Posterior vascular anatomy of the encephalon: a comprehensive review.

PURPOSE: This article presents a comprehensive exploration of neurovascular anatomy of the encephalon, focusing specifically on the intricate network within the posterior circulation and the posterior fossa anatomy; enhancing understanding of its dynamics, essential for practitioners in neurosurgery and neurology areas. METHOD: A profound literature review was conducted by searching the PubMed and Google Scholar databases using main keywords related to neurovascular anatomy. The selected literature was meticulously scrutinized. Throughout the screening of pertinent papers, further articles or book chapters were obtained through additional assessment of the reference lists. Furthermore, four formalin-fixed, color latex-injected cadaveric specimens preserved in 70% ethanol solution were dissected under surgical microscope (Leica Microsystems Inc, 1700 Leider Ln, Buffalo Grove, IL 60089, USA), using microneurosurgical as well as standard instruments, and a high-speed surgical drill (Stryker Instruments 1941 Stryker Way Portage, MI 49002, USA). Ulterior anatomical dissection was performed. RESULTS: Detailed examination of the basilar artery (BA), a common trunk formed by the union of the left and right vertebral arteries, denoted a tortuous course across the basilar sulcus. Emphasis is then placed on the Posterior Inferior Cerebellar Artery (PICA), Anterior Inferior Cerebellar Artery (AICA) and Superior Cerebellar Artery (SCA). Each artery's complex course through the posterior fossa, its divisions, and potential stroke-related syndromes are explored in detail. The Posterior Cerebral Artery (PCA) is subsequently unveiled. The posterior fossa venous system is explained, categorizing its channels. A retrograde exploration traces the venous drainage back to the internal jugular vein, unraveling its pathways. CONCLUSION: This work serves as a succinct yet comprehensive guide, offering fundamental insights into neurovascular anatomy within the encephalon's posterior circulation. Intended for both novice physicians and seasoned neuroanatomists, the article aims to facilitate a more efficient clinical decision-making in neurosurgical and neurological practices.

A primer to vascular anatomy of the brain: an overview on anterior compartment.

PURPOSE: Knowledge of neurovascular anatomy is vital for neurosurgeons, neurologists, neuro-radiologists and anatomy students, amongst others, to fully comprehend the brain's anatomy with utmost depth. This paper aims to enhance the foundational knowledge of novice physicians in this area. METHOD: A comprehensive literature review was carried out by searching the PubMed and Google Scholar databases using primary keywords related to brain vasculature, without date restrictions. The identified literature was meticulously examined and scrutinized. In the process of screening pertinent papers, further articles and book chapters were obtained through analysis and additional assessing of the reference lists. Additionally, four formalin-fixed, color latex-injected cadaveric specimens preserved in 70% ethanol solution were dissected under surgical microscope (Leica Microsystems Inc, 1700 Leider Ln, Buffalo Grove, IL 60089 USA). Using microneurosurgical as well as standard instruments, and a high-speed surgical drill (Stryker Instruments 1941 Stryker Way Portage, MI 49002 USA). Ulterior anatomical dissection was documented in microscopic images. RESULTS: Encephalic circulation functions as a complex network of intertwined vessels. The Internal Carotid Arteries (ICAs) and the Vertebral Arteries (VAs), form the anterior and posterior arterial circulations, respectively. This work provides a detailed exploration of the neurovascular anatomy of the anterior circulation and its key structures, such as the Anterior Cerebral Artery (ACA) and the Middle Cerebral Artery (MCA). Embryology is also briefly covered, offering insights into the early development of the vascular structures of the central nervous system. Cerebral venous system was detailed, highlighting the major veins and tributaries involved in the drainage of blood from the intracranial compartment, with a focus on the role of the Internal Jugular Veins (IJVs) as the primary, although not exclusive, deoxygenated blood outflow pathway. CONCLUSION: This work serves as initial guide, providing essential knowledge on neurovascular anatomy, hoping to reduce the initial impact when tackling the subject, albeit the intricate vasculature of the brain will necessitate further efforts to be conquered, that being crucial for neurosurgical and neurology related practice and clinical decision-making.

Mixed reality in neurosurgery: redefining the paradigm for arteriovenous malformation planning and navigation to improve patient outcomes.

OBJECTIVE: Brain arteriovenous malformations (AVMs) present significant challenges in neurosurgery, requiring detailed planning and execution. In this study, the authors aimed to evaluate the efficacy of mixed reality (MxR), a synergistic application of virtual reality (VR) and augmented reality (AR), in the surgical management of AVMs. METHODS: A retrospective review was conducted on 10 patients who underwent AVM resection between 2021 and 2023. Preoperative planning used patient-specific 360° VR models, while intraoperative guidance used AR markers for targeted disconnection of arterial feeders. Data were analyzed for surgical duration, blood loss, and postoperative outcomes, stratified by Spetzler-Martin (SM) and supplemented Spetzler-Martin (Supp-SM) grades. RESULTS: In 10 patients with cerebral AVMs, MxR significantly facilitated the identification of 21 arterial feeders, including challenging deep feeders. MxR-assisted surgeries demonstrated efficient identification and disconnection of arterial feeders, contributing to precise AVM resection. The mean surgical duration was approximately 5 hours 11 minutes, with a mean intraoperative blood loss of 507.5 ml. Statistically significant variations in surgical duration and blood loss were observed based on SM and supplemented Supp-SM grades. Two patients experienced worsened postoperative neurological deficits, underscoring the inherent risks of AVM surgeries. The marked difference in hospital stays between patients with ruptured and those with unruptured AVMs, particularly for SM grade III, highlights the significant impact of rupture status on postoperative recovery. CONCLUSIONS: In this study, the authors delineated a novel paradigm using MxR for the surgical intervention of AVMs. Using 3D VR for preoperative planning and AR for intraoperative guidance, they achieved unparalleled precision and efficiency in targeting deep arterial feeders. While the results are promising, larger studies are needed to further validate this approach.

Cervical anterior spinal artery infarction associated with anomalous vertebral artery: a case report.

We report a unique case of cervical anterior spinal artery (ASA) infarction in a 49-year-old male with hypercholesterolemia and sleep apnea. The patient experienced sudden cervical pain, quadriparesis, areflexia, and urinary incontinence after swallowing a large food bolus. Imaging revealed an infarction at the C3-C5 levels and an anomalous right vertebral artery (VA) originating from the thoracic aorta, tightly enclosed between the aorta and a vertebral column with an anterior osteophyte. This aberrant VA was the primary vascular supply to the ASA, with no contribution from the left VA or supreme intercostal arteries. We propose that transient injury to the right VA, induced by compression between the aortic arch, the food bolus, and the osteophyte, led to temporary hypoperfusion of the ASA, causing a watershed ischemic injury in the mid cervical cord's anterior gray matter. The article also provides an in-depth discussion of the developmental and clinical characteristics associated with this rare vascular anomaly.

Feasibility of exoscopic keyhole surgery: case series.

Keyhole approaches, performed with the endoscope, microscope, or exoscope, aim to minimize tissue traumatization while maximizing surgical view. The exoscope can provide better ergonomics than the microscope without restricting the space inside of the keyhole, as when using the endoscope. However, a frequently quoted reason for intraoperative exoscope-to-microscope conversion is the absence of sufficient light. In this video, the authors present 4 patients who underwent posterior fossa keyhole surgery without intraoperative conversion. The surgical objective was achieved in all patients without associated morbidity. After adequate adaptation, the exoscope allows sufficient light in the surgical field to perform safe keyhole surgery. The video can be found here: https://stream.cadmore.media/r10.3171/2023.10.FOCVID23116.

Endoscopic endonasal approach for resection of giant nonfunctional pituitary adenoma.

The giant pituitary adenoma (GPA)> 4 cm is considered a surgical challenging pathology and associated with higher surgical complications compared to non-giant pituitary adenoma [1]. These tumors are invasive and had extension to nearby neurovascular structures including cranial nerves and internal carotid artery. Endoscopic endonasal approach (EEA) is increasingly used in the last two decades, however tumors with significant height extension in the supraseller region makes surgeons in favor of transcranial approaches or combined approaches [2]. The accompanied symptoms arise from compression of neighboring structures as well as hypopituitarism [3]. In this video we present 65 year old male with PMH significant for HTN who presented with 2-3 months retro-orbital headaches, confusion, gait instability, urinary/fecal incontinence, found to have 5.1 × 2.1 × 2 cm sellaer-suprasellar mass compressing the floor of the third ventricle, mammillary body, and optic apparatus. The mass was associated with hydrocephalus. The endoscopic endonasal skull base approach (trans-sellar, transtubercular) was performed with significant tumor resection without a need for trans cranial approach. A titanium clips was used to reconstruct the diaphragma sella which was very helpful technique to change high flow CSF leak to low flow. The postoperative course of the patient was smooth with improved gait, memory, and vision. He was kept on a hormonal replacement for hypopituitarism.

Use of intravenous cangrelor in the treatment of ruptured and unruptured cerebral aneurysms: an updated single-center analysis and pooled analysis of current studies.

BACKGROUND: Intracranial stent placement for the treatment of cerebral aneurysms is increasingly utilized in both ruptured and unruptured scenarios. Intravenous (IV) cangrelor is a relatively new antiplatelet agent that was initially approved for coronary interventions. In addition to our institution, five other centers have published their results using IV cangrelor in neurointerventional procedures. This article combines the aneurysm treatment data from all prior studies to provide insight into the safety and efficacy of cangrelor for intracranial aneurysm treatment. METHODS: A prospectively maintained database was reviewed to identify all cases of IV cangrelor administration during aneurysm embolization. 20 additional patients were identified who had not been previously published. In addition, a literature search was performed to identify prior publications regarding cangrelor in neurointervention. The data from these were combined with our institutional results in a pooled-analysis. RESULTS: Overall, 85 patients who received IV cangrelor during aneurysm embolization were identified, including 46 ruptured and 39 unruptured cases. The asymptomatic and symptomatic intracranial hemorrhage rates were 4% (2/46) for ruptured cases and 2.6% (1/39) for unruptured cases. The rate of retroperitoneal hematoma and gastrointestinal bleeding was 0%. There were no incidents of intraprocedural thromboembolic complication or intraprocedural in-stent thrombosis in either cohort. One subject suffered an ischemic stroke at 24 hours secondary to in-stent thrombosis in a ruptured case. CONCLUSIONS: IV cangrelor during aneurysm embolization appears to be safe, with a symptomatic intracranial hemorrhage rate of 4% in ruptured cases and 2.6% in unruptured cases. More research is needed to determine the ideal dosing regimen.

Surgical Limitations of the Microscopic Transciliary Supraorbital Keyhole Approach to the Anterior and Middle Skull Base.

BACKGROUND: The microscopic transciliary SupraOrbital keyhole (mtSO) approach has been used for a wide variety of anterior and middle fossa pathologies, including aneurysms, meningiomas, craniopharyngiomas, and other skull-base tumors. Several clinical series have proven its efficacy and safety, but detailed anatomical demarcations of the anterior and middle cranial base exposure are lacking. Our aim was to define the surgical limitations of the mtSO approach to the ipsilateral and contralateral anterior and middle skull base. METHODS: Five cadaveric specimens (10 sides) were studied with image guidance to illustrate the limits of the surgical exposure. In addition, 30 dry skulls were used to measure the working distances between the craniotomy and key bony landmarks of the mtSO approach. RESULTS: Surgical exposure at the anterior skull base covered the area between the medial half of the contra- and the medial two-thirds of the ipsilateral sphenoid wing including both optic nerves and interoptic space. The anterior limit at the midline was the sphenoethmoidal suture. Ipsilateral anterior clinoidectomy permitted exposure of the superior orbital fissure, which defined the anteromedial limit at the middle fossa, whereas the anterolateral limit was defined by the ophthalmic branch of the trigeminal nerve. Moreover, the posteromedial and posterolateral limits were the posterior clinoid process and the petrous ridge, respectively. CONCLUSIONS: Our findings define the surgical limitations of the mtSO approach for the treatment of anterior and middle cranial base pathologies. These limits can be reliably identified on imaging studies allowing assessment of exposure to guide preoperative case selection.

Extended Middle Fossa Approach for Trigeminal Schwannoma Resection.

Trigeminal schwannomas are rare benign tumors, it is second most common intracranial schwannomas after vestibular schwannomas. The management includes not limited to observation, stereotactic radiosurgery/radiotherapy, and/or surgical resection. Tumor size and patient clinical status are the most important factors in management. In this video, we describe the technical nuances of an extended middle fossa approach for large trigeminal schwannoma with cavernous sinus extension resection. A 44-year-old right-handed female with several months' history of progressive right facial paresthesia and pain in the distribution of V3 mainly. On physical examination, she had decreased sensation to light touch over the right V1 to V3 distribution with loss of cornel reflex. The brain MRI showed 3.5 cm bilobed mass extends from the pontine root entry zone to the cavernous sinus. Craniotomy was performed and followed by middle fossa dural peeling, peeling of temporal lobe dura away from the wall of the cavernous sinus, extradurally anterior clinoidectomy, drilling of the petrous apex, coagulation of superior petrosal sinus followed incision of the tentorium up to the tentorial notch with preservation the fourth cranial nerve, and tumor dissected away from V1 and then gradually removed from the superior wall of the cavernous sinus. The technique presented here allows for complete tumor resection, safe navigation through the relative cavernous sinus compartments, and minimizes the possibility of inadvertent injury to the cranial nerves. The postoperative course was uneventful except for right eye incomplete ptosis from the swelling. Her facial pain subsided after the surgery without any extra ocular movement impairment. The link to the video can be found at: https://youtu.be/zxi2XK2R9QU .

Transcavernous Approach for Microsurgical Clipping of Ruptured Right Superior Cerebellar Artery Aneurysm with Cadaveric Stepwise Video Illustration.

Superior cerebellar artery (SCA) aneurysms are rare. The management options are not well defined. There is increasing role of endovascular treatment for all aneurysms, especially for aneurysms of the posterior circulation. However in some situations (wide base, dysmorphic features) coiling is not feasible. The surgical management of these aneurysms has its own distinct complexity and requires careful planning. The classic pterional or subtemporal approaches had its own limitation in proper visualization of the neurovascular anatomy. In this video, we describe the technical nuances of transcavernous sinus approach for microsurgical clipping SCA and A-comm aneurysms. We present the case of a 67-year-old RHF who presented with ruptured right-sided SCA aneurysm. She complained of Headache, confusion, and double vision. On physical examination, she had no focal deficits and was Hunt and Hess grade 3. A brain computed tomography (CT) scan revealed a subarachnoid hemorrhage Fisher's grade 4. A brain CT angiography (CTA) demonstrated an aneurysm at the origin of right SCA. The patient had failed attempt of endovascular coiling and she underwent microsurgical clipping. Stepwise demonstration of the approach with cadaveric anatomical dissection is illustrated. The technique presented here allows for safe clipping of the aneurysm through the cavernous sinus. The approach allows for good exposure of the aneurysm and the surrounding structures. Care is taken to visualize the perforators to avoid any devastating brain stem infarction during the clipping. The transcavernous sinus is a robust approach with good visualization of the neurovascular structures allowing safe aneurysm clipping in this location. The link to the video can be found at: https://youtu.be/oE-HyDASiKM .

Laser Interstitial Thermal Therapy for Posterior Fossa Lesions: A Systematic Review and Analysis of Multi-Institutional Outcomes.

BACKGROUND: Laser interstitial thermal therapy (LITT) has emerged as a treatment option for deep-seated primary and metastatic brain lesions; however, hardly any data exist regarding LITT for lesions of the posterior fossa. METHODS: A quantitative systematic review was performed. Article selection was performed by searching MEDLINE (using PubMed), Scopus, and Cochrane electronic bibliographic databases. Inclusion criteria were studies assessing LITT on posterior fossa tumors. RESULTS: 16 studies comprising 150 patients (76.1% female) with a mean age of 56.47 years between 2014 and 2021 were systematically reviewed for treatment outcomes and efficacy. Morbidity and mortality data could be extracted for 131 of the 150 patients. Death attributed to treatment failure, disease progression, recurrence, or postoperative complications occurred in 6.87% (9/131) of the pooled sample. Procedure-related complications, usually including new neurologic deficits, occurred in approximately 14.5% (19/131) of the pooled sample. Neurologic deficits improved with time in most cases, and 78.6% (103/131) of the pooled sample experienced no complications and progression-free survival at the time of last follow-up. CONCLUSIONS: LITT for lesions of the posterior fossa continues to show promising data. Future clinical cohort studies are required to further direct treatment recommendations.

Percutaneous balloon compression technique using intraoperative contrasted DynaCT for the treatment of refractory trigeminal neuralgia: initial experience.

OBJECTIVE: Percutaneous balloon compression (BC) is a well-established technique that can provide immediate relief to patients suffering from trigeminal neuralgia (TN). The general procedure of BC uses fluoroscopy imaging to guide the needle through the foramen ovale (FO). The aim of this study was to describe our experience with a novel technique using intraoperative contrast-enhanced DynaCT as an adjunct for more accurate and safer guidance of the needle to the FO. METHODS: In this study, DynaCT was used to perform BC in 20 TN cases. The three-dimensional path of the needle was pre-planned using DynaCT obtained during the administration of IV contrast. The FO was accessed in a single pass along the path pre-determined from the DynaCT images, avoiding any major arteries and veins. DynaCT was also used for confirmation of the final position of the needle prior to insertion of the balloon as well as for confirmation of the position of the balloon after inflation. RESULTS: Intravenous contrast-enhanced DynaCT-guided percutaneous BC allowed precise advancement and positioning of the needle within the FO. It facilitated cannulation of the FO along a pre-determined path that avoided any major vascular structures. Clinical outcomes were excellent-all patients had a quick postoperative recovery, and there were no complications. CONCLUSIONS: The advantages of the contrast-enhanced DynaCT-guided technique include a single precise needle pass and avoidance of vessel injury. Precise placement of the balloon into different aspects of the FO can target trigeminal branches more selectively and allow for a better outcome.

Blood Supply of Cranial Nerves Passing Through the Cavernous Sinus: An Anatomical Study and Its Implications for Microsurgical and Endoscopic Cavernous Sinus Surgery.

BACKGROUND: Despite improvements in surgical techniques, cranial nerve (CN) deficits remain the most frequent cause of disability following cavernous sinus (CS) surgery. The most common tumor affecting the CS is meningioma. They originate from lateral wall and have their blood supply from meningohypophyseal trunk (MHT) and inferolateral trunk (ILT). Pituitary adenomas commonly invade the CS through its medial wall and receive blood supply form medial branches of the internal carotid artery (ICA) (superior and inferior hypophyseal arteries). Some tumors may grow within the CS (e.g. trigeminal schwannomas, hemangiomas). These tumors are fed by all the intracavernous ICA branches. Tumors involving the CS may also displace the neurovascular structures, therefore, a better understanding of intracavernous neurovascular anatomy may reduce the postoperative morbidity associated with approaching CS tumors. In this anatomical study, the anatomic variations and their clinical implications of the intracavernous CNs' blood supply were evaluated through transcranial and endonasal routes. METHODS: Twenty sides of ten adult cadaveric formalin-fixed, latex-injected specimens were dissected in stepwise fashion under microscopic and endoscopic magnification. The origin and course of the intracavernous ICA branches supplying the intracavernous CNs are studied. RESULTS: The proximal segment of the oculomotor nerve receives blood supply from the ILT in 85%, and the tentorial artery of the MHT in 15% of specimens. The distal segment is exclusively supplied by the ILT. The proximal trochlear nerve receives blood supply from the ILT (75%) and the tentorial artery (25%); the distal segment is exclusively supplied by the superior orbital branch. The proximal third of the abducens nerve receives its vascularity exclusively from the dorsal meningeal artery, and its middle and distal thirds from the ILT. The ophthalmic and proximal maxillary segments of the trigeminal nerve also receive blood supply from the ILT. The distal maxillary segment is supplied by the artery of the foramen rotundum. All ILT branches terminate on the inferomedial aspects of the intra-cavernous CNs. Extensive anastomoses are found between ILT branches and the branches arising from external carotid artery. CONCLUSION: Understanding the anatomy of the intracavernous ICA's branches is important to improving surgical outcomes with tumors involving the CS.

Case report of unusual cause of trigeminal neuralgia: Trigeminal neuralgia secondary to enlarged suprameatal tubercle.

BACKGROUND: Classic trigeminal neuralgia (TN) is caused by vessels compressing the trigeminal nerve root entry zone. The cause is usually impingement of the superior cerebellar artery, anterior inferior cerebellar artery, or a vein. Other rare causes have been reported including aneurysmal compression, skull base tumors, and vascular malformations. An enlarged suprameatal tubercle (EST) as a cause of TN has not yet been described. CASE PRESENTATION: We report the first case of 37 year old female patient presented with severe TN involving the three branches of trigeminal nerve who failed medical treatment and underwent multiple balloon compression for left TN with minimal improvement. The severity of pain was assessed using Barrow Neurological Institute (BNI) pain intensity score. Patient had brain MRI with CISS sequence and CT scan for the brain. After careful revision of her imaging studies, patient found to have prominent and heavily calcified left supra meatal tubercle. Her preoperative BNI score was 5.Patient had left retrosigmoid craniotomy and drilling of left suprameatal tubercle. No other structures were seen in contact with left trigeminal nerve root entry zone. Patient had significant improvement on her pain, postoperative BNI score was 1 until the last follow-up 4 years. CONCLUSION: EST is a rare cause of TGN and should be suspected as the offending compressing structure when no other causes seen on imaging studies.

Pituitary Apoplexy Attributed to COVID-19 Infection in the Absence of an Underlying Macroadenoma or Other Identifiable Cause.

The novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), is responsible for an array of extrapulmonary manifestations, including direct and indirect neurological complications. Currently, all published cases noting pituitary apoplexy in patients with COVID-19 have discovered underlying pituitary macroadenomas. Herein, we describe the first documented case, to our knowledge, of pituitary apoplexy attributed solely to COVID-19 in the absence of other identifiable causes. While much remains to be discovered and understood regarding COVID-19, we discuss the potential pathophysiology of COVID-19-associated pituitary apoplexy and raise awareness of this clinical complication.

Intracranial Plasmacytoma Mimicking a Cavernous Sinus Meningioma.

Extramedullary plasmacytomas involving the cavernous sinus are rare manifestations of multiple myeloma, and management strategies for such a pathology are not extensively discussed in the literature. In this case report, we describe the case of a patient presenting with a cavernous sinus syndrome secondary to a presumed meningioma. Surgical intervention was avoided as a computed tomography-guided biopsy was performed yielding the diagnosis of a cavernous sinus plasmacytoma. Neurointerventional radiology obtained the cavernous sinus mass biopsy using an approach through the maxillary bone and sinus. Histopathology identified sheets of atypical plasma cells, and the patient was referred to radiation oncology for further management.

Cavernous Sinus Meningioma Resection Through Orbitozygomatic Craniotomy.

Meningiomas of the cavernous sinus (CS) present a neurosurgical challenge. The anatomic complexity of the area can create a potential for injury to neurovascular structures. This has traditionally limited total tumor removal. A thorough understanding of the cavernous sinus surgical anatomy can help overcome this problem. Patients with CS meningiomas generally present with cranial nerve deficits (III-VI), proptosis, and visual disturbances. Management of CS tumors is controversial and includes observation, stereotactic radiosurgery, and surgical resection. We present the case of a 43-year-old right-handed male who presented with right facial numbness. A magnetic resonance imaging scan of the brain showed a right cavernous sinus tumor. He underwent stereotactic radiosurgery at an outside hospital. His facial numbness gradually improved. Four years later he had recurrence of the right facial numbness in the V3 distribution associated with right eyelid ptosis and diplopia. On neurologic examination he had decreased sensation to light touch in the 3 branches of the trigeminal nerve. He had a right eyelid ptosis and a 6-VI cranial nerve palsy. A new magnetic resonance imaging scan of the brain showed radiologic progression of the tumor. An orbitozygomatic craniotomy was performed and gross total tumor resection was achieved through lateral wall of the cavernous sinus working mainly between V2 and V3. The facial numbness he had preoperatively gradually improved, and his extraocular movements and eyelid ptosis recovered completely. Histopathology showed a clear cell grade 2 meningioma. The patient received adjuvant radiosurgery. At 3-year follow-up, the patient was free of disease recurrence. CS surgery for meningioma is feasible with low morbidity and can provide benefits in improving preexisting cranial nerve dysfunction (Video 1).1-4 Complete resection of the CS meningiomas is possible in most cases. CS tumors remain a surgical challenge, but accurate knowledge of surgical neuroanatomy and surgical approaches facilitates their safe and effective treatment. The patient gave informed consent for surgery, use of images, and video publication.

Proximal Branches of the Anterior Cerebral Artery: Anatomic Study and Applications to Endoscopic Endonasal Surgery.

BACKGROUND: The endoscopic endonasal approach is a surgical alternative for midline anterior skull base tumors. A detailed understanding of the proximal anterior cerebral artery (ACA) branches' anatomy from an endonasal perspective is essential for avoiding vascular complications. OBJECTIVE: To evaluate, from an endonasal perspective, the anatomic variations of the ACA and its proximal branches, specifically the recurrent artery of Heubner (RAH), and the fronto-orbital (FOA) and frontopolar (FPA) arteries. METHODS: We study the origin, course, branching pattern, diameter, and relationship between the proximal ACA branches and the optic apparatus and olfactory tract in 25 head specimens. RESULTS: The RAH was present in all hemispheres and originated within 3 ± 1.5 mm of the AcomA, with a 0.4 ± 0.1 mm diameter. Based on its relationship with the A1 segment, we observed three RAH courses: anterior (40%), superior (22%), and posterior (38%). The FOA was present in all cases, a mean of 6 ± 4 mm from the AcomA, with a 0.7 ± 0.4 mm diameter. The FOA arose mainly from the A2 (70%), with three courses in relation to the olfactory tract: crossing its proximal third (54%), crossing its middle third (31%), and running parallel to it along the gyrus rectus (15%). The FPA was present in 92% of the hemispheres, a mean of 10 ± 5 mm from the AcomA, always arising from the A2 and coursing anteriorly within the interhemispheric fissure towards the frontal pole. CONCLUSION: The RAH, FOA, and FPA can be differentiated by origin, course, and destination using the A1 segment, olfactory tract, and interhemispheric fissure, respectively, as surgical landmarks.

Surgical Anatomy of the Subcallosal Artery: Implications for Transcranial and Endoscopic Endonasal Surgery in the Suprachiasmatic Region.

BACKGROUND: Suprachiasmatic subcallosal lesions may have an intimate relationship with the anterior communicating artery (AcomA); injury to AcomA branches can result in basal forebrain infarction and cognitive dysfunction. OBJECTIVE: To evaluate anatomic variations of the AcomA basal perforating branches, especially the subcallosal artery (ScA), for clinical implications when approaching the suprachiasmatic subcallosal region from endonasal and transcranial routes. METHODS: The origin, course, diameter, and branching pattern of the AcomA's perforating branches were studied in 33 specimens from transcranial and endonasal perspectives. RESULTS: The ScA was present in 79% of the specimens as a single dominant artery arising from the posterior/posterosuperior surface of the AcomA, along with hypothalamic arteries (55%), or as a single artery (24%). It coursed posteriorly towards the lamina terminalis region, curving superiorly to the subcallosal area. The ScA gave off many branches to provide the main blood supply to the subcallosal region. Importantly, it supplies the septal/subcallosal region bilaterally. The ScA can be found posterior, superior, or inferior to the AcomA when using a transylvian, interhemispheric, or endonasal approach, respectively. In specimens with no ScA (21%), the median callosal artery (MdCA) was the dominant artery arising from the AcomA. It followed an identical course to the ScA, providing supply to the same structures bilaterally, but its distal extension reached the body/splenium of the corpus callosum. The MdCA is a ScA variant. CONCLUSION: The ScA is a unique vessel because it supplies the septal/subcallosal region bilaterally; preservation of this vessel during surgery is crucial for successful outcomes.