Absence of Meckel Cave: A Rare Cause of Trigeminal Neuralgia

A combined radiomics and anatomical features model enhances MRI-based recognition of symptomatic nerves in primary trigeminal neuralgia

Background

The diagnosis of primary trigeminal neuralgia (PTN) in radiology lacks the gold standard and largely depends on the identification of neurovascular compression (NVC) using magnetic resonance imaging (MRI) water imaging sequences. However, relying on this imaging sign alone often fails to accurately distinguish the symptomatic side of the nerve from asymptomatic nerves, and may even lead to incorrect diagnoses. Therefore, it is essential to develop a more effective diagnostic tool to aid radiologists in the diagnosis of TN.

Purpose

This study aims to establish a radiomics-based machine learning model integrating multi-region of interest (multiple-ROI) MRI and anatomical data, to improve the accuracy in differentiating symptomatic from asymptomatic nerves in PTN.

Methods

A retrospective analysis of MRI data and clinical anatomical data was conducted on 140 patients with clinically confirmed PTN. Symptomatic nerves of TN patients were defined as the positive group, while asymptomatic nerves served as the negative group. The ipsilateral Meckel's cavity (MC) was included in both groups. Through dimensionality reduction analysis, four radiomics features were selected from the MC and 24 radiomics features were selected from the trigeminal cisternal segment. Thirteen anatomical features relevant to TN were identified from the literature, and analyzed using univariate logistic regression and multivariate logistic regression. Four features were confirmed as independent risk factors for TN. Logistic regression (LR) models were constructed for radiomics model and clinical anatomy, and a combined model was developed by integrating the radiomics score (Rad-Score) with the clinical anatomy model. The models' performance was evaluated using receiver operating characteristic curve (ROC) curves, calibration curves, and decision curve analysis (DCA).

Results

The four independent clinical anatomical factors identified were: degree of neurovascular compression, site of neurovascular compression site, thickness of the trigeminal nerve root, and trigeminal pons angle (TPA). The final combined model, incorporating radiomics and clinical anatomy, achieved an area under the curve (AUC) of 0.91/0.90 (95% CI: 0.87-0.95/0.81-0.96) and an accuracy of approximately 82% in recognizing symptomatic and normal nerves.

Conclusion

The combined radiomics and anatomical model provides superior recognition efficiency for the symptomatic nerves in PTN, offering valuable support for radiologists in diagnosing TN.

Absent Meckel's cave as a possible cause of trigeminal neuralgia: A case report

Trigeminal neuralgia (TN) is a debilitating yet potentially treatable facial pain disorder.TN is difficult to miss clinically, as patients' clinical presentation is often strikingly stereotypical: unilateral, paroxysmal, stimulus-dependent pain involving the trigeminal territory. Magnetic resonance imaging (MRI), which is used for further evaluation of an underlying etiology of TN, most commonly shows neurovascular compression of the trigeminal nerve to be the culprit. Secondary etiologies, though less common, do exist. An absent Meckel's cave with ipsilateral TN was reported in a few case reports and series, and whether an etiological relationship exists is yet to be established. We herein present a case of a 22-year-old female patient who presented with typical TN clinical manifestations. MRI was ordered to assess for the underlying cause and an ipsilateral absent Meckel's cave was the only significant finding. This case report adds to the scarcity of literature highlighting this entity, further larger clinical studies are needed to establish a causal relationship.

Absence of Meckel's Cave with Trigeminal Neuralgia: A Case Report

Trigeminal neuralgia (TN) is a disabling painful condition along the course of the sensory distribution of the trigeminal nerve that most commonly occurs due to vascular compression or conflict at the root entry zone of the trigeminal nerve. We report a 27-year-old female patient who presented with pain and an electric shock-like sensation on the right side of her face that started three years ago. Magnetic resonance imaging of the brain was done and revealed no neurovascular conflict along the course of the trigeminal nerve. The absence of Meckel's cave with atrophy of the cisternal segment of the trigeminal nerve on the affected side was reported. The absence of Meckel's cave is an exceedingly rare cause of TN, and only a handful of reported cases in the literature suggest the association between them.

The Focus and New Progress of Percutaneous Balloon Compression for the Treatment of Trigeminal Neuralgia

Trigeminal neuralgia is a condition confined to the trigeminal nerve, causing one or more branches of facial nerve pain. Surgical treatment options for trigeminal neuralgia include microvascular decompression(MVD), percutaneous balloon compression (PBC), radiofrequency thermocoagulation(RF), percutaneous retrogasserian glycerol rhizotomy(PRGR), gamma knife, etc. Of these treatments, PBC is increasingly being used by clinicians for trigeminal neuralgia. PBC is a simple surgical operation performed to treat trigeminal neuralgia. Owing to its advantages, PBC is favored by many clinicians. In this study, we aimed to emphasize the need to analyze the shape of the balloon, position, compression time, and pressure, as these factors can affect the efficacy of PBC. The relief of pain by balloon compression is related to the shape of the balloon on X-ray, which is the key to the operation. Owing to continued progress and advances in current imaging technologies, clinicians revealed that the precise positioning of the foramen ovale is no longer an intraoperative problem. Instead, the anatomy of Meckel’s cave and the shape of the balloon must be the focus to achieve the best treatment effect. For clinicians, PBC is simple and is associated with a short operation time. PBC also has other advantages, such as low cost and immediate postoperative pain relief. The recurrence rate of pain post-PBC is low, despite the occurrence of facial numbness post-op. However, this side effect is reversible and does not affect daily life of the patient. In fact, the patient can be discharged 1–2 days after surgery. Overall, PBC can be considered as one of the preferred surgical methods for the treatment of primary trigeminal neuralgia. In this paper, we explain the main points of PBC operation in detail in terms of Meckel’s cave, surgical procedure, complications, discussion of the focus and new progress, etc.