations When Using Gabapentinoids to Treat Trigeminal Neuralgia: A Review

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

Neuropathic Pain in the Emergency Setting: Diagnosis and Management

Neuropathic pain, traditionally considered a chronic condition, is increasingly encountered in the emergency department (ED), accounting for approximately 20% of patients presenting with pain. Understanding the physiology and key clinical presentations of neuropathic pain is crucial for ED physicians to provide optimal treatment. While diagnosing neuropathic pain can be challenging, emphasis should be placed on obtaining a comprehensive medical history and conducting a thorough clinical examination. Patients often describe neuropathic pain as a burning or shock-like sensation, leading them to seek care in the ED after ineffective relief from common analgesics such as paracetamol and NSAIDs. Collaboration between emergency medicine specialists, neurologists, and pain management experts can contribute to the development of evidence-based guidelines specifically tailored for the emergency department setting. This article provides a concise overview of the common clinical manifestations of neuropathic pain that may prompt patients to seek emergency care.

Trigeminal Autonomic Cephalalgias and Neuralgias in Children and Adolescents: a Narrative Review

PURPOSE OF REVIEW

To summarize the available literature as well as the authors' experience on trigeminal autonomic cephalalgias (TACs) and cranial neuralgias in children and adolescents.

RECENT FINDINGS

While TACs and cranial neuralgias are rare in children, several recent case series have been published. TACs in children share most of the clinical features of TACs in adults. However, there are many reported cases with clinical features which overlap more than one diagnosis, suggesting that TACs may be less differentiated in youth. Indomethacin-responsive cases of cluster headache and SUNCT/SUNA have been reported in children, whereas in adults indomethacin is usually reserved for paroxysmal hemicrania and hemicrania continua. Neuralgias appear to be rare in children. Clinical features are often similar to adult cases, though clinicians should maintain a high index of suspicion for underlying causes.

Online dynamic nomogram for predicting pain recurrence after microvascular decompression in trigeminal neuralgia

Trigeminal neuralgia (TN) is one of the most common causes of facial pain. Microvascular decompression (MVD) is the first-choice surgical treatment. The present study aimed to develop a novel practical assessment system based on preoperative clinical and imaging factors for clinicians to predict the likelihood of pain recurrence following MVD in TN. A total of 56 patients with primary unilateral TN who underwent MVD were retrospectively analyzed. Patients were followed up to observe pain recurrence 1 year after MVD. An online dynamic nomogram was constructed for predicting the probability of pain recurrence after MVD in patients with TN based on multivariate logistic model. The concordance index (C-index) and receiver operating characteristic (ROC) were used to measure model discrimination. Bootstrap resampling was used for internal validation of the model and calibration curve was constructed. Decision curve analysis (DCA) was used to assess clinical applicability. Factors such as numeric rating scale (to score pain degree of patients with TN), response to neuroanalgesic drugs and neurovascular contact on magnetic resonance imaging were independent risk factors affecting the pain recurrence rate (all P<0.05). C-index was 0.973 (95%CI, 0.938-1.000) and the area under the ROC was 0.973 (95%CI, 0.938-1.000). Calibration curve with a 1,000 bootstrap resampling showed a good fit between dynamic nomogram prediction and actual observations. The DCA showed that at a threshold probability between 0 and 100%, this model can achieve a greater net benefit than if all patients had surgery or none had surgery. In conclusion, this online dynamic nomogram reliably predicted risk of pain recurrence in patients with TN following MVD.

Single OnabotulinumtoxinA Session Add-On to Carbamazepine or Oxcarbazepine in Treatment-Refractory Trigeminal Neuralgia: A Case Series with 24-Week Follow Up

We sought to assess the efficacy of combining onabotulinumtoxinA (BoNTA) as add-on therapy to carbamazepine or oxcarbazepine in treatment-refractory patients with trigeminal neuralgia (TGN) who failed to respond (less than 30% response rate) to adequate monotherapy. We conducted a retrospective study on 15 patients with a definite diagnosis of TGN, according to the established criteria, and underwent BoNTA as part of their treatment plan. A single BoNTA session was administered subcutaneously, according to patients' perceived zone of pain, at different dosages ranging from 30 to 200 units (mean ± standard deviation: 87.3 ± 39.2). All patients (15/15; 100%) reported large reductions in the severity of their TGN-related neuropathic pain. The mean pain score on the VAS scale significantly decreased from 9.3 ± 1.1 to 3.7 ± 1.2 at 2 weeks after injecting BoNTA (p < 0.001) and remained stable at 4 and 24 weeks post-injection. Regarding the impact of BoNTA on patients' health-related quality of life, there were significant improvements in both the physical and mental health domains (p < 0.05) of SF-36 tool. BoNTA may be a safe and effective treatment option for patients with refractory TGN when added on to carbamazepine or oxcarbazepine. The use of a single BoNTA session for TGN treatment may be an alternative to surgical interventions and as add-on treatment to oral medications, providing patients with a minimally invasive, effective, safe and well-tolerated option.

The interaction between the nervous system and the stomatognathic system: from development to diseases

The crosstalk between the nerve and stomatognathic systems plays a more important role in organismal health than previously appreciated with the presence of emerging concept of the "brain-oral axis". A deeper understanding of the intricate interaction between the nervous system and the stomatognathic system is warranted, considering their significant developmental homology and anatomical proximity, and the more complex innervation of the jawbone compared to other skeletons. In this review, we provide an in-depth look at studies concerning neurodevelopment, craniofacial development, and congenital anomalies that occur when the two systems develop abnormally. It summarizes the cross-regulation between nerves and jawbones and the effects of various states of the jawbone on intrabony nerve distribution. Diseases closely related to both the nervous system and the stomatognathic system are divided into craniofacial diseases caused by neurological illnesses, and neurological diseases caused by an aberrant stomatognathic system. The two-way relationships between common diseases, such as periodontitis and neurodegenerative disorders, and depression and oral diseases were also discussed. This review provides valuable insights into novel strategies for neuro-skeletal tissue engineering and early prevention and treatment of orofacial and neurological diseases.

A single infusion of intravenous lidocaine for primary headaches and trigeminal neuralgia: a retrospective analysis

Introduction

Intravenous (IV) lidocaine has been used as a transitional treatment in headache and facial pain conditions, typically as an inpatient infusion over several days, which is costly and may increase the risk of adverse effects. Here we report on our experience using a single one-hour IV lidocaine infusion in an outpatient day-case setting for the management of refractory primary headache disorders with facial pain and trigeminal neuralgia.

Methods

This is a retrospective, single-center analysis on patients with medically refractory headache with facial pain and trigeminal neuralgia who were treated with IV lidocaine between March 2018 and July 2022. Lidocaine 5 mg.kg-1 in 60 mL saline was administered over 1 h, followed by an observation period of 30 min. Patients were considered responders if they reported reduction in pain intensity and/or headache frequency of 50% or greater. Duration of response was defined as short-term (< 2 weeks), medium-term (2-4 weeks) and long-term (> 4 weeks).

Results

Forty infusions were administered to 15 patients with trigeminal autonomic cephalalgias (n = 9), chronic migraine (n = 3) and trigeminal neuralgia (n = 3). Twelve patients were considered responders (80%), eight of whom were complete responders (100% pain freedom). The average duration of the treatment effect for each participant was 9.5 weeks (range 1-22 weeks). Six out of 15 patients reported mild and self-limiting side effects (40%).

Conclusion

A single infusion of IV lidocaine might be an effective and safe transitional treatment in refractory headache conditions with facial pain and trigeminal neuralgia. The sustained effect of repeated treatment cycles in some patients may suggest a role as long-term preventive therapy in some patients.

Gamma Knife Stereotactic Radiosurgery for Trigeminal Neuralgia Secondary to Multiple Sclerosis: A Case-Control Study

BACKGROUND

The efficacy of stereotactic radiosurgery (SRS) for the relief of trigeminal neuralgia (TN) is well established. Much less is known, however, about the benefit of SRS for multiple sclerosis (MS)-related TN (MS-TN).

OBJECTIVE

To compare outcomes in patients who underwent SRS for MS-TN vs classical/idiopathic TN and identify relative risk factors for failure.

METHODS

We conducted a retrospective, case-control study of patients who underwent Gamma Knife radiosurgery at our center for MS-TN between October 2004 and November 2017. Cases were matched 1:1 to controls using a propensity score predicting MS probability using pretreatment variables. The final cohort consisted of 154 patients (77 cases and 77 controls). Baseline demographics, pain characteristics, and MRI features were collected before treatment. Pain evolution and complications were obtained at follow-up. Outcomes were analyzed using the Kaplan-Meir estimator and Cox regressions.

RESULTS

There was no statistically significant difference between both groups with regards to initial pain relief (modified Barrow National Institute IIIa or less), which was achieved in 77% of patients with MS and 69% of controls. In responders, 78% of patients with MS and 52% of controls eventually had recurrence. Pain recurred earlier in patients with MS (29 months) than in controls (75 months). Complications were similarly distributed in each group and consisted, in the MS group, of 3% of new bothersome facial hypoesthesia and 1% of new dysesthesia.

CONCLUSION

SRS is a safe and effective modality to achieve pain freedom in MS-TN. However, pain relief is significantly less durable than in matched controls without MS.

Risk factors associated with trigeminocardiac reflex in patients with trigeminal neuralgia during percutaneous balloon compression: A retrospective cohort study

BACKGROUND

The trigeminocardiac reflex (TCR) is a brainstem reflex commonly elicited during percutaneous balloon compression (PBC) for the treatment of trigeminal neuralgia (TN), which is characterized by drastic hemodynamic disturbances, such as bradycardia, arrhythmias and even cardiac arrest. In order to prevent catastrophic consequences, it is vital to screen the risk factors of TCR during perioperative period. The primary purpose of this study was to identify potential risk factors associated with TCR in patients with TN undergoing PBC, and to summarize the enlightenment of clinical anesthesia management.

METHODS

The clinical data of 165 patients diagnosed with TN undergoing PBC from January 2021 to December 2021 were retrospectively analyzed. TCR was defined as a sudden decrease in heart rate of 20% or more compared with baseline, and / or cardiac arrest, coinciding with the stimulus of any branch of the trigeminal nerve. And a clear cause-effect relationship between heart rate reduction and PBC-related intervention was required. All demographic characteristics as well as surgical and anesthetic data were compared between TCR group and TCR-free group. Univariate and multivariate logistic regression analysis were used to further analyze TCR-related risk factors.

RESULTS

Of the 165 patients enrolled in this study, 73 (44.2%) were male and 92 (55.8%) were female, and the average age was 64.22 ± 9.72 years. The incidence of TCR in the patients with TN during PBC was 54.5%. The results of multivariate regression analysis indicated that the risk factor for TCR was heart rate < 60 beats/min immediately before foramen ovale puncture (OR: 4.622; 95%CI: 1.470-14.531; P < 0.05).

CONCLUSION

Heart rate < 60 beats/min immediately before foramen ovale puncture was independently associated with TCR. Therefore, it is necessary for anesthesiologists to raise heart rate appropriately to prevent TCR during PBC.

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

BACKGROUND

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

METHODS

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

CONCLUSIONS

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

Effectiveness and safety of high-voltage pulsed radiofrequency to treat patients with primary trigeminal neuralgia: a multicenter, randomized, double-blind, controlled study

BACKGROUND

Trigeminal neuralgia (TN) is a debilitating pain disorder that still lacks an ideal treatment option. Pulsed radiofrequency (PRF), especially with high output voltage, is a novel and minimally invasive technique. PRF is regarded a promising treatment option for TN patients who respond poorly to medical treatment; however, the available evidence still lacks high quality randomized controlled trials (RCTs). Our study aimed to evaluate the long-term (1 year and 2 years) effects and safety of high-voltage PRF in primary TN patients and provide stronger evidence for TN treatment options.

METHODS

We performed a multicenter, double-blind, RCT in adults (aged 18-75 years) with primary TN who responded poorly to drug therapy or were unable to tolerate the side effects of drug. Eligible participants were randomly assigned (1:1) to receive either high voltage PRF or nerve block with steroid and local anesthetic drugs. The primary endpoint was the 1-year response rate. This trial has been registered in the clinicaltrials.gov website (registration number: NCT03131466).

RESULTS

One hundred and sixty-two patients were screened for enrollment between April 28th,2017 and September1st, 2019, among whom, 28 were excluded. One hundred and thirty-four participants were randomly assigned to either receive high voltage PRF (n = 67) or nerve block (n = 67). The proportion of patients with a positive response at 1-year after the procedure in the PRF group was significantly higher than that in the nerve block group in the intention-to-treat population (73.1% vs. 32.8%, p < 0.001). There was no difference between groups in the incidence of adverse events.

CONCLUSIONS

Our findings support that high voltage PRF could be a preferred interventional choice prior to receiving more invasive surgical treatment or neuro-destructive treatment for TN patients who have poor responses to medical treatment.

TRIAL REGISTRATION

Our study has been registered at ClinicalTrials.gov (trial registration number: NCT03131466).

Successful percutaneous cannulation of foramen ovale obstructed by completely ossified pterygoalar ligament using the Hartel approach: Two case reports

RATIONALE

Ossification of the pterygoalar ligament, which lies inferolateral to the exocranial opening of the foramen ovale, is traditionally considered to be a bony bar that could obstruct percutaneous needle access to the foramen ovale using the Hartel approach. We herein present two case reports of successfully penetrating the foramen ovale by a needle across the pterygoalar bar. Lack of knowledge of this type of presentation might lead to a change in the surgical approach.

PATIENT CONCERNS

A 27-year-old woman had an 11-year history of facial pain because of a space-occupying lesion in the left cerebellopontine angle. Neither open surgery nor drug therapy resolved her facial pain. Another 67-year-old woman developed episodic facial pain because of herpes zoster infection 20 days earlier, and she could not achieve pain relief from drug therapy.

DIAGNOSES

Both patients were diagnosed with secondary trigeminal neuralgia.

INTERVENTIONS

The patients underwent radiofrequency thermocoagulation of the semilunar ganglion via the foramen ovale.

OUTCOMES

The three-dimensional computed tomography scan showed that the ipsilateral foramen ovale was obstructed by the pterygoalar bar. However, percutaneous needle cannulation of the foramen ovale was successful using the anterior approach. The facial pain was immediately and completely resolved without complications except for facial numbness.

LESSONS

During percutaneous radiofrequency thermocoagulation for the treatment of trigeminal neuralgia, the Hartel approach can still be used when the foramen ovale is blocked by a pterygoalar bar. To our knowledge, this is the first report of such a treatment. Moreover, we herein provide specific technical recommendations to assist surgeons who may encounter such cases in the future.

Foramen lacerum impingement of trigeminal nerve root as a rodent model for trigeminal neuralgia

Trigeminal neuralgia (TN) is a classic neuralgic pain condition with distinct clinical characteristics. Modeling TN in rodents is challenging. Recently, we found that a foramen in the rodent skull base, the foramen lacerum, provides direct access to the trigeminal nerve root. Using this access, we developed a foramen lacerum impingement of trigeminal nerve root (FLIT) model and observed distinct pain-like behaviors in rodents, including paroxysmal asymmetric facial grimaces, head tilt when eating, avoidance of solid chow, and lack of wood chewing. The FLIT model recapitulated key clinical features of TN, including lancinating pain-like behavior and dental pain-like behavior. Importantly, when compared with a trigeminal neuropathic pain model (infraorbital nerve chronic constriction injury [IoN-CCI]), the FLIT model was associated with significantly higher numbers of c-Fos-positive cells in the primary somatosensory cortex (S1), unraveling robust cortical activation in the FLIT model. On intravital 2-photon calcium imaging, synchronized S1 neural dynamics were present in the FLIT but not the IoN-CCI model, revealing differential implication of cortical activation in different pain models. Taken together, our results indicate that FLIT is a clinically relevant rodent model of TN that could facilitate pain research and therapeutics development.

The Value of Interdisciplinary Collaboration in Lateral Medullary Syndrome Rehabilitation: A Case Report

Wallenberg's syndrome, also known as lateral medullary syndrome (LMS), is a neurological condition resulting from damage to the lateral portion of the medulla oblongata. We present a case of a 64-year-old man with Wallenberg's syndrome who presented for acute rehabilitation after sustaining a cerebrovascular accident (CVA). As seen in our patient, common symptoms of LMS include difficulty swallowing, hoarseness, ipsilateral weakness, and ipsilateral loss of sensation or numbness. Although the prognosis following infarction is often good, dysfunction in swallowing is one of the key deficits that have a long-term impact on patient quality of life. We aim to emphasize the significance of the interdisciplinary approach to achieving favorable health outcomes in patients with LMS.

Augmented Reality-Assisted Percutaneous Rhizotomy for Trigeminal Neuralgia

BACKGROUND

Percutaneous rhizotomy of the trigeminal nerve is a common surgery to manage medically refractory trigeminal neuralgia. Traditionally, these procedures have been performed based on anatomic landmarks with fluoroscopic guidance. Augmented reality (AR) relays virtual content on the real world and has the potential to improve localization of surgical targets based on preoperative imaging.

OBJECTIVE

To study the potential application and benefits of AR as an adjunct to traditional fluoroscopy-guided glycerol rhizotomy (GR).

METHODS

We used traditional fluoroscopy-guided percutaneous GR technique as previously described, performed under general anesthesia. Anatomic registration to the Medivis SurgicalAR system was performed based on the patient's preoperative computerized tomography, and the surgeon was equipped with the system's AR goggles. AR was used as an adjunct to fluoroscopy for trajectory planning to place a spinal needle into the medial aspect of the foramen ovale.

RESULTS

A 50-year-old woman with multiple sclerosis-related right-sided classical trigeminal neuralgia had persistent pain, refractory to medications, previous gamma knife stereotactic radiosurgery, and percutaneous radiofrequency rhizotomy performed elsewhere. The patient underwent AR-assisted fluoroscopy-guided percutaneous GR. The needle was placed into the right trigeminal cistern within seconds. She was discharged home after a few hours of observation with no complications and reported pain relief.

CONCLUSION

AR-assisted percutaneous rhizotomy may enhance the learning curve of these types of procedures and decrease surgery duration and radiation exposure. This allowed rapid and correct placement of a spinal needle through the foramen ovale.

Radiosurgery for classical trigeminal neuralgia: impact of the shot size on clinical outcome

BACKGROUND

This study compares the outcome of patients suffering from medically refractory classical trigeminal neuralgia (TN) after treatment with radiosurgery using two different shot sizes (5- and 6-mm).

METHODS

All patients included in this open, prospective, non-controlled study were treated in a single institution for TN (95 cases in 93 patients) with LINear ACcelerators (LINAC) single-dose radiosurgery using a 5-mm shot (43 cases) or 6-mm shot (52 cases). The target was positioned on the intracisternal part of the trigeminal nerve.

RESULTS

The mean Dmax (D0.035) to the brainstem was higher in the 6-mm group: 12.6 vs 21.3 Gy (p < 0.001). Pain relief was significantly better in the 6-mm group: at 12 and 24 months in the 6-mm group the rate of pain-free patients was 90.2 and 87.8%, respectively vs. 73.6 and 73.6% in the 5-mm group (p = 0.045). At 12 and 24 months post-radiosurgical hypoesthesia was more frequent in the 6-mm group: 47.0 and 58% vs.11.3 and 30.8% in the 5-mm group (p = 0.002). To investigate the effect of cone diameter and the dose to the brainstem on outcomes, patients were stratified into three groups: group 1 = 5-mm shot, (all Dmax < 25 Gy, 43 cases), group 2 = 6-mm shot, Dmax < 25 Gy (32 cases), group 3 = 6-mm shot Dmax > 25 Gy (20 cases). At 12 months the rates of hypoesthesia were 11.3, 33.5 and 76.0%, respectively in groups 1, 2 and 3 (p < 0.001) and the rates of recurrence of pain were 26.4, 16.5 and 5%, respectively, (p = 0.11).

CONCLUSION

LINAC treatment with a 6-mm shot provided excellent control of pain, but increased the rate of trigeminal nerve dysfunction, especially when the maximum dose to the brainstem was higher than 25 Gy.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Robot-assisted percutaneous balloon compression for trigeminal neuralgia- preliminary experiences

OBJECTIVES

This study aims to discuss the availability of robot-assisted percutaneous balloon compression (PBC) for trigeminal neuralgia (TN) and share our preliminary experiences.

METHODS

Patients with TN who underwent robot-assisted PBC from June to September 2022 were enrolled. We designed a fixing plug for robot-assisted PBC, three-dimensional structured light registration was used, puncture trajectory was the line connects the medial third of inner and outer aperture of foramen ovale. Numerical Rating Scale (NRS), Barrow Neurological Institute (BNI) pain and numbness intensity score were used to evaluate the facial pain and numbness.

RESULTS

Eventually, nine patients were enrolled, the structured light registrations were successfully finished in all patients with a mean registration error of 0.68 mm. All the punctures of foramen ovales were successfully done one-time. Of note, the balloons were all got pear-shaped followed by 150 to 180 s compression. Though, postoperatively, all the patients complained of facial numbness and four patients suffered from transient masseter weakness, all patients got fully or mostly pain relief. It should be noted that is the numbness and weakness gradually relieved during follow-up.

CONCLUSION

Three-dimensional structured light registration and robot assisted PBC is an effective choice for patients with TN. Extension line between the medial third of the inner and outer aperture of foramen ovale might be a safe and effective puncture trajectory to this procedure.

Orofacial Pain Management: An Overview of the Potential Benefits of Palmitoylethanolamide and Other Natural Agents

Pain is the most common symptom that dentists are confronted with, whether acute (pulpitis, acute periodontitis, post-surgery, etc.) or chronic diseases, such as periodontitis, muscle pain, temporomandibular joint (TMJ) disorders, burning mouth syndrome (BMS), oral lichen planus (OLP) and others. The success of therapy depends on the reduction in and management of pain through specific drugs, hence the need to analyze new pain medications with specific activity, which are suitable for long-term use, with a low risk of side effects and interactions with other drugs, and capable of leading to a reduction in orofacial pain. Palmitoylethanolamide (PEA) is a bioactive lipid mediator, which is synthesized in all tissues of the body as a protective pro-homeostatic response to tissue damage and has aroused considerable interest in the dental field due to its anti-inflammatory, analgesic, antimicrobial, antipyretic, antiepileptic, immunomodulatory and neuroprotective activities. It has been observed that PEA could play a role in the management of the pain of orofacial origin, including BMS, OLP, periodontal disease, tongue a la carte and temporomandibular disorders (TMDs), as well as in the treatment of postoperative pain. However, actual clinical data on the use of PEA in the clinical management of patients with orofacial pain are still lacking. Therefore, the main objective of the present study is to provide an overview of orofacial pain in its many manifestations and an updated analysis of the molecular pain-relieving and anti-inflammatory properties of PEA to understand its beneficial effects in the management of patients with orofacial pain, both neuropathic and nociceptive in nature. The aim is also to direct research toward the testing and use of other natural agents that have already been shown to have anti-inflammatory, antioxidant and pain-relieving actions and could offer important support in the treatment of orofacial pain.

Computed tomography-guided Gasserian ganglion interventions for cancer-related facial pain in patients with complex anatomy: insights and recommendations

BACKGROUND

The Gasserian ganglion is a well-known target for facial pain management, and patients with cancer present an anatomical challenge owing to tumor progression or treatment itself. Computed tomography (CT) is an alternative method for guiding these procedures.

METHODS

This was an observational retrospective analysis of patients with cancer-related facial pain who underwent CT-guided Gasserian ganglion interventions using local anesthetics, local anesthetics with steroids, phenol, and radiofrequency. Demographic, clinical, and procedure-related variables were collected from January 1, 2015, to December 30, 2018, at the National Cancer Institute. Data distribution was determined using the Kolmogorov-Smirnov test. A paired sample t-test (with a cut-off of P < 0.05 for statistical significance) was used for comparing outcome.

RESULTS

We observed a significant reduction in numerical rating scale (NRS) and douleur neuropathique 4 (DN4) scores from 7.6 ± 1.4 and 4.4 ± 1.4 to 3.2 ± 2.0 and 2.2 ± 1.4 points, respectively (P < 0.001). After the procedure, 70.8% of the patients were satisfied; 16.7% were very satisfied, and 12.5% were unsatisfied. No intra- or postoperative complications were observed. The most common neoplasms were head and neck tumors (83.3%).

CONCLUSIONS

Our data suggest that CT guidance is an effective and safe option for managing cancer-related facial pain in patients with complex anatomy, resulting in a significant reduction in pain, high satisfaction rates, and no mechanical complications. Future research should aim to refine the role of CT guidance in multimodal pain management in this population.

Trigeminal Sensory Neuropathy Predicts Chemosensory Dysfunction After Skull Base Surgery

BACKGROUND

Trigeminal sensory neuropathy, characterized by diminished or exaggerated/painful sensation along the distribution of trigeminal branches, is one of the complications after skull base surgery. These procedures can also affect chemosensory functions and compromise the patients' quality of life.

OBJECTIVE

To examine those postoperative complications in chemosensory and facial cutaneous sensory functions as well as their interaction.

METHODS

A total of 61 patients being operated for various pathologies in the vicinity of trigeminal pathway (17 with trigeminal neuralgia, 20 with meningiomas, and 24 with vestibular schwannomas) and 50 healthy controls were enrolled in this case-control study. Postoperative trigeminal neuropathic symptoms were evaluated. The olfactory, gustatory, and intranasal trigeminal functions were assessed using the Sniffin' Stick olfactory test, lateralized taste strip test, and the lateralized intranasal trigeminal CO 2 detection thresholds, respectively.

RESULTS

Patients with trigeminal neuralgia and meningioma had relatively decreased olfactory function, whereas those with vestibular schwannoma had a relative decrease in taste function. As for the relationship between the distribution of trigeminal neuropathy and chemosensory dysfunction, we found that V3 involvement predicted lower side-specific taste function. In addition, V2/V3 involvement predicted relatively lower side-specific intranasal trigeminal function.

CONCLUSION

The present results suggest a differential involvement of the chemical senses in relation to the site and pathology of the lesions after surgery. The presence of trigeminal neuropathy is associated with taste and intranasal trigeminal dysfunction. The results serve as a basis for consultation regarding outcome prediction and patient education.

The Role of Radiofrequency Ablation in the Treatment of Trigeminal Neuralgia: A Narrative Review

Trigeminal neuralgia (TN) is a chronic pain condition that affects the trigeminal nerve, the largest of the cranial nerves. It is characterized by severe, sudden, and recurrent facial pain, often triggered by light touch or a breeze. Treatment options for TN include medication, nerve blocks, and surgery, but radiofrequency ablation (RFA) has emerged as a promising alternative. RFA is a minimally invasive procedure that uses heat energy to destroy the small portion of the trigeminal nerve responsible for the pain. The procedure is performed under local anesthesia and can be done as an outpatient procedure. RFA has been shown to provide long-term pain relief for TN patients with a low complication rate. However, RFA is not suitable for all TN patients and may not be effective for those with multiple pain sites. Despite these limitations, RFA is a valuable option for TN patients who are not responding to other treatments. Furthermore, RFA is a good alternative for a patient unsuitable for surgery. Further research is needed to fully understand the long-term effectiveness of RFA and identify the best candidates for the procedure.

Microvascular decompression for young onset primary trigeminal neuralgia: a single-center experience

This study aims to explore the causes of primary young onset trigeminal neuralgia (TN) and the clinical outcomes of these patients. From May 2015 to December 2020, 19 primary TN patients with onset age under 30 years underwent microvascular decompression (MVD) in Nanjing Drum Tower Hospital. In this study, the clinical characteristics, surgical outcomes, and postoperative complications of these patients were analyzed retrospectively. Of the 19 patients, 5 were males and 14 were females, and the pain was located on the right side in 10 cases (52.6%). Vascular compression was observed in 17 patients, including 14 cases of superior cerebellar artery (SCA) alone, 2 cases of superior petrosal vein (SPV) alone, and 1 case of SCA and SPV combined. Two patients had no neurovascular conflict, and nerve combing was performed. After surgery, 18 patients got immediate pain relief; 1 patient improved but still had occasional pain. With a mean follow-up of 42.7 ± 22.3 months, one patient was found to have a relapse 45 months after MVD. Surgical complications including mild facial numbness in two patients and hearing impairment in one patient. Neurovascular compression is the main cause of young onset primary TN, and the most commonly encountered vascular was SCA. MVD is a safe and effective treatment for these patients.

Highly synchronized cortical circuit dynamics mediate spontaneous pain in mice

Cortical neural dynamics mediate information processing for the cerebral cortex, which is implicated in fundamental biological processes such as vision and olfaction, in addition to neurological and psychiatric diseases. Spontaneous pain is a key feature of human neuropathic pain. Whether spontaneous pain pushes the cortical network into an aberrant state and, if so, whether it can be brought back to a "normal" operating range to ameliorate pain are unknown. Using a clinically relevant mouse model of neuropathic pain with spontaneous pain-like behavior, we report that orofacial spontaneous pain activated a specific area within the primary somatosensory cortex (S1), displaying synchronized neural dynamics revealed by intravital two-photon calcium imaging. This synchronization was underpinned by local GABAergic interneuron hypoactivity. Pain-induced cortical synchronization could be attenuated by manipulating local S1 networks or clinically effective pain therapies. Specifically, both chemogenetic inhibition of pain-related c-Fos-expressing neurons and selective activation of GABAergic interneurons significantly attenuated S1 synchronization. Clinically effective pain therapies including carbamazepine and nerve root decompression could also dampen S1 synchronization. More important, restoring a "normal" range of neural dynamics through attenuation of pain-induced S1 synchronization alleviated pain-like behavior. These results suggest that spontaneous pain pushed the S1 regional network into a synchronized state, whereas reversal of this synchronization alleviated pain.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Alteration of the cortical morphology in classical trigeminal neuralgia: voxel-, deformation-, and surface-based analysis

OBJECTIVE

This study aimed to combine voxel-based morphometry, deformation-based morphometry, and surface-based morphometry to analyze gray matter volume and cortex shape in classical trigeminal neuralgia patients.

METHODS

This study included 79 classical trigeminal neuralgia patients and age- and sex-matched 81 healthy controls. The aforementioned three methods were used to analyze brain structure in classical trigeminal neuralgia patients. Spearman correlation analysis was used to analyze the correlation of brain structure with the trigeminal nerve and clinical parameters.

RESULTS

The bilateral trigeminal nerve was atrophied, and the ipsilateral trigeminal nerve volume was smaller than the contralateral volume in the classical trigeminal neuralgia. The gray matter volume of Temporal_Pole_Sup_R and Precentral_R was found to be decreased using voxel-based morphometry. The gray matter volume of Temporal_Pole_Sup_R had a positive correlation with disease duration and a negative correlation with the cross-section area of the compression point and the quality-of-life score in trigeminal neuralgia. The gray matter volume of Precentral_R was negatively correlated with the ipsilateral volume of the trigeminal nerve cisternal segment, cross-section area of compression point, and visual analogue scale. The gray matter volume of Temporal_Pole_Sup_L was found to be increased using deformation-based morphometry and had a negative correlation with the self-rating anxiety scale. The gyrification of the middle temporal gyrus_L increased and the Postcentral_L thickness decreased, as detected using surface-based morphometry.

CONCLUSIONS

The gray matter volume and cortical morphology of pain-related brain regions were correlated with clinical and trigeminal nerve parameters. voxel-based morphometry, deformation-based morphometry, and surface-based morphometry complemented each other in analyzing the brain structures of patients with classical trigeminal neuralgia and provided a basis for studying the pathophysiology of classical trigeminal neuralgia.

PACAP inhibition alleviates neuropathic pain by modulating Nav1.7 through the MAPK/ERK signaling pathway in a rat model of chronic constriction injury

BACKGROUND

Trigeminal neuralgia is a common chronic maxillofacial neuropathic pain disorder, and voltage-gated sodium channels (VSGCs) are likely involved in its pathology. Prior studies report that pituitary adenylate cyclase-activating polypeptide (PACAP), a neuropeptide highly expressed in the trigeminal ganglion, may contribute to dorsal root ganglion neuron excitability by modulating the Nav1.7.

OBJECTIVE

We investigated whether PACAP can regulate Nav1.7 through the mitogen-activated protein kinase/ERK kinase/extracellular-signal-regulated kinase (MEK/ERK) pathway in the trigeminal ganglion after chronic constriction injury of the infraorbital nerve (ION-CCI) in rats.

STUDY DESIGN

Sprague-Dawley rats underwent ION-CCI, followed by intrathecal injection of PACAP 6-38 (PAC1 receptor antagonist) and PD98059 (MEK/ERK antagonist). Quantitative real-time PCR and western blot were used to quantify ATF3, PACAP, ERK, p-ERK, and Nav1.7 expression.

RESULTS

The mechanical pain threshold decreased from day 3 to day 21 after ION-CCI and reached the lowest testing value by day 14; however, it increased after PACAP 6-38 and PD98059 injections. Additionally, ION-CCI surgery increased ATF3, PACAP, and p-ERK expression in the rat trigeminal ganglion and decreased Nav1.7 and PAC1 receptor expression; however, there was no difference in ERK expression. PACAP 6-38 injection significantly decreased PACAP, p-ERK, and Nav1.7 expression and increased the PAC1 receptor expression, with no change in ERK expression. Moreover, PD98059 injection decreased PACAP, p-ERK, and Nav1.7 expression and increased the expression of PAC1 receptor.

CONCLUSION

After ION-CCI, PACAP in the rat trigeminal ganglion can modulate Nav1.7 through the MEK/ERK pathway via the PAC1 receptor. Further, PACAP inhibition alleviates allodynia in ION-CCI rats.

Kinins and their B1 and B2 receptors as potential therapeutic targets for pain relief

Kinins are endogenous peptides that belong to the kallikrein-kinin system, which has been extensively studied for over a century. Their essential role in multiple physiological and pathological processes is demonstrated by activating two transmembrane G-protein-coupled receptors, the kinin B₁ and B₂ receptors. The attention is mainly given to the pathological role of kinins in pain transduction mechanisms. In the past years, a wide range of preclinical studies has amounted to the literature reinforcing the need for an updated review about the participation of kinins and their receptors in pain disorders. Here, we performed an extensive literature search since 2004, describing the historical progress and the current understanding of the kinin receptors' participation and its potential therapeutic in several acute and chronic painful conditions. These include inflammatory (mainly arthritis), neuropathic (caused by different aetiologies, such as cancer, multiple sclerosis, antineoplastic toxicity and diabetes) and nociplastic (mainly fibromyalgia) pain. Moreover, we highlighted the pharmacological actions and possible clinical applications of the kinin B₁ and B₂ receptor antagonists, kallikrein inhibitors or kallikrein-kinin system signalling pathways-target molecules in these different painful conditions. Notably, recent findings sought to elucidate mechanisms for guiding new and better drug design targeting kinin B₁ and B₂ receptors to treat a disease diversity. Since the kinin B₂ receptor antagonist, Icatibant, is clinically used and well-tolerated by patients with hereditary angioedema gives us hope kinin receptors antagonists could be more robustly tested for a possible clinical application in the treatment of pathological pains, which present limited pharmacology management.

Incidence of trigeminal neuralgia: A population-based study in Central Sweden

BACKGROUND

The primary aim of this observational study was to determine the incidence of trigeminal neuralgia (TN) in a county in central Sweden. The secondary aim was to investigate TN characteristics including the affected side and nerve branches.

METHODS

Patients that received the ICD-10 diagnostic codes TN (G50.0), atypical facial pain (G50.1) and other/unspecified disorder of the trigeminal nerve (G50.8 and G50.9) in Uppsala County, between 2009 and 2017, were eligible for inclusion. Case ascertainment was conducted by the authors by review of the medical records.

RESULTS

The incidence of TN was estimated to be 5.5 (95% confidence interval 4.7-6.4) per 100,000 person-years. The incidence increased with age, from 0.1 in 0- to 19-year-olds to 23.1 per 100,000 person-years in 80+-year-olds. Females exhibited a higher incidence at 7.3 than males at 3.7 per 100,000 person-years. Most of the trigeminal neuralgia cases were diagnosed in the Neurology department (47%). Trigeminal neuralgia was most frequently right sided (59%) and limited to one cranial nerve V-branch, of which V2 was the most common.

CONCLUSIONS

Trigeminal neuralgia incidence was estimated to be 5.5 per 100,000 person-years. The incidence was higher for females and increased with older age.

SIGNIFICANCE

There is limited knowledge about the true incidence of trigeminal neuralgia. This manuscript provides an estimate of 5.5 cases per 100,000 person-years, by using a thorough case ascertainment methodology.

Case report: Trigeminal neuralgia misdiagnosed as glossopharyngeal neuralgia

Background

Trigeminal neuralgia (TN) and glossopharyngeal neuralgia (GPN) are cranial nerve neuralgias with the same clinical manifestations, pathological features, and trigger factors; their affected sites are adjacent. Performing a magnetic resonance imaging (MRI) examination alone can easily lead to a misdiagnosis.

Case presentation

A 72-year-old man had visited another hospital with severe left-sided tongue pain. On MRI, vascular compression of the glossopharyngeal nerve had been visible, with unclear evidence of trigeminal nerve involvement. He had been diagnosed with left-sided GPN and underwent microvascular decompression (MVD) of the left glossopharyngeal nerve. However, no improvement was observed after surgery. During a second surgery at our hospital, MVD of the trigeminal nerve was performed, and the trigeminal nerve was fully explored and separated. The patient's pain resolved after surgery. Ultimately, the patient was definitively diagnosed with left-sided TN.

Discussion and conclusion

MVD is currently the most efficacious surgical option for treating cranial nerve neuralgia. To select patients for MVD, having an MRI criteria for identifying true neurovascular compression will be helpful. However, clinicians should focus more on a patient's clinical symptoms and not rely solely on MRI findings. This patient's case can help clinicians distinguish between TN and GPN, improve the understanding of these diseases, avoid misdiagnosis, and reduce the possibility of secondary damage.

MARS1 mutations linked to familial trigeminal neuralgia via the integrated stress response

BACKGROUND

While new genetic analysis methods are widely used in the clinic, few researchers have focused on trigeminal neuralgia (TN) with familial clustering (≥ 2 TN patients in one kindred family). Previous literature suggests that familial trigeminal neuralgia (FTN) may be associated with inherited genetic factors. To date, few next-generation sequencing studies have been reported for FTN. This study investigated the pathogenic mechanism of FTN by using whole-exome sequencing (WES) technology, which may enhance our understanding of human TN pathophysiology.  METHOD: We performed WES for 7 probands from families of FTN. Sanger sequencing was performed for two control groups (FTN family members group and nonfamilial TN subject group) to potentially identify new FTN-related gene mutations. In families where FTN probands carried potentially pathogenic gene mutations, the ribonucleic acid (RNA) of FTN probands and related family members, as well as nonfamilial TN patients were analysed by RNA sequencing (RNA-seq) to confirm differential gene expression.

RESULTS

Seven probands were derived from 3 Chinese families. WES and Sanger sequencing identified MARS1 mutation c.2398C > A p.(Pro800Thr) in Family 1. MARS1 mutation was confirmed in 14/26 [53.8%] members of Family 1 in FTN family member group, while none of nonfamilial TN subjects had this MARS1 mutation. RNA-seq showed that 3 probands in Family 1 had higher expression of Fosl1 (Fos-like antigen 1) and NFE2 (Nuclear factor, erythroid 2) than 3 subjects in the nonfamilial TN subject group. Fosl1 and NFE2 are genes related to integrated stress response (ISR).

CONCLUSION

MARS1 mutations may cause chronic activation of ISR, contribute to ISR pathophysiological changes in FTN, and cause/accelerate peripheral nerve degeneration. The findings of this study can enrich our knowledge of the role of molecular genetics in TN in humans.

Case report: Fully endoscopic microvascular decompression for trigeminal neuralgia

Microvascular decompression is safe, effective, and micro-invasive. Due to these advantages, it has become the mainstream treatment for trigeminal neuralgia, glossopharyngeal neuralgia, and hemifacial spasm. Initially, microvascular decompression was performed under a microscope, which limited the light source and visualization capabilities. With the development of endoscopic technology, the endoscope has been used in microvascular decompression, which further improved the visualization range and light source properties. The purpose of the present study was to investigate the efficacy of fully endoscopic microvascular decompression for the treatment of trigeminal neuralgia. In total, three patients with trigeminal neuralgia who underwent fully endoscopic microvascular decompression were evaluated. After surgery, the facial pain of all patients was significantly relieved. In addition, there were no obvious postoperative complications and no recurrence after 6 months of follow-up. These excellent surgical outcomes indicate that fully endoscopic microvascular decompression is an effective and safe method for the treatment of trigeminal neuralgia. Furthermore, it also shows that the endoscope presents advantages for use in microvascular decompression.

Alteration of brain network centrality in CTN patients after a single triggering pain

Objective

The central nervous system may also be involved in the pathogenesis of classical trigeminal neuralgia (CTN). The present study aimed to explore the characteristics of static degree centrality (sDC) and dynamic degree centrality (dDC) at multiple time points after a single triggering pain in CTN patients.

Materials and methods

A total of 43 CTN patients underwent resting-state function magnetic resonance imaging (rs-fMRI) before triggering pain (baseline), within 5 s after triggering pain (triggering-5 s), and 30 min after triggering pain (triggering-30 min). Voxel-based degree centrality (DC) was used to assess the alteration of functional connection at different time points.

Results

The sDC values of the right caudate nucleus, fusiform gyrus, middle temporal gyrus, middle frontal gyrus, and orbital part were decreased in triggering-5 s and increased in triggering-30 min. The sDC value of the bilateral superior frontal gyrus were increased in triggering-5 s and decreased in triggering-30 min. The dDC value of the right lingual gyrus was gradually increased in triggering-5 s and triggering-30 min.

Conclusion

Both the sDC and dDC values were changed after triggering pain, and the brain regions were different between the two parameters, which supplemented each other. The brain regions which the sDC and dDC values were changing reflect the global brain function of CTN patients, and provides a basis for further exploration of the central mechanism of CTN.

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.

Amelioration of central neurodegeneration by docosahexaenoic acid in trigeminal neuralgia rats through the regulation of central neuroinflammation

Trigeminal neuralgia (TN) is a stubborn head and face neuropathic pain with complex pathogenesis. Patients with TN have a significantly increased risk of central neurodegeneration, which manifests as cognitive impairment and memory loss, but the specific mechanism underlying central nervous degeneration is still unclear. This study aimed to explore central neurodegeneration and its possible mechanism of action in TN rats based on changes in the brain fatty acid content and microglia-related neuroinflammation. Using a TN neuropathic pain model established by us, we found that TN rats have obvious cognitive impairment. Furthermore, changes in the brain fatty acid content were analyzed using gas chromatography-mass spectrometry (GC-MS). It was found that the docosahexaenoic acid (DHA) content in the central nervous system (CNS) of TN rats was significantly decreased compared to that in the CNS of Sham rats. An important component in maintaining brain cognition, DHA also plays a key role in regulating central neuroinflammation. Here, by continuous supplementation of DHA, the CNS DHA content was increased to a certain extent in TN rats. The cognitive impairment of TN rats was improved after restoring the central DHA level; this may be related to the improvement of neuroinflammation through the DHA-mediated regulation of microglial polarization. Overall, this study provides a theoretical basis for explaining the pathogenesis of central neurodegeneration in TN. It also suggests DHA as a target for protecting the CNS of patients with TN from damage.

Internal neurolysis versus intraoperative glycerin rhizotomy for trigeminal neuralgia

OBJECTIVE

Internal neurolysis (IN) and intraoperative glycerin rhizotomy (ioGR) are emerging surgical options for patients with trigeminal neuralgia without neurovascular contact. The objective of this study was to compare the neurological outcomes of patients who underwent IN with those of patients who underwent ioGR.

METHODS

The authors retrospectively reviewed all patients who underwent IN or ioGR for trigeminal neuralgia at our institution. Patient demographic characteristics and immediate postoperative outcomes, as well as long-term neurological outcomes, were compared.

RESULTS

Of 1044 patients who underwent open surgical treatment for trigeminal neuralgia, 56 patients underwent IN and 91 underwent ioGR. Of these 147 patients, 37 had no evidence of intraoperative neurovascular conflict. All patients who underwent IN and 96.7% of patients who underwent ioGR had immediate postoperative pain relief. At last follow-up, patients who underwent IN had lower Barrow Neurological Institute (BNI) pain intensity scores (p = 0.05), better BNI facial numbness scores (p < 0.01), and a greater degree of pain improvement (p = 0.05) compared with those who underwent ioGR. Patients who underwent IN also had significantly lower rates of symptomatic pain recurrence (p < 0.01) at last follow-up over an average of 9.5 months.

CONCLUSIONS

IN appears to provide patients with a greater degree of pain relief, lower rates of facial numbness, and lower rates of pain recurrence compared with ioGR. Future prospective studies will better characterize long-term pain recurrence and outcomes.

Potential novel therapeutic strategies for neuropathic pain

Purpose

To explore the potential therapeutic strategies of different types of neuropathic pain (NP) and to summarize the cutting-edge novel approaches for NP treatment based on the clinical trials registered on ClinicalTrials.gov.

Methods

The relevant clinical trials were searched using ClinicalTrials.gov Dec 08, 2022. NP is defined as a painful condition caused by neurological lesions or diseases. All data were obtained and reviewed by the investigators to confirm whether they were related to the current topic.

Results

A total of 914 trials were included in this study. They were divided into painful diabetic neuropathy (PDN), postherpetic neuralgia (PHN), sciatica (SC), peripheral nerve injury-related NP (PNI), trigeminal neuralgia (TN), chemotherapy-induced NP (CINP), general peripheral NP (GPNP) and spinal cord injury NP (SCI-NP). Potential novel therapeutic strategies, such as novel drug targets and physical means, were discussed for each type of NP.

Conclusion

NP treatment is mainly dominated by drug therapy, and physical means have become increasingly popular. It is worth noting that novel drug targets, new implications of conventional medicine, and novel physical means can serve as promising strategies for the treatment of NP. However, more attention needs to be paid to the challenges of translating research findings into clinical practice.