Classifier Using Pontine Radial Diffusivity and Symptom Duration Accurately Predicts Recurrence of Trigeminal Neuralgia After Microvascular Decompression: A Pilot Study and Algorithm Description

Advanced neuroimaging of the trigeminal nerve and the whole brain in trigeminal neuralgia: a systematic review

ABSTRACT

For trigeminal neuralgia (TN), a major role of imaging is to identify the causes, but recent studies demonstrated structural and microstructural changes in the affected nerve. Moreover, an increasing number of studies have reported central nervous system involvement in TN. In this systematic review, recent quantitative magnetic resonance imaging (MRI) studies of the trigeminal nerve and the brain in patients with TN were compiled, organized, and discussed, particularly emphasizing the possible background mechanisms and the interpretation of the results. A systematic search of quantitative MRI studies of the trigeminal nerve and the brain in patients with TN was conducted using PubMed. We included the studies of the primary TN published during 2013 to 2023, conducted for the assessment of the structural and microstructural analysis of the trigeminal nerve, and the structural, diffusion, and functional MRI analysis of the brain. Quantitative MRI studies of the affected trigeminal nerves and the trigeminal pathway demonstrated structural/microstructural alterations and treatment-related changes, which differentiated responders from nonresponders. Quantitative analysis of the brain revealed changes in the brain areas associated with pain processing/modulation and emotional networks. Studies of the affected nerve demonstrated evidence of demyelination and axonal damage, compatible with pathological findings, and have shown its potential value as a tool to assess treatment outcomes. Quantitative MRI has also revealed the possibility of dynamic microstructural, structural, and functional neuronal plasticity of the brain. Further studies are needed to understand these complex mechanisms of neuronal plasticity and to achieve a consensus on the clinical use of quantitative MRI in TN.

Trigeminal Neuralgia: Disease Characterization and Prediction of Response to Surgical Intervention

PURPOSE OF REVIEW

Trigeminal neuralgia (TN) is a highly heterogeneous condition with a wide choice of successful treatment options. However, differences between subtypes are poorly understood and it remains unknown which patients will respond to different treatments. This review aims to summarize the current state of the TN field and explore the problem of predicting surgical outcomes.

RECENT FINDINGS

Attempts have been made to standardize classification, outcome reporting, and treatment guidelines. Identification of risk factors for poor surgical treatment outcomes has led to the development of prognostic scoring systems to predict outcomes and guide management. Advances in imaging techniques including diffusion tensor imaging show promise in better understanding the underlying pathophysiology and predicting surgical outcomes. Progress is hampered by lack of understanding of the pathophysiology in TN and differences between disease subtypes. Further work needs to be done to create accurate prediction tools for widespread use, including use of advanced imaging and computing tools, multicenter collaboration, and prospective validation.

A novel potential measurement indicator with objective and quantitative effect for trigeminal neuralgia: fractional anisotropy in MR-DTI

Objectives

To investigate the effect of diffusivity metrics of magnetic resonance diffusion tensor imaging (MR-DTI) in the assessment of treatment effects.

Methods

MR-DTI examination for trigeminal neuralgia (TN) patients and the diffusivity metrics of the trigeminal ganglion (TG) were analyzed. Before and after the percutaneous stereotactic radiofrequency rhizotomy (PSR) operation, the treatment effect was assessed using pain scores and MR-DTI. The correlation between the diffusivity metrics of cranial nerve five (CNV) and visual analog scale (VAS) pain scores before and after treatment in TN patients was explored.

Results

In PSR patients, the fractional anisotropy (FA) of the affected TG is a significantly lower than that of the unaffected side (p < 0.01). After PSR, the diffusivity metrics on the bilateral TGs are not significantly different (p > 0.05). Following PSR treatment, both of the diffusivity metrics (FA) in the lowest area of the CNV and the VAS scores of TN patients show changes. Furthermore, diffusivity metric (FA) on the lowest area of the CNV preoperative is significantly negatively correlated with the VAS scores (p < 0.05).

Conclusion

MR-DTI is capable of investigating the longitudinal changes of FA before and after radiofrequency treatment, and diffusivity metrics could be an independent reliable efficacy indicator for TN.

Significance

The alteration of the diffusivity on TG may be correlated with the effect of radiofrequency treatment.

Pre-treatment DTI markers: predicting clinical outcomes in microvascular decompression for classic trigeminal neuralgia - a systematic review

BACKGROUND AND PURPOSE

Trigeminal neuralgia (TN) is a severe chronic pain condition, typically affecting patients over 50-year-old, caused by the compression of the nerve at the root entry zone (REZ) by blood vessels. While the diagnosis is clinical, advanced imaging like diffusion tensor imaging (DTI) is crucial to identify underlying causes and assessing nerve damage. DTI may help develop neuroimaging markers to improve understanding of TN and predict surgical outcomes. The goal of the present systematic review is to evaluate the effectiveness of DTI and tractography in order to better assess treatment planning and outcome prediction through the analysis of trigeminal nerve alterations.

METHODS

The authors conducted a systematic review and meta-analysis of the literature to compare radiological parameters identified in pre- and post-operative MRI with DTI sequences, including fractional anisotropy (FA), quantity of anisotropy (QA), radial diffusivity (RD), and to correlate these findings with post-operative clinical outcomes. A comprehensive search of the PubMed and Scopus databases was carried out for studies published between April 2010 and January 2024.

RESULTS

This review included 11 studies and 603 patients. Of the 363 patients with trigeminal neuralgia (TN), 193 underwent microvascular decompression (MVD), with 72.5% showing clinical improvement and 27.5% not improving, possibly due to chronic nerve damage. Four studies assessed radiological parameters before and after MVD, while two focused only on post-MVD data. The mean fractional anisotropy (FA) in affected nerves increased from 0.328 before MVD to 0.382 afterward. Five studies did not report postoperative outcomes, just comparing radiological parameters in TN patients versus healthy controls.

CONCLUSIONS

Recent studies show that MRI-DTI parameters, including FA, RD, and QA, are useful for diagnosing trigeminal neuralgia and predicting treatment outcomes. Lower FA and higher RD values indicate better results after surgery. More research is mandatory to guide treatment decisions and enhance patients' care.

Application research on the diagnosis of classic trigeminal neuralgia based on VB-Net technology and radiomics

BACKGROUND

This study aims to utilize the deep learning method of VB-Net to locate and segment the trigeminal nerve, and employ radiomics methods to distinguish between CTN patients and healthy individuals.

METHODS

A total of 165 CTN patients and 175 healthy controls, matched for gender and age, were recruited. All subjects underwent magnetic resonance scans. VB-Net was used to locate and segment the bilateral trigeminal nerve of all subjects, followed by the application of radiomics methods for feature extraction, dimensionality reduction, feature selection, model construction, and model evaluation.

RESULTS

On the test set for trigeminal nerve segmentation, our segmentation parameters are as follows: the mean Dice Similarity Coefficient (mDCS) is 0.74, the Average Symmetric Surface Distance (ASSD) is 0.64 mm, and the Hausdorff Distance (HD) is 3.34 mm, which are within the acceptable range. Analysis of CTN patients and healthy controls identified 12 features with larger weights, and there was a statistically significant difference in Rad_score between the two groups (p < 0.05). The Area Under the Curve (AUC) values for the three models (Gradient Boosting Decision Tree, Gaussian Process, and Random Forest) are 0.90, 0.87, and 0.86, respectively. After testing with DeLong and McNemar methods, these three models all exhibit good performance in distinguishing CTN from normal individuals.

CONCLUSIONS

Radiomics can aid in the clinical diagnosis of CTN, and it is a more objective approach. It serves as a reliable neurobiological indicator for the clinical diagnosis of CTN and the assessment of changes in the trigeminal nerve in patients with CTN.

A novel indicator to predict the outcome of percutaneous stereotactic radiofrequency rhizotomy for trigeminal neuralgia patients: diffusivity metrics of MR-DTI

Magnetic resonance-diffusion tensor imaging (MR-DTI) has been used in the microvascular decompression and gamma knife radiosurgery in trigeminal neuralgia (TN) patients; however, use of percutaneous stereotactic radiofrequency rhizotomy (PSR) to target an abnormal trigeminal ganglion (ab-TG) is unreported. Fractional anisotropy (FA), mean and radial diffusivity (MD and RD, respectively), and axial diffusivity (AD) of the trigeminal nerve (CNV) were measured in 20 TN patients and 40 healthy control participants immediately post PSR, at 6-months, and at 1 year. Longitudinal alteration of the diffusivity metrics and any correlation with treatment effects, or prognoses, were analyzed. In the TN group, either low FA (value < 0.30) or a decreased range compared to the adjacent FA (dFA) > 17% defined an ab-TG. Two-to-three days post PSR, all 15 patients reported decreased pain scores with increased FA at the ab-TG (P < 0.001), but decreased MD and RD (P < 0.01 each). Treatment remained effective in 10 of 14 patients (71.4%) and 8 of 12 patients (66.7%) at the 6-month and 1-year follow-ups, respectively. In patients with ab-TGs, there was a significant difference in treatment outcomes between patients with low FA values (9 of 10; 90%) and patients with dFA (2 of 5; 40%) (P < 0.05). MR-DTI with diffusivity metrics correlated microstructural CNV abnormalities with PSR outcomes. Of all the diffusivity metrics, FA could be considered a novel objective quantitative indicator of treatment effects and a potential indicator of PSR effectiveness in TN patients.

The role of artificial intelligence in the management of trigeminal neuralgia

Trigeminal neuralgia (TN) is the most frequent facial pain. It is difficult to treat pharmacologically and a significant amount of patients can become drug-resistant requiring surgical intervention. From an etiologically point of view TN can be distinguished in a classic form, usually due to a neurovascular conflict, a secondary form (for example related to multiple sclerosis or a cerebello-pontine angle tumor) and an idiopathic form in which no anatomical cause is identifiable. Despite numerous efforts to treat TN, many patients experience recurrence after multiple operations. This fact reflects our incomplete understanding of TN pathogenesis. Artificial intelligence (AI) uses computer technology to develop systems for extension of human intelligence. In the last few years, it has been a widespread of AI in different areas of medicine to implement diagnostic accuracy, treatment selection and even drug production. The aim of this mini-review is to provide an up to date of the state-of-art of AI applications in TN diagnosis and management.

Predictive value of preoperative magnetic resonance imaging structural and diffusion indices for the results of trigeminal neuralgia microvascular decompression surgery

PURPOSE

To explore the predictive value of preoperative magnetic resonance imaging structural and diffusion indices of the spinal trigeminal tract (SpTV) on the results of microvascular decompression (MVD) in patients with trigeminal neuralgia (TN).

METHODS

This retrospective study included patients diagnosed with TN and treated with MVD in the Jining First People's Hospital between January 2020 and January 2021. The patients were divided into good and poor results groups according to postoperative pain relief. Logistic regression analysis was performed to explore independent risk factors for poor results of MVD, and their predictive value was examined using receiver operating characteristic (ROC) curves.

RESULTS

A total of 97 TN cases were included, 24 cases with a poor result and 73 with a good result. They were comparable in demographic characteristics. Fractional anisotropy (FA) was lower (P < 0.001), and radial diffusivity (RD) was higher (P < 0.001) in the poor result group compared to the good result group. Patients in the good result group showed a higher proportion of grade 3 neurovascular contact (NVC) (39.7% vs. 16.7%, P = 0.001) and a lower RD (P < 0.001). The multivariate analysis showed that the RD of SpTV (OR = 0.000016, 95% CI: 0.000-0.004, P < 0.001) and NVC (OR = 8.07, 95% CI: 1.67-38.93, P = 0.009) were independently associated with poor results. The area under the curve (AUC) of RD and NVC were 0.848 and 0.710, and their combination achieved an AUC of 0.880.

CONCLUSION

NVC and RD of SpTV are independent risk factors for poor results after MVD surgery, and combining the NVC and RD might achieve relatively high predictive value for poor results.

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.

The Underlying Pathogenesis of Neurovascular Compression Syndromes: A Systematic Review

Neurovascular compression syndromes (NVC) are challenging disorders resulting from the compression of cranial nerves at the root entry/exit zone. Clinically, we can distinguish the following NVC conditions: trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia. Also, rare cases of geniculate neuralgia and superior laryngeal neuralgia are reported. Other syndromes, e.g., disabling positional vertigo, arterial hypertension in the course of NVC at the CN IX-X REZ and torticollis, have insufficient clinical evidence for microvascular decompression. The exact pathomechanism leading to characteristic NVC-related symptoms remains unclear. Proposed etiologies have limited explanatory scope. Therefore, we have examined the underlying pathomechanisms stated in the medical literature. To achieve our goal, we systematically reviewed original English language papers available in Pubmed and Web of Science databases before 2 October 2021. We obtained 1694 papers after eliminating duplicates. Only 357 original papers potentially pertaining to the pathogenesis of NVC were enrolled in full-text assessment for eligibility. Of these, 63 were included in the final analysis. The systematic review suggests that the anatomical and/or hemodynamical changes described are insufficient to account for NVC-related symptoms by themselves. They must coexist with additional changes such as factors associated with the affected nerve (e.g., demyelination, REZ modeling, vasculature pathology), nucleus hyperexcitability, white and/or gray matter changes in the brain, or disturbances in ion channels. Moreover, the effects of inflammatory background, altered proteome, and biochemical parameters on symptomatic NVC cannot be ignored. Further studies are needed to gain better insight into NVC pathophysiology.