Kristian Bechev

Background: The sphenoid sinus occupies a strategically central position at the base of the skull, in close proximity to critical neurovascular structures including the pituitary gland, optic nerves, internal carotid arteries, and the cavernous sinus. Its complex anatomical configuration and pronounced individual variability render it a structure of paramount clinical importance in transsphenoidal approaches to the sellar and parasellar regions. Methods: A narrative review of the literature was conducted in accordance with the SANRA (Scale for the Assessment of Narrative Review Articles) guidelines for narrative reviews. A comprehensive search was performed across four electronic databases—PubMed/MEDLINE, Scopus, Web of Science, and Google Scholar—covering publications from January 2000 through March 2026, with the final search update completed in March 2026. An initial pool of 826 articles was identified. Following title and abstract screening, 421 articles were retained for full-text assessment; of these, 307 contributed to the conceptual synthesis, and 100 are directly cited in the manuscript. The literature selection process followed a structured flow diagram consistent with PRISMA reporting principles for identification and screening stages. Results: We synthesise current evidence on the embryological development, macroscopic and microscopic anatomy, morphological classifications, and epidemiological distribution of anatomical variations in the sphenoid sinus, with emphasis on radiological assessment and surgical relevance. The spectrum of pneumatization patterns—from the conchal type through presellar and sellar variants to the postsellar, clival, and lateral types—is reviewed alongside population-level prevalence data. Common and rare variations are examined, including intrasinus septation, Onodi cells, and bony dehiscences overlying the internal carotid artery and optic nerve. The comparative diagnostic capabilities of computed tomography and magnetic resonance imaging are evaluated, alongside emerging modalities such as three-dimensional reconstruction, virtual reality, and augmented reality. Conclusions: Detailed morphological knowledge of the sphenoid sinus plays an important role in surgical strategy, instrument selection, and risk mitigation in skull base surgery. Individualised preoperative imaging—integrating CT, MRI, and, where available, immersive digital technologies—is essential for safe transsphenoidal planning and cannot be replaced by standard anatomical templates.

Background/Objectives: Artificial intelligence (AI) is increasingly being integrated into vascular surgery, particularly in diagnostic imaging, perioperative planning, intraoperative guidance, and postoperative surveillance. This literature review evaluates the current applications of artificial intelligence in vascular surgery and endovascular practice, with a particular focus on imaging technologies and their role in improving diagnostic precision, workflow efficiency, and patient outcomes. In addition, the review examines emerging AI applications in operative workflow optimization, endovascular navigation, postoperative surveillance, training platforms, and AI-assisted clinical decision support. Methods: A literature review was conducted using PubMed and Scopus with the search terms: (artificial intelligence OR AI OR neural network) AND (vascular surgery) AND (diagnosis OR treatment). Reference lists of included studies were manually screened, and additional recent studies were identified from relevant journals. Articles published in English up to April 2026 were included. Studies were assessed for their applications in vascular diagnostics, plaque characterization, endovascular workflow optimization, and postoperative surveillance. Results: AI demonstrated strong diagnostic performance across multiple imaging modalities. Deep learning systems achieved a sensitivity of 91.3% and specificity of 95.2% in peripheral arterial stenosis classification, while plaque characterization models showed accuracies up to 96% and substantial agreement with expert imaging interpretation. AI-assisted operative systems improved procedural efficiency through reductions in operative duration, radiation exposure, and contrast utilization. However, many studies were retrospective, single-center, and based on relatively small cohorts with heterogeneous endpoints. Conclusions: AI has significant potential to improve vascular surgical practice through enhanced image interpretation, procedural guidance, and individualized treatment planning. Despite promising outcomes, current evidence remains limited by methodological heterogeneity and insufficient external validation. Prospective multicenter studies and standardized evaluation frameworks are required before widespread clinical implementation can be achieved.

Endometriosis is a chronic, debilitating condition affecting approximately 10–15% of reproductive-aged women and it is often associated with significant diagnostic delays due to its heterogeneity and unreliable non-invasive tests. Artificial intelligence (AI) offers innovative methods for improving endometriosis diagnosis, prognosis and research via advanced pattern recognition and data analysis capabilities. The integration of AI in diagnostic workflow has the potential to improve efficiency, accuracy, and patient outcomes. This review summarises current developments of AI—including machine learning, deep learning, and natural language processing—in the diagnostic workflow of endometriosis. It analyses different fields of diagnostics ranging from AI-assisted imaging in detection of pouch of Douglas to multi-omics biomarkers assisting the clinical decision process. AI can enhance accuracy, reducing diagnostic delays and supporting personalised treatment planning. However, there are multiple limitations, such as small datasets, overfitting, and lack of external validation and variability. Further research and evaluation are required before it can be implemented into healthcare systems. AI holds promise as a non-invasive, scalable adjunct to current diagnostics, potentially reducing the economic and personal burden endometriosis carries.

Background/Objectives: Transsphenoidal surgery has become the gold standard for the treatment of sellar and parasellar lesions, but it remains associated with significant anatomical challenges and the risk of intraoperative complications. The limitations of conventional imaging in depicting the complex three-dimensional anatomy of the skull base have led to a growing interest in virtual (VR) and augmented reality (AR) technologies, which offer enhanced spatial visualization, preoperative simulation, and image-guided intraoperative navigation. This systematic review aims to evaluate the current evidence on the role of virtual and augmented reality in transsphenoidal surgical interventions, with a focus on their impact on preoperative planning, intraoperative orientation, surgical outcomes, and neurosurgical training. Methods: A systematic literature search was conducted in accordance with PRISMA 2020 guidelines across PubMed, Scopus, and Web of Science for the period 2015–2025. MeSH terms and free-text keywords related to transsphenoidal surgery, sphenoid sinus anatomy, and VR/AR technologies were combined using Boolean operators. Risk of bias was assessed using RoB 2.0 for RCTs; methodological quality was assessed using the Newcastle–Ottawa Scale for observational studies and AMSTAR 2 for systematic reviews. Clinical, morphometric, and experimental studies evaluating VR/AR applications were included. Data were extracted using a standardized protocol and synthesized through qualitative analysis, with subgroup analysis by technology type (VR vs. AR) and clinical application domain. Results: A total of 218 publications were identified, of which 52 met the inclusion criteria (clinical studies n = 12, simulation and technology studies n = 30, morphological studies n = 10). VR-based three-dimensional reconstructions were consistently associated with improved preoperative spatial orientation and anatomical landmark recognition. AR systems demonstrated a meaningful contribution to intraoperative navigation, with reported reductions in time to target and improved visualization of critical neurovascular structures. VR platforms showed high effectiveness in surgical training, with shorter learning curves and improved technical performance. However, the majority of included studies were small observational cohorts, simulation studies, or expert overviews, with substantial heterogeneity in methodology, technology platforms, and outcome measures, precluding quantitative meta-analysis. Conclusions: Virtual and augmented reality represent clinically promising adjuncts to transsphenoidal surgery, with demonstrated benefits in preoperative planning, intraoperative navigation, and surgical training. These conclusions should be interpreted in the context of a predominantly early-phase and heterogeneous evidence base. Standardized protocols, larger prospective studies, and randomized trials are needed before the integration of VR/AR with navigation systems and artificial intelligence can be established as a routine component of personalized transsphenoidal surgery.

Introduction : Malignant pleural effusions (MPEs) are a frequent complication of cancer, causing significant morbidity and representing a major diagnostic challenge. Tumor markers in pleural fluid have been studied, but their interrelationships remain poorly understood. Aim : To investigate the correlations among commonly used tumor markers in pleural effusions and to assess their potential role in differentiating malignant from benign cases. Materials and methods : A cross-sectional case-control study was conducted on 151 Bulgarian patients with hydrothorax. The control group consisted of 72 patients with benign pleural effusions (38 inflammatory, 34 non-inflammatory), while 79 patients had malignant pleural involvement. Correlation analysis was applied to evaluate the relationships between carcinoembryonic antigen (CEA), CA19-9, CA72-4, CA125, CA15-3, and PIVKA-II. Results : Significant moderate positive correlations were found between CEA, CA19-9, CA72-4, and CA125, indicating overlapping tumor biology. CA125 also correlated with CA15-3, consistent with their role in epithelial malignancies. In contrast, PIVKA-II showed no significant correlation with other markers, suggesting limited utility in pleural malignancy diagnosis. These findings point to both redundancy and complementarity among tumor markers. Conclusions : Tumor markers in pleural fluid, particularly CEA, CA125, CA19-9, and CA72-4, may provide valuable diagnostic information when assessed together. Their interrelationships support the rational selection of marker panels to improve diagnostic accuracy for MPEs. PIVKA-II appears less informative in this setting. Understanding these correlations may enhance minimally invasive diagnostic strategies and contribute to more personalized management of pleural malignancy.

The sacroiliac joints are among the largest joints in the human body. They are subjected to heavy loads on a daily basis. The pathology of the sacroiliac joints can be easily missed due to the many common and overlapping symptoms with other diseases in this area. The thin joint capsule, the high mechanical load, and the asymmetrical movement of the pelvic girdle explain the frequent involvement of the sacroiliac joint. Chronic degenerative processes in the joint may result from rheumatic, infectious, drug-dependent and oncological causes. Diseases such as ankylosing spondylitis, psoriatic arthropathy, Bechet’s disease, hyperparathyroidism and various pyogenic causes also cause changes in the joint. Hormonal changes during pregnancy and being overweight are predisposing factors for the development of chronic sacroiliac arthritis. According to the literature, 10-25% of the pain in the area is due to sacroiliac joint pain. Due to the often irradiating pain in different directions, a correct diagnosis is difficult. The therapy of chronic sacroilitis is continuously improving due to the high social importance of this disease. Twenty-eight patients were treated in the Department of Neurosurgery of Pulmed University Hospital with hyaluronic acid injection and corticosteroid blockade, under X-ray control in both sacroiliac joints. Preoperatively, the patients were evaluated using neurological examination and the Oswestry Disability Index, VAS, and “Facial Pain Rating Scale” scales. The results after the minimally invasive methodology showed an excellent response to the pain syndrome. Follow-up of the patients continued up to nine months after the manipulation.

Meningiomas are divided into three subtypes according to the World Health Organization (WHO), which give rise to about 15 histological variants with varying degrees of malignancy. WHO grade I tumors are the most common, which are predominantly benign in nature and have a good prognosis after total surgical removal. Spinal meningiomas are one of the most common intradural, extramedullary tumors, accounting for about 20% of all lesions localized on the spinal cord and its envelope. Meningiomas arise from arachnoid cells and have a very close relationship with the dural meninges. They can be located in all places where there are arachnoid cells and cause neurological symptoms. Due to their slow-growing nature, symptoms manifest within a few months. In this report, we present an unusual case of a 44-year-old woman with spinal angiomatous meningioma presenting with the clinicopathology of inferior spastic paraplegia debuting at eight months, pelvic reservoir disorders, and decreased bowel motility, resulting in neurological paresis of the latter. The patient underwent two operations for hydrocephalus with normal pressure and subsequent infection of the ventricular catheter, which required its removal in the neurosurgical department and prolonged antibiotic treatment. The woman stayed for about three months in the intensive care unit with the clinical picture of meningitis and secondary superimposed pulmonary pneumonia. Magnetic resonance imaging of the thoracic region revealed a heterogeneous cystic formation over a wide area, and a tumor formation or arachnoiditis in the chronic phase was considered in the differential diagnosis. Surgical treatment with partial extirpation of the pathological formation (Simpsom grade III) was undertaken, and the histological diagnosis confirmed the presence of an angiomatous meningioma in the thoracic region.

The nasal cavity and paranasal sinuses form an anatomically intricate and highly variable region that plays a vital role in the physiological functions of the upper respiratory tract and is intimately associated with a wide range of pathological and surgical considerations. Anatomical variations in this area – such as concha bullosa, septal deviation, Haller and Onodi cells – are frequently linked to impaired mucociliary clearance, obstruction of natural drainage pathways, and an increased risk for the development of chronic rhino-sinusitis. Moreover, the presence of such variations significantly influences the planning and execution of functional endoscopic sinus surgery (FESS) and transnasal approaches to the skull base, increasing the likelihood of complications involving the optic nerve, internal carotid artery, or orbital structures. This review aims to provide a structured analysis of the most clinically relevant anatomical variants of the nasal cavity and paranasal sinuses, grounded in contemporary literature from the past decade across radiological imaging, anatomical studies, and skull base surgery. It explores the relationship between structural anomalies and the frequency and severity of sinonasal pathology, as well as their implications for endoscopic surgical practice. Special attention is given to surgical hazards posed by variations such as dehiscent lamina papyracea, accessory maxillary ostia, and pneumatization of the anterior clinoid process. The review includes tabular and graphical representations illustrating the associations between specific anatomical features and their related clinical and surgical risks. This integrative approach is intended to support clinicians in enhancing diagnostic accuracy, optimizing preoperative planning, and minimizing intra-operative complications through a personalized anatomical understanding of this region.

Background: The sphenoid sinus is essential for transsphenoidal surgical accesses to the sellar and parasellar regions because of its anatomic proximity to vital vascular and neurologic structures such as the internal carotid artery, optic nerve, and cavernous sinus. The high degree of morphological variability of the sphenoid sinus has a significant impact on surgical technique and the risk of intraoperative complications. Detailed knowledge of individual anatomy is therefore crucial for the safety and efficacy of transsphenoidal approaches. Objectives: This review aims to conduct a systematic analysis of the current scientific literature on anatomical variations in the sphenoid sinus and their clinical relevance in surgical interventions to the skull base. Special attention is paid to the influence of morphological features on surgical strategies to pathological processes in this area and postoperative outcomes. Materials and Methods: A systematic review of the literature was conducted according to PRISMA 2020 guidelines. The PubMed, Scopus, Web of Science, and Google Scholar databases were searched for the period March 2010 to March 2025. Keywords such as “sphenoid sinus”, “anatomical variations”, “transsphenoidal surgery” and “skull base” were used. Original studies, systematic reviews, and meta-analyses focused on the anatomy, pneumatization, and surgical significance of sphenoid sinus variations are included. Quality and relevance criteria for published material were considered in the selection of articles. Results: The most commonly identified anatomic variations included sellar and lateral pneumaticity, the presence of Onodi cells, multiple and deviated septa, and dehiscence of the posterior wall of the sphenoid sinus and prolapse into its cavity of the internal carotid artery. These variations are associated with an increased risk of intraoperative vascular injury, visual deficit, and postoperative liquorrhea. Accurate preoperative assessment by high-resolution computed axial tomography and magnetic resonance imaging, as well as the use of intraoperative neuronavigation, are critical to reduce surgical risk. Conclusions: Anatomic variations in the sphenoid sinus are an essential factor to consider when planning and performing transsphenoidal surgical accesses. An individualized approach based on detailed diagnostic imaging analysis and neuronavigation technologies contributes to a higher safety of the performed surgical interventions, a better radicality of tumor resection and more favorable postoperative outcomes.

Background/Objectives: The cavernous segment of the internal carotid artery (ICA) is a critical neurovascular structure with complex cranial nerve relationships. Understanding its morphometric variability is essential for safe microsurgical and endovascular procedures. This study aimed to characterize the morphometry of the cavernous ICA using Magnetic resonance imaging (MRI) and assess associations with demographic variables. Methods: A retrospective observational study was conducted on 135 MRI scans of adult patients, distributed among 79 women and 56 men with an average age of 50.8 years, without cerebrovascular pathology, performed between March 2023 and January 2025. The diameters of the left and right cavernous ICA and the intercarotid distance were measured using RadiAnt DICOM Viewer. Statistical analyses included descriptive statistics, t-tests, correlations, and multivariate regression models adjusted for age and sex. Principal component and cluster analyses were applied to identify morphometric patterns. Results: The mean left and right ICA diameters were both 5.09 ± 0.65 mm, with a mean intercarotid distance of 17.4 ± 4.22 mm. No age-related associations were found (p > 0.05). Male patients showed significantly larger right ICA diameters (p = 0.008). Bilateral symmetry was confirmed (p > 0.05). Two morphometric clusters were identified: Morphotype 1 (larger ICA caliber and narrower spacing) and Morphotype 2 (smaller caliber and wider spacing), showing a significant sex distribution difference (p = 0.012). Conclusions: The cavernous ICA demonstrates stable bilateral symmetry with minor sex-dependent differences. Morphometric characterization supports safer planning of transsphenoidal, endovascular, and skull-base surgeries by reducing the risk of iatrogenic neurovascular injury.