Trigeminal Root Research Articles

An anatomical study of the subarachnoid space surrounding the trigeminal ganglion in horses-in preparation for a controlled glycerol rhizotomy in equids.

Equine trigeminal-mediated headshaking is a painful neuropathic disorder comparable to trigeminal neuralgia in humans. The selective destruction of pain fibers within the trigeminal ganglion, called rhizotomy, is the surgical treatment of choice for idiopathic trigeminal neuralgia refractory to medical treatment in humans. The human trigeminal ganglion is enclosed by a dural recess called the Meckel's or trigeminal cave, in which the ganglion is surrounded by a cerebrospinal fluid (CSF)-filled subarachnoid space. During glycerol rhizotomy, glycerol is percutaneously injected in this CSF-filled space. Until now, information about the anatomy of the dural recess and the subarachnoid space surrounding the trigeminal ganglion is lacking in horses. The aim of this study was to explore if a CSF-filled subarachnoid space around the trigeminal ganglion exists in horses. Six equine cadaver heads were investigated for CSF accumulation around the ganglion with a 3 Tesla MRI. After anatomical dissection to expose the trigeminal root, a polymer-based radiopaque contrast agent was injected through the porus trigeminus into the subarachnoid space (cisternography). The exact delineation and the volume of the contrast agent accumulation were determined on subsequent micro-computed tomographic scans and segmentation. Finally, the distribution of the contrast agent within the subarachnoid space was examined histologically in three specimens. In all 12 specimens included in this study, the trigeminal ganglion was surrounded by a subarachnoid space forming a trigeminal cistern. The mean volume of the trigeminal cave in this study was 0.31 mL (±SD: 0.11 mL). Distribution of the contrast agent along the peripheral nerves (i.e., ophthalmic, maxillary and/or mandibular nerve) was observed in 7 out of 12 specimens. A subarachnoid space surrounding the trigeminal ganglion exists in the horse and could be targeted for glycerol rhizotomy in horses suffering from trigeminal-mediated headshaking. However, the clinical relevance of contrast agent distribution along the peripheral nerves remains to be assessed.

Features of trigeminal nerve exit on the base of the brain: neurovascular conflict

The trigeminal nerve is a complex anatomical formation that performs very important tasks in terms of functionality. This article focuses on the study of the exit of the trigeminal nerve and its syntopy with arteries. It is the study of the location of nearby vessels relative to the nerve and their neurovascular conflict that determines the relevance of this work. The prevalence of trigeminal neuralgia (TN) is quite high and amounts to 40–60 patients per 100,000 population, and the incidence according to the World Health Organization is within 2–4 people per 10,000 population. The maximum risk of neurovascular conflict is observed in the age group of people from 45 to 60 years. It is also known that women suffer from neuralgia significantly more often than men. Not only the exact diagnosis, but also the selection of the most appropriate treatment tactics will depend on the result of studies of the individual anatomical features of the pons area. The authors of the article studied 17 preparations of the base of the brain of middle-aged individuals, fixed in a 7 % formalin solution. Of the 17 preparations studied, neurovascular relationships were noted in 14, which is 82.4 % of the total. As a result of morphometric measurements, the data on the length and width of the pons, the thickness of the trigeminal nerve roots, and the middle cerebellar peduncles were obtained. Statistical data processing and photographic documentation were carried out. The clinical manifestations of the disease, diagnostic options, and various methods of treatment were considered. The most effective method of treating neurovascular conflict is surgery, the first mention of which dates back to 1934.

Trigeminal neuralgia and cerebrovascular malformations. Two cases presentation

Two rare cases of combined pathology, representing trigeminal neuralgia caused by cerebrovascular malformations (cavernous malformation, arteriovenous malformation), are detailed and analyzed. The study involved two patients, a 39-year-old woman and a 63-year-old man, with pain syndrome along the V2‒V3 branches of the left trigeminal nerve that was resistant to medical therapy. Neurological status otherwise unchanged. After thorough examination, neurosurgical treatment was performed in the form of microsurgical decompression of the trigeminal neuralgia via a retrosigmoid approach to the cerebellopontine angle and removal/mobilization of the cerebrovascular malformation, significantly improving the patients' overall condition and providing long-term pain-free postoperative periods: 5 years in the first and 6 months in the second cases.Trigeminal neuralgia may be the initial or sole manifestation of existing cerebrovascular malformations. Standard evaluation of patients with trigeminal neuralgia includes MRI of the brain using 3D sequences, particularly T2-weighted 3D DRIVE mode, for better visualization of vascular-nerve structures to identify the provocative factor, although this mode does not always provide complete reliable information regarding the microstructural features of the cerebellopontine angle. Accordingly, the surgeon must always be prepared for both standard microvascular decompression surgery and work with pathological vascular formations without disrupting blood flow in this area of the brainstem. Decompression of the trigeminal nerve root with maximal possible removal or isolation of the compressive factor plays an important role in the treatment of pain syndrome and is effective when properly performed.

Acute on Chronic Presentation of Trigeminal Neuralgia

Trigeminal neuralgia (TN) is characterized by sudden, severe, brief, stabbing, usually unilateral, and recurrent pain within one or more branches of the trigeminal nerve. It is divided into three types: (1) primary or classical TN, which requires demonstration of morphologic changes in the trigeminal nerve root from vascular compression, (2) secondary to other identifiable neurologic causes such as multiple sclerosis and intracranial space-occupying lesion, and (3) idiopathic, in which the etiology is unknown. Treatment and prognosis depend on the type. We present this case of an elderly woman with an unusual presentation of TN in a previously diagnosed case. The episodes were increasing in severity and duration, not responding to medical management, allodynia and constant pain was present, and they were accompanied by uncontrolled hypertension. These features strongly suggested other likely causes such as intracranial space-occupying lesions, multiple sclerosis, and central pain. Expert consultations from physicians and neurologists were sought for control of hypertension and reaching a diagnosis. Magnetic resonance angiogram of the brain was done and a diagnosis of classical TN with persistent background facial pain was established. The treatment was successfully done by radiofrequency ablation of the Gasserian ganglion. The pain and blood pressure responded to the treatment.

Heightened presence of inflammatory mediators in the cerebrospinal fluid of patients with trigeminal neuralgia.

Trigeminal neuralgia (TN) is a chronic, debilitating facial pain disease causing stabbing pain attacks in the sensory distribution of the trigeminal nerve. The underlying pathophysiology of TN is incompletely understood, although microstructural abnormalities consistent with focal demyelination of the trigeminal nerve root have been shown in patients with TN. Studies of the cerebrospinal fluid (CSF) in patients with TN suggest an increased prevalence of inflammatory mediators, potentially implicating neuroinflammation in the pathophysiology of TN, as it has been implicated in other chronic pain conditions. This study aimed to further assess the inflammatory profile of CSF in TN. Cerebrospinal fluid was collected from 8 medically refractory patients with TN undergoing microvascular decompression surgery and 4 pain-free controls (2 with hemifacial spasm; 2 with normal pressure hydrocephalus). Cerebrospinal fluid was collected from the cerebellopontine angle cistern intraoperatively in the patients with TN. Inflammatory profiles of CSF samples were analyzed using a 71-plex cytokine and chemokine multiplex assay. Ten inflammatory markers were found to be significantly higher in TN CSF, and no analytes were significantly lower. Elevated factors can be classified into pro-inflammatory cytokines (IL-9, IL-18, and IL-33), chemokines (RANTES and ENA-78), the tumor necrosis factor superfamily (TRAIL and sCD40L), and growth factors (EGF, PDGF-AB/BB, and FGF-2). This study further supports the notion that neuroinflammation is present in TN, and that multiple molecular pathways are implicated.

The role of cyberKnife in the treatment of trigeminal neuralgia :A retrospective study

ObjectiveTo investigate the efficacy of stereotactic radiotherapy (CyberKnife) in treating primary trigeminal neuralgia and to summarize the treatment experience. MethodsA retrospective analysis was conducted on the efficacy and efficacy of CyberKnife treatment in 33 patients with primary trigeminal neuralgia from August 2012 to April 2023. Targets are selected in the trigeminal nerve root and half-moon segment. The length of treatment is about 6-8 mm, the prescribed dose is 54-65 Gy. Classified according to the (BNI) scale, trigeminal neuralgia and sensory impairment. Follow-up assessed the time and extent of pain relief and the time and extent of numbness. Wilcoxon Signed Ranks Test was used to analyze pain scores before and after radiotherapy. The KM curve analysis using the R survival package was used to analyze the survival. ResultsAmong them, 12 were males (36.4%) and 21 females (63.6%), with an average age of 67.76±10.62 years. Facial numbness scores after treatment averaged 2.61 ± 0.86. Pain relief started on average 28.26 ± 47.27 days. The pain scores of 33 patients before and after radiotherapy were statistically significant (P<0.001), and the effect was significant after treatment. The average occurrence time of facial numbness was 248.47±182.88 days, and the proportion of drooling was 39.4%. In this study, pain score before and after treatment, and numbness score after treatment were analyzed by Log-rank test survival. ConclusionCyberKnife is the advantage of being non-invasive and effective in reducing pain for primary trigeminal neuralgia.

Prdm12 represses the expression of the visceral neuron determinants Phox2a/b in developing somatosensory ganglia

Prdm12 is a transcriptional regulator essential for the emergence of the somatic nociceptive lineage during sensory neurogenesis. The exact mechanisms by which Prdm12 promotes nociceptor development remain, however, poorly understood. Here, we report that the trigeminal and dorsal root ganglia hypoplasia induced by the loss of Prdm12 involves Bax-dependent apoptosis and that it is accompanied by the ectopic expression of the visceral sensory neuron determinants Phox2a and Phox2b, which is, however, not sufficient to impose a complete fate switch in surviving somatosensory neurons. Mechanistically, our data reveal that Prdm12 is required from somatosensory neural precursors to early post-mitotic differentiating nociceptive neurons to repress Phox2a/b and that its repressive function is context dependent. Together, these findings reveal that besides its essential role in nociceptor survival during development, Prdm12 also promotes nociceptor fate via an additional mechanism, by preventing precursors from engaging into an alternate Phox2 driven visceral neuronal type differentiation program.

A Rare Occurrence of Demyelinating Lesions of Bilateral Trigeminal Nerves: An Atypical Presentation of Pediatric Multiple Sclerosis

AbstractPontine trigeminal root entry zone is a typical, although uncommon, location for multiple sclerosis (MS) lesions to occur. Here, we present a 17-year-old girl with nausea, vomiting, and vertigo. Neurological examination was consistent with central nystagmus, positive Romberg's test, and left-sided hyperreflexia. Baseline magnetic resonance imaging fulfilled McDonald 2017 criteria for MS and showed T2-hyperintense and T1-hypointense bilateral demyelinating lesions at the intramedullary portion of the trigeminal root of the fifth nerve, with no contrast enhancement or restricted diffusion. Bilateral intrapontine trigeminal involvement is a rare finding in MS, as well as the combined central and peripheral demyelination. Furthermore, very limited information and cases have been described in pediatric patients.

Comprehensive Treatment of Patients With Classical Trigeminal Neuralgia

Trigeminal neuralgia is a chronic disease characterized by short paroxysms of intense excruciating shooting pains in the innervation zone of one or more branches of the trigeminal nerve. Trigeminal neuralgia is a common disease, it occurs with a frequency of 4-5 to 30-50 cases per 100,000 population — according to reports, about 15,000 new patients are diagnosed in the United States annually. The practical social severity of trigeminal neuralgia is high — the severity of pain attacks leads to a significant disruption of the flow of the normal rhythm of life of patients. Among the conservative methods of treatment of classical trigeminal neuralgia, first-line drugs are anticonvulsants and, above all, carbamazepine, which suppresses cortical and stem foci of sensitization. In parallel with the increase in tolerance to the drug, the number of adverse events also increases. If drug therapy is ineffective, surgical methods of treatment are used. Microvascular decompression of the trigeminal nerve root is considered the “gold standard” among them. The microvascular decompression ensures the complete elimination of the pain syndrome, but the percentage of relapses of the disease varies widely. According to scientists, the relapse rate after the microvascular decompression was 28%. The mortality rate is from 0.5 to 2% and averages 1.4%. The main cause of death is a violation of blood circulation in the brain stem. In addition, damage to adjacent nerve structures occurs with varying frequency: IV, VI, VII and VIII nerves. In this regard, there was a need to develop alternative approaches to the treatment of trigeminal neuralgia with paroxysmal facial pain. The results of a clinical and instrumental study of various treatment methods are presented. The effectiveness of complex treatment for trigeminal neuralgia has been proven.

Diffusion tensor imaging in trigeminal neuralgia: beyond the normal morphology

BackgroundTrigeminal neuralgia (TN) is an electric-like recurrent pain of a sudden onset and is localized to the area supplied by the trigeminal nerve, and the patients are usually free in between the attacks. It’s one of the most common causes of facial pain and is commonly induced by mechanical irritation, and there’s strong evidence suggesting an insult at the trigeminal nerve root which is usually caused by a neurovascular compression. The aim of the study was to evaluate the role of diffusion tensor imaging (DTI) in the detection of microstructural changes of normal appearing trigeminal nerve in patients with trigeminal neuralgia and the correlation between DTI parameters and pain severity.ResultsThirty one cases were included in the study (16 patients with TN and 15 healthy controls) underwent MRI with diffusion tensor imaging. The fractional anisotropy (FA) values of the trigeminal nerves were recorded and then comparison between the affected and unaffected sides in TN patients and healthy controls was done, also the degree of FA reduction was correlated with the pain severity in TN groups. The mean FA value of the affected trigeminal nerves was 0.43 ± 0.083, while that of the unaffected sides was 0.56 ± 0.058. The mean FA value of the trigeminal nerves in the healthy controls was 0.54 ± 0.057. A significant statistical differences was found between affected and unaffected sides (P < 0.00001) and between the affected sides and healthy controls (P < 0.0003), while no statistically significant difference was detected between the unaffected side and the healthy controls. A strong negative correlation was found between the pain score and the degree of FA reduction (P < 0.001).ConclusionsDiffusion tensor imaging is a functional MRI technique which can detect the microstructural changes in the normal appearing trigeminal nerves in patients with trigeminal neuralgia with a strong negative correlation between the severity of pain and the degree of FA reduction of the affected trigeminal nerve.

Microanatomical findings with relevance to trigeminal ganglion enhancement on post-contrast T1-weighted magnetic resonance images in dogs.

Trigeminal ganglion contrast enhancement (TGCE) is reported to be a normal and a common finding on magnetic resonance imaging studies of dogs, cats and humans. The intent of the present study was to describe the anatomical characteristics of the trigeminal ganglion, its surrounding structures, and histological features that are relevant to explain or hypothesize on the reason for TGCE on T1-weighted post-contrast MRI studies of the brain in dogs. Eight dog cadavers were dissected to study the anatomy of the trigeminal ganglion. The presence and anatomy of vessels was studied by dissection and by histological techniques. Two trigeminal ganglia were isolated and stained with hematoxylin-eosin (HE). Two other trigeminal ganglia included in the trigeminal canal and trigeminal cavity were decalcified with formic acid/formalin for 12 weeks and stained with HE to study the related vessels. Additionally, a corrosion cast was obtained from a separate canine specimen. Leptomeninges and a subarachnoid space were identified at the level of the trigeminal nerve roots and the trigeminal ganglion. No subarachnoid space was identified and leptomeninges were no longer present at the level of the three trigeminal nerve branches. Small arterial vessels ran to and supplied the trigeminal ganglion, passing through the dura mater. No venous plexus was visualized at the level of the trigeminal ganglion in the dissections. A complex arterial vascular network was identified within the leptomeningeal covering of the trigeminal ganglion and was best appreciated in the corrosion cast. Histological examination revealed small-to moderate-sized blood vessels located in the epineurium around the ganglion; from there a multitude of arterioles penetrated into the perineurium. Small endoneurial branches and capillaries penetrated the ganglion and the trigeminal nerve branches. Limitations to this study include the limited number of canine specimens included and the lack of electron microscopy to further support current hypotheses included in our discussion. In conclusion, this study provides further support to the theory that TGCE in dogs may be due an incomplete blood-nerve barrier or blood-ganglion barrier at the interface between the central nervous system and the peripheral nervous system.

Meckel’s cave compression with Teflon for the treatment of idiopathic trigeminal neuralgia: its possibility as a modified surgical technique

Objective: We analyzed the clinical outcomes of Meckel’s cave compression with Teflon (Rhee’s method) as a new modified and additional surgical technique for trigeminal neuralgia (TN).Methods: Between March 1996 and December 2014, out of 78 patients who were treated with microvascular decompression (MVD) or partial sensory root rhizotomy, 28 patients additionally underwent Meckel’s cave compression with Teflon. The mean age at initial treatment was 54.3 years (range: 40–69 years). The mean duration from onset to operation was 70.5 months (range: 5–360 months) and the mean follow-up period was 26 months (range: 1–77 months). Results: Fifteen patients (53.6%) had facial pain in the V2/V3 distribution. The offending or associating vessel was the superior cerebellar artery in four patients (14.3%), the superior petrosal vein in six (21.4%), the anterior inferior cerebellar artery in two (7.1%), multiple vessels in nine (32.1%), and miscellaneous arteries or veins in six (21.4%). One patient (3.6%) had no offending vessel, and seven patients were had no definite offending vessels that contacted the trigeminal root entry zone. Meckel’s cave compression with Teflon was applied to all patients: 10 (35.7%) in combination with MVD, one (3.6%) with partial rhizotomy, and 17 (60.7%) with both MVD and partial rhizotomy. TN was relieved in 26 patients (92.9%) and symptoms recurred in three patients (pain-free rate: 82.1%). The complication rate of this method appeared to be similar to other treatment procedures. Conclusion: Meckel’s cave compression with Teflon may be a safe and useful additional treatment procedure for TN.

Atrophy and Severe Kinking of Trigeminal Nerve Root by Duplicate Trunks of Superior Cerebellar Artery in an Elderly Patient with Trigeminal Neuralgia

Trigeminal neuralgia, or tic douloureux, clinically presents as a unilateral paroxysmal, stabbing, intense pain of the face, lasting for seconds but occurring frequently. Alternative causes including multiple sclerosis or mass of the brainstem or cranial nerves must be ruled out. Medical treatment, most commonly with carbamazepine, remains an effective first-line treatment. Ultimately, if medical management becomes refractory or symptoms progressive, then procedural and surgical options including microvascular decompression, stereotactic radiosurgery, radiofrequency thermocoagulation, and others should be considered. Most notably, microvascular decompression, as in this case, can be considered with an 85%-95% initial success rate.

Time-Course Progression of Whole Transcriptome Expression Changes of Trigeminal Ganglia Compared to Dorsal Root Ganglia in Rats Exposed to Nerve Injury

Mechanisms underlying neuropathic pain (NP) are complex with multiple genes, their interactions, environmental and epigenetic factors being implicated. Transcriptional changes in the trigeminal (TG) and dorsal root (DRG) ganglia have been implicated in the development and maintenance of NP. Despite efforts to unravel molecular mechanisms of NP, many remain unknown. Also, most of the studies focused on the spinal system. Although the spinal and trigeminal systems share some of the molecular mechanisms, differences exist. We used RNA-sequencing technology to identify differentially expressed genes (DEGs) in the TG and DRG at baseline and 3 time points following the infraorbital or sciatic nerve injuries, respectively. Pathway analysis and comparison analysis were performed to identify differentially expressed pathways. Additionally, upstream regulator effects were investigated in the two systems. DEG (differentially expressed genes) analyses identified 3,225 genes to be differentially expressed between TG and DRG in naïve animals, 1,828 genes 4 days post injury, 5,644 at day 8 and 9,777 DEGs at 21 days postinjury. A comparison of top enriched canonical pathways revealed that a number of signaling pathway was significantly inhibited in the TG and activated in the DRG at 21 days postinjury. Finally, CORT upstream regulator was predicted to be inhibited in the TG while expression levels of the CSF1 upstream regulator were significantly elevated in the DRG at 21 days postinjury. This study provides a basis for further in-depth studies investigating transcriptional changes, pathways, and upstream regulation in TG and DRG in rats exposed to peripheral nerve injuries. PerspectiveAlthough trigeminal and dorsal root ganglia are homologs of each other, they respond differently to nerve injury and therefore treatment. Activation/inhibition of number of biological pathways appear to be ganglion/system specific suggesting that different approaches might be required to successfully treat neuropathies induced by injuries in spinal and trigeminal systems.

Trigeminal Neuralgia as An Atypical Manifestation of Intracranial Hypertension. Case Report and Literature Review

Trigeminal neuralgia, a chronic neuropathic pain, is characterized by frequent episodes of stabbing facial pain, in the territory of the trigeminal nerve, which can severely impair patient’s quality of life. It is primarily caused by vascular compression of the trigeminal nerve root, but it is sometimes secondary to other identifiable neurological conditions, such as multiple sclerosis or a cerebellopontine angle tumor. Uncommonly, it may be caused by the presence of idiopathic intracranial hypertension, a condition most likely identified by headache, visual disturbances, and sixth nerve palsy, among other manifestations. Secondary causes of trigeminal neuralgia are usually detected after an atypical clinical manifestation, such as ophthalmic rather than maxillary or mandibular nerve involvement, more than one branch affected, or bilateral symptoms. We present a patient who presented with trigeminal neuralgia as a primary manifestation, and after thorough evaluation she was diagnosed with intracranial hypertension as the underlying mechanism responsible of the trigeminal neuralgia.

Sex differences in trigeminal neuralgia: a focus on radiological and clinical characteristics

BackgroundIt is well established that trigeminal neuralgia is more prevalent in females than in males. Neurovascular compression with morphological changes of the trigeminal root represents the most recognized etiological factor. However, other factors may play a role in the framework of a multi-hit model. The primary aim of this study was to investigate sex differences in radiological and clinical characteristics of trigeminal neuralgia to better understand the multifactorial origin of this peculiar neuropathic pain condition.MethodsIn this cross-sectional study patients with a definite diagnosis of primary trigeminal neuralgia were consecutively enrolled. Each patient underwent 3T MRI with sequences dedicated to the study of neurovascular compression. Major morphological changes of the trigeminal root were quantitatively assessed. Clinical characteristics were systematically collected through a dedicated questionnaire. A logistic regression model was implemented to predict radiological and clinical characteristics based on sex.ResultsA total of 114 patients with classical (87) or idiopathic trigeminal neuralgia (27) were enrolled. Female sex was predictive for idiopathic trigeminal neuralgia. Male sex was predictive, among the comorbidities and clinical characteristics, for hypertension, the involvement of the left side and the second trigeminal division, alone or with the ophthalmic division.DiscussionThe preponderance of TN in the female sex and the association between idiopathic TN and the female sex suggest the role of additional etiological factors in the framework of a multi-hit model. The identification of clinical variables predicted by sex suggests the possibility that distinct phenotypes, with peculiar pathophysiological and therapeutic aspects, may occur in females and males.

A Trivalent HSV-2 gC2, gD2, gE2 Nucleoside-Modified mRNA-LNP Vaccine Provides Outstanding Protection in Mice against Genital and Non-Genital HSV-1 Infection, Comparable to the Same Antigens Derived from HSV-1.

HSV-1 disease is a significant public health burden causing orofacial, genital, cornea, and brain infection. We previously reported that a trivalent HSV-2 gC2, gD2, gE2 nucleoside-modified mRNA-lipid nanoparticle (LNP) vaccine provides excellent protection against vaginal HSV-1 infection in mice. Here, we evaluated whether this HSV-2 gC2, gD2, gE2 vaccine is as effective as a similar HSV-1 mRNA LNP vaccine containing gC1, gD1, and gE1 in the murine lip and genital infection models. Mice were immunized twice with a total mRNA dose of 1 or 10 µg. The two vaccines produced comparable HSV-1 neutralizing antibody titers, and surprisingly, the HSV-2 vaccine stimulated more potent CD8+ T-cell responses to gE1 peptides than the HSV-1 vaccine. Both vaccines provided complete protection from clinical disease in the lip model, while in the genital model, both vaccines prevented death and genital disease, but the HSV-1 vaccine reduced day two vaginal titers slightly better at the 1 µg dose. Both vaccines prevented HSV-1 DNA from reaching the trigeminal or dorsal root ganglia to a similar extent. We conclude that the trivalent HSV-2 mRNA vaccine provides outstanding protection against HSV-1 challenge at two sites and may serve as a universal prophylactic vaccine for HSV-1 and HSV-2.

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

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

Trigeminal Nerve Isolation Application in Microvascular Decompression for Treating Trigeminal Neuralgia: A Retrospective Study.

This study aimed to compare the outcomes of trigeminal nerve isolation (TNI) with conventional microvascular decompression (CMVD) in cases of trigeminal neuralgia (TN). We retrospectively reviewed 143 TN cases who underwent microvascular decompression from January 2017 to January 2020. The surgical management of TNI or CMVD in all patients was randomized. The cases were divided into two groups, one group underwent a TNI and the other one received CMVD. The general data, postoperative outcomes, and complications were reviewed retrospectively. Cases with a narrow cistern of cerebellopontine, short trigeminal nerve root, and arachnoid adhesion were defined as difficult cases. All of the cases were followed up for at least 1 year. Surgical outcomes were assessed and compared between the two groups. In results, we found no significant differences in the general data, duration of hospitalization and blood loss between the two procedures. However, of the 143 cases, 12 cases (17.1%) recurred after surgery in the CMVD group, and four cases (5.5%) recurred after TNI operation. The rates of pain relief were 69 (94.5%) in the CMVD group, and 58 (82.9%) for TNI ( P =0.027). In the TNI group, there was only one difficult case among four no pain-relief cases, while in the CMVD group, 10 difficult cases were found among the 12 no pain-relief cases ( P =0.008). In conclusion, the TNI technique is more effective than the CMVD procedure and could also be performed on patients with classical TN. Future double-blind and randomized controlled trials are necessary to confirm this result.

Assessing trigeminal microstructure changes in patients with classical trigeminal neuralgia

Introduction. The crucial role of neuro-vascular conflict (NVC) in trigeminal neuralgia (TN) is getting increasingly challenged. Microstructural changes can be assessed using fractional anisotropy (FA) in diffusion tensor images (DTI).&#x0D; Objective. To evaluate usefulness of FA in brain MRI with DTI for TN lateralization assessment.&#x0D; Materials and methods. The study included 51 patients with classical TN divided into two groups: neurosurgical intervention free, post radiofrequency ablation (RFA), and a control group (patients without facial pain). All the patients were tested for NVC with FIESTA (Fast Imaging Employing Steady State Acquisition) brain MRI at 3Т. Difference in thickness of trigeminal roots on the intact and symptomatic sides was assessed for each group. The findings were compared to those in the control group. The MRI protocol was supplemented with DTI. The FA difference in thickness of the intact and symptomatic roots (∆FA) was calculated for each study group to assess microstructural root changes. The results were compared to those in the control group.&#x0D; Results. In trigeminal root DTIs, ∆FA over 0.075 [0.029; 0.146] is statistically significant to establish NVC-associated microstructural changes on the symptomatic side in patients without any past surgeries (p = 0,030). In patients with a history of trigeminal ganglion RFA, statistically significant (p = 0.026) thinned symptomatic trigeminal root (difference in thickness of trigeminal roots over 0.45 cm [0.4; 0.6]) was found as compared to that of the control patients.&#x0D; Conclusion. FA may be used as a quantitative demyelination biomarker in clinical TN. Trigeminal ganglion RFA leads to hypotrophy throughout the trigeminal nerve root.