Small Meckel’s Cave Volume and Localization of the Foramen Ovale and Rotundum Are Associated with No-Neurovascular Compression Trigeminal Neuralgia

Abstract

Abstract Objective To investigate the new pathogenesis of no-neurovascular compression (N-NVC) trigeminal neuralgia (TN). Methods Twenty-two patients (mean age 57 years; male-to-female 4:18) with N-NVC TN who were diagnosed by trigeminal nerve MRI (TN-MRI), then another 22 sex-matched healthy controls (mean age 56 years)with skull base computerized tomography (CT) and TN-MRI was selected to investigate the pathogenesis.The volume of Meckel’s Cave (MC) was measured by the Brainlab navigation imaging system in MRI, and the areas of foramen ovale (FO) and foramen rotundum (FR) were evaluated by the three-dimensional reconstruction of skull base CT using the Radiant DICOM software. The sagittal (y) axis was passing through the middle of the dorsum sellae, which connected the anterior-most point and the rearmost point of the skull. The coordinates perpendicular to the y-axis and transverse (x) axis passing through the middle of the sellar dorsum were established to determine the positions of FO and FR in the x-axis (FO-x, FR-x), and y-axis (FO-y, FR-y), and the region of the area of interest enclosed within the x and y axes (ROI-FO, ROI-FR). Results No difference was found in the volume of bilateral Meckel’s Cave, area and location of the FO and FR, and area of ROI in HCs.The volume of MC on the affected side of patients with N-NVC TN was (0.402 ± 0.116) mm3, FO-x (2.109 ± 0.216) cm, FO-y (0.892 ± 0.103) cm, ROI-FO (1.889 ± 0.333) cm2, FR-x (2.090 ± 0.117) cm, and ROI-FR (4.353 ± 0.272) cm2. The volume of MC on the healthy side was (0.473 ± 0.158) mm3, FO-x (2.379 ± 0.171) cm, FO-y (1.142 ± 0.154) cm, ROI-FO (2.719 ± 0.432) cm2, FR-x (2.294 ± 0.103) cm, and ROI-FR (4.828 ± 0.319) cm2.U test showed that the above parameters on the affected side of patients with TN were significantly less than those on the healthy side (P˂0.01). Conclusion In patients who classify as idiopathic TN based on ICHD-3, a statistically smaller volume of MC, area of ROI, and the distances of FO and FR to the sagittal or transverse axis suggested that they could be the causes of N-NVC TN.