Trigeminal Root Research Articles

Blood-nerve barrier disruption and coagulation system activation induced by mechanical compression injury participate in the peripheral sensitization of trigeminal neuralgia.

The aim of this study was to investigate the effect and possible mechanisms of the blood-nerve barrier (BNB) and the coagulation-anticoagulation system in modulating the mechanical allodynia in a trigeminal neuralgia (TN) rat model induced by chronic compression of the trigeminal root entry zone (TREZ). Von Frey filaments were applied to determine the orofacial mechanical allodynia threshold. The BNB permeability was evaluated by Evans blue extravasation test. Immunohistochemical staining and laser confocal microscopy were used to measure the length of the depletion zones of the nodes of Ranvier in the TREZ, the diameter of nerve fibers and the length of the nodal gap. The transcriptional levels of prothrombin and endogenous thrombin inhibitor protease nexin-1 (PN-1) in the TREZ of TN rats were assessed by RT-qPCR. A Western blotting assay was performed to detect the expression of paranodal proteins neurofascin-155 (NF155) and neurofascin-125 (NF125) in the TREZ. The spatiotemporal expression pattern of thrombin activated receptor (i.e. protease activated receptor 1, PAR1) in TREZ were defined by immunostaining and immunoblotting assays. PAR1 receptor inhibitors SCH79797 were administrated to TN rats to analyze the effect of thrombin-PAR1 on orofacial hyperalgesia. A compression injury of a rat's TREZ successfully induced TN-like behavior and was accompanied by the destruction of the permeability of the BNB and the promotion of prothrombin and thrombin inhibitor protease nexin-1 (PN-1) expression. The expression of the paranodal proteins neurofascin-155 (NF155) and neurofascin-125 (NF125) was increased, while the nodal gap length of the nodes of Ranvier was widened and the length of node-depleted zones was shortened. Moreover, the expression of PAR1 within the TREZ was upregulated at an early stage of TN, and administration of the PAR1 antagonist SCH79797 effectively ameliorated orofacial mechanical allodynia. A compression injury of the TREZ increased the permeability of the BNB and induced disturbances in the local coagulation-anticoagulation system, concomitant with the structural changes in the nodes of Ranvier, thrombin-PAR1 may play a critical role in modulating orofacial mechanical hyperalgesia in a TN rat model.

Electrophysiological and computational analysis of Cav3.2 channel variants associated with familial trigeminal neuralgia

Trigeminal neuralgia (TN) is a rare form of chronic neuropathic pain characterized by spontaneous or elicited paroxysms of electric shock-like or stabbing pain in a region of the face. While most cases occur in a sporadic manner and are accompanied by intracranial vascular compression of the trigeminal nerve root, alteration of ion channels has emerged as a potential exacerbating factor. Recently, whole exome sequencing analysis of familial TN patients identified 19 rare variants in the gene CACNA1H encoding for Cav3.2T-type calcium channels. An initial analysis of 4 of these variants pointed to a pathogenic role. In this study, we assessed the electrophysiological properties of 13 additional TN-associated Cav3.2 variants expressed in tsA-201 cells. Our data indicate that 6 out of the 13 variants analyzed display alteration of their gating properties as evidenced by a hyperpolarizing shift of their voltage dependence of activation and/or inactivation resulting in an enhanced window current supported by Cav3.2 channels. An additional variant enhanced the recovery from inactivation. Simulation of neuronal electrical membrane potential using a computational model of reticular thalamic neuron suggests that TN-associated Cav3.2 variants could enhance neuronal excitability. Altogether, the present study adds to the notion that ion channel polymorphisms could contribute to the etiology of some cases of TN and further support a role for Cav3.2 channels.

Dosimetric Comparison between a Frameless Robotic Radiosurgery System and HyperArc Treatment Plans for Trigeminal Neuralgia: Cone-Based Robotic System vs. High-Definition MLC Based Linac System

<h3>Purpose/Objective(s)</h3> SRS is an effective and safe treatment option for trigeminal neuralgia (TN). Good dosimetric distribution has made HyperArc (HA) an attractive SRS/FRST technique for treating benign brain lesions. This study aims to evaluate the feasibility of HA for TN by comparing it with the dose distribution of frameless robotic radiosurgery systems. <h3>Materials/Methods</h3> Twenty patients with TN treated by cone-based CK were enrolled. The treatment location was targeted on the whole trigeminal nerve root entry zone (REZ) segment, leaving a 2-mm sparing from the brainstem. The prescription dose was 65 Gy in a single fraction, prescribing to the 80% isodose line with the highest dose of 81.25 Gy in the REZ. The segment of the trigeminal nerve encompassed by the 80% isodose line averaged 7.2 mm in length. Dose to brainstem surface was constrained with a maximum dose of 40 Gy. The corresponding HA plans were generated for the 20 patients to meet the same CK treatment plan criteria, using the high-definition MLC (2.5mm at the center) and SRS NTO optimization algorithm. The CK and HA treatment plans were compared with target coverage, sparing of organs at risk (OARs), and dose distribution metrics. <h3>Results</h3> All the OAR constraints were met in the HA treatment plans. The HA plans exhibited higher coverage of the PTVs than the CK plans, with statistically significant differences (HA vs. CK, 97.2% vs. 92.2%, P = 0.008). The HA plans consistently demonstrate better sparing of the OARs than the CK plans. The mean brain doses were 0.83 Gy and 1.15 Gy for HA and CK (P < 0.001), respectively. The brain V12 was significantly smaller with HA plans than with CK plans (5.9 c.c. in HA vs. 6.9 c.c. in CK, P = 0.019). Significant differences in the maximal and mean doses of the ipsilateral/contralateral CN VII/VIII were observed between the HA and CK plans. The HA plans exhibited a significantly greater conformity index than the CK plans (HA vs. CK, 1.59 vs. 1.71, P = 0.001). The dose gradient radius was similar in the CK and HA plans (HA, 0.28 vs. CK, 0.29). <h3>Conclusion</h3> Excellent sparing of OARs and good dosimetric distribution demonstrated HA is a feasible SRS technique for the treatment of TN. Further clinical studies using HA for TN would be necessary to confirm the therapeutic benefits and toxicity profiles.

3D-visualization of neurovascular conflict in patients with classical trigeminal neuralgia

Introduction. MRI is well-recognized as a leading method of neurovascular conflict (NVC) evaluation in patients with classical trigeminal neuralgia (CTN). NVC is regarded as the cause of the development of deformity, atrophy, or dislocation of the trigeminal nerve root. Currently, the number of worldwide publications concerning the analysis of NVC 3D-reconstruction for the diagnosis of cranial nerve hyperfunction syndromes is still small. The aim of the study was to evaluate the efficacy of NVC 3D-visualization for CTN diagnosis compared to conventional examination protocols. Materials and methods. From 2018 to 2020, 30 patients with CTN who underwent 3D-visualization of the NVC as a preoperative examination were involved in prospective nonrandomized study. T-2 3D (FIESTA), 3D-TOF and T1 FRSGR were utilized for 3D rendering (Fusion protocol). The obtained data were compared only FIESTA-based «prediction» of NVC and with intraoperative findings. Results. FIESTA-only prediction was effective in 93 %, and Fusion protocol — in 97 % of arterial type of NVC cases. Fusion protocol showed its supremacy in detecting venous type of compression. Average efficacy of FIESTA-only prediction was 84 %, whereas Fusion protocol showed 97 % correlation with intraoperative findings. Conclusion. Fusion protocol allows fast detection of NVC, its type and localization (not only at the REZ of the fifth nerve but also at its cisternal portion). It makes possible tracing the course of the compressing vessel and assess the «convenience» of decompressing the TN root, taking into account the spatial relationship of the brainstem, vessels of the cerebellopontine angle and cranial nerves. Unlike FIESTA-only scanning, 3D-rendering also offers a possibility of preoperative simulation of microvascular decompression by recreating intraoperative view with precise details. Patient examination with FIESTA-only scanning is inferior to the «extended» algorithm for NVC diagnosis and does not have these capabilities.

Correlation study between multiplanar reconstruction trigeminal nerve angulation and trigeminal neuralgia

ObjectivesNeurovascular compression (NVC) produces morphological changes on the trigeminal nerve root is considered the cause of trigeminal neuralgia (TN), but there were some patients with TN found no NVC, and also NVC was found in asymptomatic individuals. Many studies found tight relationships of TN and morphological structures of trigeminal nerve. We designed this study to explore the correlation between multiplanar reconstruction (MPR) trigeminal nerve angulation (TNA) and TN.MethodsPatients with classical symptoms of TN were recruited as observation group (OG) in this study, 50 healthy controls were enrolled as control group (CG), the OG was further subtyped into young patients (YP), middle-aged patients (MP) and old patients (OP) based to the onset age of symptoms, and also divided into patients with or without trigger maneuvers (TM) based on the presence of TM or not. All the participants underwent magnetic resonance (MR) examinations in same device, bilateral TNA measurements were carried out in OG and CG, then TNA was compared between different groups or subgroups. All images were interpreted by two radiologists who were blinded to the study, diagnosis of TN was made by two senior neurosurgery professors.ResultUltimately, 95 patients with primary TN were recruited in OG, aged from 25 to 84 (61.15 ± 12.70) years with a course of 0.5 to 30 (5.03 ± 5.41) years, their onset age ranged from 24 to 82 (56.13 ± 11.98) years. There were 34 males and 61 females in OG, and 58 cases involved right side. The CG aged from 22 to 85 (61.86 ± 13.03) years. No statistical difference was found between the age of OG and CG(p = 0.76), and also the bilateral TNA of CG (154.92 ± 16.90° vs 155.55 ± 17.03°, p > 0.05), while TNA of OG was significantly smaller than CG (150.78 ± 11.29° vs 155.24 ± 16.88°, p = 0.019). In OG, TNA on the affected side was significantly smaller than the unaffected side (149.29 ± 12.44° vs 152.27 ± 9.85°, p = 0.014). TNA showed a positive correlation with onset age of patients with TN, as TNA on the affected side of YP was significantly smaller than MP and OP (139.00 ± 11.64° vs 148.86 ± 11.54°, 139.00 ± 11.64° vs 152.18 ± 12.61°, p = 0.004 and 0.026). Furthermore, patients with TM showed smaller TNA than those without TM (147.05 ± 11.30° vs 164.75 ± 8.39°, p < 0.001).ConclusionsThis study suggested that TNA might play a role in TN, small TNA could be a risk factor of TN. Furthermore, patients with small TNA are more likely to combine with TM, but more studies are needed to explore the exact role of TNA in TN.

Cellular Mechanisms Mediating the Antinociceptive Effect of Botulinum Toxin A in a Rodent Model of Trigeminal Irritation by a Foreign Body

Although numerous studies have described botulinum toxin type A (BTX-A) efficacy against trigeminal neuralgia (TN), the underlying cellular mechanisms remain unclear. We have investigated cellular mechanisms that mediate the antinociceptive effect of BTX-A in a rodent model of TN produced by compression of the trigeminal nerve root (TNR). Anesthetized male Sprague-Dawley rats were fixed in a stereotaxic instrument and compression of the TNR was then achieved with a 4% agar solution. This model produced a significant mechanical allodynia and increased the expression of hypoxia-inducible factor (HIF)-1α and cytokines levels including interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in the trigeminal ganglion (TG) by postoperative day (POD) 7. Single or double treatments with a high BTX-A dose (3 U/kg) led to significantly prolonged antinociceptive effects. Furthermore, a single treatment with BTX-A (3 U/kg) significantly suppressed the upregulation of HIF-1α expression and IL-1β, IL-6, and TNF-α concentrations in the TG. Intraganglionic injection of PX-12, a HIF-1α inhibitor, led to significant anti-allodynic effects and lowered the IL-1β, IL-6, and TNF-α levels in the TG. These findings indicate that the antinociceptive effect of BTX-A is mediated via HIF-1α associated cytokines modulation in the TG and is therefore a potentially relevant treatment strategy for TN. PerspectiveThe antinociceptive properties of BTX-A in a rat model of trigeminal neuralgia are mediated through the regulation of the HIF-1α associated cytokine pathway in the trigeminal ganglion. BTX-A is therefore a potentially effective treatment strategy for trigeminal neuralgia.

Technical Assessment of Microvascular Decompression for Trigeminal Neuralgia Using a 3-Dimensional Exoscope: A Case Series.

Detailed anatomic visualization of the root entry zone of the trigeminal nerve is crucial to successfully perform microvascular decompression surgery (MVD) in patients with trigeminal neuralgia. To determine advantages and disadvantages using a 3-dimensional (3D) exoscope for MVD surgery. A 4K 3D exoscope (ORBEYE) was used by a single surgical team for MVD in a retrospective case series of 8 patients with trigeminal neuralgia in a tertiary center. Clinical and surgical data were collected, and advantages/disadvantages of using the exoscope for MVD were recorded after each surgery. Descriptive statistics were used to summarize the data. Adequate MVD of the trigeminal nerve root was possible in all patients by exclusively using the exoscope. It offered bright visualization of the cerebellopontine angle and the root entry zone of the trigeminal nerve that was comparable with a binocular operating microscope. The greatest advantages of the exoscope included good optical quality, the pronounced depth of field of the image for all observers, and its superior surgeon ergonomics. Disadvantages were revealed with overexposure at deep surgical sites and the lack of endoscope integration. In 6 patients, facial pain improved significantly after surgery (Barrow Neurological Institute pain intensity score I in 5 and III in 1 patient), whereas it did not in 2 patients (Barrow Neurological Institute score IV and V). No complications occurred. Utilization of a 3D exoscope for MVD is a safe and feasible procedure. Surgeons benefit from better ergonomics, excellent image quality, and an improved experience for observers.

Involvement of Histone Lysine Crotonylation in the Regulation of Nerve-Injury-Induced Neuropathic Pain.

Histone lysine crotonylation (KCR), a novel epigenetic modification, is important in regulating a broad spectrum of biological processes and various diseases. However, whether KCR is involved in neuropathic pain remains to be elucidated. We found KCR occurs in macrophages, sensory neurons, and satellite glial cells of trigeminal ganglia (TG), neurons, astrocytes, and microglia of the medulla oblongata. KCR in TG was detected mainly in small and medium sensory neurons, to a lesser extent in large neurons. Peripheral nerve injury elevated KCR levels in macrophages in the trigeminal and dorsal root ganglia and microglia in the medulla oblongata but reduced KCR levels in sensory neurons. Inhibition of histone crotonyltransferases (p300) by intra-TG or intrathecal administration of C646 significantly alleviated partial infraorbital nerve transection (pIONT)- or spinal nerve ligation (SNL)-induced mechanical allodynia and thermal hyperalgesia. Intra-TG or intrathecal administration of Crotonyl coenzyme A trilithium salt to upregulate KCR dose-dependently induced mechanical allodynia and thermal hyperalgesia in mice. Mechanismly, inhibition of p300 alleviated pIONT-induced macrophage activation and reduced the expression of pain-related inflammatory cytokines Tnfα, Il1β and chemokines Ccl2 and Cxcl10. Correspondingly, exogenous crotonyl-CoA induced macrophage activation and the expression of Tnfα, Il1β, Il6, Ccl2 and Ccl7 in TG, which C646 can repress. These findings suggest that histone crotonylation might be functionally involved in neuropathic pain and neuroinflammation regulation.

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.

A single centre case series of microvascular decompression surgery for classical trigeminal neuralgia: functional outcomes and report of a unique conflict

BackgroundMicrovascular decompression surgery for trigeminal neuralgia is now considered the benchmark surgical procedure for intractable trigeminal neuralgia of any variety. The objective of this study is to share our experience in managing classical trigeminal neuralgia with microvascular decompression surgery looking into both immediate and late functional outcomes at 3 and 6 months post op. We also report a unique case of trigeminal neuralgia due to a tributary of the petrosal vein passing through the substance of the trigeminal nerve itself at its root entry zone.ResultsThis study included 20 patients; it showed that microvascular decompression surgery of the trigeminal nerve is an effective method for treatment of classic trigeminal neuralgia (p value < 0.001). The trigeminal root was compressed by the superior cerebellar artery in 75% of patients. A vein contributed to the compression in 45% of patients and was the only compressing vessel in 15%.ConclusionMicrovascular decompression surgery is the treatment of choice in patients with medically refractory trigeminal neuralgia, unless their general condition prohibits it. It’s also worth noting that the normal anatomy of the veins in this region is quite variable and the venous structures causing a neurovascular contact are more or less inconsistent. To the best of our knowledge and despite the wide range and progress in microvascular decompression surgery for trigeminal neuralgia, this is the first reported case in the literature for a neurovascular conflict caused by a vein passing through the trigeminal nerve itself.

Vertebrobasilar Dolichoectasia, An Unusual Cause of Trigeminal Neuralgia: A Case Report

Background: Trigeminal neuralgia is a facial pain syndrome that generally occur unilateral following the sensory distribution of the trigeminal nerve. It is classified into trigeminal neuralgia with no apparent cause, classic trigeminal neuralgia, which is caused by vascular compression of the trigeminal nerve root, and secondary trigeminal neuralgia caused by major neurological diseases such as cerebellopontine angle tumour or multiple sclerosis.Case: A 60 years old male, complained of pain in the right face since &gt;4 years ago, intermittent, radiating from around the upper right molars to the right face, like an electric shock, and appeared mainly when chewing. MRI and MRA examination of the patient revealed vertebrobasilar dolichoectasia causing displacement of the pons and right trigeminal nerve.Discussion: Vascular compression of the trigeminal nerve root is the most common cause of trigeminal neuralgia, which is commonly caused by small arteries such as the superior cerebellar artery. Vascular compression due to large arteries such as the basilar and vertebral arteries may occur in a minority of cases. MRI is an examination that plays an important role in cases of trigeminal neuralgia, because it can assess the pathology of cerebellopontine angle area, as well as assess the presence of neurovascular compression and morphological changes of the trigeminal nerve roots.

Dolichoectasia of cerebellar arteries is the basis of neurovascular conflict as an etiological factor of classical trigeminal neuralgia in residents of the Rostov region

Objective: to study the formation of neurovascular conflicts of two types in patients with classical trigeminal neuralgia, depending on the influence of the environment of the Rostov region.Materials and methods: a retrospective study of the features of neurovascular conflict was conducted in 175 patients from the Rostov region who suffered from classical trigeminal neuralgia. The diagnosis of a variant of neurovascular conflict was carried out using spiral computed tomography on the device «Philips Ingenuity Core 128» The variant of neurovascular conflict was verified intraoperatively, when performing microvascular decompression of the trigeminal nerve root.Results: neurovascular conflict, both of the first and second types, occurs twice as often in women as in men. The development of the adhesive process in the zone of neurovascular conflict, which brings the root even closer to the artery that injures it, is due to the duration of the pathological process, during which inflammatory diseases of the paranasal sinuses, carious teeth, persistent herpesvirus infection play a significant role.Conclusions: variants of the syntopia of the trigeminal nerve root with the superior cerebellar artery in neurovascular conflict do not depend on environmental factors, and the frequency of occurrence of one type or another, as well as the gender ratio, correspond to the population.

TRPA1 Role in Inflammatory Disorders: What Is Known So Far?

The transient receptor potential ankyrin 1 (TRPA1), a member of the TRP superfamily of channels, is primarily localized in a subpopulation of primary sensory neurons of the trigeminal, vagal, and dorsal root ganglia, where its activation mediates neurogenic inflammatory responses. TRPA1 expression in resident tissue cells, inflammatory, and immune cells, through the indirect modulation of a large series of intracellular pathways, orchestrates a range of cellular processes, such as cytokine production, cell differentiation, and cytotoxicity. Therefore, the TRPA1 pathway has been proposed as a protective mechanism to detect and respond to harmful agents in various pathological conditions, including several inflammatory diseases. Specific attention has been paid to TRPA1 contribution to the transition of inflammation and immune responses from an early defensive response to a chronic pathological condition. In this view, TRPA1 antagonists may be regarded as beneficial tools for the treatment of inflammatory conditions.

Application of morphological characteristics of radiofrequency lesions to individual parameters of thermal rhizolysis for trigeminal neuralgia.

Thermic rhizolysis is a reliable therapy for pharmaco-resistant trigeminal neuralgia (TN). Temperature, duration of electrocautery and needle location can influence the efficacy and complications of the therapy. We performed experimental thermocautery on egg white with increasing parameters of time (30-120s) and temperature (60-95°C); we analysed the shape, size and volume of the thermic lesions produced. We developed a surgical procedure to assess peroperatively the probable thermocoagulation field and its geometric relations with the trigeminal roots and other anatomical structures of Meckel's cave, and we individually adapted the parameters of rhizolysis to optimize the results. This procedure was applied on 22 patients with TN. The volume of the lesions produced by rhizolysis on egg white had a spheroidal shape and increased linearly with the level of temperature and the time of electrocautery from 1.595mm3 (SD 0.38) to 54.454mm3 (SD 10.41); higher temperatures induced larger thermocoagulation fields than longer time periods. The calculated volumes measured at all levels of temperature and time were applied in vivo on the patient stereotactic planning during the thermocoagulation procedure in order to select the optimal parameters for rhizolysis. The median values used were 75°C (range 70-85°C) and 60s (range 45-60s). At 6-month follow-up, pain outcome was Barrow-Neurological-Institute class-I for 72.7%, IIIa for 22.7% and IIIb for 4.6%; the only complication due to rhizolysis was mild facial numbness in 13 subjects (59%) at 6-month follow-up. We conclude that geometric analysis of the position of the electrode before trigeminal thermocoagulation with morphometric-related individual adaptation of treatment parameters could avoid serious injuries and optimize pain control. We have adapted the technique of radiofrequency rhizolysis for TN. Our procedure allows individual peroperative adaptation of the parameters of thermocoagulation, according to the specific position of the electrode during rhizolysis. Preliminary results on a series of 22 patients have shown promising results.

Bening paraxysmal torticollis is a sensoriomotos trigeminocervical convergence merchanisms? Experimental evidence.

Introduction Benign paroxysmal torticollis (BPT) is likely an age-sensitive, childhood periodic syndromes that are commonly precursors of migraine, with atypical postural behavior (torticollis) to start early and self-limited, which of unknown etiology. Objective To prove the existence of forms of sensorimotor convergence between the trigeminal nerve and upper cervical roots respectively. Methods Ninety-five rats Norvegicus were submitted to infraorbital nerve blockade using botulinum neurotoxin type A (BoNT/A) (n=48) controlled by isotonic saline solution animals (ISS) (n=47). After 84 days the animals were evaluated on their motor functions using open field test and postural behavior. Results Of the 48 animals in the BoNT/A group one animal showed the torticollis ipsilateral to BoNT/A injection. The macroscopic analysis showed fasciculations on clavotrapezius muscle. The biopsy with optical and electronic microscopy of this muscle showed changes suggestive of denervation secondary to BoNT/A. Conclusion We suggested the existence of a pathway sensoriomotor probably in the brainstem involves the trigeminal system and cervical motoneurons.

A study to evaluate neurovascular conflict of trigeminal nerve in trigeminal neuralgia patients with the help of 1.5\xa0T MR imaging

IntroductionTrigeminal neuralgia is a neuropathic pain that occurs in the sensory supply region of the trigeminal nerve (V cranial nerve). The common etiology of trigeminal neuralgia is said to be vascular compression on the trigeminal nerve root. In our day-to-day practice, we see many asymptomatic patients having vascular loops around the trigeminal nerve root. We undertook this study to see the significance of nerve root compression by the vascular loop as a cause for trigeminal neuralgia.Materials and methodsA total of 67 classical trigeminal neuralgia patients with NVC involving the trigeminal nerve as diagnosed on MRI brain sequences including FIESTA sequence were included in the study. NVC in all the patients were studied for the side, site of neurovascular contact of cisternal segment of the trigeminal nerve from the brainstem, deviation of nerve at NVC, atrophy of nerve, nature and origin of vascular loop causing NVC and correlated with TGN symptoms.ResultsOut of 67 patients studied, all of them (100%) had NVC on ipsilateral side and 26 patients (34%) had NVC at contralateral trigeminal nerve. Incidence of trigeminal neuralgia was most commonly seen between the 41 and 60 years age (64%) followed by 61–80 years with mean age of 55.6 years. Incidence in females (64%) was found to be more common than in males (35%). NVC was observed at the root entry zone (< 7 mm from brain stem) in 63 trigeminal nerves on symptomatic side and 5 trigeminal nerves on the asymptomatic side. NVC occurring at REZ on symptomatic side was found to be statistically significant with P < 0.001. Mean distance of NVC from brain stem at symptomatic side was 3.4 mm and was 8.4 mm in asymptomatic side NVCs. Atrophy was seen in 8 trigeminal nerves, all on symptomatic side and NVC occurring at root entry zone. No displacement of nerve root at the point of neurovascular contact was observed in our study. Most common vessel causing was found to be ipsilateral superior cerebellar artery followed by the ipsilateral anterior inferior cerebellar artery.ConclusionsNeurovascular contact of trigeminal nerve occurring at the nerve root entry zone has a strong association with ipsilateral trigeminal neuralgia symptoms. In addition, the presence of the trigeminal nerve thinning is also associated with ipsilateral trigeminal neuralgia. With the increase in age, there are higher chances of association of NVC with ipsilateral trigeminal neuralgia symptoms.

A Preliminary Study of the Efficacy of Transcranial Direct Current Stimulation in Trigeminal Neuralgia.

The purpose of this study is to assess the efficacy of transcranial direct current stimulation (tDCS) in patients with treatment-refractory trigeminal neuralgia (TN) and examine the utility of neuroimaging methods in identifying markers of such efficacy. Six patients with classical TN refractory to maximal medical treatment, underwent tDCS (three cases inhibitory/cathodic and three cases excitatory/anodic stimulation). All patients underwent pre- and posttreatment functional magnetic resonance imaging (fMRI) during block-design tasks (i.e., Pain, Pain + tDCS, tDCS) as well as single-shell diffusion MRI (dMRI) acquisition. The precise locations of tDCS electrodes were identified by neuronavigation. Five therapeutic tDCS sessions were carried out for each patient with either anodic or cathodic applications. The Numeric Rating Scale of pain (NRS) and the Headache Disability Index (HDI) were used to score the subjective efficacy of treatment. Altered activity of regional sites was identified by fMRI and associated changes in the spinothalamocortical sensory tract (STCT) were measured by the dMRI indices of fractional anisotropy (FA) and mean diffusivity (MD). Fiber counts of the bilateral trigeminal root entry zone (REZ) were performed as an added measure of fiber loss or recovery. All patients experienced a significant reduction in pain scores with a substantial decline in HDI (P value < 0.01). Following a course of anodic tDCS, the ipsilateral caudate, globus pallidus, somatosensory cortex, and the contralateral globus pallidus showed a significantly attenuated activation whereas cathodic tDCS treatment resulted in attenuation of the thalamus and globus pallidus bilaterally, and the somatosensory cortex and anterior cingulate gyrus contralaterally. dMRI analysis identified a substantial increase (>50%) in the number of contralateral sensory fibers in the STCT with either anodic or cathodic tDCS treatment in four of the six patients. A significant reduction in FA (>40%) was observed in the ipsilateral REZ in the posttreatment phase in five of the six patients. Preliminary evidence suggests that navigated tDCS presents a promising method for alleviating the pain of TN. Different patterns of activation manifested by anodic and cathodic stimulation require further elaboration to understand their implication. Activation and attenuation of responses at various sites may provide further avenues for condition treatment.

Treatment of redo-microvascular decompression or internal neurolysis plus microvascular decompression for recurrent trigeminal neuralgia: a review of long-term effectiveness and safety.

ObjectiveWe examined the clinical characteristics and outcomes of patients with recurrent trigeminal neuralgia (TN) and assessed the long-term efficacy and safety of microvascular decompression (MVD) to treat typical recurrent TN.MethodsWe identified 3024 patients who underwent MVD for treatment of TN at the China-Japan Friendship Hospital from March 2009 to December 2020. We retrospectively analyzed the data and outcomes of 137 patients who underwent redo-MVD and 74 patients who did not undergo redo-MVD as the control group. These outcomes were evaluated using the Barrow Neurological Institute scoring system.ResultsRecurrence in 68 of the 137 patients was due to incomplete or absent decompression or new responsible vessels. To ensure thorough pain relief, redo-MVD should include decompression of both the trigeminal root entry zone and the peripheral nerve segments, where blood vessels can cause symptoms. Factors associated with reduced effectiveness of redo-MVD were no period of initial pain relief after the first MVD and a longer duration of symptoms before the first MVD.ConclusionsRedo-MVD should not be excluded as a treatment option for patients with refractory TN who develop recurrent pain after a first MVD procedure.

Hyperintense areas in the cisternal segments of the cranial nerves: a magnetic resonance imaging study.

The study aimed to explore hyperintense areas in the cisternal segments of the cranial nerves using magnetic resonance imaging (MRI). Seventy outpatients underwent thin-sliced, coronal constructive interference steady-state (CISS) sequence and sagittal T2-weighted MRI following conventional MRI examination. With the coronal CISS sequence, hyperintense areas were located in the central parts of the olfactory bulbs in 65.7% of patients. For the intracranial optic nerve and optic chiasm, hyperintense areas were detected in 98.6% of the CISS sequences and 100% of the T2-weighted images. In the optic tract, hyperintense areas were detected in 51.4% of cases. In 35% of the patients who underwent the CISS sequence, the intracranial optic nerves were considerably compressed by the internal carotid and anterior cerebral arteries, with hyperintense areas similar to those in patients without vascular compression. Hyperintense areas of the cisternal segments of the oculomotor nerve and trigeminal root were identified in 52.9% and 87.1% of the patients, respectively. The hyperintense areas found within the cisternal segments of the cranial nerves delineated on the coronal CISS sequence and sagittal T2-weighted imaging may indicate the intracranial part of the glymphatic pathway through the cranial nerves. The cranial nerves may function as part of the glymphatic pathway.

Efficiency and Efficacy of Real-Time Fluoroscopic Image-Guided Percutaneous Gasserian Glycerol Rhizotomy (PGGR), for Intractable Cases of Trigeminal Neuralgia.

To evaluate the ease, efficiency, effectiveness, and associated complications of the technique of percutaneous Gasserian glycerol rhizotomy (PGGR) under real-time fluoroscopic image guidance, for management of severe and refractory cases of primary trigeminal neuralgia, in medical compromised patients. To also assess the long-term efficacy and the necessity, if any, for repeat procedures to salvage recurrences. In a prospective study conducted at a single institution over a period of three years, 25 cases of Idiopathic Trigeminal Neuralgia refractory to conservative modalities of treatment including medication were managed with PGGR under real-time fluoroscopic image guidance. All the 25 patients included in this study were known surgical risks for relatively invasive treatment procedures, owing to factors such as advanced age and/or presence of co-morbidities. In order to minimize the risks related to the conventional techniques of Trigeminal root rhizotomy based on cutaneous landmarks alone, and to eliminate the need for frequent repositioning of the needle/cannula, we adopted a technique of real-time fluoroscopic image-guided negotiation of a 22 gauge (0.7mm dia), 10-cm-long spinal nerve block needle through the foramen ovale, to reach the trigeminal cistern within the Meckel's cave. The efficiency of the technique was assessed in terms of time taken, effort, and ease in performing it. Associated intra- and post-procedural complications were recorded. The immediate and long-term effectiveness of the procedure was evaluated by analysing the degree and duration of pain control achieved, time to recurrence, and the necessity for repeat procedures. There were nil intra- or post-procedural complications encountered, and no failures associated with this procedure. Real-time fluoroscopic imaging enabled easy, quick, and successful negotiation of the nerve-block needle through the Foramen Ovale, so as to reach the Trigeminal cistern within the Meckel's cave, within 11min on an average. An immediate and long lasting post-procedural pain relief was achieved in all the patients. During the follow-up period of 36months, recurrence of pain was observed in six cases, the mean timing of the recurrence being 26months or more. Five of these cases were manageable with medication alone, and only one required a repeat procedure. These results indicate that PGGR under real-time fluoroscopic image guidance is a safe, simple, time-efficient, convenient, efficacious, reliable, and minimally invasive means of treating refractory and intractable cases of trigeminal neuralgia.