Introduction

Facial pain is a frequent occurrence with various mechanisms of its development. Trigeminal neuralgia (TN), or tic douloureux, is one of the most common causes of facial pain [1]. TN is neuropathic pain involving one or more branches of the trigeminal nerve (cranial nerve V) [2]. This disease is characterized by stereotypic attacks that can last from a second to several minutes and are manifested by a feeling of "shooting," "electric shock," and "provocative zones" [3]. In the United Kingdom, the disease has been found to be the most common among women of all ages, with the highest incidence occurring between the ages of 45 and 59 years [4]. V2 and V3 are the branches most commonly affected by TN, whereas branch V1 occurs in less than 5% of all TN cases [5]. It has been established that even 17 percent of patients receive hospital TN treatment [6]. The complete mechanism of TN development is still not fully understood, knowing that this disease can be caused by several different factors (Figure 1).

Magnetic resonance imaging (MRI) is used as an auxiliary tool to determine the possible cause [8]. When analyzing the MRI, contact between the nerve and blood vessels can be detected (neurovascular conflict (NVC)). It is hypothesized that an artery or vein's neurovascular pressure on the trigeminal nerve can disrupt neuronal disruption, resulting in neuropathic pain. During pressure, the myelin sheath and neurons are damaged, and as altered impulses are transmitted, a person perceives it and understands it as pain [9]. In common cases, the MRI method is not used to confirm the diagnosis of TN but to make a surgical decision [7]. The superior cerebellar artery was mobilised in a patient with TN following the first microsurgical decompression of the trigeminal nerve, which resulted in long-term pain alleviation. For patients who do not respond to conventional therapy, this procedure provides good and safe results [10].

Reviewing the trigeminal nerve architecture pertinent to trigeminal neuralgia (TN) and describing the imaging look of vascular compression of the trigeminal nerve in TN patients, along with their correlation with the causative TN branch, are the goals of this article.

Materials and Methods

Protocol and registration

Following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) criteria, this systematic review and meta-analysis was carried out [11]. Our study protocol complied with PRISMA guidelines and was filed under the registration number CRD42023334610 with the International Prospective Register of Systematic Reviews and Meta-analysis (PROSPERO).

Literature selection

Two investigators independently queried PubMed/MEDLINE, ScienceDirect, ResearchGate, and Google Scholar databases to identify and select original research. The investigators reviewed all titles and relevant abstracts. The following combination of search terms was used: ((neurovascular conflict) AND (trigeminal nerve)) AND (neuralgia). Only English-language publications published in the last five years, from December 2017 to December 2022, were included in the literature search. There were no restrictions on the search based on publication status or country.

Randomised controlled trials, comparative studies, split-mouth randomised studies with double blinds, and controlled clinical trials in adult patients that determined the relationship between vascular conflict and pain of the various trigeminal nerve branches for patients with TN were among the inclusion criteria. Only one age group was the subject of one article rejection. Other research was not included, including case studies, studies using animals, systematic reviews, and meta-analyses.

Data extraction and quality assessment

Data from all included studies were extracted using a standard expressing form, and the following summary information was gathered: first author's surname and initials, year of submission, study design, total number of included cases, mean age, assessment, and results (branches and vessels of each patient).

Statistical methods

SPSS version 27 was used to conduct the statistical analysis. For the meta-analysis, MedCalc (Statistical Software Version 17.1) was employed. Because of the significant clinical heterogeneity across the included studies, a random effect model was employed for analysis. To assess statistical heterogeneity, the chi-square and I-square tests were employed. 25%, 50%, and 75% of the I2 values, respectively, showed low, moderate, and high heterogeneity. P values less than.05. was the threshold for statistical significance. The mean difference (MD) and its associated 95% confidence interval (CI) were used to demonstrate the impact of the assessment.

Results and Discussion

Literature search

The primary database search yielded 3886 articles after applying the search criteria. The full texts of 24 articles were retrieved and reviewed, and 20 articles were excluded as they failed to meet the inclusion criteria. Studies in the review were included if individual patient data was shown. A total of 4 articles were selected for study (Figure 2).

Reviewed studies included sample sizes of 1 to 22 patients. All 4 studies were presented, where NVC was detected using MRI [12-15]. After analyzing the articles, it was noticed that the sample sizes of all the conducted studies were not large enough (Table 1).

Quality assessment (Risk of bias)

Table 1. Data of interest

MR, Magnetic resonance

All articles were analyzed after assessing the probability of errors (Bias). The methodological indicator of non-randomized studies – MINORS [16] was used. Two reviewers carried out the Risk of bias assessment independently; a third reviewer mediated disagreement. All information is presented in Figure 3.

Outcomes

Wang et al. [12] analyzed 8 patients in their study and found that the second and third branches were the most common in TN, and the most common vessel involved in NVC was the superior cerebellar artery. In the study by Son et al. [13], NVC was detected in one patient. In another study by Liu et al. [14], it was found that the dominant blood vessel in NVC or in combination with other vessels was the vertebral artery (17), another blood vessel related to NVC was the superior cerebellar artery (12), veins (1), and anterior inferior cerebellar artery (6). Interestingly, after applying a special biomedical glue technique, as many as 20 out of 22 patients recovered (91%). Moon et al. [15] found that the most common blood vessel causing NVC was the superior cerebellar artery (11/14) (Table 2).

Table 2. The results of trigeminal nerve neuralgia studies, which were used in this review [12-15]

F, female; M, male; L, left, R, right; VA, vertebral artery; SCA, superior cerebellar artery; SPV, superior petrosal vein; BA, basilar artery; AICA, anterior inferior cerebellar artery; V, trigeminal nerve