Diffusion tensor and kurtosis imaging reveal microstructural changes in the trigeminal nerves of patients with trigeminal neuralgia.

OBJECTIVES: To evaluate the use of diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) for detection of microstructural changes in the trigeminal nerves of trigeminal neuralgia (TN) patients. METHODS: Forty TN patients and 40 healthy controls were examined using 3 T magnetic resonance imaging (MRI) to evaluate DTI and DKI parameters in trigeminal nerves. One-way ANOVA was used to test the differences in age, sex, and DTI and DKI parameters between the TN-affected sides, TN-unaffected sides, and controls. For parameters with inter-group differences, pairwise comparisons were performed. Then, the difference ratios (DRs) of the parameters with statistical differences were calculated and used for the receiver operating characteristic (ROC) analysis to assess their diagnostic performance. In addition, for the DTI and DKI parameter values with differences, we used pure DTI and DKI values to perform the ROC analysis. RESULTS: Compared to the unaffected sides and controls, the FA, MK, and Kr of the affected sides of TN patients were significantly reduced, while ADC was significantly increased (p < 0.05). The diagnostic efficiency of the FA DRs (AUC: 0.974; cutoff value: 0.038; sensitivity: 100%; specificity: 95.0%) was the highest among all DTI and DKI parameters. The DRs of FA and MK more efficiently diagnosed TN than pure FA and MK values. CONCLUSIONS: DTI and DKI allowed detection of microstructural changes in TN-affected trigeminal nerves. FA DR was the best independent predictor of microstructural changes in TN. CLINICAL RELEVANCE STATEMENT: Both DTI and DKI can be used for noninvasive quantitative evaluation of the changes in the microstructure of the cisternal segment of the cranial nerves in clinical practice. KEY POINTS: • Diffusion tensor imaging (DTI) can be used to evaluate the in vivo integrity of white matter and nerve fiber pathway. • Diffusion kurtosis imaging (DKI) has been shown to be considerable sensitive to microstructural changes. • DTI combined with DKI can comprehensively evaluate the status of the TN-affected trigeminal nerve.

Probabilistic tractography of the extracranial branches of the trigeminal nerve using diffusion tensor imaging.

PURPOSE: The peripheral course of the trigeminal nerves is complex and spans multiple bony foramen and tissue compartments throughout the face. Diffusion tensor imaging of these nerves is difficult due to the complex tissue interfaces and relatively low MR signal. The purpose of this work is to develop a method for reliable diffusion tensor imaging-based fiber tracking of the peripheral branches of the trigeminal nerve. METHODS: We prospectively acquired imaging data from six healthy adult participants with a 3.0-Tesla system, including T2-weighted short tau inversion recovery with variable flip angle (T2-STIR-SPACE) and readout segmented echo planar diffusion weighted imaging sequences. Probabilistic tractography of the ophthalmic, infraorbital, lingual, and inferior alveolar nerves was performed manually and assessed by two observers who determined whether the fiber tracts reached defined anatomical landmarks using the T2-STIR-SPACE volume. RESULTS: All nerves in all subjects were tracked beyond the trigeminal ganglion. Tracts in the inferior alveolar and ophthalmic nerve exhibited the strongest signal and most consistently reached the most distal landmark (58% and 67%, respectively). All tracts of the inferior alveolar and ophthalmic nerve extended beyond their respective third benchmarks. Tracts of the infraorbital nerve and lingual nerve were comparably lower-signal and did not consistently reach the furthest benchmarks (9% and 17%, respectively). CONCLUSION: This work demonstrates a method for consistently identifying and tracking the major nerve branches of the trigeminal nerve with diffusion tensor imaging.

Primary neurolymphomatosis of the trigeminal nerve.

We report a case of a primary malignant lymphoma of the trigeminal nerve that was associated with facial pain. A 65-year-old man was examined at another hospital for unilateral facial pain. Carbamazepine was prescribed, but his symptoms did not improve. Magnetic resonance imaging (MRI) revealed swelling of the trigeminal nerve and a mass lesion in Meckel's cave. The patient was referred to our hospital at this point. Gadolinium-enhanced MRI and F18-Fluorodeoxyglucose-position emission tomography suggested a likely malignant tumour and a biopsy was performed. Histopathological examination showed diffuse a large B cell lymphoma. The patient was treated with high-dose methotrexate (HD-MTX) and radiotherapy. Despite responding well to initial treatment, the patient relapsed, with lymphoma observed throughout the body. He died of pneumonia 18 months after the initial diagnosis. Facial pain is a symptom that is commonly managed in general practice. If symptoms do not improve, repeated imaging studies, including contrast MRI, is warranted. This is the first reported case of primary neurolymphomatosis (NL) of the trigeminal nerve associated with facial pain alone. Furthermore, HD-MTX and radiotherapy may be considered for the management of primary NL of a cranial nerve.

Trigeminal hybrid nerve sheath tumor - a case report and literature review.

BACKGROUND: Hybrid nerve sheath tumors (HNST) contain elements of more than one established sub-type of nerve sheath tumor and have been recently recognized in the 2016 WHO classification of central nervous system tumors. While common in the peripheral nerves and extracranial branches of cranial nerves, only one case has been previously documented of an intracranial HNST arising from a cranial nerve. CASE DESCRIPTION: We describe a large, multi-compartmental intracranial hybrid nerve sheath tumor arising from the trigeminal nerve in a 22-year-old lady who presented with clinical and radiological features suggestive of a right cerebellopontine angle mass. Histopathological examination following retrosigmoid excision of the tumor revealed histological and immunohistochemical features of a schwannoma and a perineurioma. CONCLUSIONS: HNSTs are likely to be underreported in the intracranial region. The clinical course of these tumors and the reason for their occurrence in this location are not known.

Significance of different offending vessels and development of a potential screening tool for trigeminal neuralgia.

OBJECTIVES: This study was performed amongst trigeminal neuralgia (TN) patients with neurovascular contact (NVC) to 1) investigate the association of the demographic and radiologic factors/variables with TN occurrence, and 2) develop a screening tool for TN/TN-affected nerves based on the factors/variables associated with it. METHODS: Eighty-five TN patients were recruited, and 121 trigeminal nerves with NVC were derived from them. Based on MRI sequences, including balanced turbo field echo and enhanced T1 high-resolution isotropic volume excitation, radiologic factors/variables for each nerve, from the offending vessel to the presence of nerve displacement, were identified by a neuroradiologist and a neurosurgeon. Demographic and clinical data were obtained from clinical notes. Logistic regression was performed to assess the association of the factors/variables with TN occurrence (i.e., affected vs. unaffected nerves). RESULTS: Three factors/variables were significantly (p < 0.05) associated with TN occurrence amongst patients with NVC: nerve laterality, vertebral artery (VA) involvement, and the presence of nerve displacement. The nerves with VA involvement, those on the right side, and those with nerve displacement exhibited a significantly higher likelihood/odd of being affected by TN, compared to those without VA involvement, those on the left side, and those without nerve displacement, respectively. Based on these factors/variables, a screening tool/nomogram with acceptable accuracy was established (C-statistic/AUC = 0.80). CONCLUSIONS: This study revealed an association of the three radiologic factors/variables with TN occurrence. A screening tool for TN/TN-affected nerves was established based on them. The findings may lay a foundation for an improvement of the diagnosis and clinical management of TN. KEY POINTS: • VA involvement and nerve displacement could be identified using MRI, and are significantly associated with TN occurrence. • A potential objective screening tool/nomogram for TN/TN-affected nerves could be established based on the three radiologic factors/variables: VA involvement, the presence of nerve displacement, and nerve laterality. • The screening accuracy of the tool/nomogram is acceptable as the C-statistic is 0.80.

Correlation study between multiplanar reconstruction trigeminal nerve angulation and trigeminal neuralgia.

OBJECTIVES: Neurovascular 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. METHODS: Patients 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. RESULT: Ultimately, 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). CONCLUSIONS: This 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.

Microvascular decompression in trigeminal neuralgia with the offending artery transfixing the nerve: a case report.

BACKGROUND: An anterior inferior cerebellar artery (AICA) that crosses the right trigeminal nerve is an uncommon arterial anatomic variation. In this anatomical position, it is difficult to separate or move the offending blood vessels and nerves. We report an uncommon case of trigeminal neuralgia (TN) caused by compression of the trigeminal ganglion by a branch of the AICA. CASE PRESENTATION: A 34-year-old man with 5 years history who complained of pain on the right side of the face (area V1). The symptoms gradually worsened, and the pain episodes became intense and frequent. Magnetic resonance imaging (MRI) of the cerebrum showed a small blood vessel passing through the right trigeminal nerve. Microvascular decompression (MVD) was performed,because medication was ineffective. Intraoperative exploration confirmed that the vessel which was a branch of the AICA passing through the right trigeminal nerve. As while the artery was temporarily clipped, electrophysiological monitoring showed a decrease in the amplitude of nerve activity. As the artery was considered too important to be sacrificed, the space between the nerves was enlarged mildly, the artery was liberated, the Teflon implant was shredded and placed between the artery branches and nerve to make the blood vessels as perpendicular as possible to the nerve. The patient had no neurological dysfunction and no pain after 8 months of follow-up. CONCLUSION: MVD is an effective treatment for artery-induced trigeminal nerve compression, but we report a novel procedure that avoids the complication of facial numbness caused by cutting the offending vessels and incision of the trigeminal nerve.

Identifying symptomatic trigeminal nerves from MRI in a cohort of trigeminal neuralgia patients using radiomics.

INTRODUCTION: Trigeminal neuralgia (TN) is a devastating neuropathic condition. This work tests whether radiomics features derived from MRI of the trigeminal nerve can distinguish between TN-afflicted and pain-free nerves. METHODS: 3D T1- and T2-weighted 1.5-Tesla MRI volumes were retrospectively acquired for patients undergoing stereotactic radiosurgery to treat TN. A convolutional U-net deep learning network was used to segment the trigeminal nerves from the pons to the ganglion. A total of 216 radiomics features consisting of image texture, shape, and intensity were extracted from each nerve. Within a cross-validation scheme, a random forest feature selection method was used, and a shallow neural network was trained using the selected variables to differentiate between TN-affected and non-affected nerves. Average performance over the validation sets was measured to estimate generalizability. RESULTS: A total of 134 patients (i.e., 268 nerves) were included. The top 16 performing features extracted from the masks were selected for the predictive model. The average validation accuracy was 78%. The validation AUC of the model was 0.83, and sensitivity and specificity were 0.82 and 0.76, respectively. CONCLUSION: Overall, this work suggests that radiomics features from MR imaging of the trigeminal nerves correlate with the presence of pain from TN.

Pediatric benign triton tumor of trigeminal nerve: a case report and literature review.

PURPOSE: Benign triton tumors (BTTs) in the pediatric population are extremely rare occurrences. Paucity of data on BTTs poses both diagnostic and therapeutic challenges, particularly when found intracranially. METHODS: A case report of a 10-year-old male diagnosed with incidental maxillary trigeminal (V2) BTT is presented. We discuss radiographic and histopathological interpretations. Furthermore, we provide a brief review of current literature and historical background on pediatric trigeminal BTT diagnosis, histopathology, and management. RESULTS: Successful gross total resection of the tumor was achieved via Dolenc approach to the cavernous sinus. Management options with consideration of outcomes from the few prior cases reported in the literature are presented. CONCLUSION: Treatment of trigeminal nerve tumors requires a broad differential diagnosis and understanding rare tumors is essential in the diagnosis and treatment algorithm.

Morphometric examination of trigeminal nerve and its adjacent structures in patients with trigeminal neuralgia: a case-control study.

BACKGROUND: Morphological differences that can lead the trigeminal nerve to neurovascular conflict and a new solitary pontine lesion are associated with the pathogenesis of trigeminal neuralgia (TN). In this case-control study, we aimed to contribute to the current discussions about the pathogenesis of TN by investigating the anatomical structures that may have an effect on the morphometric parameters of the trigeminal nerve. METHODS: This study included 25 patients with TN followed up for pain in the Department of Algology, Faculty of Medicine, and 25 age- and gender-matched controls. We performed morphometric measurements including the length and volume of the trigeminal nerve, cerebellopontine cistern, pons, and posterior fossa in the MRIs of these individuals. Comparative analyses were performed for the mean of the affected and unaffected sides of the TN patients and the right, left, and both sides of the control group. RESULTS: In patients with TN, on the affected side, length and volume of the trigeminal nerve and cerebellopontine cistern volume were found smaller than controls (p < 0.05). Pons volume was higher in patients with TN compared to controls (p < 0.05). The length of the affected nerve was significantly related to prepontine cistern length and cerebellopontine cistern volume (p < 0.05). DISCUSSION: The cerebellopontine cistern volume has a significant impact on the morphometric characteristics of the trigeminal nerve. Especially, whether the increase in the volume of pons causes a decrease in the volume of cerebellopontine cistern should be clarified with further research.

High spatial resolution nerve-specific DTI protocol outperforms whole-brain DTI protocol for imaging the trigeminal nerve in healthy individuals.

Diffusion tensor imaging (DTI) can provide markers of axonal micro-structure of the trigeminal nerve (cranial nerve five [CNV]), which may be affected in trigeminal neuralgia (TN) and other disorders. Previous attempts to image CNV have used low spatial resolution DTI protocols designed for whole-brain acquisition that are susceptible to errors from partial volume effects, particularly with adjacent cerebrospinal fluid (CSF). The purpose of this study was to develop a nerve-specific DTI protocol in healthy subjects that provides more accurate CNV tractography and diffusion quantification than whole-brain protocols. Four DTI protocols were compared in five healthy individuals (age 22-45 years, three males) on a 3 T Siemens Prisma MRI scanner: two newly developed nerve-specific high resolution (1.2 x 1.2 x 1.2 = 1.7 mm3 ) DTI protocols without (3.5 minutes) and with CSF suppression (fluid-attenuated inversion recovery [FLAIR]; 7.5 minutes) with limited slice-coverage, and two typical whole-brain protocols with either isotropic (2 x 2 x 2 = 8 mm3 ) or thicker slice anisotropic (1.9 x 1.9 x 3 = 10.8 mm3 ) voxels. Deterministic tractography was used to identify the CNV and quantify bilateral fractional anisotropy (FA), and mean (MD), axial (AD) and radial diffusivity (RD). CNV volume was determined by manual tracing on T1-weighted images. High spatial resolution nerve-specific protocols yielded better delineation of CNV, with less distortions and blurring, and markedly different diffusion parameters (42% higher FA, 35% lower MD, 27% lower RD and 43% lower AD) compared with the two lower resolution whole-brain protocols. The anisotropic whole-brain protocol showed a positive correlation between CNV FA and volume. The high resolution nerve-specific protocol with FLAIR yielded additional reductions in CNV AD and MD with a value of 1.0 x 10-3 mm2 /s, approaching that expected for healthy young adult white matter. In conclusion, high resolution nerve-specific DTI with FLAIR enhances the identification of CNV and provides more accurate quantification of diffusion compared with lower resolution whole-brain approaches.

The impact of edema and fiber crossing on diffusion MRI metrics assessed in an ex vivo nerve phantom: Multi-tensor model vs. diffusion orientation distribution function.

Diffusion tensor imaging (DTI) has been employed for over 2 decades to noninvasively quantify central nervous system diseases/injuries. However, DTI is an inadequate simplification of diffusion modeling in the presence of coexisting inflammation, edema and crossing nerve fibers. We employed a tissue phantom using fixed mouse trigeminal nerves coated with various amounts of agarose gel to mimic crossing fibers in the presence of vasogenic edema. Diffusivity measures derived by DTI and diffusion basis spectrum imaging (DBSI) were compared at increasing levels of simulated edema and degrees of fiber crossing. Furthermore, we assessed the ability of DBSI, diffusion kurtosis imaging (DKI), generalized q-sampling imaging (GQI), q-ball imaging (QBI) and neurite orientation dispersion and density imaging to resolve fiber crossing, in reference to the gold standard angles measured from structural images. DTI-computed diffusivities and fractional anisotropy were significantly confounded by gel-mimicked edema and crossing fibers. Conversely, DBSI calculated accurate diffusivities of individual fibers regardless of the extent of simulated edema and degrees of fiber crossing angles. Additionally, DBSI accurately and consistently estimated crossing angles in various conditions of gel-mimicked edema when compared with the gold standard (r2 = 0.92, P = 1.9 × 10-9 , bias = 3.9°). Small crossing angles and edema significantly impact the diffusion orientation distribution function, making DKI, GQI and QBI less accurate in detecting and estimating fiber crossing angles. Lastly, we used diffusion tensor ellipsoids to demonstrate that DBSI resolves the confounds of edema and crossing fibers in the peritumoral edema region from a patient with lung cancer metastasis, while DTI failed. In summary, DBSI is able to separate two crossing fibers and accurately recover their diffusivities in a complex environment characterized by increasing crossing angles and amounts of gel-mimicked edema. DBSI also indicated better angular resolution compared with DKI, QBI and GQI.

Greater occipital nerve block modulates nociceptive signals within the trigeminocervical complex.

INTRODUCTION: The pharmacological block of the greater occipital nerve has been proven effective in numerous headache and facial pain syndromes. This clinical effect supports the hypothesis of a strong functional interaction between the occipital and trigeminal nerves which has been proposed in neurophysiological in vivo experiments in rodents. Although it is likely that the interaction has to occur in the central nervous system, the exact site and the mechanisms of the interaction remain largely unknown. METHODS: Focusing on these questions we investigated in a double-blind, placebo-controlled, randomised study the influence of an occipital nerve block with lidocaine 1% on neuronal activation in the trigeminocervical complex using high-resolution functional magnetic resonance on a 3T scanner. In order to investigate potential clinical effects on the trigeminal nerve, we further performed quantitative sensory testing and analysed a potential shift in thermal detection and pain thresholds. RESULTS: The pharmacological block of the greater occipital nerve induced an occipital anaesthesia ipsilateral to the block. Functional imaging revealed that the occipital injection of lidocaine but not placebo significantly reduced nociceptive trigeminal activation. CONCLUSIONS: These data suggest that the functional inhibition of the occipital nerve block on trigeminal nociceptive activity is likely to occur at the C2 level where the occipital nerve enters the trigeminocervical complex and converges on the same central nuclei before the signal crosses the midline at that level and is then transmitted to higher processing centres.

Clinical and molecular evaluation of 13 Brazilian patients with Gomez-López-Hernández syndrome.

We aim to characterize patients with Gomez-López-Hernández syndrome (GLHS) clinically and to investigate them molecularly. A clinical protocol, including a morphological and neuropsychological assessment, was applied to 13 patients with GLHS. Single-nucleotide polymorphism (SNP) array and whole-exome sequencing were undertaken; magnetic resonance imaging was performed in 12 patients, including high-resolution, heavily T2-weighted sequences (HRT2) in 6 patients to analyze the trigeminal nerves. All patients presented alopecia; two did not present rhombencephalosynapsis (RES); trigeminal anesthesia was present in 5 of the 11 patients (45.4%); brachycephaly/brachyturricephaly and mid-face retrusion were found in 84.6 and 92.3% of the patients, respectively. One patient had intellectual disability. HRT2 sequences showed trigeminal nerve hypoplasia in four of the six patients; all four had clinical signs of trigeminal anesthesia. No common candidate gene was found to explain GLHS phenotype. RES does not seem to be an obligatory finding in respect of GLHS diagnosis. We propose that a diagnosis of GLHS should be considered in patients with at least two of the following criteria: focal non-scarring alopecia, rhombencephalosynapsis, craniofacial anomalies (brachyturrycephaly, brachycephaly or mid-face retrusion), trigeminal anesthesia or anatomic abnormalities of the trigeminal nerve. Studies focusing on germline whole genome sequencing or DNA and/or RNA sequencing of the alopecia tissue may be the next step for the better understanding of GLHS etiology.

Neurovascular contact plays no role in trigeminal neuralgia secondary to multiple sclerosis.

INTRODUCTION: A demyelinating plaque and neurovascular contact with morphological changes have both been suggested to contribute to the etiology of trigeminal neuralgia secondary to multiple sclerosis (TN-MS). The aim of this study was to confirm or refute whether neurovascular contact with morphological changes is involved in the etiology of TN-MS. METHODS: We prospectively enrolled consecutive TN-MS patients from the Danish Headache Center. Clinical characteristics were collected systematically. MRI scans were done using a 3.0 Tesla imager and were evaluated by the same experienced blinded neuroradiologist. RESULTS: Sixty-three patients were included. Fifty-four patients were included in the MRI analysis. There was a low prevalence of neurovascular contact with morphological changes on both the symptomatic side (6 (14%)) and the asymptomatic side (4 (9%)), p = 0.157. Demyelinating brainstem plaques along the trigeminal afferents were more prevalent on the symptomatic side compared to the asymptomatic side (31 (58%) vs. 12 (22%), p < 0.001). A demyelinating plaque was highly associated with the symptomatic side (odds ratio = 10.6, p = 0.002). CONCLUSION: The primary cause of TN-MS is demyelination along the intrapontine trigeminal afferents. As opposed to classical trigeminal neuralgia, neurovascular contact does not play a role in the etiology of TN-MS. Microvascular decompression should generally not be offered to patients with TN-MS.The study was registered at ClinicalTrials.gov (number NCT04371575).

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

OBJECTIVES: 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. METHODS: 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 = 4330 ms), SMS with identical TR (4330 ms), and SMS with short TR (2400 ms). 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. RESULTS: 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. CONCLUSION: SMS RESOLVE-DTI enables fast and reliable evaluation of microstructural integrity of the trigeminal nerve, with potential application in the clinical management of TN. KEY POINTS: • 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.

Trigeminal neurovascular contact in SUNCT and SUNA: a cross-sectional magnetic resonance study.

Emerging data-points towards a possible aetiological and therapeutic relevance of trigeminal neurovascular contact in short lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and perhaps in short lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA). We aimed to assess the prevalence and significance of trigeminal neurovascular contact in a large cohort of consecutive SUNCT and SUNA patients and evaluate the radiological differences between them. The standard imaging protocol included high spatial and nerve-cistern contrast resolution imaging acquisitions of the cisternal segments of the trigeminal nerves and vessels. MRI studies were evaluated blindly by two expert evaluators and graded according to the presence, location and degree of neurovascular contact. The degree of contact was graded as with or without morphological changes. Neurovascular contact with morphological changes was defined as contact with distortion and/or atrophy. A total of 159 patients (SUNCT = 80; SUNA = 79) were included. A total of 165 symptomatic and 153 asymptomatic trigeminal nerves were analysed. The proportion of neurovascular contact on the symptomatic trigeminal nerves was higher (80.0%) compared to the asymptomatic trigeminal nerves (56.9%). The odds on having neurovascular contact over the symptomatic nerves was significantly higher than on the asymptomatic nerves [odds ratio (OR): 3.03, 95% confidence interval (CI) 1.84-4.99; P < 0.0001]. Neurovascular contact with morphological changes were considerably more prevalent on the symptomatic side (61.4%), compared to the asymptomatic side (31.0%) (OR 4.16, 95% CI 2.46-7.05; P < 0.0001). On symptomatic nerves, neurovascular contact with morphological changes was caused by an artery in 95.0% (n = 77/81). Moreover, the site of contact and the point of contact around the trigeminal root were respectively proximal in 82.7% (67/81) and superior in 59.3% (48/81). No significant radiological differences emerged between SUNCT and SUNA. The multivariate analysis of radiological predictors associated with the symptomatic side, indicated that the presence of neurovascular contact with morphological changes was strongly associated with the side of the pain (OR: 2.80, 95% CI 1.44-5.44; P = 0.002) even when adjusted for diagnoses. Our findings suggest that neurovascular contact with morphological changes is involved in the aetiology of SUNCT and SUNA. Along with a similar clinical phenotype, SUNCT and SUNA also display a similar structural neuroimaging profile, providing further support for the concept that the separation between them should be abandoned. Furthermore, these findings suggest that vascular compression of the trigeminal sensory root, may be a common aetiological factor between SUNCT, SUNA and trigeminal neuralgia thereby further expanding the overlap between these disorders.

Prediction of trigeminal nerve position based on the main feeding artery in petroclival meningioma.

The trigeminal nerve is often displaced by petroclival meningioma (PCM) compression, making it difficult to locate during PCM surgery. This study investigated whether the deviated position of the trigeminal nerve could be easily predicted using the main tumor feeding artery. We retrospectively examined 32 patients who underwent surgery for primary PCM. The deviation of the trigeminal nerve was classified as either Type 1 (displacement toward the back of the cerebellar tentorium), Type 2 (toward the back of the superior petrosal sinus), Type 3 (toward the back of the petrous apex dura), Type 4 (toward the inferior aspect of the tumor), or Type 5 (toward the surface of the brain stem). The main feeding artery was determined by preoperative angiography. The trigeminal nerve was classified as Type 2 in 60% of cases where the proximal tentorial artery (TA) was the main feeding vessel. The nerve was Type 5 where the distal portion of the TA was the main feeding vessel (60% of the cases). The nerves were Type 3 and Type 4 where the proximal inferior lateral trunk (ILT) (60%) and distal ILT (75%), respectively, were the main feeding vessels. In 66.7% of the cases where the dorsal meningeal artery was the main feeding vessel, the nerve was Type 3. Type 1 classification applied in all cases where the ascending pharyngeal artery was the main feeding artery. The main feeding artery can be used to predict trigeminal nerve transposition during PCM surgery.

[Trigeminal nerve lipoma presenting with trigeminal neuralgia: case report and literature review]. / Lipoma koreshka troinichnogo nerva, proyavlyayushchayasya trigeminal'noi nevralgiei: opisanie klinicheskogo nablyudeniya i obzor literatury.

Cerebellopontine angle lipomas are benign mass lesions and rarely result trigeminal neuralgia. A 61-year-old male with right-sided trigeminal neuralgia in V2 and V3 divisions without sensory disturbances is reported in the article. MRI revealed mass lesion 11´11´4 mm on the lateral pontine surface spreading to the right trigeminal nerve root entry zone. No signs of neurovascular compression were found. Microsurgical exploration of the cerebellopontine angle showed a fatty mass adherent to the brainstem with incorporation of inferior part of trigeminal nerve root. Fatty tissue resection was followed by partial sensory trigeminal rhizotomy. Histological examination identified lipoma. Postoperative MRI showed small residual tissue with minimal ischemic area near trigeminal nerve root entry zone. Mild hypoesthesia within V2 and V3 trigeminal branches occurred after surgery. Trigeminal neuralgia completely resolved, and medications were discontinued. This clinical case and literature review clearly demonstrated successful elimination of trigeminal neuralgia in patients with cerebellopontine angle lipoma after resection of mass lesion and partial trigeminal rhizotomy.

Creation of a novel trigeminal tractography atlas for automated trigeminal nerve identification.

Diffusion MRI (dMRI) tractography has been successfully used to study the trigeminal nerves (TGNs) in many clinical and research applications. Currently, identification of the TGN in tractography data requires expert nerve selection using manually drawn regions of interest (ROIs), which is prone to inter-observer variability, time-consuming and carries high clinical and labor costs. To overcome these issues, we propose to create a novel anatomically curated TGN tractography atlas that enables automated identification of the TGN from dMRI tractography. In this paper, we first illustrate the creation of a trigeminal tractography atlas. Leveraging a well-established computational pipeline and expert neuroanatomical knowledge, we generate a data-driven TGN fiber clustering atlas using tractography data from 50 subjects from the Human Connectome Project. Then, we demonstrate the application of the proposed atlas for automated TGN identification in new subjects, without relying on expert ROI placement. Quantitative and visual experiments are performed with comparison to expert TGN identification using dMRI data from two different acquisition sites. We show highly comparable results between the automatically and manually identified TGNs in terms of spatial overlap and visualization, while our proposed method has several advantages. First, our method performs automated TGN identification, and thus it provides an efficient tool to reduce expert labor costs and inter-operator bias relative to expert manual selection. Second, our method is robust to potential imaging artifacts and/or noise that can prevent successful manual ROI placement for TGN selection and hence yields a higher successful TGN identification rate.