Predictive value of MRI for identifying symptomatic neurovascular compressions in classical trigeminal neuralgia: a PRISMA-compliant meta-analysis.

Background: Patients with trigeminal neuralgia frequently undergo magnetic resonance imaging (MRI) prior to surgery. In patients without the signs and symptoms of face discomfort, MRI has shown the presence of neurovascular contact (NVC) in humans. Therefore, its capacity to accurately exclude NVC of the trigeminal nerve is not properly understood. A meta-analysis of the literature satisfied the criteria to further explore the value of MRI for the diagnosis of classical trigeminal neuralgia (CTN).

Study design: The association between the symptomatic and asymptomatic trigeminal nerves, NVC, root entry zone (REZ), non-REZ, and anatomical variation was measured by a comprehensive review and meta-analysis of 13 observational studies using MRI for CTN neurovascular compression diagnosis.

Objectives: This study aimed to evaluate the effectiveness of MRI in detecting the neurovascular compression that causes symptoms in individuals with classic trigeminal neuralgia.

Setting: This study was conducted at the Department of Neurosurgery, Yantai Yuhuangding Hospital, Qingdao University.

Methods: Digital searches of PubMed, Embase, and the Cochrane Library were performed to identify studies published until December 31, 2023. The following were evaluated: (1) MRI evidence of NVC in symptomatic and asymptomatic trigeminal nerves; (2) MRI indication of NVC at the REZ in symptomatic and asymptomatic trigeminal nerves; (3) MRI substantiation of non-REZ neurovascular contact in patients with CTN; and (4) asymptomatic and symptomatic anatomical changes at the NVC site of the trigeminal nerves. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using the fixed effects models.

Results: We identified 13 observational studies (1 prospective and 12 retrospective studies) with data collected from 1770 nerves (728 symptomatic and 1042 asymptomatic) were meta-analyzed. First, MRI of 649/728 (88.2%) symptomatic versus 378/1042 (36.3%) asymptomatic trigeminal nerves revealed marked differences in NVC in the REZ (OR = 16.3; CI 95%=12.2-21.8; p < 0.00001). Second, pooled data showed that REZ NVC was detected in 206/262 (78.6%) symptomatic and in 129/340 (37.9%) asymptomatic nerves (OR = 5.0; CI 95% = 3.4-7.3; p < 0.00001); Third, no significant differences were detected between 44/267 (16.5%) symptomatic and 23/189 (12.1%) asymptomatic nerves on MRI examination of NVC in the NON-REZ (OR = 0.9; CI 95% 0.5-1.6) (p = 0.77); Finally, MRI revealed marked differences in 302/567 (53.2%) symptomatic and 73/919 (7.9%) asymptomatic anatomic changes (atrophy, dislocation, distorsion, flattening or indentation) at the NVC site of the trigeminal segments (OR = 11.9; CI 95% = 8.8-16.2; p < 0.00001).

Limitations: Despite the systematic evaluation of 13 observational studies, large-scale randomized controlled trials should be conducted, focusing on the specificity of MRI for the diagnosis of trigeminal neuralgia and evaluating the specificity of the imaging findings and the impact of the patient's postoperative treatment.

Conclusions: A previous meta-analysis showed that patients with CTN were more likely to have NVC-specific anatomical changes. MRI of patients with CTN can detect anatomical changes in the REZ NVC with higher sensitivity.