Trigeminal neuralgia and its management

Causal interactions in brain networks predict pain levels in trigeminal neuralgia

Trigeminal neuralgia (TN) is a highly debilitating facial pain condition. Magnetic resonance imaging (MRI) is the main method for generating insights into the central mechanisms of TN pain in humans. Studies have found both structural and functional abnormalities in various brain structures in TN patients as compared with healthy controls. Whereas studies have also examined aberrations in brain networks in TN, no studies have to date investigated causal interactions in these brain networks and related these causal interactions to the levels of TN pain. We recorded fMRI data from 39 TN patients who either rested comfortably in the scanner during the resting state session or tracked their pain levels during the pain tracking session. Applying Granger causality to analyze the data and requiring consistent findings across the two scanning sessions, we found 5 causal interactions, including: (1) Thalamus → dACC, (2) Caudate → Inferior temporal gyrus, (3) Precentral gyrus → Inferior temporal gyrus, (4) Supramarginal gyrus → Inferior temporal gyrus, and (5) Bankssts → Inferior temporal gyrus, that were consistently associated with the levels of pain experienced by the patients. Utilizing these 5 causal interactions as predictor variables and the pain score as the predicted variable in a linear multiple regression model, we found that in both pain tracking and resting state sessions, the model was able to explain ∼36 % of the variance in pain levels, and importantly, the model trained on the 5 causal interaction values from one session was able to predict pain levels using the 5 causal interaction values from the other session, thereby cross-validating the models. These results, obtained by applying novel analytical methods to neuroimaging data, provide important insights into the pathophysiology of TN and could inform future studies aimed at developing innovative therapies for treating TN.

Trigeminal neuralgia

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

Anatomical measurements of trigeminal ganglion: a cadaver study

It is difficult to obtain specific information regarding the trigeminal ganglion (TG), especially pediatric TG. The aim of present study was to determine the parameters of the TG and assist in the neuroablative treatment of trigeminal neuralgia (TN). Thirty-seven sides of cadaver heads that had undergone gross anatomical examination were included, with 29 sides of adults and 8 sides of infants. The distance and angles were measured among 12 points, with nine points adjacent to the TG and three points on the foramen ovale (FO). The three points on FO were represented as three different surgical approaches for TN: posterior FO approach (PFO), lateral FO approach (LFO), and anterior FO approach (AFO). A high similarity was found in pediatric TG. No statistical difference was detected in either the distance or the angles between the 12 points. Statistical difference was found in adult heads in some of the distances, which included PFO to point 5 (17.97 ± 3.35 mm in the left and 15.52 ± 2.28 mm in the right; p = 0.03) and LFO to point 5 and point 8. Moreover, the angle for PFO to point 5 showed a statistically significant difference (60.10 ± 14.02 in the left and 46.63 ± 10.48 in the right; p = 0.01). These findings revealed that surgical neuroablation for patients with TN should be performed more carefully when the PFO or LFO approach is adopted, with a precise preoperative evaluation to avoid corneal complications. Two safety radiofrequency rhizotomy points are also presented to deal with two different kinds of TN.

Trigeminal neuralgia caused by a persistent primitive trigeminal artery variant passing through Meckel's cavity: a case report

BACKGROUND

Persistent primitive trigeminal artery variant (PPTAv) is a rare remnant of the primitive intracranial embryonic anastomotic arteries, and its persistence has an unknown etiology. Trigeminal neuralgia attributed to a PPTAv passing through Meckel's cavity is extremely uncommon.

CASE PRESENTATION

A 73-year-old woman presented with right-sided facial pain for 10 years that had failed to respond to medication. Magnetic resonance angiography suggested the presence of a PPTAv compressing the trigeminal nerve, as the abnormal artery originated from the right internal carotid artery. During microvascular decompression (MVD), the offending vessel was inferred to be a PPTAv, as it continued to become the anterior inferior cerebellar artery after passing through Meckel's cavity. Postoperative computed tomography angiography showed the PPTAv continuing posteriorly as the anterior inferior cerebellar artery and supplying the cerebellar hemisphere, which confirmed the intraoperative judgment. The pain resolved after MVD and has not recurred in 12 months of follow-up.

CONCLUSION

MVD is the best surgical choice for trigeminal neuralgia combined with a PPTAv. For patients with neurovascular conflicts, particularly those with suspected vascular variations, preoperative imaging examinations play a critical role in meticulously evaluating the anatomical locations of the nerves and blood vessels. Semilunar puncture (for radiofrequency ablation or percutaneous balloon compression) is contraindicated in patients with a PPTAv.

The cerebellopontine angle cistern volumetric differences in trigeminal neuralgia patients with and without vertebrobasilar compression: a case-matched study

Previous studies have indicated that the small cerebellopontine angle (CPA) cistern plays a role in the pathogenesis of trigeminal neuralgia (TN), but they are likely not involved in TN associated with vertebrobasilar artery (VBA) compression because of its rarity. Forty-four patients with VBA-associated TN and 44 age-, sex-, and hypertension-matched TN patients without VBA compression (non-VBA-associated) were included. All patients underwent high-resolution MRI. The CPA cistern volumes were measured bilaterally. The presence of vertebrobasilar dolichoectasia (VBD) and laterality of the vertebrobasilar junction (VBJ) were observed. The CPA cistern volume on the affected side was smaller than the unaffected side (714.4 ± 372.8 vs 890.2 ± 462.2 mm3, p < 0.001) in non-VBA-associated TN patients, while VBA-associated TN patients show a larger CPA cistern on the affected side than the unffected side (1107.0 ± 500.5 vs 845.3 ± 314.8 mm3, p < 0.001). The prevalence of VBD was higher in patients with VBA-associated TN than in matched non-VBA-associated TN patients (90.9% vs 4.5%, p < 0.001). A positive correlation between the laterality of VBJ and the affected side was found in the VBA-associated TN group (p < 0.0001). Large CPA cistern may be a neuroradiological feature of VBA-associated TN, and most of the VBA-associated TN is accompanied by VBD. The presence of VBD and the lateral shift of VBJ may expand the CPA cistern by squeezing the surrounding tissue on the affected side and also increase the chance of VBA compression on the trigeminal nerve, resulting in the genesis of VBA-associated TN.

Retreatment of Classical Tic Douloureux With Stereotactic Radiosurgery: A Scoping Review

Stereotactic radiosurgery (SRS), also known as gamma knife surgery (GKS), is a noninvasive procedure for treating tic douloureux (TD) or trigeminal neuralgia (TN). Due to a lack of sufficient evidence regarding the indication of SRS for the treatment of recurrent TD, the present scoping review was conducted to assess the effectiveness of repeated SRS procedures for managing recurrent TD. The literature search was performed from January 2012 to December 2022 on the PubMed, Scopus, and Web of Science databases. Of the 215 initial results obtained, 10 articles were finally selected for the review. Three studies used the SRS procedure for the third time in patients with recurrent TD. All studies were retrospective, with a mean maximal dose of 70-90 Gy and a cumulative dose of 120-180 Gy for two SRS treatments and 150-270 Gy for three SRS treatments. The target zone for irradiation was the retrogasserian zone (RGZ). Repeat SRS procedures led to pain relief in 80-90% of patients within one to four months and excellent pain relief in 50-90% of patients. Pain recurrence was noticed after one year in 20-40% of patients. Postoperative complications, such as trigeminal nerve deficits, facial numbness, and mild corneal dryness, were noted in the studies. The review concluded that repeat SRS is an effective and relatively safe procedure for pain management in patients with recurrent TD.

Characterization of head and neck pain symptoms of patients presenting to a tertiary care pain clinic

OBJECTIVE

To characterize the presentation and symptomatology of individuals presenting with pain in head and neck regions.

METHODS

A retrospective chart-review was performed on patients with pain in the HFN presenting to a tertiary pain center in Turkey between January 2016 and January 2017. Information regarding the characteristics of pain and medical and treatment history were extracted and reviewed.

RESULTS

Among 197 subjects, 135 (68.5%) were females. The average duration of pain was 60.13 ± 92.32 months. The pain was continuous in presentation and severe in intensity in 43.1% and 51.8% of the subjects, respectively. The pain was associated with at least one somatosensory symptom in 12.1% of subjects. Common diagnoses were trigeminal neuralgia, persistent idiopathic facial pain, and migraine headaches.

CONCLUSION

Painful disorders of the HFN are associated with varying and perplexing signs and symptoms. Such patients should undergo a comprehensive clinical assessment with a multidisciplinary team.

Amelioration of nerve demyelination by hydrogen-producing silicon-based agent in neuropathic pain rats

Trigeminal neuralgia (TN) is a complex orofacial neuropathic pain. The crippling condition's underlying mechanism is still not completely understood. The main cause of lightning-like pain in patients with TN may be chronic inflammation that causes nerve demyelination. Nano-silicon (Si) can safely and continuously produce hydrogen in the alkaline environment of the intestine to exert systemic anti-inflammatory effects. Hydrogen has a promising anti-neuroinflammatory impact. The study aimed to determine how intra-intestinal application of a hydrogen-producing Si-based agent affected the demyelination of the trigeminal ganglion in TN rats. We discovered that increased expression of the NLRP3 inflammasome and inflammatory cell infiltration occurred concurrently with demyelination of the trigeminal ganglion in TN rats. We could determine that the neural effect of the hydrogen-producing Si-based agent was connected to the inhibition of microglial pyroptosis by using transmission electron microscopy. The results demonstrated that the Si-based agent reduced the infiltration of inflammatory cells and the degree of neural demyelination. In a subsequent study, it was discovered that hydrogen produced by a Si-based agent regulates the pyroptosis of microglia may through the NLRP3-caspase-1-GSDMD pathway, preventing the development of chronic neuroinflammation and consequently lowering the incidence of nerve demyelination. This study offers a novel strategy for elucidating the pathogenesis of TN and developing potential therapeutic drugs.

Fluorescence visualization of the neuropathic pain triad in trigeminal neuralgia

Trigeminal neuralgia (TN), an exemplary condition of neuropathic facial pain, seriously affects the physical and mental health of patients, becoming a major medical and social problem. So far, the mechanism of TN and its relation to neuronal activity remain unclear, largely limited by the spatial resolution of visualization methods. In the meanwhile, current therapeutic strategies targeting neurons have not achieved satisfactory outcome. Here, we investigate the neuropathic pain triad in TN by establishing an animal model of TN by chronic constriction injury of the unilateral infraorbital nerve (ION-CCI) and leveraging the single-cell resolution of confocal microscopy, including neuronal hyperexcitability, glial activation, and macrophage polarization. These results can broaden the understanding of TN pathogenesis from neurons to the neuropathic pain triad, and suggest that optical microscopy can provide new opportunities for understanding the complex pathogenesis of TN at single-cell resolution, potentially contributing to the identification of more precise therapeutic targets and the development of more effective treatment modalities.

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.

Alterations of degree centrality and functional connectivity in classic trigeminal neuralgia

Objectives

Recent neuroimaging studies have indicated a wide range of structural and regional functional alterations in patients with classic trigeminal neuralgia (CTN). However, few studies have focused on the intrinsic functional characteristics of network organization in the whole brain. Therefore, the present study aimed to characterize the potential intrinsic dysconnectivity pattern of the whole brain functional networks at the voxel level using the degree centrality (DC) analysis in CTN patients.

Methods

Thirty-four patients with CTN and twenty-nine well-matched healthy controls (HCs) participated in this study. All subjects underwent resting-state functional magnetic resonance imaging (rs-MRI) examination and clinical and neuropsychologic assessments. DC is a graph theory-based measurement that represents the overall functional connectivity (FC) numbers between one voxel and other brain voxels. We first investigated brain regions exhibiting abnormal DC, and further identified their perturbation on FC with other brain regions using a seed-based FC analysis in patients with CTN. In addition, correlation analyses were performed to evaluate the relationship between the abnormal DC value and clinical variables in CTN patients.

Results

Compared with the HCs, the patients with CTN exhibited significantly greater DC values in the right pallidum and right putamen, and lower DC values in the right lingual gyrus, right calcarine sulcus, left paracentral lobule, and left midcingulate cortex. A further seed-based FC analysis revealed that the right lingual gyrus showed decreased FC within the visual network and with other core brain networks, including the sensorimotor network, default mode network, and salience network, relative to HCs. Additionally, the left midcingulate cortex exhibited decreased FC within the middle cingulate cortex and the visual network in CTN patients. Moreover, the DC value in the left midcingulate cortex was negatively correlated with the illness duration.

Conclusion

The present study shows that CTN patients exhibited specific functional connectivity network alterations in the basal ganglia, visual network, and salience network, which may reflect the aberrant neural network communication in pain processing and modulation. These findings may provide novel insight for understanding the mechanisms of pain chronicity in CTN patients.

Functional MRI-Guided Motor Cortex and Deep Brain Stimulation for Intractable Facial Pain: A Novel, Personalized Approach in 1 Patient

BACKGROUND

Facial neuropathic pain syndromes such as trigeminal neuralgia are debilitating disorders commonly managed by medications, vascular decompression, and/or ablative procedures. In trigeminal neuralgia cases unresponsive to these interventions, trigeminal deafferentation pain syndrome (TDPS) can emerge and remain refractory to any further attempts at these conventional therapies. Deep brain stimulation (DBS) and motor cortex stimulation are 2 neuromodulatory treatments that have demonstrated efficacy in small case series of TDPS yet remain largely underutilized. In addition, functional MRI (fMRI) is a tool that can help localize central processing of evoked stimuli such as mechanically triggered facial pain. In this study, we present a case report and operative technique in a patient with TDPS who underwent fMRI to guide the operative management and placement of dual targets in the sensory thalamus and motor cortex.

OBJECTIVE

To evaluate the safety, efficacy, and outcome of a novel surgical approach for TDPS in a single patient.

METHODS

The fMRI and operative technique of unilateral DBS targeting the ventroposteromedial nucleus of the thalamus and facial motor cortex stimulator placement through a single burr hole is illustrated as well as the patient's clinical outcome.

RESULTS

In less than 1 year, the patient had near complete resolution of his facial pain with no postoperative complications.

CONCLUSION

We present the first published case of successful treatment of TDPS using simultaneous DBS of the ventroposteromedial and motor cortex stimulation. fMRI can be used as an effective imaging modality to guide neuromodulation in this complex disorder.

Intraosseous Meningioma Along the Left Petrous Bone: A Rare Cause of Trigeminal Neuralgia

Trigeminal neuralgia (TN) presents with symptoms of intense recurrent shock-like brief pain localized to specific areas of the face innervated by the fifth cranial nerve. The pathology of trigeminal neuralgia is attributed to the fifth cranial nerve compression or demyelination. Most cases of this diagnosis are not due to bony structures, making this case an uncommon presentation of trigeminal neuralgia. Herein, we present a case of trigeminal neuralgia due to an intraosseous meningioma that formed along the left petrous bone, resulting in trigeminal nerve compression. On head computed tomography (CT), osteomatous growths along the left petrous bone were noticed compressing the trigeminal nerve. After trigeminal nerve decompression and drilling out the protruding part of the petrous bone through middle cranial fossa craniotomy, the patient's symptoms were completely improved postoperatively and at the two-month follow-up. To our knowledge, there are only four reported cases of trigeminal neuralgia caused by petrous bone compression in the literature. We emphasize the significance of considering petrous bone lesions as a cause of trigeminal neuralgia.

Narrow ovale foramina may be involved in the development of primary trigeminal neuralgia

Background

The etiology of primary trigeminal neuralgia remains unclear and is worthy of further study; In this study, the morphometric characteristics of ovale foramina between various groups were compared and analyzed to explore the novel cause of primary trigeminal neuralgia.

Methods

High-resolution three-dimensional reconstruction images from head computed tomography of 109 patients with primary trigeminal neuralgia affecting the third branch of the trigeminal nerve and 46 healthy controls were retrospectively reviewed. Among the 109 primary trigeminal neuralgia patients, 79 patients with apparent neurovascular compression (not simply contact) demonstrated on MRI or during surgery were divided into the classical trigeminal neuralgia group and 30 patients with MRI showing no significant abnormalities were divided into idiopathic trigeminal neuralgia group. The morphometric parameters including the area, width and length of ovale foramina were examined through the use of radiologic methods.

Results

In this study, the average minimum area, width and length of 79 ovale foramina on the affected and unaffected sides in the classical trigeminal neuralgia group were 21.83 ± 8.45, 21.94 ± 7.93 mm², 2.32 ± 0.91, 2.58 ± 0.81, 5.32 ± 1.29, and 5.26 ± 1.21 mm, respectively. No significant difference in these parameters was observed (p > 0.05). However, in the idiopathic trigeminal neuralgia group, the average minimum area, width and length of 30 ovale foramina were 21.33 ± 8.21, 22.85 ± 8.36 mm², 2.25 ± 0.90, 2.79 ± 0.96, 5.20 ± 1.27, and 5.28 ± 1.19 mm, respectively. The width on the symptomatic side was significantly smaller (p = 0.03) than that on the asymptomatic side. No significant difference in area (p = 0.48) or length (p = 0.79) was observed. In addition, when compared with the healthy control group, the area and width of ovale foramina on the symptomatic side in both groups were significantly smaller. No significant difference in length was observed.

Conclusions

By comparing and analyzing the statistical data, it can be inferred that a narrow foramen ovale is associated with primary trigeminal neuralgia, as well as its recurrence after microvascular decompression.

Therapeutic Efficacy of Botulinum Toxin in Trigeminal Neuralgia

Trigeminal neuralgia (TN) is a unilateral, paroxysmal, sharp, shooting, or jabbing pain that occurs in the trigeminal nerve divisions, including the ophthalmic (V1), maxillary (V2), and mandibular (V3) nerves. Typically, an episode is triggered by anything touching the face or teeth. TN is a clinical diagnosis with no specific diagnostic test; it is determined by the patient's medical history and pain description. Imaging is necessary to exclude secondary causes. The precise reason for TN is uncertain, but it is commonly believed to result from vascular compression of the trigeminal nerve root, typically near its origin in the pons. There are numerous surgical and medical treatment options available. The most frequently applied medical treatment therapies are carbamazepine and oxcarbazepine. Surgical alternatives are reserved for patients who do not respond to medical treatment. Botulinum toxin A (BTX-A) has emerged as a novel and promising alternative to surgery for individuals whose pain is unresponsive to medication. Multiple studies have established the safety and usefulness of BTX-A in treating TN, with the most significant benefits occurring between six weeks and three months after the surgery. This article reviews various studies published in the last 10 years regarding the therapeutic use of BTX-A in TN. These studies include various observational, clinical, pilot, and animal studies.

Structural and Functional Brain Changes in Patients With Classic Trigeminal Neuralgia: A Combination of Voxel-Based Morphometry and Resting-State Functional MRI Study

Objectives

Brain structural and functional abnormalities have been separately reported in patients with classic trigeminal neuralgia (CTN). However, whether and how the functional deficits are related to the structural alterations remains unclear. This study aims to investigate the anatomical and functional deficits in patients with CTN and explore their association.

Methods

A total of 34 patients with CTN and 29 healthy controls (HCs) with age- and gender-matched were recruited. All subjects underwent structural and resting-state functional magnetic resonance imaging (fMRI) scanning and neuropsychological assessments. Voxel-based morphometry (VBM) was applied to characterize the alterations of gray matter volume (GMV). The amplitude of low-frequency fluctuation (ALFF) method was used to evaluate regional intrinsic spontaneous neural activity. Further correlation analyses were performed between the structural and functional changes and neuropsychological assessments.

Results

Compared to the HCs, significantly reduced GMV was revealed in the right hippocampus, right fusiform gyrus (FFG), and temporal-parietal regions (the left superior/middle temporal gyrus, left operculo-insular gyrus, left inferior parietal lobule, and right inferior temporal gyrus) in patients with CTN. Increased functional activity measured by zALFF was observed mainly in the limbic system (the bilateral hippocampus and bilateral parahippocampal gyrus), bilateral FFG, basal ganglia system (the bilateral putamen, bilateral caudate, and right pallidum), left thalamus, left cerebellum, midbrain, and pons. Moreover, the right hippocampus and FFG were the overlapped regions with both functional and anatomical deficits. Furthermore, GMV in the right hippocampus was negatively correlated with pain intensity, anxiety, and depression. GMV in the right FFG was negatively correlated with illness duration. The zALFF value in the right FFG was positively correlated with anxiety.

Conclusion

Our results revealed concurrent structural and functional changes in patients with CTN, indicating that the CTN is a brain disorder with structural and functional abnormalities. Moreover, the overlapping structural and functional changes in the right hippocampus and FFG suggested that anatomical and functional changes might alter dependently in patients with CTN. These findings highlight the vital role of hippocampus and FFG in the pathophysiology of CTN.

Deep Learning Based Real-Time Semantic Segmentation of Cerebral Vessels and Cranial Nerves in Microvascular Decompression Scenes

Automatic extraction of cerebral vessels and cranial nerves has important clinical value in the treatment of trigeminal neuralgia (TGN) and hemifacial spasm (HFS). However, because of the great similarity between different cerebral vessels and between different cranial nerves, it is challenging to segment cerebral vessels and cranial nerves in real time on the basis of true-color microvascular decompression (MVD) images. In this paper, we propose a lightweight, fast semantic segmentation Microvascular Decompression Network (MVDNet) for MVD scenarios which achieves a good trade-off between segmentation accuracy and speed. Specifically, we designed a Light Asymmetric Bottleneck (LAB) module in the encoder to encode context features. A Feature Fusion Module (FFM) was introduced into the decoder to effectively combine high-level semantic features and underlying spatial details. The proposed network has no pretrained model, fewer parameters, and a fast inference speed. Specifically, MVDNet achieved 76.59% mIoU on the MVD test set, has 0.72 M parameters, and has a 137 FPS speed using a single GTX 2080Ti card.

Animal models - Mimicking the pain of trigeminal neuralgia

Trigeminal neuralgia (TN) is an episodic facial pain which feels like an electric shock of unilateral origin. This neuropathic disorder is an intensely stressful to bear for patient and impacts the quality of life. Most of the cases of TN arise when the root of fifth cranial nerve, i.e., trigeminal nerve is compressed after a few millimeters of its entry into the pons. This article describes various animal models and the role of biomarkers to study the underlying mechanisms of neuropathic pain in animal models as well as different modes of management of TN.

A Systematic Review of Repeat Microvascular Decompression for Recurrent or Persistent Trigeminal Neuralgia

OBJECTIVE

When conservative therapy fails, microvascular decompression (MVD) has been the preferred treatment of primary trigeminal neuralgia (TN). However, the management of recurrent or persistent TN after MVD can often be difficult. The purpose of the present systematic review was to objectively analyze and summarize the reported literature regarding the feasibility of repeat MVD.

METHODS

We conducted a database search using the MEDLINE and PubMed databases until July 2020. The search terms used for title and abstract screening were as follows: "recurrent trigeminal neuralgia," "persistent trigeminal neuralgia," "repeat microvascular decompression," and "reexploration." The inclusion criteria for the systematic review were as follows: clinical studies (excluding case studies), repeat MVD treatment of TN, and studies that had recorded the pain relief outcomes, operative findings, and complications (if any).

RESULTS

Of the 1771 initial results obtained, we performed a full text screening of 43 studies, and, ultimately, 19 were deemed eligible. A total of 2247 patients had undergone MVD for TN, of whom, 311 had experienced recurrence (13.84%). Of the 311 patients, 178 had undergone repeat MVD. The average pain-free interval was 27.75 months after the first MVD. The effective rate of repeat MVD was 91.66%, and 71.48% of the patients had had obvious compression found at repeat MVD. The postoperative complication rate after repeat MVD was 37.31% and was due to postoperative adhesions around the nerve and nerve injury caused by partial sensory rhizotomy. The most common complication after repeat MVD was facial numbness (21.89%), although the incidence of other complications was <5%.

CONCLUSIONS

For patients with recurrent or persistent pain after MVD, the findings from our systematic review support that repeat MVD remains a feasible treatment for recurrent or persistent TN.

Puerarin Attenuates Complete Freund's Adjuvant-Induced Trigeminal Neuralgia and Inflammation in a Mouse Model via Sirt1-Mediated TGF-β1/Smad3 Inhibition

Background

Puerarin, an active compound of radix puerariae, is a major compound used in Chinese herbal medicines and it has been well known for its pharmacological effects, including antioxidant, anti‑inflammatory, neuroprotective and cardioprotective properties. The aim of the present study was to determine the role of puerarin (Pue) in complete Freund’s adjuvant (CFA)-induced trigeminal neuralgia (TN) and the effects of this compound on Sirt1 activity and on the progression of CFA-induced TN.

Methods

Mice were injected with CFA on the unilateral face to induce TN. A cell model of inflammation-associated TN was established by interleukin-1β (IL-1β; 10 ng/mL) and tumor necrosis factor-α (TNF-α; 50 ng/mL) stimulation of neurons. Reverse transcription-quantitative PCR and Western blot analyses were performed to analyze mRNA and protein expression levels in trigeminal ganglion and nerve cells. Terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) staining was used to determine nerve cell apoptosis following IL-1β/TNF-α or Pue treatment.

Results

Pue is a conceivable Sirtuin1 (Sirt1) activator used for the prevention of trigeminal nerve injury that attenuates CFA-induced TN and inflammatory cytokine-evoked overactivation of neuronal inflammation and apoptosis. Treatment of mice with inflammatory cytokines induced upregulation of cleaved caspase-3 protein expression, which was neutralized by Pue supplementation. Both in vivo and in vitro experiments led to the conclusion that Pue modulated Sirt1 activation and repressed transforming growth factor-β1 (TGF-β1) protein expression and drosophila mothers against decapentaplegic homolog3 (Smad3) phosphorylation in order to exert neuroprotection.

Conclusion

The findings suggested that Pue functioned as a potential Sirt1 activator to improve neuroinflammation-induced TN and neuronal apoptosis via the suppression of TGF-β1/Smad3 activity. The pharmacological activity of Pue provides a new perspective for the effective prevention and treatment of TN.

Surgical Management of Trigeminal Neuralgia Induced by Brainstem Infarct: A Systematic Review of the Literature

BACKGROUND

Although cases of trigeminal neuralgia (TN) induced by brainstem infarct have been reported, the neurosurgical literature lacks a comprehensive review for this subpopulation of patients. We present the first systematic review of the literature to discuss pathology, surgical management, and future directions for therapeutic innovation in this population.

METHODS

Our systematic review was conducted according to PRISMA guidelines. Resulting articles were screened for those that presented cases of TN associated with brainstem infarct.

RESULTS

A review of the literature identified 18 case reports of 21 patients with TN induced by brainstem infarct: 14 pontine infarcts and 7 medullary infarcts. Although many cases of ischemic brainstem lesions are caused by acute stroke, cerebral small vessel disease also plays a role in certain cases, and the relationship between these chronic lesions and TN is more likely to be overlooked. Furthermore, we found that reports of self-resolving TN pain after brainstem infarct is disproportionately biased, as most case reports published their data within the first few months after initial presentation. Reports with follow-up periods >13 months reported eventual pain recurrence that necessitated surgical intervention. Microvascular decompression was not sufficient to treat TN pain associated with concurrent neurovascular compression and brainstem infarct.

CONCLUSIONS

Brainstem infarcts affecting the trigeminal pathway represent an understudied pathologic cause of TN. Although the neurosurgical literature lacks a clear picture of the most efficacious interventions in this population, we are optimistic that this review will encourage further investigation into the best treatment for these patients.

Photobiomodulation on trigeminal neuralgia: systematic review

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

Microvascular decompression for typical trigeminal neuralgia: Personal experience with intraoperative neuromonitoring with level-specific-CE-Chirp® brainstem auditory evoked potentials in preventing possible hearing loss

Background:

Permanent hearing loss after posterior fossa microvascular decompression (MVD) for typical trigeminal neuralgia (TTN) is one of the possible complications of this procedure. Intraoperative brainstem auditory evoked potentials (BAEPs) are used for monitoring the function of cochlear nerve during cerebellopontine angle (CPA) microsurgery. Level-specific (LS)-CE-Chirp® BAEPs are the most recent evolution of classical click BAEP, performed both in clinical studies and during intraoperative neuromonitoring (IONM) of acoustic pathways during several neurosurgical procedures.

Methods:

Since February 2016, we routinely use LS-CE-Chirp® BAEPs for monitoring the function of cochlear nerve during CPA surgery, including MVD for trigeminal neuralgia. From September 2011 to December 2018, 71 MVDs for TTN were performed in our department, 47 without IONM of acoustic pathways (Group A), and, from February 2016, 24 with LS-CE-Chirp BAEP (Group B).

Results:

Two patients of Group A developed a permanent ipsilateral anacusia after MVD. In Group B, we did not observe any permanent acoustic deficit after surgery. In one case of Group B, during arachnoid dissection, intraoperative LS-CE-Chirp BAEP showed a temporary lag of V wave, resolved in 5 min after application of intracisternal diluted papaverine (0.3% solution without excipients).

Conclusion:

MVD is widely considered a definitive surgical procedure in the management of TTN. Even though posterior fossa MVD is a safe procedure, serious complications might occur. In particular, the use of IONM of acoustic pathways during MVD for TTN might contribute to prevention of postoperative hearing loss.

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.

Earlier radiosurgery leads to better pain relief and less medication usage for trigeminal neuralgia patients: an international multicenter study

OBJECTIVE

Trigeminal neuralgia (TN) is a chronic pain condition that is difficult to control with conservative management. Furthermore, disabling medication-related side effects are common. This study examined how stereotactic radiosurgery (SRS) affects pain outcomes and medication dependence based on the latency period between diagnosis and radiosurgery.

METHODS

The authors conducted a retrospective analysis of patients with type I TN at 12 Gamma Knife treatment centers. SRS was the primary surgical intervention in all patients. Patient demographics, disease characteristics, treatment plans, medication histories, and outcomes were reviewed.

RESULTS

Overall, 404 patients were included. The mean patient age at SRS was 70 years, and 60% of the population was female. The most common indication for SRS was pain refractory to medications (81%). The median maximum radiation dose was 80 Gy (range 50-95 Gy), and the mean follow-up duration was 32 months. The mean number of medications between baseline (pre-SRS) and the last follow-up decreased from 1.98 to 0.90 (p < 0.0001), respectively, and this significant reduction was observed across all medication categories. Patients who received SRS within 4 years of their initial diagnosis achieved significantly faster pain relief than those who underwent treatment after 4 years (median 21 vs 30 days, p = 0.041). The 90-day pain relief rate for those who received SRS ≤ 4 years after their diagnosis was 83.8% compared with 73.7% in patients who received SRS > 4 years after their diagnosis. The maximum radiation dose was the strongest predictor of a durable pain response (OR 1.091, p = 0.003). Early intervention (OR 1.785, p = 0.007) and higher maximum radiation dose (OR 1.150, p < 0.0001) were also significant predictors of being pain free (a Barrow Neurological Institute pain intensity score of I-IIIA) at the last follow-up visit. New sensory symptoms of any kind were seen in 98 patients (24.3%) after SRS. Higher maximum radiation dose trended toward predicting new sensory deficits but was nonsignificant (p = 0.075).

CONCLUSIONS

TN patients managed with SRS within 4 years of diagnosis experienced a shorter interval to pain relief with low risk. SRS also yielded significant decreases in adjunct medication utilization. Radiosurgery should be considered earlier in the course of treatment for TN.

Factors affecting outcome in frameless non-isocentric stereotactic radiosurgery for trigeminal neuralgia: a multicentric cohort study

BACKGROUND

Stereotactic radiosurgery (SRS) is an effective treatment for trigeminal neuralgia (TN). Nevertheless, a proportion of patients will experience recurrence and treatment-related sensory disturbances. In order to evaluate the predictors of efficacy and safety of image-guided non-isocentric radiosurgery, we analyzed the impact of trigeminal nerve volume and the nerve dose/volume relationship, together with relevant clinical characteristics.

METHODS

Two-hundred and ninety-six procedures were performed on 262 patients at three centers. In 17 patients the TN was secondary to multiple sclerosis (MS). Trigeminal pain and sensory disturbances were classified according to the Barrow Neurological Institute (BNI) scale. Pain-free-intervals were investigated using Kaplan Meier analyses. Univariate and multivariate Cox regression analyses were performed to identify predictors.

RESULTS

The median follow-up period was 38 months, median maximal dose 72.4 Gy, median target nerve volume 25 mm³, and median prescription dose 60 Gy. Pain control rate (BNI I-III) at 6, 12, 24, 36, 48, and 60 months were 96.8, 90.9, 84.2, 81.4, 74.2, and 71.2%, respectively. Overall, 18% of patients developed sensory disturbances. Patients with volume ≥ 30 mm³ were more likely to maintain pain relief (p = 0.031), and low integral dose (< 1.4 mJ) tended to be associated with more pain recurrence than intermediate (1.4-2.7 mJ) or high integral dose (> 2.7 mJ; low vs. intermediate: log-rank test, χ² = 5.02, p = 0.019; low vs. high: log-rank test, χ² = 6.026, p = 0.014). MS, integral dose, and mean dose were the factors associated with pain recurrence, while re-irradiation and MS were predictors for sensory disturbance in the multivariate analysis.

CONCLUSIONS

The dose to nerve volume ratio is predictive of pain recurrence in TN, and re-irradiation has a major impact on the development of sensory disturbances after non-isocentric SRS. Interestingly, the integral dose may differ significantly in treatments using apparently similar dose and volume constraints.

Frequency-specific alterations in cortical rhythms and functional connectivity in trigeminal neuralgia

Neuroimaging studies have shown that chronic pain is maladaptive and influences brain function and behavior by altering the flexible cerebral information flow. We utilized power spectral analysis to investigate the impact of classic trigeminal neuralgia (TN) on the oscillation dynamics of intrinsic brain activity in humans. The amplitude of low-frequency fluctuations (ALFF) and fractional ALFF (fALFF) were measured in 29 TN patients and 34 age- and sex-matched healthy controls (HCs) via resting-state functional MRI (R-fMRI). Two different frequency bands (slow-5: 0.01-0.027 Hz; slow-4: 0.027-0.073 Hz) were analyzed. Differences in blood oxygen level-dependent (BOLD) signal fluctuations and related resting-state functional connectivity (rsFC) between the TN patients and HCs were identified. The TN patients had reduced ALFF/fALFF in the posterior cingulate cortex (PCC), left insula, left dorsolateral prefrontal cortex (DLPFC), left putamen and bilateral temporal lobe, exclusively in the frequency of the slow-5 band. Whole brain rsFC analyses with these six different regions as seeds revealed two weaker circuits including the PCC-medial prefrontal cortex (mPFC) and DLPFC-hippocampus circuits, indicating abnormal interactions with the default mode network (DMN) in TN patients. The functional connectivity between the default-mode regions (mPFC and PCC) in the slow-5 band tracked pain intensity. Together, our results provide novel insights into how TN disturbs the cortical rhythms and functional interactions of the brain. These insights may have implications for the understanding and treatment of brain dysfunction in chronic pain patients, including TN patients.

Grey matter volume alterations in trigeminal neuralgia: A systematic review and meta-analysis of voxel-based morphometry studies

In recent decades, a growing number of structural neuroimaging studies of grey matter (GM) in trigeminal neuralgia (TN) have reported inconsistent alterations. We carried out a systematic review and meta-analysis to identify consistent and replicable GM volume abnormalities using effect-size signed differential mapping (ES-SDM). Furthermore, we conducted a meta-regression to explore the potential effects of clinical characteristics on GM volume alterations in patients with TN. A total of 13 studies with 15 datasets, representing 407 TN patients and 376 healthy individuals, were included in the present study. The results revealed that TN patients had GM volume abnormalities mainly in the basal ganglia, including the putamen, nucleus accumbens (NAc), caudate nucleus and amygdala, as well as the cingulate cortex (CC), thalamus, insula and superior temporal gyrus (STG). The meta-regression analysis showed that verbal rating scale (VRS) scores were negatively correlated with decreased GM volume in the left striatum and that illness duration was negatively correlated with decreased GM volume in the left STG and left insula. These results provide a thorough profile of GM volume alterations in TN patients and constitute robust evidence that aberrant GM volumes in the brain regions regulating and moderating sensory-motor and affective processing may play an important role in the pathophysiology of TN.

Pain Neurology

Pain is often the initial complaint for which patients seek medical care, presenting both a diagnostic and therapeutic challenge to the primary care provider. The appreciation of pain is not merely the result of abnormal sensory stimulation causing an unpleasant sensation but rather a combination of the recognition of the somatic discomfort in association with an emotional response to that discomfort. The perception of pain and the extent of distress and disability can vary depending on previous experience, cultural background, situational factors, and comorbid psychiatric disease. Though acute pain is usually the result of tissue damage, this is not always the case, as evidenced by primary headache disorders. Chronic pain may be the result of an injury, irreversible underlying disease, or clinical conditions such as fibromyalgia for which the mechanism remains unclear. Treatment of the underlying cause will usually effect a resolution or improvement in the pain, but when the discomfort persists, a consultation with a neurologist or pain management specialist should be considered.

Pain and Psychological Distress: Effect of Microvascular Decompression on Sleep Disorders and Obsessions in Trigeminal Neuralgia

Objective  This study was aimed to investigate the effects of microvascular decompression (MVD) on sleep disorders and obsessions in trigeminal neuralgia. Methods  Clinical data from 115 patients with trigeminal neuralgia treated with MVD from August 1, 2017 to May 31, 2018 at Jining First People's Hospital were analyzed retrospectively. The preoperative and postoperative risk factors for sleep disorders and obsessions, as well as the effects of MVD on sleep disorders and obsessions, were examined. Results  In 115 patients, there were significant differences in preoperative sleep disorders associated with sex, monthly household income, pain in multiple branches, visual analog scale (VAS) score, and Self-Rating Depression Scale (SDS) score ( p  < 0.05). Preoperative obsessions were significantly different according to age, gender, pain in multiple branches, monthly household income, VAS score, and Self-Rating Anxiety Scale (SAS) score groups ( p  < 0.05). A 1-year recurrence was positively correlated with sleep disturbance (odds ratio = 3.829) and obsessions (odds ratio = 4.507). In addition, the results revealed a negative correlation between the manipulation of trigeminal neuralgia and postoperative sleep disorders ( B  ≥ 1.043). Moreover, there was a significant difference in sleep disorders and obsessions before and 1 year after MVD ( p  < 0.05). Conclusion  For patients with trigeminal neuralgia, pain caused by sleep and obsession disorders should be examined early to identify an effective solution. Moreover, MVD, as a first treatment, is valuable for improving the physiological and psychological prognosis of patients.

Prevalence of trigeminal neuralgia in Indian population visiting a higher dental care center in North India

Objectives:

The present study aims to determine the incidence and prevalence of trigeminal neuralgia (TN) in study population and difference in prevalence of TN in urban and rural population.

Materials and Methods:

This retrospective study includes 1215 study participants with typical idiopathic TN. Data regarding the age of onset, gender, site of involvement, and clinical presentations were retrieved from clinical records of patients reported from January 2011 to January 2018.

Results:

The study population consists of 1215 study participants aged between 21 and 87 years, with a mean age of 50.62 ± 15.872 years. The mandibular nerve is involved in most of the cases (56.9%), followed by maxillary nerve (42%). The right side of the face (57.1%) is more involved than the left side (38.8%). TN was more prevalent (52.4%) in rural population than urban population (47.6%).

Conclusion:

TN is more common in females than males, the right side of the face is more involved than the left side, and it is more commonly found in rural population than urban population.

Microglia in the Primary Somatosensory Barrel Cortex Mediate Trigeminal Neuropathic Pain

Trigeminal neuropathic pain (TGN) is an attacking, abrupt, electric-shock headache involving abnormal cortical activity. The neural mechanism underlying TGN remains elusive. In this study, we explored the role of microglia in the primary somatosensory barrel cortex (S1BF), which is a critical region for TGN, of a mouse model of TGN that displayed significant pain-related behaviors. Using electrophysiological recordings, we found robust neuronal hyperactivity in glutamatergic neurons of S1BF (Glu^S1BF). Chemogenetic inhibition of Glu^S1BF neurons significantly relieved mechanical allodynia in TGN mice. In naïve mice, chemogenetic activation of Glu^S1BF neurons induced pain sensitization. In addition, we found that microglia in the S1BF (microglia^S1BF) were significantly activated, with density and morphology changes. Intraperitoneal administration of minocycline, a microglia inhibitor, attenuated pain sensitization, and decreased Glu^S1BF neuronal activity. Together, these findings demonstrate the putative importance of microglia as a key regulator in TGN through actions on Glu^S1BF neuronal adaptation.

Vertebrobasilar Dolichoectasia and Basilar Artery Dissection Presenting With Trigeminal Neuralgia: A Case Report

Trigeminal neuralgia secondary to vertebrobasilar dolichoectasia and basilar artery dissection is rare. The authors report the case of a 72-year-old man with a 5-year history of right electrical facial pain identical with trigeminal neuralgia. Finally, magnetic resonance imaging and digital subtraction angiography revealed basilar artery dissection and vertebrobasilar dolichoectasia. The patient underwent partial basilar dissecting aneurysm embolization. The facial pain was relieved immediately after the operation and disappeared completely 6 months later. Three years after surgery, the patient had experienced no recurrence of the right facial pain.

Course of Concomitant Bell's Palsy and Trigeminal Neuralgia Shortened with a Multi-Modal Intervention: A Case Report

A 60-year-old man presented to the ER with lancinating right-sided facial pain following a URI. He was diagnosed with trigeminal neuralgia, yet returned several days later with right-sided facial paralysis. He was then also diagnosed with Bell's palsy and treated with corticosteroids and antiviral medication. He continued to experience facial pain and paralysis, and sought out integrative medical care including acupuncture, nutritional supplements, diet and lifestyle changes, and parenteral therapy with intravenous vitamins and minerals. Eight weeks later he reported near complete resolution of symptoms. Multi-modal interventions may shorten recovery time in some patients with trigeminal neuralgia or Bell's palsy. To the best of our knowledge, this is the first case report on concomitant trigeminal neuralgia and Bell's palsy. The CARE (CAse REport) guidelines were used in the writing of this case report.

Association Between Radiofrequency Rhizotomy Parameters and Duration of Pain Relief in Trigeminal Neuralgia Patients with Recurrent Pain

BACKGROUND

Radiofrequency rhizotomy (RFR) is a commonly used, effective procedure for trigeminal neuralgia (TN), but a subset of patients experiences pain recurrence and requires subsequent surgeries. Currently, the rhizotomy temperature and duration of application are empirically determined, and there is no consensus on what settings are most beneficial. In this study, we analyzed patients who underwent trigeminal RFR and had subsequent surgeries to identify whether rhizotomy parameters were associated with the duration of pain relief.

METHODS

Single-center, retrospective analysis of patients undergoing RFR for TN from 1995 to 2016. The primary endpoint was subsequent procedure. Associations with rhizotomy parameters and covariates were assessed using Cox regression analysis.

RESULTS

The study included 338 patients, average age 65 years; 61% were women. Temperature was significantly associated with both the degree of immediate postoperative pain relief and the duration of pain relief, and in subgroup analyses by multiple sclerosis status and RFR procedural count. Ablation duration was also independently significant, though not when analyzed alongside age, sex, and race. Duration of pain relief was generally shorter in patients with multiple sclerosis and in repeated RFR.

CONCLUSIONS

Higher temperatures may be necessary to achieve pain relief in some patients, given the progressive nature of the facial pain, but they are not associated with longer duration of pain relief in patients who have recurrent pain. Modulation of the ablation duration does not seem to affect the short-term or long-term outcomes.

Repeat microvascular decompression for patients with persistent or recurrent trigeminal neuralgia: Prognostic factors and long-term outcomes

Patients with persistent or recurrent trigeminal neuralgia (TN) after microvascular decompression (MVD) are frequently difficult to manage. This study aimed to analyze the safety and efficiency of repeat MVD, with the main focus on prognostic factors and long-term outcomes.We performed a retrospective study of 41 TN patients (19 men, 22 women) who underwent repeat MVD due to persistent or recurrent pain from January 2008 to January 2016. These patients were followed up from 12 to 96 months (mean, 42 ± 17.3 months). Univariate analysis by Spearman's rank correlation coefficient was used for analysis of prognostic factors.During the repeat MVD, compression of the trigeminal nerve was noted by an artery in 15 patients (36.6%), vein in 6 patients (14.6%), Teflon in 8 patients (19.5%), and no compression in 12 patients (29.3%). Twenty-one patients (51.2%) had already undergone 1 or more previous ablative procedures, either before the first MVD or between the surgeries. The complete pain relief rates of repeat MVD were 87.8% immediately after surgery and 75% at last follow-up. Thirteen patients (31.7%) had new or increased facial numbness after repeat surgery. Univariate analysis revealed 2 prognostic factors, negative finding during reoperation (P = .021) and no pain relief after the initial surgery (P = .038), that showed a negative influence on success rates after repeat MVD.Repeat MVD can still achieve an excellent outcome in patients with persistent or recurrent pain. However, the risk of facial numbness is increased. Surgeons should be selective in performing repeat MVD, priority should be given to patients who have a pain-free interval after initial MVD or show demonstrable compression on imaging studies.

Correlation between nerve atrophy, brain grey matter volume and pain severity in patients with primary trigeminal neuralgia

BACKGROUND

Recent neuroimaging studies have reported grey matter alterations in primary trigeminal neuralgia patients. However, few studies have focused on quantitative measurements of trigeminal nerves and the interaction between trigeminal nerve volume and brain morphology, particularly grey matter volume. In this study, we investigated the link between trigeminal nerves and grey matter volume changes in primary trigeminal neuralgia patients compared to healthy controls. Moreover, we explored the association of structure of trigeminal nerves and grey matter to collected pain clinical variables.

METHODS

Eighty participants (40 patients and 40 controls) were recruited for the study. All participants underwent MRI sessions and clinical pain assessment. Trigeminal nerve volume and whole brain grey matter volume were evaluated using quantitative imaging techniques. Sensory and affective pain rating indices were assessed using the visual analog scale and short-form McGill Pain Questionnaire. Mediation analysis was conducted to investigate the relationship between clinical pain variables and volumetric changes in trigeminal nerves and grey matter.

RESULTS

Decreased trigeminal nerve volume was detected in primary trigeminal neuralgia patients compared to controls. Additionally, reduced grey matter volume was found in several regions associated with pain in primary trigeminal neuralgia subjects, including the insula, secondary somatosensory cortex, hippocampus, dorsal anterior cingulate cortex, precuneus, and several areas of the temporal lobe. Mediation analysis revealed that decreased trigeminal nerve volume drove grey matter volume abnormality of the left insula, and further led to increased pain ratings.

CONCLUSION

This study showed a predominantly direct effect of trigeminal nerve atrophy on clinical pain variables in primary trigeminal neuralgia patients, providing new insight into the pathophysiology of the disease.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT02713646.

Greater palatine block for V2 trigeminal neuralgia: Case report

AIMS

This study describes a novel nerve block directed at the maxillary (V2) division of the fifth cranial nerve as treatment for medication-refractory trigeminal neuralgia (TN).

METHODS AND RESULTS

The authors present three cases of TN treated with V2 nerve block using commonly available local anesthetics injected through the greater palatine foramen. Patients' medications were noted before and after the procedure. Following the injection, patients were followed over time and outcome was assessed. Patients experienced rapid and long-lasting pain relief allowing for significant reduction in antineuralgia medications. This was done with the objective of breaking the pain cycle with subsequent discontinuation or reduction of analgesic medications.

CONCLUSION

This technique may be an effective treatment for medication-refractory V2 TN. By interrupting the pain cycle, this renders the condition amenable to long-term control using diminished doses of standard antineuralgia pharmaceuticals. The practical implications of the described procedure are that it is simple, safe, and well-tolerated with few or no adverse effects. This novel technique is a diagnostic feature for the dentist to differentiate between sources of facial pain.

Acupuncture treatment on idiopathic trigeminal neuralgia: A systematic review protocol

INTRODUCTION

The objective of this systematic review protocol is to provide the methods for evaluating the effectiveness and safety of acupuncture on the treatment of idiopathic trigeminal neuralgia (ITN).

METHODS AND ANALYSIS

We will search randomized controlled trials (RCTs) on this subject in 8 electronic databases and they are Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Chinese Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), the Wan-Fang Database, and Chinese Scientific Journal Database (VIP database). Other relevant literatures will be manually searched as a complement. Only RCTs related to acupuncture for ITN in English or Chinese will be included, without limitation of publication types. The risk of bias and trial quality will be assessed by the Cochrane collaboration's tool. All data will be analyzed by RevMan V.5.3.3 statistical software.

ETHICS AND DISSEMINATION

Ethical approval is not necessary as this paper does not involve patient data. This protocol will be disseminated by a peer-review journal or conference presentation.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42015022173 STRENGTHS AND LIMITATIONS OF THIS STUDY:: This systematic review will evaluate the effectivity and safety of acupuncture treatment on idiopathic trigeminal neuralgia. Two authors will perform independently study selection, data extraction and quality assessment, in order to ensure that all included studies are not personal bias. The result of this systematic review may give clinicians more ways to assist patient in relieving trigeminal neuralgia.This shortage of systematic review is due to language barriers, only 2 languages of the trials can be included, other related studies may be missing. Different methods of acupuncture and quality of methodologies may result in essential heterogeneity.

Orofacial neuralgia associated with a middle cerebral artery aneurysm

Chronic orofacial pain of neuropathic origin can present diagnostic and management dilemmas to dental practitioners and also affects the patient's quality of life. Intracranial aneurysms are a potential cause of stroke (e.g. sub-arachnoid haemorrhage) that is usually associated with, high rates of mortality and morbidity. A patient who had been previously managed for symptoms of temporomandibular joint disorder (TMD) presented with sharp, shooting pain of moderate intensity. It was precipitated by swallowing, and radiated to the right throat, posterior border of the mandible, ear and temporomandibular joint. Clinical and radiological investigations ruled out odontogenic pain, TMD and other more common types of facial pain. Magnetic resonance imaging revealed a 7 × 6 mm aneurysm in the right middle cerebral artery (MCA) which was subsequently surgically clipped. Interestingly, the facial pain resolved after this procedure. Compression of the insular region of the brain innervated by the trigeminal, glossopharyngeal and vagus nerves provides a plausible explanation for the pain reported. To our knowledge, this is the first case of facial neuralgia associated with an aneurysm in the MCA which emphasizes the importance of a multidisciplinary approach in the diagnosis and management of unusual cases of chronic orofacial pain.

Image-Guided Robotic Radiosurgery for Trigeminal Neuralgia

BACKGROUND

Frameless, non-isocentric irradiation of an extended segment of the trigeminal nerve introduces new concepts in stereotactic radiosurgery for medically resistant trigeminal neuralgia (TN).

OBJECTIVE

To report the results of the largest single-center experience about image-guided robotic radiosurgery for TN.

METHODS

A cohort of 138 patients treated with CyberKnife® (Accuray Incorporated, Sunnyvale, California) radiosurgery with a minimum follow-up of 36 mo were recruited. Pain relief, medications, sensory disturbances, rate and time of pain recurrence were prospectively analyzed.

RESULTS

Median follow-up was 52.4 mo; median dose 75 Gy; median target length 5.7-mm; median target volume 40 mm³; median prescription dose 60 Gy (80% isodose line). Actuarial pain control rate (Barrow Neurological Institute [BNI] class I-IIIa) at 6, 12, 24, and 36 mo were 93.5%, 85.8%, 79.7%, and 76%, respectively. Overall, 33 patients (24%) required a second treatment. Overall, 18.1% developed sensory disturbances after 16.4 ± 8.7 mo. One patient (0.7%) developed BNI grade IV dysfunction; 6 (4.3%) developed BNI grade III (somewhat bothersome) hypoesthesia after retreatment; BNI grade II (not bothersome) hypoesthesia was reported by 18 patients (11 after retreatment). Shorter nerve length (<6 mm vs 6 mm), smaller nerve volume (<30 mm3 vs >30 mm3), and lower prescription dose (<58 vs >58 Gy) were associated with treatment failure (P = .01, P = .02, P = .03, respectively). Re-irradiation independently predicted sensory disturbance (P < .001).

CONCLUSION

Targeting a 6-mm segment of the trigeminal nerve with a prescribed dose of 60 Gy appears safe and effective. Persistent pain control was achieved in most patients with acceptable risk of sensory complications, which were typically found after re-irradiation.