Midline Cranial Base Research Articles

Craniofacial orientation and parietal bone morphology in adult modern humans.

In adult humans, the orbits vary mostly in their orientation in relation to the frontal bone profile, while the orientation of the cranial base and face are associated with the anteroposterior dimensions of the parietal bone. Here we investigate the effect of parietal bone length on the orientation of the orbits, addressing craniofacial integration and head orientation. We applied shape analysis to a sample of computed tomography scans from 30 adult modern humans, capturing the outlines of the parietal and frontal bones, the orbits, and the lateral and midline cranial base, to investigate shape variation, covariation, and modularity. Results show that the orientation of the orbits varies in accordance with the anterior cranial base, and in association with changes in parietal bone longitudinal extension. Flatter, elongated parietal bones are associated with downwardly oriented orbits and cranial bases. Modularity analysis points to a significant integration among the orbits, anterior cranial base, and the frontal profile. While the orbits are morphologically integrated with the adjacent structures in terms of shape, the association with parietal bone size depends on the spatial relationship between the two blocks. Complementary changes in orbit and parietal bone might play a role in accommodating craniofacial variability and may contribute to maintain the functional axis of the head. To better understand how skull morphology and head posture relate, future studies should account for the spatial relationship between the head and the neck.

Morphological integration affects the evolution of midline cranial base, lateral basicranium, and face across primates.

The basicranium and face are two integrated bony structures displaying great morphological diversity across primates. Previous studies in hominids determined that the basicranium is composed of two independent modules: the midline basicranium, mostly influenced by brain size, and the lateral basicranium, predominantly associated with facial shape. To better assess how morphological integration impacts the evolution of primate cranial shape diversity, we test to determine whether the relationships found in hominids are retained across the order. Three-dimensional landmarks (29) were placed on 143 computed tomography scans of six major clades of extant primate crania. We assessed the covariation between midline basicranium, lateral basicranium, face, and endocranial volume using phylogenetically informed partial least squares analyses and phylogenetic generalized least squares models. We found significant integration between lateral basicranium and face and between midline basicranium and face. We also described a significant correlation between midline basicranium and endocranial volume but not between lateral basicranium and endocranial volume. Our findings demonstrate a significant and pervasive integration in the craniofacial structures across primates, differing from previous results in hominids. The uniqueness of module organization in hominids may explain this distinction. We found that endocranial volume is significantly integrated to the midline basicranium but not to the lateral basicranium. This finding underlines the significant effect of brain size on the shape of the midline structures of the cranial base in primates. With the covariations linking the studied features defined here, we suggest that future studies should focus on determining the causal links between them.

Endoscopic endonasal resection of midline cranial base tumors

Objective: The advent of the endoscope in transsphenoidalsurgery has permitted to expand the indications of such approach also for the treatment of on tumors located in supra, para, retro and infrasellar regions, enabling the neurosurgeon to work under direct visual control in a minimally invasive way. Since 2004 we have started to use the extended endonasal transsphenoidal approach for a variety of lesions involving the midline skull base and, in particular, the suprasellar area, the cavernous sinus and the retroclival prepontine region. Methods: Over a 36-month period, sixty-four procedures have been performed. The series consisted of 29 males and 35 females, aged from 24 to 80 years (median 49.8 years). The mean follow-up was of 18 months (ranging from 3 to 36 months). Among the patients with midline lesions, who were 90.6 % of the total, seven patients had a pituitary adenoma, sixteen patients were affected by a craniopharyngioma, six patients had a suprasellar Rathke’s cleft cyst, seven subjects had a tuberculum sellae meningioma, four had an olfactorygroove meningioma, and six a clival tumor. Other lesions ofthe midline skull base were, 1 chiasmatic astrocytoma, 1 neuroendocrine tumor, 4 post-traumatic cerebro-spinal fluid rhinorrhea, and one optic nerve glioma. Three other patients had anterior cranial base meningoencephaloceles. Results: Overall, gross total removal of the lesion was achieved in 30/49 tumoral lesions (61.2%); subtotal removal was achieved in 12/49 cases (24.5%). The three cases of meningoencephaloceles were all successfully treated. Among the patients with preoperative visual deficits, most of them fully recovered or improved and only two worsened in one eye. Major complications consisted in 2 deaths (one not directly related with the surgical procedure), 6 postoperative CSF leak (one complicated with bacterial meningitis), one ICA injury, and 6 cases of permanent diabetes insipidus.Conclusion: The extended transsphenoidal approach tothe supra and parasellar lesions seems Endoscopy; Transsphenoidal surgery; Extended approach; Parasellar; Tumors; Anterior skull base. A promising minimally invasivetechnique for the removal of lesions affecting these areas,once thought to be suitable only of the transcranial routes.Concerning the lesion removal and the recurrence rate compared with the transcranial routes, it is too early to pose a definitive word, since the follow-up is still too short.

Encephalization and diversification of the cranial base in platyrrhine primates

The cranial base, composed of the midline and lateral basicranium, is a structurally important region of the skull associated with several key traits, which has been extensively studied in anthropology and primatology. In particular, most studies have focused on the association between midline cranial base flexion and relative brain size, or encephalization. However, variation in lateral basicranial morphology has been studied less thoroughly. Platyrrhines are a group of primates that experienced a major evolutionary radiation accompanied by extensive morphological diversification in Central and South America over a large temporal scale. Previous studies have also suggested that they underwent several evolutionarily independent processes of encephalization. Given these characteristics, platyrrhines present an excellent opportunity to study, on a large phylogenetic scale, the morphological correlates of primate diversification in brain size. In this study we explore the pattern of variation in basicranial morphology and its relationship with phylogenetic branching and with encephalization in platyrrhines. We quantify variation in the 3D shape of the midline and lateral basicranium and endocranial volumes in a large sample of platyrrhine species, employing high-resolution CT-scans and geometric morphometric techniques. We investigate the relationship between basicranial shape and encephalization using phylogenetic regression methods and calculate a measure of phylogenetic signal in the datasets. The results showed that phylogenetic structure is the most important dimension for understanding platyrrhine cranial base diversification; only Aotus species do not show concordance with our molecular phylogeny. Encephalization was only correlated with midline basicranial flexion, and species that exhibit convergence in their relative brain size do not display convergence in lateral basicranial shape. The evolution of basicranial variation in primates is probably more complex than previously believed, and understanding it will require further studies exploring the complex interactions between encephalization, brain shape, cranial base morphology, and ecological dimensions acting along the species divergence process.

Expression of glutathione peroxidase 1 in the spheno-occipital synchondrosis and its role in ROS-induced apoptosis.

Chondrogenesis is an integral part of endochondral bone formation, by which the midline cranial base is developed. Reactive oxygen species (ROS) are required in chondrogenic differentiation and antioxidant enzymes regulate their levels. The aim of this study was to localize the antioxidant enzyme glutathione peroxidase 1 (Gpx1) at the spheno-occipital synchondrosis, as well as its effect on ROS challenge and its expression pattern in the course of differentiation. Gpx1 was semiquantified in immunohistochemically stained sections of spheno-occipital synchondroses of rats. The effect of Gpx1 on ROS-induced apoptosis was investigated by manipulating the expression of Gpx1 in ATDC5 cells. The temporal pattern of Gpx1 expression was determined during chondrocyte differentiation for 21 days in vitro. Proliferating chondrocytes exhibited the greatest Gpx1 immunoreactivity and hypertrophic ones the lowest (P = 0.02). Cells transfected with Gpx1-siRNA had the highest apoptotic rate, while cells overexpressing Gpx1 the lowest one (P < 0.001). Gpx1 was significantly increased on days 10 (P = 0.02) and 14 (P = 0.01). Hypertrophic chondrocytes have the lowest Gpx1 activity in the spheno-occipital synchondrosis. Gpx1 is implicated in the ROS-induced apoptosis in chondrocytes. Its expression was not constitutive during chondrogenic differentiation.

Robotic Navigation of the Infratemporal Fossa and Midline Cranial Base

Objective: With the expanding application of endoscopic techniques in skull base surgery, we conducted a feasibility preclinical study on robotic exploration of the infratemporal and midline cranial base using the Da Vinci robotic platform.

Expanded Endoscopic Multiaxial Access to the Midline Cranial Base and Infratemporal Fossa Through the Maxillary Osteoplastic Window

Expanded Endoscopic Multiaxial Access to the Midline Cranial Base and Infratemporal Fossa Through the Maxillary Osteoplastic Window

Covariation Between Midline Cranial Base, Lateral Basicranium, and Face in Modern Humans and Chimpanzees: A 3D Geometric Morphometric Analysis

Previous studies showed that in modern humans the basicranium is formed of two modules: the midline cranial base and the lateral basicranium which are integrated with the face in very different ways. The study of the relationship between these structures is of prime interest in the context of hominids craniofacial evolutionary history. In this study, we aim to test if the relationship between the midline cranial base and the face on one hand and the lateral basicranium and the face on the other hand are qualitatively and quantitatively different in modern humans and chimpanzees: two phylogenetically close but morphologically different hominids. This work is performed using three-dimensional (3D) landmarks to take into account the face and basicranium 3D shape. Modern humans and chimpanzees both exhibit a significant relationship between lateral basicranium and face, and a nonsignificant relationship between midline cranial base and face. However, the patterns of integration are different for the two species. These results underscore the essential role of the lateral basicranial shape in the setting of the facial morphology in modern humans and chimpanzees. The important differences in the patterns of integration may be related to the genetic, developmental, and functional requirements of each taxon, acquired along their respective evolution. From a common, tight, relationship between lateral basicranium, and face, each taxon may develop different patterns of integration in order to adapt to particular functions and morphologies.

Morphological integration between the cranial base and the face in children and adults

The primary aim of the present study was to assess morphological covariation between the face and the basicranium (midline and lateral), and to evaluate patterns of integration at two specific developmental stages. A group of 71 children (6-10 years) was compared with a group of 71 adults (20-35 years). Lateral cephalometric radiographs were digitized and a total of 28 landmarks were placed on three areas; the midline cranial base, the lateral cranial base and the face. Geometric morphometric methods were applied and partial least squares analysis was used to evaluate correlation between the three shape blocks. Morphological integration was tested both with and without removing the effect of allometry. In children, mainly the midline and, to a lesser extent, the lateral cranial base were moderately correlated to the face. In adults, the correlation between the face and the midline cranial base, which ceases development earlier than the lateral base, was reduced. However, the lateral cranial base retained and even strengthened its correlation to the face. This suggests that the duration of common developmental timing is an important factor that influences integration between craniofacial structures. However, despite the apparent switch of primary roles between the cranial bases during development, the patterns of integration remained stable, thereby supporting the role of genetics over function in the establishment and development of craniofacial shape.

THREE-DIMENSIONAL AND 2-DIMENSIONAL ENDOSCOPIC EXPOSURE OF MIDLINE CRANIAL BASE TARGETS USING EXPANDED ENDONASAL AND TRANSCRANIAL APPROACHES

Endoscopic endonasal approaches provide an access method to the midline cranial base. To integrate these approaches into neurosurgical practice, the extent of their anatomic exposure must be compared with that provided by more traditional transcranial approaches. Ten fresh cadaver heads were studied. Both endonasal and transcranial approaches to the midline cranial base were performed. The midline cranial base was divided into several areas, and the relative exposure provided by each approach was described and presented in both 2-dimensional and 3-dimensional images. Limitations and advantages of each approach are discussed. The endonasal approaches achieved a direct and wide exposure of the midline extracranial and intracranial cranial base anatomy. The main lateral limitations of the endonasal approaches were the optic nerves, lateral cavernous sinus, vidian nerve, internal carotid artery, abducens nerve in Dorello's canal, jugular tubercle, and hypoglossal canals. Limitations of the transcranial approaches were the neurovascular structures which lie in the operative corridor and create narrow working spaces. The endonasal approaches achieve a direct and wide exposure of the midline cranial base bilaterally. Lateral exposure, beyond the cranial nerves and carotid artery, are challenging. Transcranial approaches are limited by the narrow corridors provided by the cranial nerves, and they do not visualize the contralateral paramedian cranial base very well. Three-dimensional endoscopes augment the spatial orientation and may improve patient safety and the learning curve for endoscopic approaches to the midline cranial base.

Quantitative Analysis of Surgical Exposure and Surgical Freedom Obtained by Endoscope and Microscope in the Endonasal Transsphenoidal Approaches to Sella Using CT-Based Frameless Stereotaxy: An Anatomical Study

Introduction: Among the most significant technical advances in cranial base surgery has been the introduction of the endonasal endoscopic techniques in the management of skull base lesions. The evolution and the changing role of the endoscope in pituitary and midline cranial base surgery attract significant attention from the neurosurgical community.

Mosaic Evolution of the Basicranium in Homo and its Relation to Modular Development

Mosaic evolution describes different rates of evolutionary change in different body units. Morphologically these units are described by more relationships within a unit than between different units which relates mosaic evolution with morphological integration and modularity. Recent evidence suggests mosaic evolution at the human basicranium due to different evolutionary rates of midline and lateral cranial base morphology but this hypothesis has not yet been addressed explicitly. We this hypothesis and explore how mosaic evolution relates to modular development. Evolutionary data sets on midline (N = 186) and lateral (N = 86) basicranial morphology are compared with 3D data on pre- and postnatal basicranial ontogeny (N = 71). Our results support the hypothesis of mosaic evolution and suggest a modular nature of basicranial development. Different embryological basicranial units likely became differently modified during evolution, with relatively stable midline elements and more variable lateral elements. In addition, developmental data suggests that modularity patterns change throughout ontogeny. During prenatal ontogeny lateral basicranial elements (greater sphenoid wings and petrosal pyramids) change together compared with the midline base. Close to birth the greater sphenoid wings keep a spatially stable position, while the petrosal pyramids become dissociated and shifted posteriorly. After birth the greater sphenoid wings and petrosal pyramids change again jointly and with respect to midline cranial base elements. This sequential pattern of integration and modularization and re-integration describes human basicranial ontogeny in a way that is potentially important for the understanding of evolutionary change. Phylogenetic modifications of this pattern during morphogenesis, growth, and development may underlie the mosaic evolution of the hominin basicranium.

“GASKET-SEAL” WATERTIGHT CLOSURE IN MINIMAL-ACCESS ENDOSCOPIC CRANIAL BASE SURGERY

Transnasal endoscopic cranial base surgery is a novel minimal-access method for reaching the midline cranial base. Postoperative cerebrospinal fluid leak remains a persistent challenge. A new method for watertight closure of the anterior cranial base is presented. To achieve watertight closure of the anterior cranial base, autologous fascia lata was used to create a "gasket seal" around a bone buttress, followed by application of a tissue sealant such as DuraSeal (Confluent Surgical, Inc., Waltham, MA). The gasket-seal closure was used to seal the anterior cranial base in a series of 10 patients with intradural surgery for suprasellar craniopharyngiomas (n = 5), planum meningiomas (n = 3), clival chordoma (n = 1), and recurrent iatrogenic cerebrospinal fluid leak (n = 1). Lumbar drains were placed intraoperatively in five patients and remained in place for 3 days postoperatively. After a mean follow-up period of 12 months, there were no cerebrospinal fluid leaks. The gasket-seal closure is an effective method for achieving watertight closure of the anterior cranial base after endoscopic intradural surgery.

Thin-plate spline analysis of the cranial base in African, Asian and European populations and its relationship with different malocclusions

Objectives To test the hypothesis that midline basicranial orientation and posterior cranial base length are discriminating factors between adults of different populations and its potential maxillo/mandibular disharmonies. Design Twenty-nine 2D landmarks of the midline cranial base, the face and the mandible of dry skull X-rays from three major populations (45 Asians, 34 Africans, 64 Europeans) were digitized and analysed by geometric morphometrics. We used, first, MANOVA to test for mean shape differences between populations; then, principal components analysis (PCA) to assess the overall variation in the sample and finally, canonical variate analysis (CVA) with jack-knife validations ( N = 1000) to analyse the anatomical features that best distinguished among populations. Results Significant mean shapes differences were shown between populations ( P < 0.001). CVA revealed two significant axes of discrimination ( P < 0.001). Jack-knife validation correctly identified 92% of 15,000 unknowns. In Africans the whole cranial base is rotated into a forward–downward position, while in Asians it is rotated in the opposite way. The Europeans occupied an intermediate position. African and Asian samples showed a maxillo/mandibular prognathism. African prognathism was produced by an anterior positioned maxilla, Asian prognathism by retruded anterior cranial base and increase of the posterior cranial base length. Europeans showed a trend towards retracted mandibles with relatively shorter posterior cranial bases. Conclusions The results supported the hypothesis that basicranial orientation and posterior cranial base length are valid factors to distinguish between geographic groups. The whole craniofacial configuration underlying a particular maxillo-facial disharmony must be considered in diagnosis, growth predictions and resulting treatment planning.

Craniofacial growth in fetal Tarsius bancanus: brains, eyes and nasal septa.

The tarsier skull has been of particular interest in studies of primate taxonomy and functional morphology for several decades. Despite this, there remains no comprehensive data on how the tarsier skull develops, especially in relation to the soft-tissues of the head. Here we have documented for the first time fetal development of the skull and brain as well as the nasal septum and eyes in T. bancanus. We have also tested for the possible influence of these tissues in shaping skull architecture. Nineteen post-mortem specimens were imaged using high-resolution magnetic resonance imaging and magnetic resonance microscopy. Landmarks and volume data were collected and analysed. Findings demonstrated massive increases of brain size and eye size as well as flattening of the midline cranial base, facial projection and orbital margin frontation. Little evidence was found to support the notion that growth of the brain or nasal septum physically drives the observed changes of the skull. However, increases in the size of the eyes relative to skull size were associated with orbital margin frontation. With the possible exception of the results for eye size, the findings indicate that rather than forcing change the soft-tissues form a framework that physically constrains the morphogenetic template of the skeletal elements. This suggests, for example, that the degree of cranial base angulation seen in adulthood is not directly determined by brain expansion bending the basicranium, but by brain enlargement limiting the extent of cranial base flattening (retroflexion) in the fetus.

Sublabial transnasal approach combined with a partial resection of the nasal floor for midline skull base tumors

A variety of surgical approaches have been used in the treatment of midline cranial base tumors. These approaches usually involve complicated techniques, particularly when they are employed for tumors involving the entire clivus. This paper describes the feasibility, efficacy, and safety of the sublabial transnasal approach combined with a partial resection of the nasal floor in the treatment of midline skull base lesions. We performed this approach in three patients with midline cranial base lesions, including invasive pituitary adenoma involving the whole clivus, fibrous dysplasia, and adenocystic carcinoma. The rostrocaudal extent of surgical exposure with this technique was the planum sphenoidale superiorly and the lowermost level of the clivus inferiorly. The lateral extent of the exposure was limited to the distance between the bilateral extradural internal carotid arteries. The average time taken to expose the entire length of the clivus was approximately 30 minutes. There were no serious complications related to the surgical procedure. None of the patients developed cosmetic abnormalities. Experience with these three patients indicates that the sublabial transnasal approach combined with a partial resection of the nasal floor is a safe, less invasive and effective approach in certain cases of midline skull base tumors.

Craniofacial levels and the morphological maturation of the human skull

It is well known that the human skull achieves adult size through a superior-inferior gradient of maturation. Because the basicranium matures in size before the face, it has been suggested that the form of the basicranium might have ontogenetic knock-on effects on that of the face. However, although sequential spatially organized maturation of size is well described in the cranium, the maturation of skull shape is not. Knowledge of the maturation of shape is important, nevertheless, because it is claimed that the early determination of the spatial configuration of basicranial components, where the facial skeleton attaches, is relevant in the spatio-temporal ontogenetic cascade from basicranium to face. This paper examines the ontogeny of various components of the human skull in 28 individuals from the longitudinal Denver Growth Study. Sixty-six landmarks and semilandmarks were digitized on 228 X-rays and analysed using geometric morphometric methods. Bootstrapped confidence intervals for centroid size support previous studies suggesting a supero-inferior gradient of growth maturation (size over time), while developmental maturation (shape over time) is more complex. A sequence of shape maturation is described, in which the earliest structure to mature in shape was the midline cranial base (7-8 years), followed by the lateral cranial floor (11-12), midline neurocranium (9-10) and facial and mandibular structures (15-16). The absolute ages of shape maturation of the latter three depended on the criterion of maturity used, which was not the case for the basicranial components. Additionally, ontogenetic dissociations were found between the maturation of size and shape of the midline cranial base and lateral floor, possibly underlining its role as structural 'interface' between brain and facial ontogeny. These findings imply potential for bidirectional developmental influences between the lateral cranial floor and the face until about 11-12 years. The findings are discussed with regard to their relevance for palaeoanthropology and especially the evolutionary and developmental bases of skull morphological variation.

Correlated variation between the lateral basicranium and the face: A geometric morphometric study in different human groups

The significance of the cranial base in the contribution of normal and pathologic facial patterns is uncertain. The aim of this study was to explore and compare patterns of morphological covariation between the face and the lateral basicranium (anterior and middle cranial fossae) with covariation patterns between the face and the midline cranial base. We employed 2D geometric morphometrics and partial least squares analysis to quantify and compare correlation coefficient between principal variation patterns between basicranial and facial structures in lateral radiographs from 143 humans from Japan (N=45), Europe (N=65) and Africa (N=34). In both comparisons basicranial patterns co-varied with dolichofacial and brachyfacial morphologies. The findings showed that the midline cranial base is not significantly correlated of common facial patterns (r=0.37, P=0.09). Instead, the lateral basicranium is significantly (P=0.000), and significantly higher (r=0.6) correlated with facial variation than is the midline cranial base. The lateral basicranium may be of higher morphogenetic relevance for influencing facial variation than previously thought. This influence may be of clinical importance for the generation of skeletal class II or class III malocclusions. Further research should expand on geometric morphometric analysis of ontogenetic and clinical 3D data in order to advance in the understanding of these complex developmental relationships.

Hierarchical nature of morphological integration and modularity in the human posterior face

Morphological integration and modularity are important points of intersection between evolution and the development of organismal form. Identification and quantification of integration are also of increasing paleoanthropological interest. In this study, the "posterior face," i.e., the mandibular ramus and its integration with the associated midline and lateral basicranium, is analyzed in lateral radiographs of 144 adult humans from three different geographic regions. The null hypothesis of homogenously pervasive morphological integration among "posterior-face" components is tested with Procrustes geometric morphometrics, partial least squares, and singular warps analysis. The results reveal statistically significant differences in integration. Only loose integrative relationships are found between midline and lateral components of the basicranium, which may indicate the presence of at least two different basicranial modules. This modularity can be interpreted in terms of spatiotemporal dissociation in the development of those basicranial structures, and gives support to hypotheses of independent phylogenetic modifications at the lateral and midline basicranium in humans. In addition, morphological integration was statistically significantly stronger between the middle cranial fossa and the mandibular ramus than between the ramus and the midline cranial base. This finding confirms previous hypotheses of a "petroso-mandibular unit," which could be a developmental consequence of well-known phylogenetic modifications in coronal topology of the posterior face and base in hominoid evolution, related to middle cranial fossa expansion. This unit could be involved in later evolutionary tendencies in the hominid craniofacial system.

Exposure of Midline Cranial Base without a Facial Incision through a Combined Craniofacial-Transfacial Procedure

A single-stage combined craniofacial-transfacial approach that exposes the midline cranial base without visible facial incisions is described. Between 1992 and 1998, eight patients underwent surgery for five different anterior cranial base pathological findings: four angiofibromas, one mesenchymal chondrosarcoma, one esthesioneuroblastoma, one odontogenic myxoma, and one encephalocele. In all cases, the surgical exposure consisted of a bicoronal scalp incision with a bifrontal craniotomy and fronto-orbitonasal osteotomy, and then a sublabial incision for transmaxillary exposure. Gross total resection was achieved in five cases. The encephalocele was resected with complete reconstruction of the bony defect. Seven patients developed complications, primarily wound infections, cerebrospinal fluid leaks, and anemia. Postoperative Karnofsky Performance Scale scores ranged between 80 and 100 (mean, 92.5). Long-term follow-up information (mean, 56 mo; median, 59.5 mo; range, 5-108 mo) was available for all patients. Large anterior cranial base lesions can be resected and excellent cosmetic outcomes can be achieved with a single-stage combined transfacial-craniofacial approach that exposes the entire midline cranial base and requires no facial incisions.