Anatomical Study of the Supratentorial Extension for the Retrolabyrinthine Presigmoid Approaches.

BACKGROUND: Supratentorial craniotomy represents the upper part of the combined trans-tentorial or the supra-infratentorial presigmoid approach. In this study, we provide qualitative and quantitative analyses for the supratentorial extension of the presigmoid retrolabyrinthine suprameatal approach (PRSA). METHODS: The infratentorial PRSA followed by the supratentorial extension craniotomy with dividing and removal of the tentorial strip were performed on both sides of 5 injected human cadaver heads (n = 10 sides). Quantitative analysis was performed for the surface area gained (surgical accessibility) by adding the supratentorial craniotomy. Qualitative analysis was performed for the parts of the brainstem, cranial nerves, and vascular structures that became accessible by adding the supratentorial craniotomy. The anatomical obstacles encountered in the added operative corridor were analyzed. RESULTS: The supratentorial extension of PRSA provides an increase in surgical accessibility of 102.65% as compared to the PRSA standalone. The mean surface area of the exposed brainstem is 197.98 (standard deviation: 76.222) and 401.209 (standard deviation: 123.96) for the infratentorial and the combined supra-infratentorial presigmoid approach, respectively. Exposure for parts of III, IV, and V cranial nerves is added after the extension, and the surface area of the outer craniotomy defect has increased by 60.32%. Parts of the basilar, anterior inferior cerebellar, and superior cerebellar arteries are accessible after the supratentorial extension. CONCLUSIONS: The supratentorial extension of PRSA allows access to the supra-trigeminal area of the pons and the lower part of the midbrain. Considering this surgical accessibility and exposure significantly assists in planning such complex approaches while targeting central skull base lesions.

Recurrent artery of Heubner aneurysms in focus: insights into occurrence and current treatment paradigms.

INTRODUCTION: The recurrent artery of Heubner (RAH), also known as the medial striate artery, is the most clinically important perforator of the anterior cerebral artery. RAH aneurysm is relatively rare, with 11 cases found in the present literature review, but poses significant clinical challenges due to potential impact on cognitive and motor functions. This systematic review explored available case reports to comprehensively understand clinical presentation, diagnosis, management and outcome in RAH aneurysm. MATERIALS AND METHODS: Following PRISMA guidelines, this systematic review extensively explored RAH aneurysms, covering demographics, symptoms, diagnosis, treatments and outcomes. Comprehensive searches on PubMed, Scopus, Google Scholar, and Science Direct employed keywords such as "recurrent artery of Heubner aneurysm" and "Heubner's artery." RESULTS: After extensive screening, 9 qualifying studies were identified, with 11 patients diagnosed with rare RAH aneurysm. Median age was 55 years (standard deviation, 15.3 years), with 54.5% males. 45.5% of patients presented risk factors, including Moyamoya disease in 2 patients. The majority were classified as grade I/II on the Hunt and Hess (H&H) and World Federation of Neurological Societies (WFNS) systems. Aneurysms were predominantly located in the A1 segment, with a mean size of 4.7 mm. Treatments varied, with clipping being the most frequent (63.6%). The mortality rate was 18.2%. Clipping was associated with favorable outcomes but higher rates of infarction. CONCLUSION: This analysis highlighted the various symptoms, therapy methods and outcomes of RAH aneurysm, with A1 being the predominant origin. Future research should explore potential genetic predisposition factors and novel therapeutic interventions to address gaps in our knowledge.

Mapping the circle of Trolard: A holistic view of its role in neurosurgical practice, anatomical perspectives and clinical applications.

Introduction: An anatomical structure that resembles the circle of Willis, the circle of Trolard is generated in the basal cistern and travels around the midbrain in a roundabout manner, passing adjacent to the lateral side of the cerebral peduncle. Research question: The primary objective of this article is to provide neurosurgeons with a comprehensive understanding of Trolard's circle, emphasizing its anatomical features and clinical significance. Material and methods: A comprehensive evaluation of the available literature pertaining to the venous circle of Trolard was conducted by conducting searches in the PubMed, Web of Science, and Scopus databases. In the present overview, the terminologies "venous circle of Trolard," "basal venous circle," and "basal vein of Rosenthal" were employed. Results: Upon doing a comprehensive examination of the existing literature and primary sources pertaining to the venous circle of Trolard, it was discovered that an only six studies had been conducted on this particular subject matter. We made observations regarding the anatomical characteristics of the subject and engaged in a discussion regarding their prospective applications and importance within the context of neurosurgical procedures. Discussion and conclusion: The scarcity of research on these structures is attributed to the challenges associated in studying them in vivo. Through directing focus towards these structures, our aim is to stimulate further investigation into their potential involvement in a range of neurological and neurosurgical disorders.

Cortical incisions and transcortical approaches for intra-axial and intraventricular lesions: A scoping review.

Background: Transcortical approaches, encompassing various surgical corridors, have been employed to treat an array of intraparenchymal or intraventricular brain pathologies, including tumors, vascular malformations, infections, intracerebral hematomas, and epileptic surgery. Designing cortical incisions relies on the lesion location and characteristics, knowledge of eloquent functional anatomy, and advanced imaging such as tractography. Despite their widespread use in neurosurgery, there is a noticeable lack of systematic studies examining their common lobe access points, associated complications, and prevalent pathologies. This scoping review assesses current evidence to guide the selection of transcortical approaches for treating a variety of intracranial pathologies. Methods: A scoping review was conducted using the PRISMA-ScR guidelines, searching PubMed, EMBASE, Scopus, and Web of Science. Studies were included if ≥5 patients operated on using transcortical approaches, with reported data on clinical features, treatments, and outcomes. Data analysis and synthesis were performed. Results: A total of 50 articles encompassing 2604 patients were included in the study. The most common primary pathology was brain tumors (60.6%), particularly gliomas (87.4%). The transcortical-transtemporal approach was the most frequently identified cortical approach (70.48%), and the temporal lobe was the most accessed brain lobe (55.68%). The postoperative course outcomes were reported as good (55.52%), poor (28.38%), and death (14.62%). Conclusion: Transcortical approaches are crucial techniques for managing a wide range of intracranial lesions, with the transcortical-transtemporal approach being the most common. According to the current literature, the selective choice of cortical incision and surgical corridor based on the lesion's pathology and anatomic-functional location correlates with acceptable functional outcomes.

Occipital artery: Anatomical variations and neurosurgical applications.

Background: The occipital artery (OA) is a branch of the external carotid artery. It gives rise to several cutaneous, muscular, and meningeal branches to supply different anatomical areas. The implication of OA in the neurosurgical field is well-established in the literature. Our aim in this study is to draw a complete picture of the anatomical variations and neurosurgical applications of the OA. Methods: A literature review was conducted in Google Scholar and PubMed to review the studies discussing OA, its anatomical variation, and neurosurgical applications. Results: We identified 29 articles that discuss the anatomical variations and neurosurgical applications of the OA. Certain variables are used to describe the surgical anatomy of OA. We also discussed certain applications of OA and its importance in neurosurgical bypass, embolization, and aneurysms. Conclusion: Comprehending the anatomy of the OA is crucial for neurosurgeons to safely and effectively perform procedures such as bypass and embolization. In addition, knowledge of the anatomical variations of the OA can help surgeons anticipate potential challenges and tailor their approach accordingly.

Supraorbital artery: Anatomical variations and neurosurgical applications.

Background: The supraorbital artery (SOA) originates from the ophthalmic artery in a superomedial aspect of the orbit, exiting through the supraorbital groove to emerge onto the forehead. The SOA has important neurosurgical considerations regarding different approaches and bypasses. The SOA is poorly described in the standard anatomical textbooks. Therefore, we present this article to describe the anatomical variations of the SOA and their implications on the neurosurgical field. Methods: We conducted a literature review in PubMed and Google Scholar databases to review the existing literature describing the SOA anatomy and its neurosurgical applications. Results: While reading the available articles and original works regarding SOA, we identified 22 studies that discuss the SOA. We noticed the anatomical variations of the SOA in terms of origin, course, diameter, branches, depth, and distance in relation to the midline and vertical glabellar line. We also discussed certain applications of SOA and its importance in neurosurgical approaches, bypass, photoplethysmography, aneurysms, and reconstruction of cranial fossa defects. Conclusion: The variable anatomy of the SOA has a paramount impact on performing different neurosurgical approaches. Therefore, cadaveric studies of the SOA are important to explore potential methods for the preservation of the artery in different neurosurgical applications.

Peritrigeminal Safe Entry Zone Access to Anterolateral Pons Using the Presigmoid Retrolabyrinthine Suprameatal Approach: A Cadaveric Morphometric Study.

BACKGROUND AND OBJECTIVES: Access to the anterolateral pontine lesions can be achieved through the peritrigeminal and supratrigeminal safe entry zones using Kawase, retrosigmoid, or translabyrinthine approaches. However, these approaches entail shallow extensive dissection, tangential access, and compromise vestibulocochlear function. We aimed to investigate infratentorial presigmoid retrolabyrinthine approach to access pontine lesions through the peritrigeminal zone. METHODS: We performed 10 presigmoid retrolabyrinthine suprameatal approach dissections in 5 cadaveric heads. Anatomic-radiological characteristics and variations were evaluated. Six morphometric parameters were measured and analyzed to predict surgical accessibility. RESULTS: The pontine infratrigeminal area was accessible in all patients. The mean exposed area of the anterolateral pontine surface was 98.95 cm 2 (±38.11 cm 2 ). The mean length of the exposed trigeminal nerve was 7.9 cm (±2.9 cm). Preoperative anatomic-radiological parameters may allow to select patients with favorable anatomy that offers appropriate surgical accessibility to the anterior pontine cavernoma through a presigmoid retrolabyrinthine corridor. CONCLUSION: Anterolateral pontine lesions can be accessed through a minimally invasive infratentorial presigmoid retrolabyrinthine approach by targeting the infratrigeminal safe entry zone. Further clinical studies should be conducted to evaluate the viability of this technique for treating these complex pathologies in real clinical settings.

A proposed classification system for presigmoid approaches: a scoping review.

OBJECTIVE: The "presigmoid corridor" covers a spectrum of approaches using the petrous temporal bone either as a target in treating intracanalicular lesions or as a route to access the internal auditory canal (IAC), jugular foramen, or brainstem. Complex presigmoid approaches have been continuously developed and refined over the years, leading to great heterogeneity in their definitions and descriptions. Owing to the common use of the presigmoid corridor in lateral skull base surgery, a simple anatomy-based and self-explanatory classification is needed to delineate the operative perspective of the different variants of the presigmoid route. Herein, the authors conducted a scoping review of the literature with the aim of proposing a classification system for presigmoid approaches. METHODS: The PubMed, EMBASE, Scopus, and Web of Science databases were searched from inception to December 9, 2022, following the PRISMA Extension for Scoping Reviews guidelines to include clinical studies reporting the use of "stand-alone" presigmoid approaches. Findings were summarized based on the anatomical corridor, trajectory, and target lesions to classify the different variants of the presigmoid approach. RESULTS: Ninety-nine clinical studies were included for analysis, and the most common target lesions were vestibular schwannomas (60/99, 60.6%) and petroclival meningiomas (12/99, 12.1%). All approaches had a common entry pathway (i.e., mastoidectomy) but were differentiated into two main categories based on their relationship to the labyrinth: translabyrinthine or anterior corridor (80/99, 80.8%) and retrolabyrinthine or posterior corridor (20/99, 20.2%). The anterior corridor comprised 5 variations based on the extent of bone resection: 1) partial translabyrinthine (5/99, 5.1%), 2) transcrusal (2/99, 2.0%), 3) translabyrinthine proper (61/99, 61.6%), 4) transotic (5/99, 5.1%), and 5) transcochlear (17/99, 17.2%). The posterior corridor consisted of 4 variations based on the target area and trajectory in relation to the IAC: 6) retrolabyrinthine inframeatal (6/99, 6.1%), 7) retrolabyrinthine transmeatal (19/99, 19.2%), 8) retrolabyrinthine suprameatal (1/99, 1.0%), and 9) retrolabyrinthine trans-Trautman's triangle (2/99, 2.0%). CONCLUSIONS: Presigmoid approaches are becoming increasingly complex with the expansion of minimally invasive techniques. Descriptions of these approaches using the existing nomenclature can be imprecise or confusing. Therefore, the authors propose a comprehensive classification based on the operative anatomy that unequivocally describes presigmoid approaches simply, precisely, and efficiently.

Stephanion to cranial base penetrating stab wound with outstanding recovery: A case report.

Background: Mortality due to head trauma is common in developed countries in all age groups. Nonmissile penetrating skull base injuries (PSBIs) due to foreign bodies are quite rare, accounting for about 0.4%. PSBI carries that a poor prognosis brainstem involvement usually is often fatal. We are reporting the first case of PSBI with a foreign body insertion site through the stephanion with a remarkable outcome. Case Description: The 38-year-old male patient was referred with a penetrating stab wound to the head through the stephanion caused by a knife after a conflict in the street. He had no focal neurological deficit or cerebrospinal fluid leak, and Glasgow coma scale (GCS) was 15/15 on admission. A preoperative computed tomography scan showed the path of the stab beginning at the stephanion, which is the point where the coronal suture crosses the superior temporal line, heading toward the cranial base. Postoperatively, GCS was 15/15 without any deficit apart from the left wrist drop, possibly due to a left arm stab. Conclusion: Careful investigations and diagnoses must be made to ensure convenient knowledge of the case due to the variety of injury mechanisms, foreign body characteristics, and individual patients' characteristics. Reported cases of PSBIs in adults have not reported a stephanion skull base injury. Although brain stem involvement is usually fatal, our patient had a remarkable outcome.