Novel Classification and Microsurgical Anatomy of the Basilar Artery: A Cadaveric Study

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This study aims to address this gap by providing a detailed review of the BA's microsurgical anatomy, proposing a novel segmental classification of the artery and the significance of each segment in various surgical pathologies and approaches. Methods A total of 20 cadaveric adult brain specimens were meticulously examined under high magnification, following Institutional Review Board approval. The dissection focused on the BA and its branches, with morphometric data collected, including dimensions and anatomical variations. Results This study included 20 specimens. A novel classification was proposed base on the blood flow direction, including three segments. The inferior segment extended from the junction of the VA to the origin of the most rostral collateral artery, averaging 3.55 mm in diameter and lengths between 9.0 and 17.1 mm, with 3 to 4 caudal perforators. The middle segment, which ranged from the inferior border of the anterior inferior cerebellar artery (AICA) to the origin of the superior cerebellar artery, measured 3.44 mm in diameter and 15.2 mm in length, featuring 5–6 middle perforating branches. The superior segment ended at the bifurcation of the BA, with an average diameter of 4.2 mm and a length of 3.6 mm. The overall BA length averaged 30.7 mm, with a range of 23.5–38.2 mm. Conclusion A comprehensive understanding of the origin, course, branches and segments of the BA is crucial for mitigating vascular complications during both open and endovascular surgical procedures. Anatomy basilar artery cadaveric cerebrovascular anatomy microsurgical anatomy vertebrobasilar system Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 INTRODUCTION The basilar artery (BA) is an unpaired vessel formed by the convergence of the vertebral arteries (VA) at the pontomedullary junction. It ascends to the upper border of the pons and bifurcates into the posterior cerebral arteries (PCA), typically near the interpeduncular cistern [ 1 ]. Embryologically, the BA arises from the ventral neural longitudinal arteries, initially supplied by the trigeminal arteries [ 2 ]. As development progresses, these anastomoses regress, and the arterial supply transitions to depend on the posterior communicating arteries and other carotid-vertebral and carotid-basilar anastomoses [ 3 ]. Finally, the ventral neural longitudinal arteries converge to form the BA, starting caudally and extending rostrally [ 2 , 4 ]. Once developed, the BA branches supply the pons, midbrain, parts of the diencephalon, the temporal and occipital lobes, and cerebellum [ 5 ]. Mastery of microsurgical anatomy is crucial for managing vascular lesions to mitigate complications, execute precise preoperative planning and accurately assess neurologic syndromes. This expertise is equally indispensable for the endovascular treatment of intracranial lesions. An extensive review of the literature on neurovascular microsurgical anatomy reveals a notable gap: the trunk of the BA has been relatively underrepresented in microanatomical studies, unlike its perforating branches and bifurcation, which have been the focus of numerous investigations. This study aims to address this gap by reviewing the microsurgical anatomy of the BA, proposing a novel classification for its segments, and the significance of each of them in various surgical pathologies and approaches. METHODS The BA were meticulously examined under high magnification in 20 cadaveric adult brain specimens procured from the National Institute of Legal Medicine and Forensic Sciences of Colombia, following Institutional Review Board (IRB) approval. Specimens were excluded if they were decomposed, fetal/infant autopsies, or if there was a history or findings of neurological pathology. Each of the 20 tissue blocks analyzed encompassed the brainstem (from the cervicomedullary junction to the mesencephalon), the cerebellum, the intracranial segments of the VA, the BA with all its branches up to the P1 segment of the PCA, cranial nerves (CN) III to XII, and the surrounding arachnoid membrane. The specimens were initially washed in running water and the arteries were perfused with colored latex to enhance visibility for dissection. Vessels were thoroughly examined in situ, with detailed sketches made to document any observed variations. Dimensions were measured with Vernier calipers and a ruler was employed to calculate the length of the BA. Fresh photographs were taken for documentation, and the tissue blocks were subsequently fixed in 10% formaldehyde for two weeks. RESULTS Among the examined specimens, 80% were male, with ages ranging from 18–56 years and an average age of 31.4 years. The BA typically originates at the pontomedullary sulcus, where the two VAs converge, and courses rostrally along the basilar groove, a shallow groove on the pons surface 5 . This artery gives perforating and collateral branches to the medulla, pons, midbrain, and cerebellum. Distally, the BA generally extends to the interpeduncular cistern at the pontomesencephalic sulcus, where it bifurcates into the PCA’s. For analytical purposes we categorized the BA into three segments, based on the direction of blood flow, the arrangement of their perforating and collateral branches and their respective vascular territories. The first segment, designated as the inferior segment (Fig. 1 ), extends from the junction of the VA to the origin of the most rostral collateral artery resembling the anterior inferior cerebellar artery (AICA). Its perforating branches, directed toward the foramen caecum, were termed caudal perforators, while the collateral branches extending to the pontomedullary sulcus were classified as pontomedullary arteries [ 6 , 7 ]. The morphometric characteristics, including the length and diameter of each BA segment, as determined in our study, are summarized in Table 1 . Table 1 Diameter and length of the basilar artery and other arteries. Diameter (mm) Lenght (mm) Average Range Average Range Basilar artery 4.05 3.5–4.3 30.7 23.5–38.2 Lower segment 3.55 3.0-4.2 11.9 9-17.1 Middle segment 3.44 3.0-4.2 15.2 10.5–19.5 Upper segment 4.2 4.01–4.6 3.6 2.4-5 Other arteries Posterior cerebral artery 2.3 1.6-3 - - Superior Cerebellar artery 1.6 1.3–1.9 - - Anterior Inferior Cerebellar Artery R: 1.06 L: 0.71 R: 0.73–1.9 L: 0.59–1.5 - - The middle segment (Fig. 2 ) was defined as the region extending from the inferior border of the AICA to the origin of the most caudal collateral artery behaving as the superior cerebellar artery (SCA). Its perforating branches course toward the lateral aspect of the basilar groove and were termed middle perforators, while its collateral branches included: AICA, long pontine arteries, short pontine arteries and pontomesencephalic artery. The upper segment (Fig. 3 ) corresponds to the BA between the upper limit of the middle segment and the bifurcation of the artery. Its perforating branches primarily course toward the posterior perforated substance in the interpeduncular fossa, and its collateral branches include cerebellar arteries (SCA) and mesencephalic arteries. The terminal branches (PCA) are out of the scope of this study. The BA, had an average length of 30.13 mm, ranging from 23.5–38.2 mm. In 20% of the cases, the artery exhibited tortuosity, with left-sided concavity in its lower and middle segments in 75% of cases, which was associated with the presence of left vertebral artery dominance. Perforating and Collateral Branches of the Basilar Artery by Segment ( Table 2 ) Table 2 Perforating and Collateral Branches of the Basilar Artery by Segment Inferior Segment Middle Segment Superior Segment - Caudal perforating arteries - Pontomedullary arteries - Anteroinferior cerebellar arteries (AICA) - Middle perforating arteries - Anterolateral arteries (short pontine arteries) - Long or transverse pontine arteries *Inferolateral pontine arteries *Superolateral pontine arteries - Posterolateral arteries (ponto-mesencephalic artery) - Superior cerebellar arteries (SCA) - Posterior cerebral arteries (PCA) - Rostral perforating arteries Inferior segment (Fig. 4 ) The average diameter of the BA at its origin was 4.05 mm, ranging from 3.5 to 4.3 mm. At the level of the origin of the AICA, the average diameter was 3.55 mm (3.0 to 4.2 mm), with a segment length of 9.0 to 17.1 mm (average 11.9 mm). On average, there were 3–4 caudal perforating arteries (range of 3–6), directed towards the foramen caecum. Almost all caudal perforating arteries arose from this segment, except for two cases (10%), where each artery originated from the middle segment of the BA, above the origin of AICA. In these cases, the artery traversed along the basilar groove, giving rise to smaller branches, and ultimately entered the foramen caecum. The caudal perforating arteries originated, on average, 6.67 mm above the VA junction, (range: 0.51–12.7 mm). Frequently, these arteries also originated from the VA and the pontomedullary arteries; 83% branched before penetrating the foramen caecum. Their average diameter was 0.34 mm (0.17 to 0.43 mm). The collateral arteries identified were the pontomedullary arteries, which originated at various levels within the lower segment, either as direct branches of the basilar trunk or as branches of the caudal perforating arteries. These pontomedullary arteries followed an inferolateral course towards the pontomedullary sulcus, sending small branches to the pons, the upper ends of the pyramid and olive, and the sixth CN, ultimately reaching the retro-olivary fossa and the restiform body. The number of these arteries varied from 0–3 per side and from 1–4 per specimen (with an average of 2). Their average diameter was 0.66 mm, ranging from 0.19 to 0.46 mm. In all specimens, the junction of the VA occurred above the level of the pontomedullary sulcus, at a distance of 1.0 to 8.3 mm, with an average of 3.35 mm. Middle segment (Fig. 5 ) The average diameter of the BA at the upper limit of this segment was 3.44 mm, ranging from 3.0 to 4.2 mm. The middle segment had an average length of 15.2 mm (10.5 to 19.5 mm). The middle perforating branches, characteristic of this segment, generally originated from a common trunk with the anterior lateral arteries or as collateral branches of the long pontine arteries. These branches were noted for their tortuous course, directed towards the lateral aspect of the basilar groove and its margins. They branched out before penetrating the pontine parenchyma, where they remained medial; some branches were long, while others were short, supplying midline structures. On average, there were 5–6 of these middle perforating branches per specimen (range: 5 to 8), with diameters from 0.21 to 0.74 mm. The anterior lateral arteries, also known as short pontine arteries, originated from a common trunk with the middle perforating arteries. They were tortuous as well, branching before penetrating the pons and extending in an inferolateral direction, reaching approximately halfway between the BA trunk and the apparent origin of the fifth CN. In some cases, they also originated from the long pontine arteries, following a similar course and distribution. There were 4–6 long pontine (or transverse pontine) arteries with a diameter ranging from 0.4 to 0.8 mm (average 0.57 mm). Their origin was, on average, 11.1 mm from the caudal edge of the AICA’s origin, with a range from 5.5 to 19.9 mm. These arteries followed a lateral course, emitting few branches to the anterior surface of the pons, except at their most lateral aspect. They were categorized into two major groups based on their distribution relative to the fifth CN: those above were termed superolateral, and those below were termed inferolateral. Both groups irrigated the nerve between its major and minor portions. An additional collateral artery, identified in all specimens, was the posterolateral or pontomesencephalic artery. This artery originated immediately proximal to the upper boundary of the segment on both sides, coursing parallel to the SCA within the pontomesencephalic groove. It gave branches to the cerebral peduncle and terminated by branching at the junction of the peduncle with the tectal plate. The AICA was found in 100% of the specimens, exhibiting asymmetrical caliber in 60%, with the right side consistently larger. The average diameter at their origin was 1.06 mm on the right and 0.71 mm on the left. These arteries followed an inferolateral course toward the seventh and eighth CN. The detailed microsurgical anatomy of these arteries was not covered in this study. Superior segment (Fig. 6 ) The superior segment ends at the BA bifurcation, where it divides into PCA (rostral edge of the bifurcation). The average diameter of the artery between the SCA and the PCA was 4.2 mm (range 4.01 to 4.6 mm). The segment's length averaged 3.6 mm, ranging from 2.4 to 5.0 mm. The arteries supplying the posterior perforated substance were termed rostral perforating arteries and there were 1–3. Their diameter ranged from 0.2 to 0.5 mm (average 0.3 mm). These arteries typically reached their entry site as single trunks or immediately divided just before penetrating the parenchyma. No branches were found originating directly from the upper wall of the artery bifurcation, and all rostral perforators depended on the posterior wall of the basilar artery. While there were numerous arteries directed to the posterior perforated substance, most of them originated from the first segment of the PCA (P1 or pre-communicating segment), especially from the thalamogeniculate or medial thalamoperforating artery. This artery entered the posterior perforated substance after dividing into multiple branches or as a single trunk (less frequently). There were also anastomoses between thalamogeniculate arteries. Other perforating branches to this area originated from the superior cerebellar artery, posterior communicating artery, and post-communicating posterior cerebral artery. The SCA were present in 100% of the specimens, with an average diameter of 1.6 mm (1.3–1.9 mm). The microsurgical anatomy of these arteries, as well as that of the PCA, was beyond the scope of this study. The PCA was also present in all cases, with diameters ranging from 1.6 to 3.0 mm (average 2.3 mm). A fetal configuration of the posterior communicating - posterior cerebral complex was found in 2 cases (10%). Notably, one of these cases featured a hypoplastic posterior cerebral artery with a double fenestration, a variant not previously described in the literature and discussed in a separate paper. The collateral branches included the mesencephalic circumferential arteries, which in this study, originated from the basilar artery in only 5% of the cases. Their average diameter was 0.57 mm, with a range of 0.45 to 0.68 mm. Circumferential arteries dependent on the first segment of the posterior cerebral artery were also found, especially the posteromedial choroidal artery, which had a special relationship with the third CN (Fig. 6 ). Other mesencephalic circumferential branches originated as collaterals from the thalamogeniculate arteries and the SCA. DISCUSSION The classification of the BA segments proposed in this study is based on the morphological characteristics of its perforating and collateral branches, and correlates well with the microsurgical implications on each of these segments [ 8 ]. The upper segment of the BA is crucial in common procedures like microvascular decompression for trigeminal neuralgia, given the proximity of its branches to crucial neural structures [ 9 ]. It is also relevant in less frequent cases of basilar compression of the trigeminal nerve. Janetta et al reported a series of 1404 patients who undergoing microvascular decompression for trigeminal neuralgia, noting that 2% were caused by vertebrobasilar compression [ 10 ]. Specifically, the trigeminal nerve was compressed by the VA in 18 cases, the BA in 12 cases, and the vertebrobasilar junction in one case. The surgical anatomy of the upper segment is very relevant when treating basilar tip aneurisms because all rostral perforators depended on the posterior or posterolateral walls of the artery. Thus, this type of aneurysms in high-riding BA can be accessed through an orbitozygomatic approach, sparing all rostral perforators. On the other hand, this anatomic considerations should be pondered when performing an endoscopic third ventriculostomy [ 11 , 12 ] and treating SCA aneurysms [ 13 ]. Some authors [ 14 , 15 ], have described that pre-mesencephalic subarachnoid hemorrhages are secondary to basilar perforating arteries aneurysm rupture. The aneurysms of the AICA account for less than 1% of all intracranial aneurysms, the surgical approach is partly determined by the aneurysm's position relative to the clivus [ 16 ]. Various approaches are utilized, including retrosigmoid, far-lateral, middle fossa, transcochlear, translabyrinthine, orbitozygomatic, and combined supratentorial-infratentorial presigmoid techniques [ 17 ].The anatomy of the middle segment is particularly relevant in this context, asi it influences the choice of surgical technique. The importance of preservation of the middle segment`s collateral and perforating vessels deserves attention when performing a microvascular decompression for hemifacial spam [ 18 ] or when determining the safe entry zones to treat pontine cavernomas [ 19 , 20 ]. Although very rare, hemifacial spams secondary to verterbrobasilar dolicoechtasia has been described [ 21 , 22 ]. Considering that aneurysms of the lower BA are difficult to expose and clip, Kumar et al described the far-lateral approach without occipital condyle drilling for clipping these aneurysms [ 23 ]. Occasionally, an extensive lateral exposure of the clivus is required to treat giant aneurysms of this segment. Such an exposure can be achieved by combining the far-lateral and combined supra- and infratentorial approaches [ 24 ]. In 1997, Rhoton et al noted a mean diameter of the BA just below SCA and between the SCA and P1 of 4.1 mm and 4.5 mm, respectively [ 5 ]. Padmavathi et al [ 25 ] described that the diameter at origin, midlevel and termination were 4.5 mm, 4 mm and 4.8 mm. Vijayakumar et al reported diameters of 3.7 mm, 3.6 mm and 3.9 mm at the origin, midlevel and termination [ 1 ]. Our findings were comparable to those previously described. Likewise, the BA length described in our study (mean: 30.7 mm) was comparable to the one described by other authors of 32 mm and 28 mm [ 5 , 8 ]. This consistency with existing literature enhances the reliability of our results. In Rhoton et al. study, the posterior and lateral surfaces of the upper centimeter of the BA were a rich source of perforating arteries, with an average of eight branches of 0.1–0.5 mm diameter [ 5 ]. Approximately one-half were described to arise from the posterior surface and one-fourth from each side [ 5 ]. No arteries emerged from the anterior surface. This aligns with Kwiatkowska et al.`s analysis of 100 specimens (2226 pontine perforating arteries), in which 77.1% emerged from the posterior aspect, 22.8% from the lateral surface and only 0.2% from the anterior surface [ 8 ]. In our study all rostral perforators originated from the posterior wall. The vascular configuration of the foramen caecum and the interpeduncular cistern exhibits significant individual variability [ 6 ]. The main trunk, particularly in the middle segment, is less variable, despite being the largest segment [ 26 ]. This stability can be attributed to embryological factors, as most anastomoses and territory recruitment at the margins of this vascular system, responding to the developing brain`s metabolic demands [ 4 ]. In contrast, the junction of the posterior communicating and PCA exhibits all possible variations in vascular morphology resulting from the incorporation of the caudal segment of the internal carotid artery into the vertebrobasilar system. Limitations The sample size may restrict our ability to capture the anatomical variations of the BA and its branches. Additionally, the conservation and coloration processes of cadaveric specimens may yield measurements that differ from those in living subjects. Lastly, underlying pathologies in vivo can alter anatomical structures, impacting the applicability and accuracy of our measurements. CONCLUSIONS The detailed microsurgical anatomy of the BA presented herein adds value to existing literature, particularly with a novel segmental classification. Our findings are relevant for neurosurgeons, interventional radiologists, and neurologists, enhancing their ability to navigate BA pathology. Knowledge of BA anatomy also aids in addressing conditions like arteriovenous malformations, aneurysms, and tumors. Recognizing anatomical variations is essential, as they may indicate hemodynamic changes influencing pathology development (e.g., aneurysms in arteries with fenestrations) or affect the cerebral vasculature's adaptive capacity. Abbreviations AICA: Anterior Inferior cerebellar artery BA: Basilar Artery CN: Cranial nerve(s) PCA: Posterior Cerebral Artery SCA: Superior cerebellar artery VA: Vertebral Artery Declarations Competing Interests Disclosures: Pablo Harker reports advisory fees and convertible notes from Magnendo Corp, unrelated to the present work. Funding: None. Disclosures: Pablo Harker reports advisory fees and convertible notes from Magnendo Corp, unrelated to the present work. Author Contribution MION, FMN, DADM: made substantial contributions to the conception or design of the work; acquisition, analysis, and interpretation of data;drafted the work or revised it critically for important intellectual content; approved the version to be published; and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.PH, RCDO, MEBC: made substantial contributions to the conception or design of the work; acquisition, analysis, and interpretation of data;revised it critically for important intellectual content; approved the version to be published; and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Acknowledgement The authors acknowledge and thank Sabrina Zorio for the illustrations. 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Study of the variations in the origin and termination of basilar artery. Anat Karnataka . 2011;5:54-59. Tsantili AR, Karampelias V, Samolis A, et al. Anatomical variations of human vertebral and basilar arteries: A current review of the literature. Morphologie . 2023;107(357):169-175. doi:10.1016/j.morpho.2022.07.001 Additional Declarations Competing interest reported. Disclosures: Pablo Harker reports advisory fees and convertible notes from Magnendo Corp, unrelated to the present work. Cite Share Download PDF Status: Published Journal Publication published 02 Apr, 2025 Read the published version in Surgical and Radiologic Anatomy → Version 1 posted Editorial decision: Revision requested 03 Feb, 2025 Reviews received at journal 01 Feb, 2025 Reviewers agreed at journal 23 Jan, 2025 Reviewers agreed at journal 22 Jan, 2025 Reviewers agreed at journal 22 Jan, 2025 Reviewers invited by journal 22 Jan, 2025 Editor assigned by journal 22 Jan, 2025 Submission checks completed at journal 22 Jan, 2025 First submitted to journal 20 Jan, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5867946","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":406168830,"identity":"71145245-2d88-46d1-bc68-8052dfe14a98","order_by":0,"name":"Maria Isabel Ocampo-Navia","email":"data:image/png;base64,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","orcid":"","institution":"Hospital Universitario San Ignacio and Pontificia Universidad Javeriana","correspondingAuthor":true,"prefix":"","firstName":"Maria","middleName":"Isabel","lastName":"Ocampo-Navia","suffix":""},{"id":406168831,"identity":"82aa39ea-8200-4b23-8104-baf4982f9cd7","order_by":1,"name":"Diego Armando Devia-Manosalva","email":"","orcid":"","institution":"Pontificia Universidad Javeriana","correspondingAuthor":false,"prefix":"","firstName":"Diego","middleName":"Armando","lastName":"Devia-Manosalva","suffix":""},{"id":406168832,"identity":"8227f6d7-e4d6-48be-8cc0-a099ef021102","order_by":2,"name":"Felipe Marín-Navas","email":"","orcid":"","institution":"Hospital Universitario San Ignacio and Pontificia Universidad Javeriana","correspondingAuthor":false,"prefix":"","firstName":"Felipe","middleName":"","lastName":"Marín-Navas","suffix":""},{"id":406168833,"identity":"3e1a136d-8a93-4473-8413-c94ad55eaffc","order_by":3,"name":"Pablo Harker","email":"","orcid":"","institution":"University of Cincinnati","correspondingAuthor":false,"prefix":"","firstName":"Pablo","middleName":"","lastName":"Harker","suffix":""},{"id":406168834,"identity":"98ccae1a-4b4d-427f-aa93-14411c97c9a3","order_by":4,"name":"Roberto Díaz","email":"","orcid":"","institution":"Hospital Universitario San Ignacio and Pontificia Universidad Javeriana","correspondingAuthor":false,"prefix":"","firstName":"Roberto","middleName":"","lastName":"Díaz","suffix":""},{"id":406168835,"identity":"89920a53-234a-47eb-8b9b-421ef499f6c7","order_by":5,"name":"Miguel Enrique Berbeo-Calderón","email":"","orcid":"","institution":"Hospital Universitario San Ignacio and Pontificia Universidad Javeriana","correspondingAuthor":false,"prefix":"","firstName":"Miguel","middleName":"Enrique","lastName":"Berbeo-Calderón","suffix":""}],"badges":[],"createdAt":"2025-01-20 17:38:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5867946/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5867946/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00276-025-03612-0","type":"published","date":"2025-04-02T15:57:38+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":74691971,"identity":"e593e8cb-895f-4226-b8dc-51cdfd52d4dd","added_by":"auto","created_at":"2025-01-24 18:48:46","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":9345277,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eInferior Segment of the Basilar Artery. \u003c/strong\u003eThe green shaded area delineates this segment, while the green boxes denote the branches of this segment.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-5867946/v1/245df3b8589ce11709d2dc49.png"},{"id":74691980,"identity":"3fc773e4-da23-4c14-9b21-86517b021653","added_by":"auto","created_at":"2025-01-24 18:48:46","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":7490680,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMiddle Segment of the Basilar Artery. \u003c/strong\u003eThe pink shaded area corresponds to this segment, and the orange boxes indicate the branches of this segment.\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-5867946/v1/afa8e9d703ad478a9add3b4a.png"},{"id":74691972,"identity":"b1cead29-5d0f-47e4-8b18-23106300c480","added_by":"auto","created_at":"2025-01-24 18:48:46","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":7775504,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSuperior Segment of the Basilar Artery. \u003c/strong\u003eThe gray shaded area corresponds to this segment, and the gray boxes indicate the branches from this segment.\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-5867946/v1/826d1a0e9f0bdedad7f0fbaf.png"},{"id":74692417,"identity":"a78530fa-71bf-481a-b2b5-0ff23f209145","added_by":"auto","created_at":"2025-01-24 18:56:46","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":10816350,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eInferior Segment of the Basilar Artery.\u003c/strong\u003e BA: Basilar Artery, VA: Vertebral Artery (right side), dotted circle depicts the level of the foramen caecum\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-5867946/v1/758e96350133d4e80cab6488.png"},{"id":74691976,"identity":"4c410256-0f08-448a-aa57-b1a367d9f36d","added_by":"auto","created_at":"2025-01-24 18:48:46","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":9918910,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMiddle segment of the Basilar Artery.\u003c/strong\u003e AICA: Anterior Inferior Cerebellar Artery, BA: Basilar Artery, PCA: Posterior Cerebral Artery, SCA: Superior Cerebellar Artery, VA: Vertebral Artery. 1: Mesencephalon (crus cerebri), 2: Third cranial nerve, 3: Posteromedial Choroidal Artery, 4: Sixth cranial nerve, 5: Posterior Inferior Cerebellar Artery, 6: parahipocampal gyrus\u003c/p\u003e","description":"","filename":"Figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-5867946/v1/7c97f6d72325b4ae9765a36c.png"},{"id":74692421,"identity":"41b4301a-0f84-4901-943d-b880eb02d114","added_by":"auto","created_at":"2025-01-24 18:56:47","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":10662342,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSuperior segment of the Basilar Artery.\u003c/strong\u003e Basilar Artery, PCA: Posterior Cerebral Artery, SCA: Superior Cerebellar Artery. 1: Third ventricle floor, 2: Posterior Communicating Artery, 3: Mamillary bodies, 4: Third cranial nerve, 5: Optic tract, 6: parahipocampal gyrus, 7: Peduncular perforating branches (from the Posterior Cerebral Artery)\u003c/p\u003e","description":"","filename":"Figure6.png","url":"https://assets-eu.researchsquare.com/files/rs-5867946/v1/c327e658622be74e73a55579.png"},{"id":80082080,"identity":"8524a0c4-948c-481c-8e54-2ead217dd235","added_by":"auto","created_at":"2025-04-07 16:06:50","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":118910513,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5867946/v1/ea12e782-822a-46a9-8249-a6c7531e2b85.pdf"}],"financialInterests":"Competing interest reported. Disclosures: Pablo Harker reports advisory fees and convertible notes from Magnendo Corp, unrelated to the present work.","formattedTitle":"Novel Classification and Microsurgical Anatomy of the Basilar Artery: A Cadaveric Study","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eThe basilar artery (BA) is an unpaired vessel formed by the convergence of the vertebral arteries (VA) at the pontomedullary junction. It ascends to the upper border of the pons and bifurcates into the posterior cerebral arteries (PCA), typically near the interpeduncular cistern [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEmbryologically, the BA arises from the ventral neural longitudinal arteries, initially supplied by the trigeminal arteries [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. As development progresses, these anastomoses regress, and the arterial supply transitions to depend on the posterior communicating arteries and other carotid-vertebral and carotid-basilar anastomoses [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Finally, the ventral neural longitudinal arteries converge to form the BA, starting caudally and extending rostrally [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Once developed, the BA branches supply the pons, midbrain, parts of the diencephalon, the temporal and occipital lobes, and cerebellum [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMastery of microsurgical anatomy is crucial for managing vascular lesions to mitigate complications, execute precise preoperative planning and accurately assess neurologic syndromes. This expertise is equally indispensable for the endovascular treatment of intracranial lesions.\u003c/p\u003e \u003cp\u003eAn extensive review of the literature on neurovascular microsurgical anatomy reveals a notable gap: the trunk of the BA has been relatively underrepresented in microanatomical studies, unlike its perforating branches and bifurcation, which have been the focus of numerous investigations. This study aims to address this gap by reviewing the microsurgical anatomy of the BA, proposing a novel classification for its segments, and the significance of each of them in various surgical pathologies and approaches.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cp\u003eThe BA were meticulously examined under high magnification in 20 cadaveric adult brain specimens procured from the National Institute of Legal Medicine and Forensic Sciences of Colombia, following Institutional Review Board (IRB) approval. Specimens were excluded if they were decomposed, fetal/infant autopsies, or if there was a history or findings of neurological pathology.\u003c/p\u003e \u003cp\u003eEach of the 20 tissue blocks analyzed encompassed the brainstem (from the cervicomedullary junction to the mesencephalon), the cerebellum, the intracranial segments of the VA, the BA with all its branches up to the P1 segment of the PCA, cranial nerves (CN) III to XII, and the surrounding arachnoid membrane. The specimens were initially washed in running water and the arteries were perfused with colored latex to enhance visibility for dissection. Vessels were thoroughly examined in situ, with detailed sketches made to document any observed variations. Dimensions were measured with Vernier calipers and a ruler was employed to calculate the length of the BA. Fresh photographs were taken for documentation, and the tissue blocks were subsequently fixed in 10% formaldehyde for two weeks.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eAmong the examined specimens, 80% were male, with ages ranging from 18\u0026ndash;56 years and an average age of 31.4 years. The BA typically originates at the pontomedullary sulcus, where the two VAs converge, and courses rostrally along the basilar groove, a shallow groove on the pons surface \u003csup\u003e5\u003c/sup\u003e. This artery gives perforating and collateral branches to the medulla, pons, midbrain, and cerebellum. Distally, the BA generally extends to the interpeduncular cistern at the pontomesencephalic sulcus, where it bifurcates into the PCA\u0026rsquo;s.\u003c/p\u003e \u003cp\u003eFor analytical purposes we categorized the BA into three segments, based on the direction of blood flow, the arrangement of their perforating and collateral branches and their respective vascular territories. The first segment, designated as the inferior segment (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), extends from the junction of the VA to the origin of the most rostral collateral artery resembling the anterior inferior cerebellar artery (AICA). Its perforating branches, directed toward the foramen caecum, were termed caudal perforators, while the collateral branches extending to the pontomedullary sulcus were classified as pontomedullary arteries [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The morphometric characteristics, including the length and diameter of each BA segment, as determined in our study, are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDiameter and length of the basilar artery and other arteries.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eDiameter (mm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eLenght (mm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAverage\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRange\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAverage\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRange\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBasilar artery\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.5\u0026ndash;4.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e23.5\u0026ndash;38.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLower segment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.0-4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9-17.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMiddle segment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.0-4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10.5\u0026ndash;19.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUpper segment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.01\u0026ndash;4.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.4-5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOther arteries\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePosterior cerebral artery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.6-3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSuperior Cerebellar artery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.3\u0026ndash;1.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnterior Inferior Cerebellar Artery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR: 1.06\u003c/p\u003e \u003cp\u003eL: 0.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eR: 0.73\u0026ndash;1.9\u003c/p\u003e \u003cp\u003eL: 0.59\u0026ndash;1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe middle segment (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) was defined as the region extending from the inferior border of the AICA to the origin of the most caudal collateral artery behaving as the superior cerebellar artery (SCA). Its perforating branches course toward the lateral aspect of the basilar groove and were termed middle perforators, while its collateral branches included: AICA, long pontine arteries, short pontine arteries and pontomesencephalic artery.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe upper segment (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) corresponds to the BA between the upper limit of the middle segment and the bifurcation of the artery. Its perforating branches primarily course toward the posterior perforated substance in the interpeduncular fossa, and its collateral branches include cerebellar arteries (SCA) and mesencephalic arteries. The terminal branches (PCA) are out of the scope of this study.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe BA, had an average length of 30.13 mm, ranging from 23.5\u0026ndash;38.2 mm. In 20% of the cases, the artery exhibited tortuosity, with left-sided concavity in its lower and middle segments in 75% of cases, which was associated with the presence of left vertebral artery dominance.\u003c/p\u003e \u003cp\u003e \u003cb\u003ePerforating and Collateral Branches of the Basilar Artery by Segment\u003c/b\u003e \u003cem\u003e(\u003c/em\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u003cem\u003e)\u003c/em\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePerforating and Collateral Branches of the Basilar Artery by Segment\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInferior Segment\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMiddle Segment\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSuperior Segment\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e- Caudal perforating arteries\u003c/p\u003e \u003cp\u003e- Pontomedullary arteries\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e- Anteroinferior cerebellar arteries (AICA)\u003c/p\u003e \u003cp\u003e- Middle perforating arteries\u003c/p\u003e \u003cp\u003e- Anterolateral arteries (short pontine arteries)\u003c/p\u003e \u003cp\u003e- Long or transverse pontine arteries\u003c/p\u003e \u003cp\u003e*Inferolateral pontine arteries\u003c/p\u003e \u003cp\u003e*Superolateral pontine arteries\u003c/p\u003e \u003cp\u003e- Posterolateral arteries (ponto-mesencephalic artery)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e- Superior cerebellar arteries (SCA)\u003c/p\u003e \u003cp\u003e- Posterior cerebral arteries (PCA)\u003c/p\u003e \u003cp\u003e- Rostral perforating arteries\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eInferior segment\u003c/b\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe average diameter of the BA at its origin was 4.05 mm, ranging from 3.5 to 4.3 mm. At the level of the origin of the AICA, the average diameter was 3.55 mm (3.0 to 4.2 mm), with a segment length of 9.0 to 17.1 mm (average 11.9 mm). On average, there were 3\u0026ndash;4 caudal perforating arteries (range of 3\u0026ndash;6), directed towards the foramen caecum. Almost all caudal perforating arteries arose from this segment, except for two cases (10%), where each artery originated from the middle segment of the BA, above the origin of AICA. In these cases, the artery traversed along the basilar groove, giving rise to smaller branches, and ultimately entered the foramen caecum. The caudal perforating arteries originated, on average, 6.67 mm above the VA junction, (range: 0.51\u0026ndash;12.7 mm). Frequently, these arteries also originated from the VA and the pontomedullary arteries; 83% branched before penetrating the foramen caecum. Their average diameter was 0.34 mm (0.17 to 0.43 mm).\u003c/p\u003e \u003cp\u003eThe collateral arteries identified were the pontomedullary arteries, which originated at various levels within the lower segment, either as direct branches of the basilar trunk or as branches of the caudal perforating arteries. These pontomedullary arteries followed an inferolateral course towards the pontomedullary sulcus, sending small branches to the pons, the upper ends of the pyramid and olive, and the sixth CN, ultimately reaching the retro-olivary fossa and the restiform body. The number of these arteries varied from 0\u0026ndash;3 per side and from 1\u0026ndash;4 per specimen (with an average of 2). Their average diameter was 0.66 mm, ranging from 0.19 to 0.46 mm. In all specimens, the junction of the VA occurred above the level of the pontomedullary sulcus, at a distance of 1.0 to 8.3 mm, with an average of 3.35 mm.\u003c/p\u003e \u003cp\u003e \u003cb\u003eMiddle segment\u003c/b\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe average diameter of the BA at the upper limit of this segment was 3.44 mm, ranging from 3.0 to 4.2 mm. The middle segment had an average length of 15.2 mm (10.5 to 19.5 mm).\u003c/p\u003e \u003cp\u003eThe middle perforating branches, characteristic of this segment, generally originated from a common trunk with the anterior lateral arteries or as collateral branches of the long pontine arteries. These branches were noted for their tortuous course, directed towards the lateral aspect of the basilar groove and its margins. They branched out before penetrating the pontine parenchyma, where they remained medial; some branches were long, while others were short, supplying midline structures. On average, there were 5\u0026ndash;6 of these middle perforating branches per specimen (range: 5 to 8), with diameters from 0.21 to 0.74 mm.\u003c/p\u003e \u003cp\u003eThe anterior lateral arteries, also known as short pontine arteries, originated from a common trunk with the middle perforating arteries. They were tortuous as well, branching before penetrating the pons and extending in an inferolateral direction, reaching approximately halfway between the BA trunk and the apparent origin of the fifth CN. In some cases, they also originated from the long pontine arteries, following a similar course and distribution.\u003c/p\u003e \u003cp\u003eThere were 4\u0026ndash;6 long pontine (or transverse pontine) arteries with a diameter ranging from 0.4 to 0.8 mm (average 0.57 mm). Their origin was, on average, 11.1 mm from the caudal edge of the AICA\u0026rsquo;s origin, with a range from 5.5 to 19.9 mm. These arteries followed a lateral course, emitting few branches to the anterior surface of the pons, except at their most lateral aspect. They were categorized into two major groups based on their distribution relative to the fifth CN: those above were termed superolateral, and those below were termed inferolateral. Both groups irrigated the nerve between its major and minor portions.\u003c/p\u003e \u003cp\u003eAn additional collateral artery, identified in all specimens, was the posterolateral or pontomesencephalic artery. This artery originated immediately proximal to the upper boundary of the segment on both sides, coursing parallel to the SCA within the pontomesencephalic groove. It gave branches to the cerebral peduncle and terminated by branching at the junction of the peduncle with the tectal plate.\u003c/p\u003e \u003cp\u003eThe AICA was found in 100% of the specimens, exhibiting asymmetrical caliber in 60%, with the right side consistently larger. The average diameter at their origin was 1.06 mm on the right and 0.71 mm on the left. These arteries followed an inferolateral course toward the seventh and eighth CN. The detailed microsurgical anatomy of these arteries was not covered in this study.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSuperior segment\u003c/b\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe superior segment ends at the BA bifurcation, where it divides into PCA (rostral edge of the bifurcation). The average diameter of the artery between the SCA and the PCA was 4.2 mm (range 4.01 to 4.6 mm). The segment's length averaged 3.6 mm, ranging from 2.4 to 5.0 mm.\u003c/p\u003e \u003cp\u003eThe arteries supplying the posterior perforated substance were termed rostral perforating arteries and there were 1\u0026ndash;3. Their diameter ranged from 0.2 to 0.5 mm (average 0.3 mm). These arteries typically reached their entry site as single trunks or immediately divided just before penetrating the parenchyma. No branches were found originating directly from the upper wall of the artery bifurcation, and all rostral perforators depended on the posterior wall of the basilar artery.\u003c/p\u003e \u003cp\u003eWhile there were numerous arteries directed to the posterior perforated substance, most of them originated from the first segment of the PCA (P1 or pre-communicating segment), especially from the thalamogeniculate or medial thalamoperforating artery. This artery entered the posterior perforated substance after dividing into multiple branches or as a single trunk (less frequently). There were also anastomoses between thalamogeniculate arteries. Other perforating branches to this area originated from the superior cerebellar artery, posterior communicating artery, and post-communicating posterior cerebral artery.\u003c/p\u003e \u003cp\u003eThe SCA were present in 100% of the specimens, with an average diameter of 1.6 mm (1.3\u0026ndash;1.9 mm). The microsurgical anatomy of these arteries, as well as that of the PCA, was beyond the scope of this study. The PCA was also present in all cases, with diameters ranging from 1.6 to 3.0 mm (average 2.3 mm). A fetal configuration of the posterior communicating - posterior cerebral complex was found in 2 cases (10%). Notably, one of these cases featured a hypoplastic posterior cerebral artery with a double fenestration, a variant not previously described in the literature and discussed in a separate paper.\u003c/p\u003e \u003cp\u003eThe collateral branches included the mesencephalic circumferential arteries, which in this study, originated from the basilar artery in only 5% of the cases. Their average diameter was 0.57 mm, with a range of 0.45 to 0.68 mm. Circumferential arteries dependent on the first segment of the posterior cerebral artery were also found, especially the posteromedial choroidal artery, which had a special relationship with the third CN (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Other mesencephalic circumferential branches originated as collaterals from the thalamogeniculate arteries and the SCA.\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThe classification of the BA segments proposed in this study is based on the morphological characteristics of its perforating and collateral branches, and correlates well with the microsurgical implications on each of these segments [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe upper segment of the BA is crucial in common procedures like microvascular decompression for trigeminal neuralgia, given the proximity of its branches to crucial neural structures [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. It is also relevant in less frequent cases of basilar compression of the trigeminal nerve. \u003cem\u003eJanetta et al\u003c/em\u003e reported a series of 1404 patients who undergoing microvascular decompression for trigeminal neuralgia, noting that 2% were caused by vertebrobasilar compression [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Specifically, the trigeminal nerve was compressed by the VA in 18 cases, the BA in 12 cases, and the vertebrobasilar junction in one case.\u003c/p\u003e \u003cp\u003eThe surgical anatomy of the upper segment is very relevant when treating basilar tip aneurisms because all rostral perforators depended on the posterior or posterolateral walls of the artery. Thus, this type of aneurysms in high-riding BA can be accessed through an orbitozygomatic approach, sparing all rostral perforators. On the other hand, this anatomic considerations should be pondered when performing an endoscopic third ventriculostomy [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] and treating SCA aneurysms [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Some authors [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], have described that pre-mesencephalic subarachnoid hemorrhages are secondary to basilar perforating arteries aneurysm rupture.\u003c/p\u003e \u003cp\u003eThe aneurysms of the AICA account for less than 1% of all intracranial aneurysms, the surgical approach is partly determined by the aneurysm's position relative to the clivus [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Various approaches are utilized, including retrosigmoid, far-lateral, middle fossa, transcochlear, translabyrinthine, orbitozygomatic, and combined supratentorial-infratentorial presigmoid techniques [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].The anatomy of the middle segment is particularly relevant in this context, asi it influences the choice of surgical technique. The importance of preservation of the middle segment`s collateral and perforating vessels deserves attention when performing a microvascular decompression for hemifacial spam [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] or when determining the safe entry zones to treat pontine cavernomas [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Although very rare, hemifacial spams secondary to verterbrobasilar dolicoechtasia has been described [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eConsidering that aneurysms of the lower BA are difficult to expose and clip, \u003cem\u003eKumar et al\u003c/em\u003e described the far-lateral approach without occipital condyle drilling for clipping these aneurysms [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Occasionally, an extensive lateral exposure of the clivus is required to treat giant aneurysms of this segment. Such an exposure can be achieved by combining the far-lateral and combined supra- and infratentorial approaches [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn 1997, \u003cem\u003eRhoton et al\u003c/em\u003e noted a mean diameter of the BA just below SCA and between the SCA and P1 of 4.1 mm and 4.5 mm, respectively [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. \u003cem\u003ePadmavathi et al\u003c/em\u003e [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] described that the diameter at origin, midlevel and termination were 4.5 mm, 4 mm and 4.8 mm. \u003cem\u003eVijayakumar et al\u003c/em\u003e reported diameters of 3.7 mm, 3.6 mm and 3.9 mm at the origin, midlevel and termination [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Our findings were comparable to those previously described. Likewise, the BA length described in our study (mean: 30.7 mm) was comparable to the one described by other authors of 32 mm and 28 mm [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. This consistency with existing literature enhances the reliability of our results.\u003c/p\u003e \u003cp\u003eIn \u003cem\u003eRhoton et al.\u003c/em\u003e study, the posterior and lateral surfaces of the upper centimeter of the BA were a rich source of perforating arteries, with an average of eight branches of 0.1\u0026ndash;0.5 mm diameter [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Approximately one-half were described to arise from the posterior surface and one-fourth from each side [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. No arteries emerged from the anterior surface. This aligns with \u003cem\u003eKwiatkowska et al.`s\u003c/em\u003e analysis of 100 specimens (2226 pontine perforating arteries), in which 77.1% emerged from the posterior aspect, 22.8% from the lateral surface and only 0.2% from the anterior surface [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. In our study all rostral perforators originated from the posterior wall.\u003c/p\u003e \u003cp\u003eThe vascular configuration of the foramen caecum and the interpeduncular cistern exhibits significant individual variability [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The main trunk, particularly in the middle segment, is less variable, despite being the largest segment [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. This stability can be attributed to embryological factors, as most anastomoses and territory recruitment at the margins of this vascular system, responding to the developing brain`s metabolic demands [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. In contrast, the junction of the posterior communicating and PCA exhibits all possible variations in vascular morphology resulting from the incorporation of the caudal segment of the internal carotid artery into the vertebrobasilar system.\u003c/p\u003e\n\u003ch3\u003eLimitations\u003c/h3\u003e\n\u003cp\u003eThe sample size may restrict our ability to capture the anatomical variations of the BA and its branches. Additionally, the conservation and coloration processes of cadaveric specimens may yield measurements that differ from those in living subjects. Lastly, underlying pathologies in vivo can alter anatomical structures, impacting the applicability and accuracy of our measurements.\u003c/p\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003eThe detailed microsurgical anatomy of the BA presented herein adds value to existing literature, particularly with a novel segmental classification. Our findings are relevant for neurosurgeons, interventional radiologists, and neurologists, enhancing their ability to navigate BA pathology. Knowledge of BA anatomy also aids in addressing conditions like arteriovenous malformations, aneurysms, and tumors. Recognizing anatomical variations is essential, as they may indicate hemodynamic changes influencing pathology development (e.g., aneurysms in arteries with fenestrations) or affect the cerebral vasculature's adaptive capacity.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eAICA: Anterior Inferior cerebellar artery\u003c/p\u003e\n\u003cp\u003eBA: Basilar Artery\u003c/p\u003e\n\u003cp\u003eCN: Cranial nerve(s)\u003c/p\u003e\n\u003cp\u003ePCA: Posterior Cerebral Artery\u003c/p\u003e\n\u003cp\u003eSCA: Superior cerebellar artery\u003c/p\u003e\n\u003cp\u003eVA: Vertebral Artery\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDisclosures: Pablo Harker reports advisory fees and convertible notes from Magnendo Corp, unrelated to the present work.\u003c/p\u003e\n\u003ch2\u003eFunding:\u003c/h2\u003e\n\u003cp\u003eNone.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDisclosures:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePablo Harker reports advisory fees and convertible notes from Magnendo Corp, unrelated to the present work.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eMION, FMN, DADM: made substantial contributions to the conception or design of the work; acquisition, analysis, and interpretation of data;drafted the work or revised it critically for important intellectual content; approved the version to be published; and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.PH, RCDO, MEBC: made substantial contributions to the conception or design of the work; acquisition, analysis, and interpretation of data;revised it critically for important intellectual content; approved the version to be published; and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.\u003c/p\u003e\n\u003ch2\u003eAcknowledgement\u003c/h2\u003e\n\u003cp\u003eThe authors acknowledge and thank Sabrina Zorio for the illustrations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments:\u0026nbsp;\u003c/strong\u003eThe authors acknowledge and thank Sabrina Zorio for the illustrations included in this article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eUsha Vijayakumar A, Sudhakaran M, Janaki Yovel L. 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Microvascular decompression for trigeminal neuralgia caused by vertebrobasilar compression. \u003cem\u003eJ Neurosurg\u003c/em\u003e. 1994;81(1):1-9. doi:10.3171/jns.1994.81.1.0001\u003c/li\u003e\n\u003cli\u003eFarag AA, Asiri FA, Khoudir MA, et al. Endoscopic third ventriculostomy complications: avoidance and management in a stepwise manner. \u003cem\u003eEgypt J Neurosurg\u003c/em\u003e. 2022;37(1). doi:10.1186/s41984-022-00166-w\u003c/li\u003e\n\u003cli\u003eMcLaughlin MR, Wahlig JB, Kaufmann AM, Albright AL. Traumatic basilar aneurysm after endoscopic third ventriculostomy: case report. \u003cem\u003eNeurosurgery\u003c/em\u003e. 1997;41(6):1400-1404. doi:10.1097/00006123-199712000-00034\u003c/li\u003e\n\u003cli\u003eMuhammad S, Rezai Jahromi B, Kaukovalta H, et al. Anatomic Risk Factors for S1 Segment Superior Cerebellar Artery Aneurysm Rupture: A Radiologic Study on 81 Consecutive Patients. \u003cem\u003eWorld Neurosurg\u003c/em\u003e. 2022;158:e344-e351. doi:10.1016/j.wneu.2021.10.177\u003c/li\u003e\n\u003cli\u003ePark SQ, Kwon OK, Kim SH, Oh CW, Han MH. Pre-mesencephalic subarachnoid hemorrhage: rupture of tiny aneurysms of the basilar artery perforator. \u003cem\u003eActa Neurochir (Wien)\u003c/em\u003e. 2009;151(12):1639-1646. doi:10.1007/s00701-009-0416-0\u003c/li\u003e\n\u003cli\u003eMan IC, Pan TM, U KC. An unusual etiology of subarachnoid hemorrhage, basilar artery perforator aneurysms, in Macao: Three case reports and review of literature. \u003cem\u003eWorld J Clin Cases\u003c/em\u003e. 2024;12(20):4337-4347. doi:10.12998/wjcc.v12.i20.4337\u003c/li\u003e\n\u003cli\u003eMuhammad S, Hafez A, Kaukovalta H, et al. Anterior inferior cerebellar artery (AICA) aneurysms: a radiological study of 15 consecutive patients. \u003cem\u003eFront Radiol\u003c/em\u003e. 2023;3:1229921. doi:10.3389/fradi.2023.1229921\u003c/li\u003e\n\u003cli\u003eBambakidis NC, Manjila S, Dashti S, Tarr R, Megerian CA. Management of anterior inferior cerebellar artery aneurysms: an illustrative case and review of literature. \u003cem\u003eNeurosurg Focus\u003c/em\u003e. 2009;26(5):1-8. doi:10.3171/2009.1.FOCUS0915\u003c/li\u003e\n\u003cli\u003eKim KJ, Kim JM, Bae YJ, et al. The association between vertebrobasilar dolichoectasia and hemifacial spasm. \u003cem\u003ePark Relat Disord\u003c/em\u003e. 2016;32:54-59. doi:10.1016/j.parkreldis.2016.08.015\u003c/li\u003e\n\u003cli\u003eCatapano JS, Rumalla K, Srinivasan VM, Lawrence PM, Larson Keil K, Lawton MT. A taxonomy for brainstem cavernous malformations: subtypes of pontine lesions. Part 2: inferior peduncular, rhomboid, and supraolivary. \u003cem\u003eJ Neurosurg\u003c/em\u003e. 2022;137(5):1477-1490. doi:10.3171/2022.1.JNS212691\u003c/li\u003e\n\u003cli\u003eCatapano JS, Rumalla K, Srinivasan VM, Lawrence PM, Larson Keil K, Lawton MT. A taxonomy for brainstem cavernous malformations: subtypes of pontine lesions. Part 1: basilar, peritrigeminal, and middle peduncular. \u003cem\u003eJ Neurosurg\u003c/em\u003e. 2022;137(5):1462-1476. doi:10.3171/2022.1.JNS212690\u003c/li\u003e\n\u003cli\u003eLibrata PN, Sani AF, Kurniawan D, Hamdan M, Nugraha P. Hemifacial spasm caused by tortuous vertebrobasilar artery: a case report. \u003cem\u003eEgypt J Neurol Psychiatry Neurosurg\u003c/em\u003e. 2022;58(1):0-3. doi:10.1186/s41983-022-00488-4\u003c/li\u003e\n\u003cli\u003eChan J, Jolly K, Darr A, Bowyer DJ. A rare case of unilateral hemifacial spasm and facial palsy associated with an abnormal anatomical variant of the posterior basilar circulation. \u003cem\u003eAnn R Coll Surg Engl\u003c/em\u003e. 2019;101(6):E147-E149. doi:10.1308/rcsann.2019.0069\u003c/li\u003e\n\u003cli\u003eKumar CR, Vannemreddy P, Nanda A. Far-lateral approach for lower basilar artery aneurysms. \u003cem\u003eSkull Base\u003c/em\u003e. 2009;19(2):141-149. doi:10.1055/s-0028-1096197\u003c/li\u003e\n\u003cli\u003eGonzalez L, Amin-Hanjani S, Bambakidis N, Spetzler R. Skull base approaches to basilar artery. \u003cem\u003eJ Neurosurg\u003c/em\u003e. 2005;19(2):1-12.\u003c/li\u003e\n\u003cli\u003ePadmavathi G, Niranjana Murthy KV RT. Study of the variations in the origin and termination of basilar artery. \u003cem\u003eAnat Karnataka\u003c/em\u003e. 2011;5:54-59.\u003c/li\u003e\n\u003cli\u003eTsantili AR, Karampelias V, Samolis A, et al. Anatomical variations of human vertebral and basilar arteries: A current review of the literature. \u003cem\u003eMorphologie\u003c/em\u003e. 2023;107(357):169-175. doi:10.1016/j.morpho.2022.07.001\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"surgical-and-radiologic-anatomy","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"sara","sideBox":"Learn more about [Surgical and Radiologic Anatomy](http://link.springer.com/journal/276)","snPcode":"276","submissionUrl":"https://submission.nature.com/new-submission/276/3","title":"Surgical and Radiologic Anatomy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Anatomy, basilar artery, cadaveric, cerebrovascular anatomy, microsurgical anatomy, vertebrobasilar system","lastPublishedDoi":"10.21203/rs.3.rs-5867946/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5867946/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eThe trunk of the BA remains underrepresented in microsurgical studies. This study aims to address this gap by providing a detailed review of the BA's microsurgical anatomy, proposing a novel segmental classification of the artery and the significance of each segment in various surgical pathologies and approaches.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA total of 20 cadaveric adult brain specimens were meticulously examined under high magnification, following Institutional Review Board approval. The dissection focused on the BA and its branches, with morphometric data collected, including dimensions and anatomical variations.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThis study included 20 specimens. A novel classification was proposed base on the blood flow direction, including three segments. The inferior segment extended from the junction of the VA to the origin of the most rostral collateral artery, averaging 3.55 mm in diameter and lengths between 9.0 and 17.1 mm, with 3 to 4 caudal perforators. The middle segment, which ranged from the inferior border of the anterior inferior cerebellar artery (AICA) to the origin of the superior cerebellar artery, measured 3.44 mm in diameter and 15.2 mm in length, featuring 5\u0026ndash;6 middle perforating branches. The superior segment ended at the bifurcation of the BA, with an average diameter of 4.2 mm and a length of 3.6 mm. The overall BA length averaged 30.7 mm, with a range of 23.5\u0026ndash;38.2 mm.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eA comprehensive understanding of the origin, course, branches and segments of the BA is crucial for mitigating vascular complications during both open and endovascular surgical procedures.\u003c/p\u003e","manuscriptTitle":"Novel Classification and Microsurgical Anatomy of the Basilar Artery: A Cadaveric Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-24 18:48:41","doi":"10.21203/rs.3.rs-5867946/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-02-03T07:07:00+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-01T17:31:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"174247844021247268043442118875060151123","date":"2025-01-23T12:54:17+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"109981246826444438439927147242320042254","date":"2025-01-23T00:32:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"17674605969720377483326882494633008991","date":"2025-01-22T22:40:36+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-01-22T21:10:30+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-01-22T15:14:21+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-01-22T14:20:34+00:00","index":"","fulltext":""},{"type":"submitted","content":"Surgical and Radiologic Anatomy","date":"2025-01-20T17:28:35+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"surgical-and-radiologic-anatomy","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"sara","sideBox":"Learn more about [Surgical and Radiologic Anatomy](http://link.springer.com/journal/276)","snPcode":"276","submissionUrl":"https://submission.nature.com/new-submission/276/3","title":"Surgical and Radiologic Anatomy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"e95bcc61-a3b5-4e76-a71d-8dbb5ac91371","owner":[],"postedDate":"January 24th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-04-07T16:01:20+00:00","versionOfRecord":{"articleIdentity":"rs-5867946","link":"https://doi.org/10.1007/s00276-025-03612-0","journal":{"identity":"surgical-and-radiologic-anatomy","isVorOnly":false,"title":"Surgical and Radiologic Anatomy"},"publishedOn":"2025-04-02 15:57:38","publishedOnDateReadable":"April 2nd, 2025"},"versionCreatedAt":"2025-01-24 18:48:41","video":"","vorDoi":"10.1007/s00276-025-03612-0","vorDoiUrl":"https://doi.org/10.1007/s00276-025-03612-0","workflowStages":[]},"version":"v1","identity":"rs-5867946","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5867946","identity":"rs-5867946","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}