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.

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.

Angiographic measurement of the superficial temporal artery for potential use in cerebral bypass surgery: a combined radiological and cadaveric study.

PURPOSE: This study aims to investigate the microsurgical anatomy of the superficial temporal artery (STA), explore the relationship between STA length and lumen diameter, and develop a reliable radiologic method for selecting STA segments for bypass surgery. METHODS: This study used 10 cadaveric dissections (20 STAs, both sides) and 20 retrospective radiological examinations (40 STAs, both sides), employing curved multiplanar reformation and flow color lookup table (CLUT) DICOM processing. Measurements included vessel lumen diameters and luminal cross-sectional thicknesses 3 mm proximal to the STA bifurcation, 3 mm distal to the frontal branch, 5 cm distal to the frontal branch, 3 mm distal to the parietal branch, and 5 cm distal to the parietal branch. The distance between the STA bifurcation and the superior zygomatic border (SZB) was also measured. In our analysis, descriptive statistics encompassed mean, standard deviation (SD), standard error, minimum and maximum values, and distributions. Comparative statistics were performed using Student's t-test, with statistical significance set at p < 0.05. RESULTS: There were no statistically significant differences between STA measurements of bifurcation distances (p = 0.88) and lumen diameters (p = 0.46) between cadavers and radiological measures. However, lumen thicknesses were larger in frontal branches than parietal branches at the seventh and eighth centimeter (p = 0.012, p = 0.039). Branches became thinner distally from the zygoma in both cadavers and radiological image measurements. CONCLUSION: The CLUT DICOM processing radiological measures provided the high-precision required to enable pre-surgical vessel selection for extracranial-intracranial bypass. The results show that STA vessel luminal diameters are sufficient (> 1 mm) for bypass surgery in the first 9 cm but gradually decrease after that. Also shown is that the choice of frontal versus parietal branches depends on individual anatomical features; therefore, careful preoperative radiological examination is critical.

Anatomical Variations and Anomalies of the Middle Cerebral Artery.

OBJECTIVE: Intracranial arteries have a high rate of variation, but a clear schematic overview is lacking. In this pictorial review we classify and depict all the variations and anomalies within the middle cerebral artery (MCA). METHODS: PubMed was searched with the MeSH-term "Middle Cerebral Artery." Articles were selected based on their description of variants within the MCA. Cross-referencing was used to broaden the range of articles. The anatomical variants were then schematically drawn using the anteroposterior and lateral view during angiography of the internal carotid artery. RESULTS: A total of 29 unique medical illustrations were made, depicting variation in number of vessels; variation in vessel origin; and variation in morphology. CONCLUSIONS: The MCA provides vital blood supply to the frontal, parietal, temporal, and central brain structures. An overview of these variations is important to diagnose and treat patients with MCA-related pathology correctly and safely. They can aid in distinguishing pathology from normal anatomical variance; aid neurosurgeons during aneurysmal clipping or arteriovenous malformation resections; and aid interventional radiologists during thrombectomy or coiling. This article provides a summary regarding current knowledge of anatomical variations within the MCA, their prevalence and clinical relevance. A total of 29 unique illustrations were made, depicting currently known variants. We encourage all who diagnose, treat, and study the MCA to use this overview for a uniform and better understanding of its anatomy.

Anatomical Variations and Anomalies of the Anterior Communicating Artery Complex.

BACKGROUND: Intracranial arteries have a high rate of variation, but a clear schematic overview is lacking. In this pictorial review we classify and depict all variations and anomalies within the anterior communicating artery complex. METHODS: PubMed was searched with the terms "Anterior Communicating Artery" AND "Variations" OR "Anomalies." Articles were selected based on their description of variants. Cross-referencing was used to broaden the range of variations. Surgical view during pterional craniotomy and transsylvian approach was used as a baseline for schematic drawings of the variations. RESULTS: A total of 42 variants were identified, schematically drawn and classified into A1-A2 segment, anterior communicating artery, and the recurrent artery of Heubner. CONCLUSIONS: The anterior communicating artery complex consists of the anterior cerebral artery, anterior communicating artery and the recurrent artery of Heubner. An overview of these variations may be helpful in distinguishing pathology from anatomical variations, assist neurosurgeons during clipping of cerebral aneurysms, and support interventional radiologists during endovascular treatments. This article summarizes the current knowledge of anatomical variations within the anterior communicating artery complex, their prevalence and clinical relevance. A total of 42 variants were identified and schematically depicted. We encourage all who diagnose, treat, and study the anterior communicating artery complex to use this overview for a uniform and better understanding of its anatomy.

[Anatomical bases of brain revascularization: choosing an extra-intracranial bypass option]. / Anatomicheskie osnovy khirurgicheskoi revaskulyarizatsii golovnogo mozga: obosnovanie vybora shuntiruyushchei operatsii.

Surgical brain revascularization is an important treatment for acute or chronic ischemia, intracranial aneurysms and skull base tumors. Individual anatomy of brain vessels should be clearly understood for this procedure. Variants of collateral cerebral blood flow in patients with cerebrovascular diseases depend on individual characteristics of circle of Willis and reserve mechanisms of collateral circulation. These anatomical variations require careful preoperative planning to choose the optimal revascularization option.

Definitions of intracranial aneurysm size and morphology: A call for standardization.

BACKGROUND: Intracranial aneurysms (IAs) are classified based on size (maximal dome diameter) as well as additional parameters such as neck diameter and dome-to-neck ratio (DNR). The neurosurgical literature includes a wide variety of definitions for both IA size and neck classifications. Standardizing the definitions of IA size and wide-neck classifications would help eliminate inconsistencies and potential misunderstandings of aneurysm morphology and rupture risk. METHODS: We queried the MEDLINE (EBSCO) database using the terms "unruptured IA" and ("small" or "medium" or "large") and filtered based on publication date, language, and scholarly journals. The resulting articles and their references were further screened for eligibility. This identified 286 records, of which 104 were excluded, leaving 182 articles for analysis. The review found several different IA size classifications and neck classifications. RESULTS: A review of the existing literature describing size and neck classifications revealed 13 size classifications for small aneurysms, four classifications for medium aneurysms, 15 classifications for large aneurysms, and one classification for giant aneurysms. There were also seven different wide-neck classifications found. CONCLUSION: It is imperative that a standardization in classification be implemented to help interventionalists make the most informed decisions regarding emerging treatment options as new endovascular technologies and devices are emerging with indications based around these classifications. Based on the database findings, this article recommends standardized quantitative measurement ranges for IA size and neck classifications.

Neurovascular anatomy: Spine.

The arterial supply of the spinal cord is provided by the spinal branch of the cervical, thoracic, and lumbar intersegmental arteries. While supply is initially provided at each embryonic segment, only a few prominent anterior radiculomedullary arteries remain at the adult stage, including the arteries of the cervical and lumbosacral enlargements as well as a constant upper thoracic contributor. The spinal cord is surrounded by the vasocorona, an arterial network that includes several longitudinal anastomotic chains, notably the anterior and posterior spinal arteries, which respectively supply the central and peripheral components of the intrinsic vascularization. The intrinsic venous circulation is also divided into central and peripheral components. The perimedullary venous system includes several longitudinal anastomotic chains interconnected by the coronary plexus. The radiculomedullary veins loosely follow the spinal nerve roots on their way to the epidural plexus. Their point of passage through the thecal sac forms an important valve-like structure, the antireflux mechanism.

Neurovascular anatomy of the adult female medial arm in relationship to potential sites for insertion of the etonogestrel contraceptive implant.

OBJECTIVE: Anatomic assessment of the medial upper arm to identify potential sites for insertion of the etonogestrel (ENG) implant. STUDY DESIGN: Forty female cadaveric arms were dissected. Two rows of 1×2-cm dissection windows were created in the inner arm overlying the triceps approximately 2-3 and 4-5 cm posterior to the bicipital sulcus (sulcus). The primary window was 8-10 cm proximal to the medial epicondyle and approximately 2-3 cm posterior to the sulcus. Neurovascular structures within each window were identified. The entire medial upper arm was dissected to visualize underlying structures. RESULTS: Mean age (± SD) of cadavers at death was 72.0±11.0 years. Arm measurements at the primary window were circumference 28.2±4.8 cm [range: 21-41], skin thickness 0.6±0.2 mm [0.3-1.0] and subcutaneous tissue thickness: 12.3±4.9 mm [4.7-21]. The basilic vein and the medial brachial cutaneous, ulnar and medial antebrachial cutaneous nerves were located in 40%, 58%, 40% and 18% of the primary windows, respectively. No major neurovascular structures were located 3-5 cm posterior to the sulcus. More neurovascular structures were identified overlying the biceps than triceps. Elbow flexion with the hand underneath the head displaced the ulnar nerve anteriorly towards the sulcus. CONCLUSION: As no major neurovascular structures were identified overlying the triceps 8-10 cm proximal to the medial epicondyle and 3-5 cm posterior to the sulcus, ENG implant insertion at this location may minimize risk of injury associated with improper deep insertion. Elbow flexion deflects the ulnar nerve away from this area and may further decrease risk of injury secondary to inadvertent deep insertion. IMPLICATIONS: Although a limited cadaver study, this anatomic assessment provides rationale for insertion of the ENG implant overlying the triceps 8-10 cm proximal to the medial epicondyle and 3-5 cm posterior to the sulcus. This area is theoretically safer for insertion of the ENG implant than areas of the inner arm where major neurovascular structures are commonly located.

Heart-Shaped Bilateral Medullary Pyramidal Infarction as a Pathognomonic Finding of Anterior Spinal Artery Occlusion.

BACKGROUND: Unilateral anterior spinal artery (ASA) occlusion resulting in bilateral medullary pyramidal (BMP) infarction is a rare and devastating stroke subtype. We present two cases highlighting the diagnostic and clinical challenges of BMP infarction. METHODS: Case reports and literature review. RESULTS: A 57-year-old man rapidly had severe vomiting and diarrhea 2 h after a meal. Examination revealed bulbar weakness and areflexic tetraplegia. Respiratory failure developed, requiring intubation and mechanical ventilation. Brain magnetic resonance imaging (MRI) showed a heart-shaped region of diffusion abnormality, characteristic of BMP infarction. Cerebral angiography showed an occluded left vertebral artery with unilateral left-sided origin of ASA. The patient required tracheostomy and percutaneous gastrostomy tube and was discharged to rehabilitation, with little improvement of his tetraplegia at 3-month follow-up. A 43-year-old woman presented to the emergency department with acute onset of lower-extremity paresthesia and history of upper respiratory infection 2 weeks prior. Initial examination findings included bulbar weakness, dysphagia, hyporeflexia, and generalized weakness. After admission, she had severe respiratory distress and required intubation. Lumbar puncture was evaluated for Guillain-Barré syndrome, but cerebrospinal fluid protein concentration was normal. Changes on diffusion-weighted MRI of the brain showed the characteristic heart-shaped BMP infarction, indicating occlusion of a unilateral ASA. She required tracheostomy and percutaneous gastrostomy tube placement, with no paralysis resolution. CONCLUSION: Acute BMP infarction may present with flaccid tetraplegia mimicking neuromuscular disorders. When the infarction is recognized early, intravenous thrombolysis can be considered to reduce morbidity of this rare stroke subtype.