Posterior Skull Research Articles

Endoscopic Endonasal Transpterygoid Approach: Technical Lessons.

The endoscopic endonasal transpterygoid approach (EETPA) provides direct access to the petrous apex, lateral clivus, inferior cavernous sinus compartment, jugular foramen, and infratemporal fossa. 1,2 In the coronal plane, it provides exposure far beyond a traditional sphenoidotomy. The pterygoid process of the sphenoid bone forms the junction between the body and greater sphenoid wing before bifurcating because it descends into medial and lateral plates. The key to this exposure lies in the region's bony foramina: the palatovaginal canal, vidian canal, and foramen rotundum. 3. After performing a maxillary antrostomy, stepwise exposure of these foramina leads to the pterygopalatine fossa. The sphenopalatine artery is cauterized as it becomes the posterior septal artery at the sphenopalatine foramen, and the maxillary sinus' posterior wall is opened to expose the pterygopalatine fossa. After mobilizing and retracting the contents of the pterygopalatine fossa, the pterygoid process is removed, improving access in the coronal plane. 4. Vidian neurectomy causes decreased or absent lacrimation. Injury to the maxillary nerve or its branches results in facial, palatal, or odontogenic anesthesia or neuralgia. In addition, the EEPTA precludes the ability to raise an ipsilateral nasal septal flap, making it crucial to plan reconstruction preoperatively. 4,5. There are 5 variants of the EEPTA: extended pterygopalatine fossa, lateral recess of the sphenoid sinus, petrous apex, infratemporal fossa and petrous carotid artery, and middle and posterior skull base. 5The patient consented to the procedure.Images in the video used with permission as follows: images at 0:33 and 1:15 reused from Bozkurt et al, 3 © Georg Thieme Verlag KG; image at 0:39 from Prosser et al, 5 © John Wiley and Sons; images at 0:54, 9:03, and 9:38 from Kasemsiri et al, 1 © John Wiley and Sons; images at 1:07 and 9:44 from Falcon et al, 2 © John Wiley and Sons; image at 1:15 from Sandu et al, 4 © Springer Nature.

Retrosigmoid Craniotomy and Intradural Variations: Role of Patient-Specific Preoperative Imaging to Identify Landmarks and Relevant Structures

There are several landmarks to safely identify the limits of the retrosigmoid approach and its intradural variations, however, little has been discussed about how those landmarks may vary among patients. We provided a review of patient positions, surface landmarks for the retrosigmoid craniotomy, and structures to recognize for transmeatal, suprameatal, suprajugular and transtentorial extensions. The position of the dural sinuses in relation with the zygomatic-inion line, and digastric notch line is readily identified on MRI. For transmeatal drilling, the position of the semicircular canals, vestibular aqueduct and jugular bulb is best evaluated on CT. For suprameatal drilling, the labyrinth and the position and integrity of the carotid canal are relevant to plan the anterior extension of the approach. For transtentorial extension, it is desirable to identify incisural structures. For suprajugular drilling, the position of the jugular bulb, invasion of venous structures, and integrity of the roof of the jugular foramen must be checked preoperatively. The retrosigmoid approach is the workhorse of posterior skull base surgery. By recognizing patient-specific variations in known landmarks, the approach may be tailored prevent complications.

PC31. Splenius Capitis Muscle Flap for Treatment of Chiari I Malformation Decompression Reconstruction - A Case Series

PURPOSE: The purpose of this study is to report outcomes of patients who have undergone the splenius capitis muscle flap for posterior neck space obliteration after Chiari I malformation decompression procedures. METHODS: The Institutional Review Board exemption was obtained. Patients who underwent Chiari I malformation decompression with splenius capitis muscle flap reconstruction were evaluated. Patient demographics, prior surgical intervention; variations in surgical techniques, as well intraoperative and postoperative complications were analyzed between the years of 2009 and 2022. RESULTS: A total of 22 patients who had undergone Chiari I malformation decompression with splenius capitis muscle flap reconstruction were identified. Age ranged between 16 and 59, with 19 (86.4%) females and 3 (13.6%) males. Six complications were identified, with 2 patients experiencing a CSF leak, 2 with superficial wound infection, and 2 with incisional dehiscence. The CSF leak patients were treated with a lumbar drain placement and healed without compromising the reconstruction. Likewise the superficial wound dehiscence and infection did not compromise muscle coverage with successful healing outcomes. Finally, none of the patients experienced donor site functional morbidity. CONCLUSION: The splenius capitis flap is a safe and effective muscle flap for posterior neck space obliteration in Chiari I malformation decompression procedures. With six patients experiencing surgical site dehiscence/infection and CSF leak, all patients healed with minimal intervention and no reconstruction compromise. [1] Elsahy NI, Achecar FA. Use of the splenius capitis muscle flap for reconstruction of the posterior neck and skull in complicated Arnold-Chiari malformation. Plast Reconstr Surg. 1994;93(5):1082–1086.

Long-term Outcomes of Non-vascularized Multilayer Fascial Closure Technique for Dural Repair in Endoscopic Transnasal Surgery: Efficacy, Durability, and Limitations

Non-vascularized multilayer fascial closure technique (NMFCT) can be used instead of nasoseptal flap reconstruction for dural repair in endoscopic transnasal surgery (ETS); however, due to the lack of blood supply, its long-term durability and possible limitations need to be clarified. This was a retrospective study on patients who underwent ETS with intraoperative cerebrospinal fluid (CSF) leakage. We assessed the postoperative and delayed CSF leakage rates and the associated risk factors. Among 200 ETSs with intraoperative CSF leakage, 148 (74.0%) ETSs were performed for skull base pathologies other than pituitary neuroendocrine tumor. The mean follow-up period was 34.4 months. Esposito grade 3 leakage was confirmed in 148 (74.0%) cases. NMFCT was used either with (67 [33.5%]) or without (133 [66.5%]) lumbar drainage. There were 10 cases (5.0%) of postoperative CSF leakage that necessitated reoperation. In 4 other cases (2.0%), CSF leakage was suspected but lumbar drainage alone successfully restored the condition. Multivariate logistic regression analyses revealed that posterior skull base location (P < 0.01, odds ratio 11.5, 95% CI 1.99-2.17× 102) and craniopharyngioma pathology (P= 0.03, odds ratio 9.4, 95% CI 1.25-1.92× 102) were significantly associated with postoperative CSF leakage. No delayed leakage occurred during the observation period except for 2 patients who underwent multiple radiotherapies. NMFCT is a reasonable alternative with long-term durability, though vascularized flap may be a better choice for cases in which vascularity of the surrounding tissues is significantly impaired due to interventions including multiple radiotherapies.

Introducing the “Temporal Thumb Sign” in Pediatric Patients With New-Onset Idiopathic Seizures With and Without Elevated Cerebrospinal Fluid Opening Pressure

BackgroundTemporal lobe changes, such as anterior temporal lobe meningoceles or encephaloceles, have been documented as possible epileptogenic foci in a subset of pediatric patients with seizures. In our study, we aim to analyze a different structural change in the temporal lobe, remodeling of the posterior temporal skull base by the inferior temporal gyrus called the “temporal thumb sign” (TTS), in pediatric patients presenting with new-onset seizures with or without elevated opening pressure (OP), patients presenting with confirmed diagnosis of idiopathic intracranial hypertension (IIH) without seizure presentation, and healthy controls. MethodsMagnetic resonance imaging scans of 163 pediatric patients were studied retrospectively for the presence of TTS. We analyzed the scans of 43 patients with elevated OP and confirmed IIH, 40 patients with elevated OP and new-onset idiopathic seizures, 40 patients with normal OP and new-onset idiopathic seizures, and 40 age- and sex-matched healthy controls. ResultsThe TTS was detected most frequently in patients with elevated OP and seizures at 72.5% compared with patients with IIH with no seizures and patients with normal OP and seizures (32.6% and 27.5%, respectively). The TTS had a frequency of 12.5% in the control group. The TTS had the highest combination of specificity and sensitivity (72.5% and 72.5%) in patients with seizures and elevated OP compared with patients with seizures and normal OP (P value < 0.001). ConclusionsOur results suggest the Kamali “temporal thumb sign” is a novel imaging feature that may be used as a sensitive and specific imaging finding associated with seizures and elevated OP in the pediatric population.

A novel 3D surgical neuroanatomy course for medical students: Outcomes from a pilot 6-week elective

BackgroundDeveloping and maintaining a three-dimensional working knowledge of neuroanatomy is an essential skill in neurosurgery. However, conventional 2D head, neck, and neuroanatomy education is typically characterized by the separate rote learning of constituent tissues and often fails to provide learners with a contextual understanding of the relationships between these highly complex and interconnected structures. This can pose a significant challenge to medical students entering neurosurgery who lack a topographic understanding of intracranial anatomy. MethodsWe report on the design and efficacy of a novel 6-part 3D surgical neuroanatomy pilot elective for medical students that utilized a navigation-based pedagogical technique with the goal of providing students with a framework for developing a 3D mental map of the skull base, neurovasculature, ventricular system, and associated brain regions. Students took on the perspective of physically traveling along the paths of key structures with a 360-degree view of surrounding anatomy such that they could appreciate the integration and relative spatial relationships of the varying tissues within the cranium. Mental navigation exercises and pre- and post-course surveys were used to assess students’ baseline and learned familiarity with the different anatomical regions covered. ResultsAt the conclusion of the course, all students were able to successfully complete all of the multifaceted mental navigation exercises. Post-course survey data indicated that respondents perceived significant increases in their knowledge of cranial nerves; anterior, middle, and posterior skull base anatomy; anterior and posterior cranial circulation; and the ventricular system. Conclusion3D navigation-based fly-through instruction is a novel and effective technique for teaching complex anatomy and can provide learners with the foundational skills for developing and maintaining a 3D mental map of intracranial anatomy.

First evidence of Proganochelys quenstedtii (Testudinata) from the Plateosaurus bonebeds (Norian, Late Triassic) of Frick, Canton Aargau, Switzerland

Proganochelys quenstedtii represents the best-known stem turtle from the Late Triassic, with gross anatomical and internal descriptions of the shell, postcranial bones and skull based on several well-preserved specimens from Central European fossil locations. We here report on the first specimen of P. quenstedtii from the Late Triassic (Klettgau Formation) Frickberg near the town of Frick, Canton Aargau, Switzerland. Similar to other Late Triassic ‘Plateosaurus-bearing bonebeds’, Proganochelys is considered to be a rare faunal element in the Swiss locality of Frick as well. The specimen, which is largely complete but was found only partially articulated and mixed with large Plateosaurus bones, overall resembles the morphology of the classical specimens from Germany. Despite being disarticulated, most skull bones could be identified and micro-computed tomography (CT) scanning of the posterior skull region reveals new insights into the braincase and neurovascular anatomy, as well as the inner ear region. These include the presence of a fenestra perilymphatica, potentially elongated cochlear ducts, and intense vascularization of small tubercles on the posterior end of the skull roof, which we interpret as horn cores. Other aspects of the skull in the braincase region, such as the presence or absence of a supratemporal remain ambiguous due to the fusion of individual bones and thus lack of visible sutures (externally and internally). Based on the size of the shell and fusion of individual elements, the specimen is interpreted as a skeletally mature animal.

Evaluation of the correlations between the cephalo- and somatometric parameters and parameters of teleroentgenograms of the head in boys and girls of the Omsk city

The aim of the study was to identify correlations between the cephalo- and somatometric parameters and parameters of teleroentgenograms of the head (in the lateral projection) to assess their influence on the face shape. Material and methods. An anthropometric study of the head and body was carried out in 70 boys and 70 girls. To obtain teleroentgenograms of the head in the lateral projection, 39 boys and 39 girls (out of those examined, based on their informed consent) underwent an X-ray examination using a Planmeca ProMax 3D CT scanner (Finland). Cephalometric analysis of the obtained images was carried out using the Mave Cloud online service. Quantitative data were statistically processed using Statistica 6.0 program. Results. Gender differences in values (p&lt;0,05) were detected for the following parameters: length of the anterior skull base according to Bjork, anterior face height, length of the body of the lower jaw according to Jarabac, height of the lower jaw branch, length of the posterior skull base, posterior face height, length of the anterior skull base according to Schwarz, lengths of the lower jaw, length of the upper jaw, thickness of soft tissues in the chin area on the segments Me-me, Gn-gn, Pog-pg. A direct moderate relationship was found between the values of the intermaxillary angle and zygomatic diameter, on the one hand, and the face shape, on the other hand (p&lt;0,05). Conclusion. A number of linear parameters of lateral teleroentgenograms have gender and regional features. In addition, teleroentgenograms and somatotype parameters affect the face shape; this fact has to be considered when correcting occlusion and facial aesthetics in the dental practice.

Reconstruction and Quantitative Evaluation of Blunt Injury Cases by Finite Element Method.

To reconstruct the cases of acceleration craniocerebral injury caused by blunt in forensic cases by finite element method (FEM), and to study the biomechanical mechanism and quantitative evaluation method of blunt craniocerebral injury. Based on the established and validated finite element head model of Chinese people, the finite element model of common injury tool was established with reference to practical cases in the forensic identification, and the blunt craniocerebral injury cases were reconstructed by simulation software. The cases were evaluated quantitatively by analyzing the biomechanical parameters such as intracranial pressure, von Mises stress and the maximum principal strain of brain tissue. In case 1, when the left temporal parietal was hit with a round wooden stick for the first time, the maximum intracranial pressure was 359 kPa; the maximum von Mises stress of brain tissue was 3.03 kPa at the left temporal parietal; the maximum principal strain of brain tissue was 0.016 at the left temporal parietal. When the right temporal was hit with a square wooden stick for the second time, the maximum intracranial pressure was 890 kPa; the maximum von Mises stress of brain tissue was 14.79 kPa at the bottom of right temporal lobe; the maximum principal strain of brain tissue was 0.103 at the bottom of the right temporal lobe. The linear fractures occurred at the right temporal parietal skull and the right middle cranial fossa. In case 2, when the forehead and left temporal parietal were hit with a round wooden stick, the maximum intracranial pressure was 370 kPa and 1 241 kPa respectively, the maximum von Mises stress of brain tissue was 3.66 kPa and 26.73 kPa respectively at the frontal lobe and left temporal parietal lobe, and the maximum principal strain of brain tissue was 0.021 and 0.116 respectively at the frontal lobe and left temporal parietal lobe. The linear fracture occurred at the left posterior skull of the coronary suture. The damage evaluation indicators of the simulation results of the two cases exceeded their damage threshold, and the predicted craniocerebral injury sites and fractures were basically consistent with the results of the autopsy. The FEM can quantitatively evaluate the degree of blunt craniocerebral injury. The FEM combined with traditional method will become a powerful tool in forensic craniocerebral injury identification and will also become an effective means to realize the visualization of forensic evidence in court.

The Bigger the Better? Analysis of Surgical Complications and Outcome of the Retrosigmoid Approach in 449 Oncological Cases.

IntroductionExposure of the posterior skull base and the cerebellopontine angle is challenging due to important neurovascular structures. The retrosigmoid approach (RSA) has become the standard method used in surgery. We report our experiences with RSAs regarding technical obstacles, complications, and approach-related outcomes.Materials and MethodsWe performed a retrospective chart review at a tertiary neurosurgical center between January 2007 and September 2020. We included all patients undergoing surgery for oncologic lesions through RSAs, concentrating on surgical technique, postoperative outcome, and complications.ResultsA total of 449 RSAs were included. The median age at the time of surgery was 58 years; 168 (37.4%) were male and 281 (62.6%) were female. The median approach surface was 7.8 cm2. The median tumor volume was 5.9 cm3. The median Clavien–Dindo grade was 2, the total complication rate was 28.7%, and gross total resection (GTR) was 78.8%. Findings revealed that tumor volume had no significant impact on postoperative complications in general (p = 0.086) but had a significant impact on postoperative hemorrhage (p = 0.037) and hydrocephalus (p = 0.019). Tumor volume was significant for several preoperative symptoms (p < 0.001). The extent of the approach had no significant impact on complications in general (p = 0.120) but was significant regarding postoperative cerebrospinal fluid (CSF) leaks (p = 0.008). Craniotomy size was not significant regarding GTR (p = 0.178); GTR rate just missed significant correlation with tumor volume (p = 0.056). However, in the case of vestibular schwannomas, the size of craniotomy was important for GTR (p = 0.041).ConclusionTumor volume has an important impact on preoperative symptoms as well as on postoperative complications. Although the extent of the craniotomy barely missed significance regarding GTR, a correlation can be assumed. Thus, the extent of craniotomy should be taken into presurgical consideration, especially in the case of postoperative CSF leaks. Regarding vestibular schwannomas, craniotomy size plays an important role in achieving satisfactory oncological outcomes. Different approaches should be selected where necessary regarding superior resection rates.

The dissorophoid temnospondyl Parioxys ferricolus from the early Permian (Cisuralian) of Texas

AbstractParioxys ferricolus Cope, 1878 is a long-neglected taxon of dissorophid temnospondyls from the early Permian (Cisuralian) of Texas. Reexamination of the original material and preparation of a previously undescribed specimen shed some light on the ontogeny and reveal numerous eucacopine features. P. ferricolus is characterized by: (1) a preorbital region 1.5 times as long as the posterior skull table in juveniles and twice as long in adults, (2) a parietal only two-thirds the length of the frontal, (3) interpterygoid vacuities shorter than half the skull length, (4) choanae posteriorly extended, and (5) vomer with enlarged, V-shaped median depression. P. ferricolus is found nested with Kamacops acervalis Gubin, 1980, with which it shares synapomorphies in the palate, within the dissorophid clade Eucacopinae.

Complete posterior cranial vault distraction osteogenesis to correct Chiari malformation type I associated with craniosynostosis.

Posterior vault distraction osteogenesis (PVDO) is an effective tool to increase intracranial volume and expand the posterior cranial fossa. During PVDO, the authors extended osteotomy posterior to the foramen magnum to fully expand the posterior cranial fossa. The aim of this study was to investigate the efficacy of complete PVDO in posterior fossa expansion and treatment of Chiari malformation type I (CM-I) in patients with craniosynostosis. Patients with craniosynostosis who had undergone complete PVDO between January 2012 and May 2020 were reviewed retrospectively. A coronal osteotomy extending to the foramen magnum was performed and the foramen magnum was decompressed by removing its posterior rim with a 1-mm Kerrison rongeur. Four distractor devices were placed and the vector of distraction was controlled from the posterior to the inferior-posterior direction, depending on the deformity. Changes in the intracranial volume, posterior cranial fossa area, and cerebellar tonsillar descent were measured after complete PVDO by using CT and MRI. A total of 11 patients with craniosynostosis and concurrent CM-I were included in the study. The mean age was 34.6 ± 24.0 months (continuous variables are expressed as the mean ± SD throughout). One patient had sleep apnea, which was consistent with CM-I, and another patient had a headache, which was nonspecific. The intracranial volume increased from 1179.6 ± 180.2 cm3 to 1440.6 ± 251.5 cm3 (p = 0.003; 24.5% increase compared to the preoperative volume). The posterior skull base area increased from 44.9 ± 19.3 cm2 to 72.7 ± 18.1 cm2 (p = 0.004). Cerebellar tonsillar descent decreased in all 11 patients after complete PVDO (preoperative: 10.8 ± 3.7 mm, postoperative: 2.7 ± 3.0 mm; p = 0.003). Among the 11 patients, 5 showed complete resolution of cerebellar tonsillar herniation. Complete PVDO can more efficiently expand the posterior cranial fossa, unlike conventional methods. Moreover, it helps to relieve cerebellar tonsillar herniation. Complete PVDO is a powerful tool to increase the intracranial and posterior fossa volumes in patients with craniosynostosis and concurrent CM-I.

Intradermal Injection of Normal Saline for Treatment of Fat Atrophy Following Corticosteroid Injection

A 20-year-old woman with a Fitzpatrick score of 2 presented via telehealth with “divots” on her forehead and scalp. She reported that 2 months prior to presentation she had received multiple steroid injections into her forehead and posterior skull by a neurologist for treatment of migraines.

The Posterior Part Influences the Anterior Part of the Mouse Cranial Base Development.

ABSTRACTThe cranial base is a critical structure in the head, which is composed of endoskeletal and dermal skeletal. The braincase floor, part of the cranial base, is a midline structure of the head. Because it is a midline structure connecting the posterior skull with the facial region, braincase floor is critical for the orientation of the facial structure. Shortened braincase floor leads to mid‐facial hypoplasia and malocclusions. During embryonic development, elongation of the braincase floor occurs through endochondral ossification in the parachordal cartilage, hypophyseal cartilage, and trabecular cartilage, which leads to formation of basioccipital (BO), basisphenoid (BS), and presphenoid (PS) bones, respectively. Currently, little is known about whether maturation of parachordal cartilage, hypophyseal cartilage, and trabecular cartilage occurs in a simultaneous or sequential manner and if the formation of one impacts the others. Our previous studies demonstrated that loss of function of ciliary protein Evc2 leads to premature fusion in the intersphenoid synchondrosis (ISS). In this study, we take advantage of Evc2 mutant mice to delineate the mechanism governing synchondrosis formation. Our analysis supports a cascade mechanism on the spatiotemporal regulation of the braincase floor development that the hypertrophy of parachordal cartilage (posterior side) impacts the hypertrophy of hypophyseal cartilage (middle) and trabecular cartilage (anterior side) in a sequential manner. The cascade mechanism well explains the premature fusion of the ISS in Evc2 mutant mice and is instructive to understand the specifically shortened anterior end of the braincase floor in various types of genetic syndromes. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Imaging of Skull Base Trauma: Fracture Patterns and Soft Tissue Injuries.

This article provides an overview of the patterns of skull base trauma and provides a review of the pertinent soft tissue injuries and complications that can ensue. A brief review of skull base anatomy is provided with subsequent focus on the important findings in anterior, central, and posterior skull base trauma.

Imaging of Developmental Skull Base Abnormalities.

The skull base is a critical structure in the craniofacial region, supporting the brain and vital facial structures in addition to serving as a passageway for important structures entering and exiting the cranial cavity. This paper will review and highlight some of the embryology, developmental anatomy, including ossification, and related abnormalities of the anterior, central and posterior skull base using illustrative cases and tables. Pathologies such as dermoids/epidermoids, cephaloceles, nasal gliomas, glioneuronal heterotopias, various notochordal remnants, persistent craniopharyngeal canal, teratomas, platybasia, basilar invagination, clival anomalies and Chiari malformations will be discussed. Developmental pearls and pitfalls will also be highlighted.

Treatment and Prognosis of Inflammatory Pseudotumor of the Skull Base.

Background Inflammatory pseudotumor (IPT) of the skull base is a rare, locally destructive lesion managed with a variety of treatments. We explore the impact of treatment on outcome and assess the prognosis of IPT. Methods This is a retrospective review of IPT of the skull base at a tertiary academic medical center. The primary outcome was radiographic progression after treatment. Outcome versus tumor location was also examined and a prognostic model was developed using a logistic regression. Results The demographics of 21 patients with IPT are reported. Treatment consisted of corticosteroids (in 80.1% of patients), disease modifying antirheumatic drugs (DMARDs; 33.3%), surgical resection (28.6%), radiation (23.8%), antibiotics (14.3%), chemotherapy (rituximab; 9.5%), and antivirals (4.8%). At 50.7 months, 50.8% had radiographic progression. Local therapy trended toward having a better response than systemic therapy ( p = 0.60). IPT of the orbit required 2.4 treatment modalities, compared with 2.0 for pharyngeal IPT, and 1.3 for posterior skull base masses ( p = 0.14). A total of 75% orbital IPT underwent radiographic progression, compared with 71% of pharyngeal IPT and 50% of posterior skull base masses ( p = 0.62). Sixteen patients were used to create the logistic model of radiographic progression. The Cox-Snell R 2 was 0.71 ( p = 0.03). No individual variables were statistically significant. Conclusion To our knowledge, this is among the largest sample of cases describing the presentation, treatment, and prognosis of IPT of the skull base. Our data suggest that there may be an improved response with local therapy over systemic therapy and better prognosis among posterolateral skull base masses.

Virtual Coordinate System in Unicoronal Synostosis.

Background:We propose a landmark-based, virtual coordinate system, specifically designed for assessment of asymmetrical craniofacial anatomy associated with unicoronal synostosis.Method:CT scans of 33 patients with nonsyndromic unicoronal synostosis were included. Proposed mid-sagittal plane was compared with commonly used sagittal planes: (1) nasion, sella, and basion (N-S-BA); (2) midplane of bilateral frontozygomatic sutures (midFZ); and (3) the skull gravity center plane, to evaluate reliability and validity in the assessments of the anterior and posterior skull base.Results:The proposed midplane is similar to the midFZ plane in describing the direction of the anterior skull base. However, it has less bias than the N-S-BA (P < 0.001), and the gravity center planes (P < 0.001). The proposed midplane measures the direction of the posterior skull base plane, similar to the midFZ and gravity center planes, but it has less measurement deviation than the N-S-BA plane (P < 0.001). The most protrusive point on the frontal bone in unicoronal patients is contralateral to the fused suture and distant from the mid-sagittal plane by 13.93 ± 4.01 mm. In addition, it is more anteriorly positioned, by 5.32 mm (P < 0.001), when compared with the corresponding point on the synostotic side. The uppermost point of the supraorbital rim on the synostotic side is cephalic to that of the contralateral side by 4.09 mm (P < 0.001).Conclusions:Prioritized orientation of an averaged Frankfort horizontal plane, followed by the location of the mid-sagittal and coronal planes, can generate a reliable and valid coordinate framework for the assessment of asymmetric skull shape in unicoronal synostosis.

Different transformations underlie blowhole and nasal passage development in a toothed whale (Odontoceti: Stenella attenuata) and a baleen whale (Mysticeti: Balaenoptera physalus).

Reorientation of the nasal passage away from the anteroposterior axis has evolved rarely in mammals. Unlike other mammals, cetaceans (e.g., whales, dolphins, and porpoises) have evolved a "blowhole": posteriorly repositioned nares that open dorsad. Accompanying the evolution of the blowhole, the nasal passage has rotated dorsally. Neonatal cetaceans possess a blowhole, but early in development, cetacean embryos exhibit head morphologies that resemble those of other mammals. Previous workers have proposed two developmental models for how the nasal passage reorients during prenatal ontogeny. In one model, which focused on external changes in the whole body, dorsad rotation of the head relative to the body results in dorsad rotation of the nasal passage relative to the body. A second model, based on details of the cartilaginous nasal skull, describes dorsad rotation of the nasal passage itself relative to the palate and longitudinal axis of the skull. To integrate and revise these models, we characterized both external and internal prenatal changes in a longitudinal plane that are relevant to nasal passage orientation in the body and head of the pantropical spotted dolphin (Odontoceti: Stenella attenuata). These changes were then compared to those in a prenatal series of a baleen whale, the fin whale (Mysticeti: Balaenoptera physalus), to determine if they were representative of both extant cetacean suborders. In both species, the angle between the nasal passage and the sagittal axis of the foramen magnum decreased with age. In S.attenuata, this was associated with basicranial retroflexion and midfacial lordosis: the skull appeared to fold dorsad with the presphenoid as the vertex of the angle. In contrast, in B.physalus, alignment of the nasal passage and the sagittal axis of the plane of the foramen magnum was associated with angular changes within the posterior skull (specifically, the orientations of the supraoccipital and foramen magnum relative to the posterior basicranium). With these results, we propose a new developmental model for prenatal reorientation of the odontocete nasal passage and discuss ways in which mysticetes likely deviate from this model.

Morphological and Morphometric study of Jugular Foramen in human dry skull of Eastern Indian origin: An Anatomical Investigation

Background: Jugular foramen (JF) is one of the complex foramen present in base of skull. It varies in shape and size from side to side in same cranium, in different cranium and in different races. It is associated with many diseases of posterior cranial fossa and many skull base surgeries are being carried out by drilling the skull bone around JF for better exposure. Aim and objectives: The present study aims to carry out the morphological and morphometric analysis of jugular foramen of skulls of eastern Indian origin. Materials and Methods: The study was carried out on 100 JF of 50 dried human skulls. Anteroposterior(width), medio-lateral diameter(length) of JF, width and depth of the jugular fossa were measured. Mean and standard deviation of different measurements of left and right side were statistically analysed by student’s t-test. Presence of dome and septum were also studied. Results: The mean of all the measurements are more on right side than left side but it is statistically insignificant (p&gt;0.05). Bony septum was found in 76% cases on left side and 60% on right side. Complete septation wasn’t found in our study. Domed roof was present in 66% cases on right side as compared to 52% on left side. Conclusion: Shape and size of JF may vary due to different size of internal jugular vein and it’s superior bulb. These variations can be due to constitutional, racial or genetic. This anatomical knowledge of JF may help the neurosurgeons, ENT surgeons and radiologists during their clinical exploration.