Karl Jacobs

Cerebrovascular disorders, encompassing conditions such as stroke, aneurysms, and arteriovenous malformations, are often associated with developmental malformations of the intracranial arterial system, including the circle of Willis. The circle of Willis plays a crucial role in establishing a collateral vascular network essential for ensuring adequate cerebral blood supply. However, the intricate process of human intracranial vascular development, known as vascular neuroembryology, remains complex and incompletely understood. The diverse array of anatomical vascular variations observed in clinical practice is a direct outcome of this developmental process. We present a chronological overview of human neurovascular embryology using stage-resolved three-dimensional reconstructions of the developing intracranial arterial system. Histological sections of 26 human embryos ranging from Carnegie stages (CS) 11 to 23 were digitally reconstructed and manually segmented in Amira software (versions 5.3–5.6; Thermo Fisher Scientific, Waltham, MA, USA) to generate detailed 3D models of the cranial vasculature and adjacent anatomical structures, including the neural tube, cranial nerves, eye, and ear. Sequential 3D reconstruction revealed progressive remodeling of the primitive cranial vasculature and key developmental transitions underlying formation of the circle of Willis. By integrating these developmental observations with existing embryological literature, we refine current models of neurovascular development, with particular emphasis on the ophthalmic and trigeminal arterial systems. These findings provide an updated developmental framework for interpreting normal and variant intracranial vascular anatomy encountered in clinical practice.

Background: Hemifacial microsomia (HFM) is a congenital craniofacial malformation characterized by unilateral hypoplasia of structures derived from the first and second pharyngeal arches. Although the phenotype is well described, the underlying etiology remains incompletely understood. Disturbances in embryonic vascular development have long been proposed as a potential mechanism contributing to the characteristic unilateral craniofacial phenotype. Methods: A systematic literature review was conducted following PRISMA guidelines. Searches were performed in PubMed, Embase, Web of Science, and CINAHL to identify studies investigating vascular mechanisms in hemifacial microsomia and related craniofacial microsomia phenotypes. Evidence from epidemiological, clinical, radiological, and genetic studies was synthesized narratively because of methodological heterogeneity. Results: Of 450 screened records, eight studies met the inclusion criteria. Epidemiological studies identified associations between HFM and maternal factors potentially affecting embryonic perfusion, including vasoactive medication exposure, maternal diabetes, multiple gestations, and second‐trimester vaginal bleeding. Population‐based data further demonstrated an increased prevalence of single umbilical artery and growth restriction among affected infants. Clinical and radiological observations described regional vascular abnormalities, including carotid artery attenuation. One genetic association study suggested interactions between pathways involved in vascular development and neural crest cell biology. Conclusions: The available evidence is consistent with a possible contribution of disturbances in vascular development to the pathogenesis of hemifacial microsomia, particularly in unilateral presentations. However, current evidence remains indirect and heterogeneous. Vascular mechanisms may interact with genetic susceptibility and neural crest cell biology within a broader multifactorial developmental framework. Further studies integrating genomic analyses, developmental models, and detailed vascular imaging are needed to clarify the role of vascular mechanisms in craniofacial microsomia.

Background: This research investigates the accuracy of the anatomical representation of the dissected forearm as depicted in The Anatomy Lesson of Dr. Nicolaes Tulp (1632) by Rembrandt van Rijn, focusing on whether the anatomical structures depicted, correspond to actual human forearm anatomy.Methods: Ten human forearms were dissected following a standardized research dissection protocol. The study was conducted in three phases, including an exploratory phase, a research phase, and a verification phase. The forearm was positioned in external rotation and supination, as shown in the painting, and dissected layer by layer to identify the relevant muscular and neurovascular structures. The findings were compared to the depiction in the painting and previous research.Results: The anatomical structures were prepared in four regions. The m. palmaris longus, m. flexor digitorum superficialis and profundus, m. flexor carpi ulnaris, and a cutaneous branch of the n. ulnaris were identified. The majority of the identified structures corresponded closely to those represented in the painting. The only discrepancy was a reversed configuration of the muscle bellies of the m. flexor digitorum superficialis compared to the dissected specimen.Conclusion: These findings confirm that Rembrandt’s depiction shows a remarkable degree of anatomical accuracy. The sole discrepancy is most likely due to an anatomical or interpretative inaccuracy, although normal anatomical variation cannot be ruled out.

Background: The process of vascular development is essential for shaping complex craniofacial structures. Investigating the interplay between vascular development and orofacial morphogenesis holds critical importance in clinical practice and contributes to advancing our comprehension of (vascular) developmental biology. New insights into specific vascular developmental pathways will have far-reaching implications across various medical disciplines, enhancing clinical understanding, refining surgical techniques, and elucidating the origins of congenital abnormalities. Embryonic development of the craniofacial vasculature remains, however, under-exposed in the current literature. We imaged and created 3-dimensional (D) reconstructed images of the craniofacial arterial system from two early-stage human embryonic samples. Objective: The aim of this study was to investigate the vascular development of the craniofacial region in early-stage human embryos, with a focus on understanding the interplay between vascular development and orofacial morphogenesis. Materials and methods: Reconstructions (3-D) were generated from high-resolution diffusible iodine-based contrast-enhanced computed tomography (diceCT) images, enabling visualization of the orofacial arterial system in human embryonic samples of Carnegie stages (CS) 14 and 18 from the Dutch Fetal Biobank, corresponding to weeks 7 and 8.5 of gestation. Results: From two human embryonic samples (ages CS 14 and 18), the vascular development of the orofacial region at two different stages of development was successfully stained with B-Lugol and imaged using a micro-computed tomography (micro-CT) scanner with resolutions of 2.5-μm and 9-μm voxel sizes, respectively. Additionally, educational 3-D reconstructions of the orofacial vascular system were generated using AMIRA 2021.2 software. Conclusion: Micro-CT imaging is an effective strategy for high-resolution visualization of vascular development of the orofacial region in human embryonic samples. The generated interactive 3-D educational models facilitate better understanding of the development of orofacial structures. Graphical

Background: Visualizing (micro)vascular structures remains challenging for researchers and clinicians due to limitations in traditional radiological imaging methods. Exploring the role of vascular development in craniofacial malformations in experimental settings can enhance understanding of these processes, with the effectiveness of high-resolution imaging techniques being crucial for successful research in this field. Micro-CT imaging offers 3D microstructural insights, but requires contrast-enhancing staining agents (CESAs) for visualizing (micro)-vascular tissues, known as contrast-enhanced micro-CT (CECT). As effective contrast agents are crucial for optimal visualization, this review focuses on comparative studies investigating such agents for micro-vascular tissue imaging using micro-CT. Furthermore, we demonstrate the utilization of B-Lugol solution as a promising contrast agent for acquiring high-quality micro-CT images of (micro)vascular structures in human embryonic samples. Method: This scoping review followed Preferred Reporting Items for Systematic Reviews and Meta-analysis Protocols. PubMed database provided relevant articles, screened initially by title and Inclusion and exclusion criteria defined outcomes of interest. Results: From an initial search, 273 records were identified, narrowed down to 9 articles after applying our criteria. Additionally, two articles were added through citation searching. This, a total of 11 articles were incorporated in this study. Conclusion: This micro-CT contrast agent review underscores the need for tailored choices based on research goals. Both Barium sulfate and Iodine-based agents showing excellent results, providing high resolution (micro) vascular content, especially in ex-vivo specimens. However, careful consideration of protocols and tissue characteristics remains imperative for optimizing the effectiveness of micro-CT imaging for the study of cranio-facial vascular development.

Introduction: Although the maxillary nerve block (MNB) provides adequate pain relief in cleft palate surgery, it is not routinely used globally, and reported techniques are heterogeneous. This study aims to describe relevant anatomy and to present the preferred technique of MNB administration based on the current literature and the expert opinion of the authors. Method and materials: First, a survey was sent to 432 registrants of the International Cleft Palate Master Course Amsterdam 2023. Second, MEDLINE (PubMed interface) was searched for relevant literature on maxillary artery (MA) anatomy and MNB administration in pediatric patients. Results: Survey response rate was 18% (n=78). Thirty-five respondents (44.9%) used MNB for cleft palate surgery before the course. A suprazygomatic approach with needle reorientation towards the ipsilateral commissure before incision was most frequently reported, mostly without the use of ultrasound. Ten and 20 articles were included on, respectively, MA anatomy and MNB administration. A 47.5% to 69.4% of the MA’s run superficial to the lateral pterygoid muscle and 32% to 52.5% medially. The most frequently described technique for MNB administration is the suprazygomatic approach. Reorientation of the needle towards the anterior aspect of the contralateral tragus appears optimal. Needle reorientation angles do not have to be adjusted for age, unlike needle depth. The preferred anesthetics are either ropivacaine or (levo)bupivacaine, with dexmedetomidine as an adjuvant. Conclusion: Described MNB techniques are heterogeneous throughout the literature and among survey respondents and not routinely used. Further research is required comparing different techniques regarding efficacy and safety.

To increase our understanding of the etiology of specific neurological disorders (e.g., Duane syndrome, glossoptosis in Pierre Robin sequence), proper knowledge of anatomy and embryology of cranial nerves is necessary. We investigated cranial nerve development, studied histological sections of human embryos, and quantitatively analyzed the 3D reconstructions. A total of 28 sectioned and histologically stained human embryos (Carnegie stage [CS] 10 to 23 [21–60 days of development]) were completely digitalized by manual annotation using Amira software. Two specimens per stage were analyzed. Moreover, quantitative volume measurements were performed to assess relative growth of the cranial nerves. A chronologic overview of the morphologic development of each of the 12 cranial nerves, from neural tube to target organ, was provided. Most cranial nerves start developing at CS 12 to 13 (26–32 days of development) and will reach their target organ in stage 17 to 18 (41–46 days). In comparison to the rest of the developing brain, a trend could be identified in which relative growth of the cranial nerves increases at early stages, peaks at CS 17 and slowly decreases afterwards. The development of cranial nerves in human embryos is presented in a comprehensive 3D fashion. An interactive 3D‐PDF is provided to illuminate the development of the cranial nerves in human embryos for educational purposes. This is the first time that volume measurements of cranial nerves in the human embryonic period have been presented.