Unilateral Trigeminal Neuralgia Research Articles

A novel 3D multimodal fusion imaging surgical guidance in microvascular decompression for primary trigeminal neuralgia and hemifacial spasm

BackgroundNeurovascular compression (NVC) is a primary etiology of trigeminal neuralgia (TN) and hemifacial spasm (HFS). Despite Magnetic Resonance Tomographic Angiography (MRTA) being a useful tool for 3D multimodal fusion imaging (MFI) in microvascular decompression (MVD) surgery planning, it may not visualize smaller arterial vessels and veins effectively. We validate a novel computed tomography angiography and venography (CTA/V) - diffusion tensor tractography (DTT) -3D-MFI to enhance the MVD surgical guidance.MethodsIn this prospective study, 80 patients with unilateral primary TN or HFS who underwent MVD surgery were included. Imaging was conducted using CTA/V-DTT-3D-MFI compared with CT-MRTA-3D-MFI in predicting the responsible vessel and assessing the severity of NVC. Surgical outcomes were subsequently analyzed. Neurosurgery residents were provided with questionnaires to evaluate and compare the two approaches.ResultsCTA/V-DTT-3D-MFI significantly improved accuracy in identifying the responsible vessel (kappa = 0.954) and NVC (kappa = 0.969) compared to CT-MRTA-3D-MFI, aligning well with surgical findings. CTA/V-DTT-3D-MFI also exhibited higher sensitivity in identifying responsible vessels (98.0%) and NVC (98.7%) than CT-MRTA-3D-MFI. Additionally, CTA/V-DTT-3D-MFI showed fewer complications, shorter operation times, and lower recurrence after one year (all p < 0.05). Resident neurosurgeons emphasized that CTA/V-DTT-3D-MFI greatly assisted in formulating precise surgical strategies for more accurate identification and protection of responsible vessels and nerves (all p < 0.001).ConclusionCTA/V-DTT-3D-MFI enhances MVD surgery guidance, improving accuracy in identifying responsible vessels and NVC for better outcomes. This advanced imaging plays a crucial role in safer and more effective MVD surgery, as well as in training neurosurgeons.

Microvascular Decompression Using the Gelatin Sponge Insertion Technique for Trigeminal Neuralgia: A Retrospective Cohort Study.

Microvascular decompression (MVD) is the primary surgical intervention for trigeminal neuralgia (TN), with Teflon being the most conventional decompressing material. However, Teflon has been associated with adhesion and granulomas after MVD, which closely correlated with the recurrence of TN. Therefore, we developed a new technique to prevent direct contact between Teflon and nerve. The purpose of this study is to compare the efficacy of MVD using the gelatin sponge (GS) insertion technique with that of Teflon inserted alone in treating primary TN. We retrospectively analyzed the medical records and the follow-up data of 734 patients with unilateral primary TN who underwent MVD at our center from January 2014 to December 2019. After exclusions, we identified 313 cases of GS-inserted MVD and 347 cases of traditional MVD. The follow-up exceeded 3 years. The operating time of the GS-inserted group was longer than that of the Teflon group (109.38 ± 14.77 vs 103.53 ± 16.02 minutes, P < .001). There was no difference between 2 groups in immediate surgical outcomes and postoperative complications. The yearly recurrence rate for GS-inserted MVD was lower at first (1.0%), second (1.2%), and third (1.2%) years after surgery, compared with its counterpart of Teflon group (3.7%, 2.9%, and 1.7% respectively). The first-year recurrence rate (P = .031) and total recurrence rate in 3 years (P = .013) was significantly lower in the GS-inserted group than Teflon group. Kaplan-Meier survival analysis demonstrated better outcomes in GS-inserted MVD groups (P = .020). The application of the GS insertion technique in MVD reduced first-year postoperative recurrence of TN, with similar complications rates compared with traditional MVD.

Bilateral brain microstructural alterations in patients with left-sided classic trigeminal neuralgia: a diffusion kurtosis imaging study.

White matter microstructural abnormalities in patients with classic trigeminal neuralgia (TN) have been observed. However, the impact of classic TN in both hemispheres, the difference and extent of alterations in bilateral hemispheres, and the relationship between the impaired area and pain conduction are not fully understood. The purpose of this study was to investigate brain microstructural alterations and compare the bilateral hemispheres in patients with unilateral classic TN, as well as to explore their clinical implications. The authors performed a cross-sectional study of 36 patients with left classic TN (TN group; age 40-66 years) and 36 healthy controls (HC group; age 40-66 years). Diffusion kurtosis imaging (DKI; b-values = 0, 1250, and 2500 sec/mm2) was performed in all patients using a 3T MRI scanner. The FMRIB Software Library with tract-based spatial statistics was used to analyze intergroup differences in both hemispheres. Atlas-based region of interest analysis was conducted in fiber tracts and gray matter structures. Decreased fractional anisotropy (FA) and increased mean diffusivity in 2.70% and 5.34% of white matter regions, such as the corona radiata, corpus callosum, internal capsule, superior longitudinal fasciculus, and cingulum, were detected in the TN group compared with the HC group (p < 0.05, family-wise error correction). Reduced mean kurtosis (MK), axial kurtosis, and radial kurtosis were detected in the bilateral thalamus in TN patients. The FA and MK values decreased asymmetrically in both cerebral hemispheres. Atlas-based region of interest analysis revealed more pronounced FA and MK reductions in the left thalamus and posterior corona radiata. There were negative associations of disease duration and pain intensity with the MK values in the thalamus, internal capsule, and superior corona radiata. The authors concluded that unilateral TN could have asymmetrical microstructural alterations in bilateral hemispheres, which might be due to the compromised fiber tract integrity and abnormal neurons and synapses. The thalamus could be an important relay station in the pain conduction and modulation pathway and could have microstructural abnormalities in both the left and right sides. DKI could provide important information on the CNS pathophysiology of TN and assist in prognostic evaluation.

Sphenopalatine Ganglion Block Using Intranasal Lignocaine Spray for Trigeminal Neuralgia: A Case Series

Abstract Various interventions have been tried for the management of trigeminal neuralgia which is a sharp, shooting recurrent neuropathic pain. The use of the sphenopalatine ganglion (SPG) block has been established as a fast, safe, and effective means of pain relief for these patients. Recently, 10% lignocaine spray has been described as a less invasive alternative for this block. We report seven patients of idiopathic trigeminal neuralgia with acute unilateral severe pain managed by SPG blocks using 10% intranasal lignocaine spray. Seven patients with unilateral trigeminal neuralgia were included in the study. Two puffs of 10% lignocaine were sprayed into the nostril of the affected side in a slightly medial and inferior direction. Before the procedure and 30 min later, Visual Analog Scale (VAS) scoring was done. The procedure was repeated in case of no pain relief after 1 h of nasal spray (VAS 4 or 5). All patients were observed for 2 h and oral medication was prescribed if required after assessment at 24 h. Four patients reported complete relief (VAS 0 or 1) and two of them reported pain (VAS 4 and 5) after 24 h. The procedure had to be repeated in two patients with no pain relief (VAS 4 and 5) after 1 h. There was no relief in one patient even after repeated administration (VAS 5). The findings suggest a role for intranasal lignocaine spray for SPG block in trigeminal neuralgia for alleviating acute exacerbations of pain and obtaining quick relief.

Analyzing the risk factors of unilateral trigeminal neuralgia under neurovascular compression.

This study aimed to explore the risk factors and potential causes of unilateral classical or idiopathic trigeminal neuralgia (C-ITN) by comparing patients and healthy controls (HCs) with neurovascular compression (NVC) using machine learning (ML). A total of 84 C-ITN patients and 78 age- and sex-matched HCs were enrolled. We assessed the trigeminal pons angle and identified the compressing vessels and their location and severity. Machine learning was employed to analyze the cisternal segment of the trigeminal nerve (CN V). Among the C-ITN patients, 53 had NVC on the unaffected side, while 25 HCs exhibited bilateral NVC, and 24 HCs showed unilateral NVC. By comparing the cisternal segment of CN V between C-ITN patients on the affected side and HCs with NVC, we identified the side of NVC, the compressing vessel, and certain texture features as risk factors for C-ITN. Additionally, four texture features differed in the structure of the cisternal segment of CN V between C-ITN patients on the unaffected side and HCs with NVC. Our findings suggest that the side of NVC, the compressing vessel, and the microstructure of the cisternal segment of CN V are associated with the risk of C-ITN. Furthermore, microstructural changes observed in the cisternal segment of CN V on the unaffected side of C-ITN patients with NVC indicate possible indirect effects on the CN V to some extent.

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

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

Percutaneous balloon compression for trigeminal neuralgia: experience and surgical techniques from a single institution

ObjectiveThe treatment experience and the technical skill with percutaneous balloon compression (PBC) for treatment of primary trigeminal neuralgia (TN) were summarised in a single institution.MethodsThis is a retrospective review including consecutive patients with typical symptoms of uni-lateral primary TN who underwent PBC from June 2020 to September 2021 in our institution. We excluded secondary aetiologies of TN. Patient demographics, surgical techniques and outcomes were reviewed. All included patients were initially managed with carbamazepine before PBC.ResultsA total of 70 patients were included. The mean length of follow-up was 10.6 months. Sixty-nine (98.6%) were successfully treated, and only one patient failed due to particularly narrow foramen ovale. Amongst successfully treated patients, 68 (97.1%) had immediate pain relief, with one having delayed relief. Sixty-eight patients (97.1%) had immediate facial numbness post-operatively and one (1.4%) presented delayed numbness 7 days after surgery. In the last follow-up, regarding facial numbness, 22 (31.9%) patients had complete resolution, whilst 46 (67.6%) had different degrees of benefit. Forty-nine (71.0%) patients developed masseter muscle weakness with recovery at 3-month follow-up. No anaesthesia dolorosa, keratitis, intracranial infection or death occurred in this study.ConclusionPBC for treatment of TN has quick and effective result, and could be safely performed under general anaesthesia without discomfort to the patient. The common postoperative complications are facial numbness and masseter muscle weakness, with most being improved or recovered at follow-up.

Sex-Specific Pain Outcomes Following Microvascular Decompression for Trigeminal Neuralgia

Trigeminal neuralgia (TN) is more prevalent among women. However, while microvascular decompression (MVD) is the most effective long-term surgical treatment for TN, it is unclear whether it is equally efficacious for men and women. We sought to characterize the relationship between sex and pain outcomes following MVD for TN. From 2007 to 2020, 938 unilateral TN patients were treated with MVD at our institution. Patient demographics, clinical characteristics, operative features, and pain outcomes were recorded. Differences between men and women were analyzed via t-test and chi-squared analyses. A multivariate ordinal regression was used to establish significant predictors of pain outcome. Differences in time to pain recurrence were assessed via Cox proportional hazards and Kaplan-Meier nonparametric survival analysis. A majority (67%) of the 938 patients analyzed were female. Men and women presented with similar preoperative pain severity (P= 0.17). Female sex (P= 0.048) and younger age (P= 0.03) were independently associated with worsened Barrow Neurological Institute pain scores at 3-month follow-up on multivariate analysis. Women were also more likely to experience recurrence than men (P= 0.01), and time to recurrence was shorter among women (P= 0.02). Only female sex was independently associated with increased risk of postoperative pain recurrence on multivariate Cox proportional hazards regression (P= 0.01). Female TN patients undergoing MVD had worse pain outcomes, more frequent pain recurrence, and shorter time to recurrence. Our results indicate a sex-specific dimorphism in response to MVD among TN patients.

A TRPM7 mutation linked to familial trigeminal neuralgia: Omega current and hyperexcitability of trigeminal ganglion neurons.

Trigeminal neuralgia (TN) is a unique pain disorder in which affected individuals experience intense paroxysmal pain in the territory of the trigeminal nerve. Although most cases of TN are sporadic, occurrence of familial TN suggests a genetic contribution to this disorder. Here we used Ca2+ and Na+ imaging and whole-cell patch clamp to assess a variant in the TRPM7 channel kinase, p.Ala931Thr, found in a man suffering from unilateral TN. We found that A931T generated a 20-fold higher inward currents than TRPM7 WT and unchanged outward currents. The inward current recorded in A931T had the following properties: i) it was carried by Na+ ions under physiological conditions; ii) it was insensitive to the pore blocker Gd3+; iii) it was observed when Na+ was replaced by Guanidinium, but it was completely suppressed by application of NMDG+.

A TRPM7 mutation linked to familial trigeminal neuralgia: Omega current and hyperexcitability of trigeminal ganglion neurons

Trigeminal neuralgia (TN) is a unique pain disorder characterized by intense paroxysmal facial pain within areas innervated by the trigeminal nerve. Although most cases of TN are sporadic, familial clusters of TN suggest that genetic factors may contribute to this disorder. Whole-exome sequencing in patients with TN reporting positive family history demonstrated a spectrum of variants of ion channels including TRP channels. Here, we used patch-clamp analysis and Ca2+ and Na+ imaging to assess a rare variant in the TRPM7 channel, p.Ala931Thr, within transmembrane domain 3, identified in a man suffering from unilateral TN. We showed that A931T produced an abnormal inward current carried by Na+ and insensitive to the pore blocker Gd3+. Hypothesizing that replacement of the hydrophobic alanine at position 931 with the more polar threonine destabilizes a hydrophobic ring, near the voltage sensor domain, we performed alanine substitutions of F971 and W972 and obtained results suggesting a role of A931-W972 hydrophobic interaction in S3-S4 hydrophobic cleft stability. Finally, we transfected trigeminal ganglion neurons with A931T channels and observed that expression of this TRPM7 variant lowers current threshold and resting membrane potential, and increases evoked firing activity in TG neurons. Our results support the notion that the TRPM7-A931T mutation located in the S3 segment at the interface with the transmembrane region S4, generates an omega current that carries Na+ influx in physiological conditions. A931T produces hyperexcitability and a sustained Na+ influx in trigeminal ganglion neurons that may underlie pain in this kindred with trigeminal neuralgia.

Impact of unilateral trigeminal neuralgia on bilateral ocular surface alterations.

To evaluate ocular surface alterations in both eyes of patients with unilateral trigeminal neuralgia (TN) compared with controls. Corneal nerves mainly originate from the trigeminal nerve, and neurosensory abnormalities are important factors in ocular surface alterations and dry eye etiopathogenesis. Twenty-four patients with idiopathic unilateral TN and 24 healthy controls with similar sex and age distributions were included in this cross-sectional study conducted from February 15 to September 15, 2021. The eyes on the affected sides of the patients with TN were treated as Group 1, their contralateral eyes as Group 2, and the right eyes of the controls as Group 3. All participants were evaluated for tear film and ocular surface using the Schirmer 1 test, tear breakup time (TBUT), Ocular Surface Disease Index (OSDI) score, and conjunctival impression cytology grading. The mean (SD) ages of the patients with TN (17 of 24 females, 70.8%) and controls (15 of 24 females, 62.5%) were 49.7 (11.7) and 48.5 (9. 6) years, respectively. The median [25th, 75th percentile] Schirmer 1 test results in Groups 1, 2, and 3 were 5.0 [4.0, 14.0], 7.0 [3.2, 11.7], and 10.0 [6.0, 15.7] mm, respectively, with no statistically significant differences between Groups 1 and 2 (p=0.697), Groups 1 and 3 (p=0.133), or Groups 2 and 3 (p=0.129). The median TBUT scores in Groups 1, 2, and 3 were 7.0 [5.0, 10.0], 8.0 [5.2, 10.0], and 12.5 [8.0, 13.0] s, respectively, showing reduced times for both Groups 1 and 2 versus Group 3 (median difference=-3.0 [95% CI: -5.0, -1.0], p=0.001, and median difference=-3.0 [95% CI: -5.0, -2.0], p=0.001, respectively). Conjunctival impression cytology grades were significantly higher in Groups 1 and 2 versus Group 3 (median difference=2.0 [95% CI: 1.0, 2.0], p < 0.001, and median difference=1.0 [95% CI: 1.0, 2.0], p < 0.001, respectively). The median OSDI score in TN patients (30.2 [25.0, 34.9]) was significantly higher than in the controls (8.3 [0.0, 18.7]), with a median difference of 20.8 (95% CI: 14.7, 27.1), p < 0.001. Even if pain is unilateral in patients with TN, there are significant abnormalities in conjunctival cytology and tear functions in both eyes. There seem to be various pathophysiological mechanisms of TN that affect the bilateral ocular surface and lead to significant alterations.

Risk Factors for Unilateral Trigeminal Neuralgia Based on Machine Learning.

PurposeNeurovascular compression (NVC) is considered as the main factor leading to the classical trigeminal neuralgia (CTN), and a part of idiopathic TN (ITN) may be caused by NVC (ITN-nvc). This study aimed to explore the risk factors for unilateral CTN or ITN-nvc (UC-ITN), which have bilateral NVC, using machine learning (ML).MethodsA total of 89 patients with UC-ITN were recruited prospectively. According to whether there was NVC on the unaffected side, patients with UC-ITN were divided into two groups. All patients underwent a magnetic resonance imaging (MRI) scan. The bilateral cisternal segment of the trigeminal nerve was manually delineated, which avoided the offending vessel (Ofv), and the features were extracted. Dimensionality reduction, feature selection, model construction, and model evaluation were performed step-by-step.ResultsFour textural features with greater weight were selected in patients with UC-ITN without NVC on the unaffected side. For UC-ITN patients with NVC on the unaffected side, six textural features with greater weight were selected. The textural features (rad_score) showed significant differences between the affected and unaffected sides (p < 0.05). The nomogram model had optimal diagnostic power, and the area under the curve (AUC) in the training and validation cohorts was 0.76 and 0.77, respectively. The Ofv and rad_score were the risk factors for UC-ITN according to nomogram.ConclusionBesides NVC, the texture features of trigeminal-nerve cisternal segment and Ofv were also the risk factors for UC-ITN. These findings provided a basis for further exploration of the microscopic etiology of UC-ITN.

Predictability of Fused 3D-T2-SPACE and 3D-TOF-MRA Images in Identifying Conflict in Trigeminal Neuralgia.

PurposeTo evaluate the efficacy of fused three-dimensional T2 sampling perfection with application-optimized contrasts using different flip-angle evolutions (3D-SPACE) and three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) sequences for detecting neurovascular compression (NVC) in patients presenting with trigeminal neuralgia (TN).MethodsA prospective study was carried in 33 consecutive patients (m/f: 17/16; mean age, 56.3 ± 10.4 years) with unilateral TN confirmed NVC and consensus by two experienced radiologists on fused 3D-SPACE and 3D-TOF-MRA sequences of 3-tesla (3-T) MRI. All patients underwent microvascular decompression (MVD), using photos and video in surgery as documents compared with MRI. Both the MRI and MVD were reported for three grades (contact, compression, distortion), vessel types (artery or vein), identification of offending vessel, site (juxtapontine, cisternal, and juxtapetrous), and location (cranial, caudal, medial, lateral). Agreement between preoperative MRI visualization and surgical findings was assessed using the kappa (K) statistic.ResultsThe k-values for the agreement were excellent for the grade of NVC (k=0.82), vessel types (k=0.78), and location of conflict (k=0.74), and good for identification of the offending vessel (0.65) and the site-affected vessel (k=0.69).ConclusionThe fused D3-SPACE and 3D-TOF-MRA images are highly effective tools for the evaluation and treatment planning of NVC in TN patients.

Association between Trigeminal Neuralgia and Multiple Sclerosis: Role of Magnetic Resonance Imaging

Background: Trigeminal neuralgia (TN) is a severe neuropathic unilateral facial pain affecting about 30% percent of the world population. Neuropathic pains are considered to be associated with multiple sclerosis (MS).Multiple sclerosis is a chronic inflammatory condition causing demyelination and degeneration of axons in central nervous system. Objective: The objective of the study is to determine role of Magnetic Resonance Imaging to find association between trigeminal neuralgia and multiple sclerosis. Methods: The prospective cohort study was conducted for six months in Radiology Department of Hayatabad Medical Complex, Peshawar from September 2020 to February 2021. Initially 250 patients were screened for multiple sclerosis. The study recruited a total of 35 patients of MS visited neuroradiology department, out of which 26 patients were enrolled in the study. The participants with age of 18 years and onward of both genders with definitive symptoms of TN with MS that is having unilateral TN pain (that is sharp shooting electric pulse like) lasting for up-to 2minutes precipitated with an environmental stimulus were included in the study. The patients (n=6) with bilateral MS with TN and cognitive disturbances (n=3) were excluded from the study. Results: The study recruited a total of 26 participants with MS related TN. The clinical examination didn’t show any difference between the three groups with the p-value less than 0.001. Age at the onset of MS was younger in patients with MS related sensory disturbances compared to other two groups, with p-value less than 0.05. The frequency of the affected side was different in all three groups with the p-value less than 0.05 as tested by Fischer exact test. Trigeminal reflex tests done for different components such as R1 and SP1 showed longer latency periods for the affected side after stimulation and unaffected side after stimulation with the mean of 14.2± 4.4 and 15.3±3.2, 16.3±4.2 and 17.4±5.2ms and p-value less than 0.001 as shown by Wilcoxon test. Conclusion: The study showed significant association between trigeminal neuralgia and multiple sclerosis with the greater efficacy of using MRI as imaging technique to find this association. Keywords: Multiple sclerosis, Magnetic Resonance Imaging, Trigeminal neuralgia

MRI features of responsible contacts in vascular compressive trigeminal neuralgia and prediction modeling.

Multiple neurovascular contacts in patients with vascular compressive trigeminal neuralgia often challenge the diagnosis of responsible contacts. To analyze the magnetic resonance imaging (MRI) features of responsible contacts and establish a predictive model to accurately pinpoint the responsible contacts. Sixty-seven patients with unilateral trigeminal neuralgia were enrolled. A total of 153 definite contacts (45 responsible, 108 non-responsible) were analyzed for their MRI characteristics, including neurovascular compression (NVC) grading, distance from pons to contact (Dpons-contact), vascular origin of compressing vessels, diameter of vessel (Dvessel) and trigeminal nerve (Dtrigeminal nerve) at contact. The MRI characteristics of the responsible and non-responsible contacts were compared, and their diagnostic efficiencies were further evaluated using a receiver operating characteristic (ROC) curve. The significant MRI features were incorporated into the logistics regression analysis to build a predictive model for responsible contacts. Compared with non-responsible contacts, NVC grading and arterial compression ratio (84.44%) were significantly higher, Dpons-contact was significantly lower at responsible contacts (P < 0.001, 0.002, and 0.033, respectively). NVC grading had a highest diagnostic area under the ROC curve (AUC) of 0.742, with a sensitivity of 64.44% and specificity of 75.00%. The logistic regression model showed a higher diagnostic efficiency, with an AUC of 0.808, sensitivity of 88.89%, and specificity of 62.04%. Contact degree and position are important MRI features in identifying the responsible contacts of the trigeminal neuralgia. The logistic predictive model based on Dpons-contact, NVC grading, and vascular origin can qualitatively improve the prediction of responsible contacts for radiologists.

Small Posterior Cranial Fossa and Cerebellopontine Cistern Volumes Are Associated With Bilateral Trigeminal Neuralgia.

Objective: To investigate whether small volumes of the posterior cranial fossa and cerebellopontine cisterns are associated with bilateral trigeminal neuralgia (BTN) and to provide further knowledge regarding the etiology and treatment of this rare disease.Methods: We retrospectively analyzed clinical data and imaging examination results for 30 BTN patients between January 2009 and December 2019. Thirty age- and sex-matched healthy individuals and 30 patients with unilateral trigeminal neuralgia (UTN) were selected as two control groups. The volume of the posterior cranial fossa (VPCF) and volumes of the cerebellopontine cisterns were measured using ITK-SNAP 3.0, which considers the cerebrospinal fluid (CSF) volume based on the region of interest (ROI). Preoperative and postoperative statuses were based on visual analog scale (VAS) pain scores and Barrow Neurological Institute (BNI) scores.Results: A total of 30 patients (11 males; 19 females) were included, and the age of the BTN participants ranged from 41 to 77 (59.93 ± 9.89) years. The duration of TN ranged from 1 to 20 (5.36 ± 3.92) years, and the interval between the two sides ranged from 0 to 3 (1.10 ± 0.79) years. Three patients (10%) in the BTN group had familial trigeminal neuralgia, with no other hereditary history of neurological disorders. In BTN patients, with 25 (83.3%) cases on the left side and 26 (86.7%) on the right side, veins were identified in the operative field and regarded as the individual or offending vessel. The mean VPCF was significantly lower in the patients with BTN than in the healthy controls (4,813 ± 1,155 mm3 vs. 5,127 ± 1,129 mm3, p = 0.008). The volumes of the cerebellopontine cisterns on both sides were significantly smaller in the BTN patients than in the healthy controls (477 ± 115 mm3 vs. 515 ± 112 mm3 on the left side, p = 0.001; and 481 ± 114 mm3 vs. 515 ± 110 mm3 on the right side, p = 0.007). There was no significant difference between the BTN group and the UTN group in terms of the VPCF (4,843 ± 1,184 mm3 vs. 4,813 ± 1,155 mm3, p = 0.402), and there was also no significant difference between the two groups in terms of preoperative VAS pain scores or BNI scores.Conclusion: Overcrowding in the posterior fossa will lead to closer neurovascular relations and, a higher incidence of NVC, and ultimately may be more likely to lead to TN. Veins are the common offending vessels that cause BTN; they might be associated with abnormal vascular development leading to NVC. Microsurgical vascular decompression (MVD) is a safe and effective method for the treatment of BTN, similar to UTN.

Evaluation of trigeminal nerve tractography using two-fold-accelerated simultaneous multi-slice readout-segmented echo planar diffusion tensor imaging.

Simultaneous multi-slice (SMS) imaging with short repetition time (TR) accelerates diffusion tensor imaging (DTI) acquisitions. However, its impact when combined with readout-segmented echo planar imaging (RESOLVE) on the cranial nerves given the challenging skull base/posterior fossa terrain is unexplored. We evaluated the reliability of trigeminal nerve DTI metrics using SMS with RESOLVE-DTI. Eight healthy controls and six patients with unilateral trigeminal neuralgia (TN) underwent brain MRI scan. Three different RESOLVE-DTI protocols were performed on a 3-T MRI system: non-SMS (TR = 4330ms), SMS with identical TR (4330ms), and SMS with short TR (2400ms). Pontine signal-to-noise ratio (SNR) and DTI metrics of the trigeminal nerve streamlines tracked by two independent raters using deterministic tractography and standardized tracking protocol were obtained. These were statistically analyzed and compared across the three protocols using intra-rater and inter-rater intraclass correlation coefficients (ICCs), one-way analysis of variance (ANOVA), post hoc analysis, and linear regression. On visual screening, there were no artifacts across the trigeminal nerves. All data also cleared objective image quality assurance analysis. Pontine SNR was similar for the two SMS protocols and higher for the non-SMS RESOLVE-DTI (F(2,36) = 4.40, p = 0.02). Intra-rater and inter-rater ICCs were very good (> 0.85). Trigeminal nerve DTI metrics were consistently measured by the three protocols, revealing significant linear relationships between non-SMS- and SMS-derived DTI metrics. SMS RESOLVE-DTI enables fast and reliable evaluation of microstructural integrity of the trigeminal nerve, with potential application in the clinical management of TN. • Readout-segmented diffusion-weighted echo planar imaging (RESOLVE-DTI) reduces image distortion artifacts in the posterior fossa but its long acquisition time limits clinical utility. • Simultaneous multi-slice (SMS) imaging combined with RESOLVE-DTI provides reliable trigeminal nerve tractography with potential applications in trigeminal neuralgia. • Two-fold-accelerated RESOLVE-DTI yields comparable trigeminal nerve streamlines and DTI metrics while near-halving acquisition time.

Changes in the muscles of mastication before and after primary stereotactic radiosurgery in patients with idiopathic trigeminal neuralgia.

The motor root of the trigeminal nerve runs close to the sensory root and receives considerable radiation during Gamma Knife radiosurgery (GKRS) for trigeminal neuralgia (TN). The object of this study was to evaluate via MRI the changes in the muscles of mastication before and after upfront GKRS in patients with idiopathic TN. In this single-institution retrospective cohort study, all patients with idiopathic unilateral TN treated with primary GKRS at the University of Virginia in the period from 2007 to 2017 were included provided that they had pre- and post-GKRS MRI data. The thicknesses of the temporalis, pterygoid, and masseter muscles were measured on both pre- and post-GKRS MRI in a blinded fashion. Changes in the muscles like fatty infiltration, MRI signal, or atrophy were noted. Among the 68 patients eligible for inclusion in the study, 136 temporalis muscles, 136 medial pterygoid muscles, 136 lateral pterygoid muscles, and 136 masseter muscles were assessed. A subset of patients was found to have muscle atrophy even prior to GKRS. Pre-GKRS atrophy of the masseter, medial pterygoid, lateral pterygoid, and temporalis muscles was seen in 18 (26%), 16 (24%), 9 (13%), and 16 (24%) patients, respectively. Logistic regression analysis showed that distribution of pain in the V3 territory (p = 0.01, OR 5.43, 95% CI 1.46-20.12) and significant pain on chewing (p = 0.02, OR 5.32, 95% CI 1.25-22.48) were predictive of pre-GKRS atrophy. Reversal of atrophy of these muscles occurred after GKRS in a majority of the patients. The incidence of new-onset permanent post-GKRS muscle atrophy was 1.5%. The median follow-up was 39 months (range 6-108 months). A subset of patients with TN with significant pain on chewing have pre-GKRS disuse atrophy of the muscles of mastication. A reversal of the atrophy occurs in a majority of the patients following GKRS. New-onset motor neuropathy post-GKRS was rare.

Gamma Knife radiosurgery for bilateral trigeminal neuralgia

OBJECTIVEA small subset of patients with trigeminal neuralgia (TN) will experience bilateral symptoms. Treatment in these patients is controversial because the population is heterogeneous and patients may have nonvascular etiologies of their pain. This study reports treatment outcomes in the largest cohort of patients with bilateral TN who have undergone Gamma Knife radiosurgery (GKRS) to date.METHODSA retrospective chart review identified 51 individual nerves in 34 patients with bilateral TN who were treated with GKRS at the authors’ institution between 2001 and 2015, with 12 nerves in 11 patients undergoing repeat GKRS for recurrent or persistent symptoms. Long-term follow-up was obtained by telephone interview. Pain outcomes were measured using the Barrow Neurological Institute (BNI) pain scale, with BNI IIIb or better considered a successful treatment.RESULTSThere was sufficient follow-up to determine treatment outcomes for 48 individual nerves in 33 patients. Of these nerves, 42 (88%) achieved at least BNI IIIb pain relief. The median duration of pain relief was 1.9 years, and 1-, 3-, and 5-year pain relief rates were 64%, 44%, and 44%, respectively. No patients experienced bothersome facial numbness, and 1 case of anesthesia dolorosa and 2 cases of corneal dryness were reported. Patients with a history of definite or possible multiple sclerosis were significantly more likely to experience BNI IV–V relapse. There was no statistically significant difference in treatment outcomes between patients in this series versus a large cohort of patients with unilateral TN treated at the authors’ institution. There was sufficient follow-up to determine treatment outcomes for 11 individual nerves in 10 patients treated with repeat GKRS. Ten nerves (91%) improved to at least BNI IIIb after treatment. The median duration of pain relief was 2.8 years, with 1-, 3-, and 5-year rates of pain relief of 79%, 53%, and 53%, respectively. There was no statistically significant difference in outcomes between initial and repeat GKRS. One case of bothersome facial numbness and 1 case of corneal dryness were reported, with no patients developing anesthesia dolorosa with retreatment.CONCLUSIONSGKRS is a safe, well-tolerated treatment for patients with medically refractory bilateral TN. Efficacy of treatment appears similar to that in patients with unilateral TN. GKRS can be safely repeated in this population if necessary.

Minimally invasive trigeminal ablation in patients with refractory trigeminal neuralgia who are ineligible for intracranial intervention

We describe the use of minimally invasive trigeminal ablation, an endoscopic ablative technique to treat trigeminal neuralgia in patients who are traditionally poor surgical candidates. We present 4 patients who presented with refractory unilateral trigeminal neuralgia. Three of the patients had previously failed stereotactic radiosurgery and three of them have multiple sclerosis. Due either to lack of neurovascular compression, minimally invasive trigeminal ablation was offered. Intraoperatively, an incision is made along the buccal mucosa or mid-brow and the tissue is endoscopically dissected in a plane towards the symptomatic nerve. Once isolated, the epineurium is partially ablated with thermocautery and the tissue surrounding the nerve is decompressed. All patients reported resolution of their pain post-operatively and were pain free at last follow up. Two patients had mild hypesthesia over the ablated nerve territory.Minimally invasive trigeminal ablation is a safe and effective technique for symptomatic control of trigeminal neuralgia. The efficacy, low risk, and relative ease of the procedure makes it ideal for use in patients who are refractory to medical management and have no neurovascular compression, are unable to tolerate traditional surgery or have failed other therapies.