Surgeons frequently approach the foramen ovale (FO) via the infratemporal fossa (ITF) to treat trigeminal neuralgia. However, this percutaneous procedure could be unsuccessful due to anatomical factors. The present study aimed to assess the FO morphology and its relationship with the lateral pterygoid process plate (LPPP), emphasizing coexisting ITF variants. One-hundred-and-eight (216 sides) adult dried skulls were evaluated at the ITF (FO and LPPP). The FO maximum anteroposterior and lateromedial distances (APD and LMD) were calculated and correlated with the FO morphology. The FO-LPPP relationship was observed, and the presence of a sphenoidal emissary foramen (SEF) and possible ossified sphenoid bone’s ligaments variants (pterygoalar and pterygospinous—PTA and PTS variable ossification) were recorded. Statistical analysis was performed using the SPSS statistical program. The FO morphology was classified into three types after taking into consideration the FO morphometry. Type 1 FO was considered when the APD was two times more than the LMD (45.83%), Type 2 FO was identified when the APD was more than the LMD but no more than two times (51.85%), and Type 3 FO was considered when the APD and LMD were equal (2.32%). The FO and LPPP relationships were classified into the following four types: the direct type when the LPPP base ended at the FO center (32.3%), the lateral type was observed when the LPPP base ended at the FO lateral margin (28.76%), the far type was considered when the LPPP base ended distally to the FO (22.57%), and the medial type was when the LPPP base ended at the FO medial margin (11.95% of cases). Concerning the impact of the sphenoid bone variants on the FO-LPPP, the SEF did not alter the FO-LPPP relationship, while the PTA or PTS bar presence significantly affected it (p < 0.001 and p = 0.007, respectively). When the sphenoid bone ossified bars were present, the most common type of FO was the medial one. A novel classification system was proposed for the FO morphology, assessing possible coexisting ITF variants that could alter the FO-LPPP relationship. Knowledge of these details would help clinicians perform percutaneous procedures to treat trigeminal neuralgia.

Background: The temporal bone’s styloid process (SP) is an important structure that extends from the skull base to the parapharyngeal space. The stylohyoid ligament (SHL) attaches it to the hyoid bone. The SP and SHL are considered the stylohyoid chain (SHC) components. The SP’s close relationship with vital head and neck structures has important clinical implications. Specifically, SP and SHC variants are linked with clinical conditions. Therefore, adequate knowledge of these variations is of paramount importance. Methods: Using the latest guidelines, a systematic literature review was performed in four online databases (PubMed, Google Scholar, Scopus, and Web of Science) to identify studies referring to the SP’s typical anatomy and possible SHC morphological variants. The meta-analysis was conducted using R programming software to calculate the prevalence of typical anatomy and possible variants and the pooled mean length of the SP. Results: A total of 104 studies were included, with a total sample of 136,010 heminecks. The typical SP (under 30 mm) was estimated to have a pooled prevalence of 74.97%. SP elongation was observed in 25.03%. The subgroup analysis identified significant differences based on the study type, with computed tomography (CT) studies having the highest pooled prevalence. The SP length was calculated to have a pooled mean of 28.91 mm. For SHC ossification, the pseudo-articulated type was identified to have a pooled prevalence of 4.39%, and that of the segmented type was detected to be 3.89%. The geographical distribution and study type affected the estimated pooled prevalence. Conclusions: The current evidence-based systematic review with meta-analysis investigated the SHC’s typical anatomy and possible variants. The elongated SP pooled prevalence of 25.03% indicates that it is not a rare variant, and CT is the optimal method to investigate such a variant. These details demonstrated by the current meta-analysis could be of importance for clinicians.

Purpose: The current systematic review, along with a meta-analysis, aims to present and calculate the pooled prevalence of the morphological variants of the vertebral artery (VA) within the suboccipital (V3) and intradural (V4) segments. Methods: According to the most recent guidelines, the systematic review was conducted using four online databases. Eligible studies were extracted, and a meta-analysis was performed utilizing R programming software. A subgroup analysis was conducted based on nationality and imaging techniques. Results: The systematic review revealed thirty-two (32) studies involving 176,391 patients. The pooled prevalence of VA fenestration was established at 0.30% (95% CI: 0.14–0.51). Furthermore, the persistent first intersegmental artery (PFIA) was estimated to have a pooled prevalence of 1.17% (95% CI: 0.36–2.34), wherein the imaging technique and nationality served as a significant moderator. An aberrant origin of the posterior inferior cerebellar artery from the V3 segment was identified, with a pooled prevalence of 2.69% (95% CI: 1.13–4.82). Additionally, the pooled VA dominance, hypoplasia, and atresia prevalences were recorded at 27.45%, 13.41%, and 5.39%, respectively. Conclusions: Magnetic resonance or computed tomography angiographies can accurately illustrate the distal VA’s diverse anatomical configurations. Specific variants hold substantial clinical significance, as they are correlated with posterior circulation cerebrovascular incidents and may complicate posterior approaches to the craniocervical region.

Background: The arcuate foramen (AF), an osseous foramen, is probably formatted from the ossification of the posterior atlanto-occipital membrane. When this morphologically ossified variant exists, it encloses the vertebral artery (VA) third segment (V3). This close relationship may cause compression to the VA with concomitant vertebrobasilar insufficiency, vertigo, headaches, or neck pain. In the published literature, no studies investigate the abovementioned potential compression pattern. The present study examines the AF ossification pattern (complete or partial type) and the variable VA diameter at the atlantal part (V3), concluding a potential risk for VA compression after correlating the relative diameters (AF and VA diameters). Materials and Methods: One hundred and fifty dried first cervical vertebrae (atlases) and one hundred fifty computed tomography (CT) scans were obtained for the present study. The presence of a complete or incomplete AF was evaluated, and when present, its diameter was measured. To correlate these findings with the vessel, 50 computed tomography angiographies (without AF presence) were obtained to measure the V3 segment diameter. Results: Out of the total 600 (N = 600) sides, 111 sides had incomplete AF (18.2%), and 67 sides had complete AF (11.1%). The AF mean diameter was 6.41 (1.12) mm. The diameter of the V3 segment ranged between 5.0 and 6.0 mm; therefore, three morphological stenosis patterns were identified. A low risk of compression (over 6.0 mm) was identified in 61.2% (N = 109 sides), a moderate risk (between 5.0–6.0 mm) was observed in 29.2% (N = 52 sides), and a high risk (under 5.0 mm) was recorded in 9.6% (N = 17 sides). There was no statistically significant correlation regarding sexes and age for the potential compression patterns. Conclusions: The present study revealed the morphological stenosis pattern of the AF to the V3 segment. The variation had a high risk of compression to the vessel in 9.6% of sides, indicating that it is not infrequent. Knowledge of these details is essential for clinicians when investigating vertebrobasilar insufficiency.

Background: The caroticoclinoid bar (CCB) or caroticoclinoid foramen (CCF) represents a well-described ossified variant of the skull base. It corresponds to an osseous bridge (resulting after homonymous ligament ossification) between the anterior and middle clinoid processes (ACPs and MCPs) surrounding the internal carotid artery (ICA)’s cavernous segment. Although extensive research has been performed on this clinically significant entity, only a few studies have been conducted on its effect on the ICA. The current study on dried skulls, using computed tomography (CT) and computed tomography angiography (CTA) scans, aimed to investigate the CCB’s presence and potential morphological stenosis patterns. Methods: One hundred (100) dried adult skulls and one hundred sixty (160) skulls from CT scans of patients were obtained (a total of 520 observations). To further calculate the ICA diameter (at the ACP-MCP region) and correlate the resulting dimeters with all potential morphological stenosis patterns of the CCB, thirty (30) CTAs of patients free of the variant were selected. Results: Concerning the osseous pattern morphology, of the total of 520 sides, the CCB was identified in 17.1%, the complete variant (creating a caroticoclinoid foramen-CCF) was calculated in 11.5%, and the incomplete one was calculated in 5.6%. No side, sex, or age impact was identified for the CCB presence. Concerning the ICA dimensions, its diameter was calculated to be between 4 and 5 mm. Thus, we observed three morphological stenosis patterns of the CCF. A low-risk pattern of stenosis (>5 mm diameter) was observed in 40 CCFs (44.9%), an intermediate risk of stenosis (4–5 mm diameter) in 38 CCFs (38.2%), and a high risk of stenosis (<4 mm diameter) was depicted in 15 CCFs (16.8%). Conclusions: In the present study, we investigated the CCF presence and potential morphological stenosis patterns by calculating and correlating the ICA diameter. In 16.8% of the current sample with CCFs (irrespective of their morphology), we observed that the ICA is probably at a high risk of compression. Radiologists and neurosurgeons intervening in the area should preoperatively diagnose the possibility of ICA compression in this area.

Background/Objectives: Variations in the course of the maxillary artery (MA) relative to the lateral pterygoid muscle (LPM) pose critical challenges in surgical, anesthetic, and interventional procedures involving the infratemporal fossa (ITF). These variations can increase the risk of hemorrhage, nerve injury, or incomplete anesthesia. The present study aimed to elucidate the topographic relationship between the MA and LPM by combining high-resolution radiological imaging with a comprehensive analysis of anatomical literature. Materials and Methods: A retrospective review of 250 brain computed tomography angiographies (CTAs), totaling 500 sides, was conducted to classify the MA course as lateral (superficial), medial (deep), or intramuscular. Additionally, a systematic review and meta-analysis of 32 eligible studies—including 5938 arteries—was performed following PRISMA 2020 and Evidence-Based Anatomy (EBA) guidelines. Study quality and risk of bias were assessed using the Anatomical Quality Assurance (AQUA) tool. Results: In the imaging cohort, the MA coursed lateral to the LPM in 64.2% of sides, medial in 29.6%, and through the muscle fibers in 6.2%. A rare temporalis-traversing variant was identified in 3.0% of cases. Bilateral symmetry was observed in 77.6% of patients. Meta-analytic findings indicated a pooled prevalence of 79.6% for the lateral course, 19.9% for the medial course, and 0.01% for the intramuscular course. Cadaveric studies and Asian populations showed a higher incidence of lateral variants, while imaging-based studies more frequently detected medial and transmuscular paths. Conclusions: While the MA most often follows a lateral course relative to the LPM, clinically significant variation—including medial, intramuscular, and temporalis-traversing routes—exists. These variants complicate access during maxillofacial surgery, TMJ procedures, and regional anesthesia. Findings emphasize the importance of individualized preoperative vascular mapping to improve procedural safety and outcomes in the ITF.