Recent advances in understanding/managing trigeminal neuralgia

An overview of the safety and efficacy of LX-9211 in treating neuropathic pain conditions

INTRODUCTION

LX-9211 is a drug designed to treat neuropathic pain conditions. It functions by inhibiting the adaptor-associated kinase 1 (AAK1) enzyme which promotes clathrin-dependent endocytosis. Preclinical studies have shown that LX-9211 does produce a reduction in nociceptive related behaviors and produces no major adverse effects in rats. Thus, LX-9211 has advanced to clinical trials to assess its safety and efficacy in humans. So far, phase 1 and phase 2 clinical trials involving patients with postherpetic neuralgia and diabetic peripheral neuropathic pain have been conducted with phase 3 trials planned in the future.

AREAS COVERED

This paper highlights preclinical studies involving LX-9211 in rodents. Additionally, phase 1 clinical trials examining the safety of LX-9211 in healthy subjects as well as phase 2 studies looking at the safety and efficacy of LX-9211 compared to placebo in patients with diabetic peripheral neuropathic pain and postherpetic neuralgia are also discussed.

EXPERT OPINION

In phase 1 and phase 2 clinical trials conducted so far, LX-9211 has been shown to produce few adverse effects as well as cause a significantly greater reduction in pain compared to placebo. However, more clinical studies are needed to further assess its effects in humans to ensure its safety.

Modern Approaches to the Treatment of Acute Facial Pain

PURPOSE OF REVIEW

Acute facial pain presents a complex challenge in medical practice, requiring a comprehensive and interdisciplinary approach to its management. This narrative review explores the contemporary landscape of treating acute facial pain, delving into pharmacological, non-pharmacological, and advanced interventions. The significance of tailored treatment strategies, rooted in the diverse etiologies of facial pain, such as dental infections, trigeminal neuralgia, temporomandibular joint disorders, sinusitis, or neurological conditions like migraines or cluster headaches, is underscored. We particularly emphasize recent advances in treating trigeminal neuralgia, elucidating current treatment concepts in managing this particular acute facial pain.

RECENT FINDINGS

Recent research sheds light on various treatment modalities for acute facial pain. Pharmacotherapy ranges from traditional NSAIDs and analgesics to anticonvulsants and antidepressants. Non-pharmacological interventions, including physical therapy and psychological approaches, play pivotal roles. Advanced interventions, such as nerve blocks and surgical procedures, are considered in cases of treatment resistance. Moreover, we explore innovative technologies like neuromodulation techniques and personalized medicine, offering promising avenues for optimizing treatment outcomes in acute facial pain management. Modern management of acute facial pain requires a nuanced and patient-centric approach. Tailoring treatment strategies to the individual's underlying condition is paramount. While pharmacotherapy remains a cornerstone, the integration of non-pharmacological interventions is essential for comprehensive care. Advanced interventions should be reserved for cases where conservative measures prove inadequate. Furthermore, leveraging innovative technologies and personalized medicine holds promise for enhancing treatment efficacy. Ultimately, a holistic approach that considers the diverse needs of patients is crucial for effectively addressing acute facial pain.

Optogenetic Approach in Trigeminal Neuralgia and Potential Concerns: Preclinical Insights

The integration of optogenetics in the trigeminal pain circuitry broadens and reinforces existing pain investigations. Similar to research on spinal neuropathic pain, the exploration of the underlying determinants of orofacial pain is expanding. Optogenetics facilitates more direct, specific, and subtle investigations of the neuronal circuits involved in orofacial pain. One of the most significant concerns of both dentistry and medicine is trigeminal neuralgia (TN) management due to its substantial impact on a patient's quality of life. Our objective is to gather insights from preclinical studies conducted in TN employing an optogenetic paradigm, thereby extending the prospects for in-depth neurobiological research. This review highlights optogenetic research in trigeminal pain circuitry involving TN. We outline the central and peripheral regions associated with pain-that have been investigated using optogenetics in the trigeminal pain circuitry. The study further reports its scope and limitations as well as its potential for future applications from bench to bedside.

A novel animal model of neuropathic corneal pain-the ciliary nerve constriction model

Introduction

Neuropathic pain arises as a result of peripheral nerve injury or altered pain processing within the central nervous system. When this phenomenon affects the cornea, it is referred to as neuropathic corneal pain (NCP), resulting in pain, hyperalgesia, burning, and photoallodynia, severely affecting patients' quality of life. To date there is no suitable animal model for the study of NCP. Herein, we developed an NCP model by constriction of the long ciliary nerves innervating the eye.

Methods

Mice underwent ciliary nerve constriction (CNC) or sham procedures. Safety was determined by corneal fluorescein staining to assess ocular surface damage, whereas Cochet-Bonnet esthesiometry and confocal microscopy assessed the function and structure of corneal nerves, respectively. Efficacy was assessed by paw wipe responses within 30 seconds of applying hyperosmolar (5M) saline at Days 3, 7, 10, and 14 post-constriction. Additionally, behavior was assessed in an open field test (OFT) at Days 7, 14, and 21.

Results

CNC resulted in significantly increased response to hyperosmolar saline between groups (p < 0.0001), demonstrating hyperalgesia and induction of neuropathic pain. Further, animals that underwent CNC had increased anxiety-like behavior in an open field test compared to controls at the 14- and 21-Day time-points (p < 0.05). In contrast, CNC did not result in increased corneal fluorescein staining or decreased sensation as compared to sham controls (p > 0.05). Additionally, confocal microscopy of corneal whole-mounts revealed that constriction resulted in only a slight reduction in corneal nerve density (p < 0.05), compared to naïve and sham groups.

Discussion

The CNC model induces a pure NCP phenotype and may be a useful model for the study of NCP, recapitulating features of NCP, including hyperalgesia in the absence of ocular surface damage, and anxiety-like behavior.

Chemokine receptor CXCR2 in primary sensory neurons of trigeminal ganglion mediates orofacial itch

The CXCR2 chemokine receptor is known to have a significant impact on the initiation and control of inflammatory processes. However, its specific involvement in the sensation of itch is not yet fully understood. In this study, we aimed to elucidate the function of CXCR2 in the trigeminal ganglion (TG) by utilizing orofacial itch models induced by incision, chloroquine (CQ), and histamine. Our results revealed a significant up-regulation of CXCR2 mRNA and protein expressions in the primary sensory neurons of TG in response to itch stimuli. The CXCR2 inhibitor SB225002 resulted in notable decrease in CXCR2 protein expression and reduction in scratch behaviors. Distal infraorbital nerve (DION) microinjection of a specific shRNA virus inhibited CXCR2 expression in TG neurons and reversed itch behaviors. Additionally, the administration of the PI3K inhibitor LY294002 resulted in a decrease in the expressions of p-Akt, Akt, and CXCR2 in TG neurons, thereby mitigating pruritic behaviors. Collectively, we report that CXCR2 in the primary sensory neurons of trigeminal ganglion contributes to orofacial itch through the PI3K/Akt signaling pathway. These observations highlight the potential of molecules involved in the regulation of CXCR2 as viable therapeutic targets for the treatment of itch.

Deep learning-driven MRI trigeminal nerve segmentation with SEVB-net

Purpose

Trigeminal neuralgia (TN) poses significant challenges in its diagnosis and treatment due to its extreme pain. Magnetic resonance imaging (MRI) plays a crucial role in diagnosing TN and understanding its pathogenesis. Manual delineation of the trigeminal nerve in volumetric images is time-consuming and subjective. This study introduces a Squeeze and Excitation with BottleNeck V-Net (SEVB-Net), a novel approach for the automatic segmentation of the trigeminal nerve in three-dimensional T2 MRI volumes.

Methods

We enrolled 88 patients with trigeminal neuralgia and 99 healthy volunteers, dividing them into training and testing groups. The SEVB-Net was designed for end-to-end training, taking three-dimensional T2 images as input and producing a segmentation volume of the same size. We assessed the performance of the basic V-Net, nnUNet, and SEVB-Net models by calculating the Dice similarity coefficient (DSC), sensitivity, precision, and network complexity. Additionally, we used the Mann-Whitney U test to compare the time required for manual segmentation and automatic segmentation with manual modification.

Results

In the testing group, the experimental results demonstrated that the proposed method achieved state-of-the-art performance. SEVB-Net combined with the ωDoubleLoss loss function achieved a DSC ranging from 0.6070 to 0.7923. SEVB-Net combined with the ωDoubleLoss method and nnUNet combined with the DoubleLoss method, achieved DSC, sensitivity, and precision values exceeding 0.7. However, SEVB-Net significantly reduced the number of parameters (2.20 M), memory consumption (11.41 MB), and model size (17.02 MB), resulting in improved computation and forward time compared with nnUNet. The difference in average time between manual segmentation and automatic segmentation with manual modification for both radiologists was statistically significant (p < 0.001).

Conclusion

The experimental results demonstrate that the proposed method can automatically segment the root and three main branches of the trigeminal nerve in three-dimensional T2 images. SEVB-Net, compared with the basic V-Net model, showed improved segmentation performance and achieved a level similar to nnUNet. The segmentation volumes of both SEVB-Net and nnUNet aligned with expert annotations but SEVB-Net displayed a more lightweight feature.

Assessing the Risk of Secondary Cancer Induction in Radiosensitive Organs During Trigeminal Neuralgia Treatment With Gamma Knife Radiosurgery: Impact of Extracranial Dose

Purpose

Gamma knife radiosurgery (GKRS) delivers high-dose external radiation to a small intracranial lesion. However, scattering and leaked radiation can deposit a portion of the dose outside the radiation field, which may pose a risk to radiation-sensitive patients, such as pregnant women. Trigeminal Neuralgia (TN) is treated with one of the highest GKRS doses (80-90 Gy). This study aimed to estimate the risk of secondary cancer induction in the uterus, ovaries, thyroid gland, and eyes of TN patients undergoing GKRS.

Methods

Radiation doses to the uterus, ovary, eyes, and thyroid gland were measured for 25 female TN patients, with a mean age of 35 years, utilizing Thermo Luminescent Dosimeters (TLD).

Results

The mean absorbed dose for the uterus, ovary, thyroid gland, and eyes were .63 ± .24, .471 ± .2, 8.26 ± 1.01, and 10.64 ± 1.08 cGy, respectively. Lifetime Attributable Risk (LAR) has been calculated using BEIR VII (2006) method. LAR for the uterus, ovary, and thyroid gland was 1, 2, and 23, respectively.

Conclusion

The results of this study and its comparison with standard values demonstrate that on average, mean doses to mentioned organs were smaller than their tolerance doses, and there is no limitation to treating patients suffering from TN by GK.

Debilitating trigeminal neuralgia secondary to idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) is characterized by raised intracranial pressure with unknown etiology. The most common neurological manifestations are headache and visual loss. Often, other cranial nerve impairments are also found, most commonly in the VI nerve. Trigeminal neuralgia (TN) is a debilitating condition that is most frequently caused by neurovascular pathology, but TN secondary to IIH is a rare and poorly described topic. Possible explanations of TN in these patients include the distortion of the local anatomy at CN entry zones and fluid displacement causing distortion of the Meckel's cave. In the case below we describe the clinical course of an obese female patient with TN-like pain who underwent a ventriculoperitoneal shunt to treat IIH and experienced complete resolution of both conditions.

Non-Surgical Treatments of Trigeminal Neuralgia from the Perspective of a Pain Physician: A Narrative Review

Trigeminal neuralgia (TN) is a unilateral disorder characterized by electric shock-like pain, abrupt onset and termination, and limited to one or more branches of the trigeminal nerve. Various therapeutic modalities for TN have been introduced. We searched for literature indexed in PubMed, Medline, and the National Library of Medicine and reviewed all relevant articles on non-surgical treatments for TN. Published studies were reviewed with no restrictions on date; reviews, clinical trials, animal studies, retrospective studies, and cases were included. Carbamazepine and oxcarbazepine are the recommended first-line pharmacotherapies. Interventional treatments should be considered when pharmacotherapy is insufficient or withdrawn because of adverse effects.

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.

Treatment of postsurgical trigeminal neuralgia with Fu's subcutaneous needling therapy resulted in prompt complete relief: Two case reports

RATIONALE

Trigeminal neuralgia is a recurrent unilateral transient electroshock-like pain. Fu's subcutaneous needling (FSN), used to treat the musculoskeletal problems, has not been reported in this field.

PATIENT CONCERNS

The pain extent of case 1 had no reduction after the previous microvascular decompression, the pain of case 2 relapsed 4 years after the microvascular decompression.

DIAGNOSES

Postsurgical trigeminal neuralgia.

INTERVENTIONS

FSN therapy was applied on the muscles around the neck and face area, which the myofascial trigger points were palpated in these muscles. The FSN needle was inserted into the subcutaneous layer and the needle tip was pointed toward the myofascial trigger point.

OUTCOMES

The following outcome measurements were observed before and after treatment, including numerical rating scale, Barrow Neurology Institute Pain Scale scores, Constant Face Pain Questionnaire scores, Brief Pain Inventory-Facial scores, Patient Global Impression of Change scores, and medication dosage. The follow-up surveys were made after 2 and 4 months respectively. The pain of Case 1 was significantly reduced after 7 times FSN treatments and the pain of Case 2 was even disappeared after 6 times FSN treatments.

LESSONS

This case report suggested that FSN can relieve postsurgical trigeminal neuralgia safely and effectively. Clinical randomized controlled studies are needed to be further conducted.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Pain Relief in a Trigeminal Neuralgia Model via Optogenetic Inhibition on Trigeminal Ganglion Itself With Flexible Optic Fiber Cannula

The trigeminal ganglion (TG) is the primary site of aberration in trigeminal neuralgia (TN), and hence a crucial site where afferent input can be modulated. Here, we postulated that inhibiting TG via optogenetics using flexible optic cannula would diminish brainstem trigeminal nucleus caudalis (TNC) neuronal activity and pain behavior in TN rat model. Infraorbital nerve constriction was employed to induce TN in female Sprague-Dawley rats, while naive and sham rats served as controls. TG-directed microinjections of AAV virus containing either the optogenetic or null vector were delivered to rats in each group. In vivo electrophysiological responses were obtained from the ventral posteromedial nucleus (VPm) of the thalamus with simultaneous TG optogenetic stimulation using flexible optic cannula as well the effects on behavioral responses were investigated. Recordings in TN rats revealed a decrease in burst firing activity during yellow laser driven inhibition on TG, as well as considerably improved behavioral responses. In contrast, we noticed persistent hypersensitivity and increased tonic firing with blue laser stimulation which indicates that TG inhibition can synchronize trigeminal pain signal transmission in a TN animal model. The potential of an optogenetic approach in TG itself with flexible optic fiber to directly disrupt the trigeminal pain circuitry delivers fundamental underpinnings toward its prospective as a trigeminal neuralgia management.

[Trigeminal Neuralgia - What Do We Know about the Causes, Diagnosis and Treatment?]

Trigeminal Neuralgia - What Do We Know about the Causes, Diagnosis and Treatment? Abstract. Classical trigeminal neuralgia is typically characterized by a stimulus-evoked, recurrent and intense short-lasting stabbing pain in the innervation area of the trigeminal nerve. Its intensity is among the most severe pain imaginable in humans, and yet it is often misdiagnosed and undertreated. Triggers are common activities of daily life like talking or eating. The classical trigeminal neuralgia is due to a neurovascular compression at the nerve root entry zone. The secondary form is related to an underlying neurological disease (caused for example by multiple sclerosis or compression by a brain tumor); the etiology of the idiopathic trigeminal neuralgia is unknown. Treatment options include both medication (mostly antiepileptic drugs) and escalated interventional approaches (microvascular decompression, neurolesional percutaneous procedures, neuromodulative therapeutic options and radiosurgery).

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

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

Potential Molecular Targets for Treating Neuropathic Orofacial Pain Based on Current Findings in Animal Models

This review highlights potential molecular targets for treating neuropathic orofacial pain based on current findings in animal models. Preclinical research is currently elucidating the pathophysiology of the disease and identifying the molecular targets for better therapies using animal models that mimic this category of orofacial pain, especially post-traumatic trigeminal neuropathic pain (PTNP) and primary trigeminal neuralgia (PTN). Animal models of PTNP and PTN simulate their etiologies, that is, trauma to the trigeminal nerve branch and compression of the trigeminal root entry zone, respectively. Investigations in these animal models have suggested that biological processes, including inflammation, enhanced neuropeptide-mediated pain signal transmission, axonal ectopic discharges, and enhancement of interactions between neurons and glial cells in the trigeminal pathway, are underlying orofacial pain phenotypes. The molecules associated with biological processes, whose expressions are substantially altered following trigeminal nerve damage or compression of the trigeminal nerve root, are potentially involved in the generation and/or exacerbation of neuropathic orofacial pain and can be potential molecular targets for the discovery of better therapies. Application of therapeutic candidates, which act on the molecular targets and modulate biological processes, attenuates pain-associated behaviors in animal models. Such therapeutic candidates including calcitonin gene-related peptide receptor antagonists that have a reasonable mechanism for ameliorating neuropathic orofacial pain and meet the requirements for safe administration to humans seem worth to be evaluated in clinical trials. Such prospective translation of the efficacy of therapeutic candidates from animal models to human patients would help develop better therapies for neuropathic orofacial pain.

Recent Advances in Trigeminal Neuralgia and Its Management: A Narrative Review

Trigeminal neuralgia (TN) is a chronic facial pain condition that affects one or more divisions of the trigeminal nerve (5th cranial nerve). It can be idiopathic, primary, or secondary. The cornerstone of the therapy has been antiepileptic medications, peripheral nerve blocks with various neurolytic agents, and surgical procedures. With the advent of newer technologies, minimally invasive neurolytic techniques like low-level laser therapy and ozone injection have revolutionized the management of TN. Novel drugs like vixotrigine and eslicarbazepine have been promising in reducing the frequency and severity of attacks. Inhaled carbon dioxide too has shown promising results in initial trials. Neuromodulation has given robust data in controlling neuralgic pain especially refractory to medical management. Pulsed radiofrequency has been used with increasing success and the side effects like dysesthesia and paresthesia are less. Cryotherapy, neural prolotherapy, and fiber knife techniques have helped us believe that TN can be controlled and cured. The need of the hour is to develop and explore newer modalities for trigeminal neuralgia treatment with minimum side effects. In this narrative review, we have tried to shed light into the newer modalities of treatment of TN along with new clinical classification for better disease recognition and management.

Assessment of Growth Factors, Cytokines, and Cellular Markers in Saliva of Patients with Trigeminal Neuralgia

We proposed to perform a comparative analysis of growth factors, cytokines, and chemokine receptors on the salivary cells in the saliva obtained from trigeminal neuralgia (TN) and normal subjects. Saliva was collected from TN and healthy subjects. Salivary cells were isolated by centrifugation. The expression of the cell surface marker was analyzed by flow cytometry. A cytometric bead array was done to measure the levels of cytokines and growth factors on the flow cytometer. Saliva from TN subjects showed lower growth factor levels of Angiopoietin-2, bFGF, HGF, SCF, TGF-α, and VEGF and higher cytokine levels of IL-1β, TNF-α, CCL2, IL-17A, IL-6, and CXCL8, as well as higher expression levels of chemokine receptors CCR1 (CD191), CR3 (CD11b), CCR2 (CD192), CXCR5 (CD185), and CCR5 (CD196) in the cells from TN saliva. A certain set of cytokines and growth factors in the saliva, as well as chemokine receptors on salivary cells, could be a useful tool in the diagnostics and prognostics of trigeminal neuralgia. Trigeminal neuralgia is one of the significant pathological conditions in the class of chronic diseases around the world. Many targeted approaches are being tried by various research groups to utilize the information of the inflammatory microenvironment to resolve the pathology of chronic TN.

Petroclival Meningioma Leading to Trigeminal Neuralgia: A Kawase Approach Application

BACKGROUND

Trigeminal neuralgia is defined by paroxysmal pain on the trigeminal nerve territory. The petroclival meningioma presents with trigeminal neuralgia in less than 5% of the cases. We report a case of a petroclival meningioma that encased the fifth nerve and was resected through a Kawase approach.

CLINICAL PRESENTATION

A 67-year-old female patient presented paroxysmal shock pain in malar and ocular region with progressive worsening, evolving with daily crises despite the use of carbamazepine. On neurologic examination the patient was oriented, with no strength or coordination impairments. Cranial nerves exam showed left V1, V2, and V3 thermal and pain hypoesthesia, without allodynia. Normal strength in masticatory muscles was observed. Magnetic resonance imaging revealed a petroclival lesion with hypersign on T2 and contrast enhancement, suggestive of a meningioma. The tumor encased the trigeminal nerve at the entrance of the Meckel's cave. A temporal craniotomy with middle fossa peeling and anterior petrosectomy (Kawase approach) was performed and a Simpson II resection was achieved. The patient evolved with transient sixth nerve palsy, recovering completely after 3 months. During a follow-up of 5 years there was no evidence of tumor recurrence and the patient is free from pain without medication.

CONCLUSIONS

The Kawase approach is an interesting access for petroclival tumor resection.

Magnetic resonance neurography in the management of trigeminal neuralgia: a cohort study of 55 patients

OBJECTIVE

To explore the usefulness of magnetic resonance neurography (MRN) in the diagnosis and management of trigeminal neuralgia (TN).

STUDY DESIGN

In total, 55 patients clinically diagnosed with TN were imaged with 3.0-T magnetic resonance imaging. Images were reconstructed to show the full course of the trigeminal nerve. Clinical findings included mean duration of symptoms (41.99 months) and mean visual analog scale pain intensity (5.98). Final diagnoses were microvascular compression (19), inflammation (21), microvascular compression with inflammation (5), normal (5), tumor (1), peripheral nerve injury (2), and multiple sclerosis (2).

RESULTS

MRN had substantial impact on diagnosis and treatment in 56.4% of cases. A total of 33 patients underwent intervention for pain. MRN had substantial impact on 54.5% of the treated patients. The correlation between MRN results and intervention response was excellent in 19 patients (57.6%) and moderate in 14 (42.4%). Pain was reduced after surgery or interventional procedure in most cases (75.8%).

CONCLUSIONS

MRN is suitable for the diagnosis of clinical TN with beneficial impact on diagnosis and clinical management and moderate-to-excellent correlation with intervention response. Diagnosis of TN should focus not only on microvascular compression but also on the conditions of the peripheral branches of the trigeminal nerve.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Medical Malpractice and Trigeminal Neuralgia: An Analysis of 49 Cases

PURPOSE

Our study fills the vacancy of litigation research related to trigeminal neuralgia management, giving health care providers the information needed to understand the potential litigious outcomes that follow treatment methods.

METHODS

We queried the Westlaw database to identify litigation cases related to trigeminal neuralgia management. Key variables extracted included medical complaints, trial outcomes, and demographics. Continuous variables were compared between cases in favor of defendant and cases in favor of plaintiff using t-test or Wilcoxon rank sum test. Categorial variables were compared using χ² or Fisher exact test.

RESULTS

About 49 cases met the inclusion criteria-for those cases surgical complications (42.9%) were cited as the most common reasons for malpractice claims. Cranial nerve deficits (34.7%) were the most frequent postoperative complaints. Verdicts ruled in favor of the plaintiff in 26.5% of cases with a mean payout of $1,982,428.46. Dentists were included in the most cases, 63.3%, and the average payout was $415,908, whereas neurosurgeons were involved in 20.4% of cases with an average payout of $618,775. Cases with verdicts in favor of the plaintiff were more likely to be older than cases with verdicts in favor of the defendant (P = .03).

CONCLUSIONS

Over one-half of cases resulted in verdicts in favor of the defendant with surgical complications cited as the most common reason for litigation. Dentistry was the most common individual clinical specialty for defendants, whereas neurosurgery contributed to the largest average payout based on specialty (for n > 1). Cranial nerve deficits were the most common plaintiff postoperative complaints. These analyses may help doctor teams involved in management of trigeminal neuralgia to have a more informed discussion with the patient at every visit so that such litigations may be avoided.

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.

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

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

Factors Associated With Long-Term Risk of Recurrence After Percutaneous Radiofrequency Thermocoagulation of the Gasserian Ganglion for Patients With Trigeminal Neuralgia Involving the Ophthalmic Division: A Retrospective Study

OBJECTIVE

To evaluate risk factors associated with recurrence after radiofrequency thermocoagulation (RFT) of the gasserian ganglion among patients with ophthalmic trigeminal neuralgia (TN) and prognostic factors in terms of recurrence-free survival (RFS) during a long-term follow-up.

METHODS

From January 2005 to December 2017, 300 patients with ophthalmic TN underwent RFT. A retrospective analysis of 14-year outcomes was performed. Kaplan-Meier analysis was used for RFS after the procedure. Univariate and multivariate Cox regression analyses were performed to identify risk factors for pain recurrence.

RESULTS

The initial effective rate of RFT for ophthalmic TN was 92%. The mean follow-up time was 77.38 ± 43.24 months. The cumulative probability of RFS was 86.94% at 1 year, 80.03% at 2 years, 77.27% at 3 years, 74.01% at 5 years, and 59.92% at 10 years after RFT. The mean duration of RFS was 114.67 months (95% confidence interval [CI] 106.27 to 123.06 months). In multivariate analysis, atypical pain (hazard ratio [HR] = 2.831, 95% CI 1.759 to 4.554, P < 0.001) and mild facial hypesthesia (HR = 2.540, 95% CI 1.309 to 4.931, P = 0.006) before RFT were independently associated with pain recurrence. Patients with a prognostic index (PI) > 1.27 were at high risk for pain recurrence. Major complications included troublesome dysesthesia (0.7%), keratitis (10.9%), diplopia (0.4%), facial paresthesia (6.2%), and masseter weakness (12.7%). Masseter weakness was more common in patients with V3 branch involvement. Three patients lost their sight due to keratitis.

CONCLUSION

Our study investigated long-term outcomes and complications of RFT for ophthalmic TN. Patients at high risk for pain recurrence were identified, which might provide a basis for clinical decision making before RFT.