Human Foramen Magnum Area and Posterior Cranial Fossa Volume Growth in Relation to Cranial Base Synchondrosis Closure in the Course of Child Development

Comprehensive assessment of supratentorial and infratentorial volumes in infants with myelomeningocele with and without Chiari malformation type II

PURPOSE

Chiari malformation type II (CM-II) is a congenital anomaly commonly associated with myelomeningocele (MMC), a severe form of open spina dysraphism. This study aimed to evaluate both supratentorial and infratentorial volumes in MMC infants with and without CM-II.

METHODS

We conducted a single-center, retrospective study of 52 MMC infants treated between April 2006 and July 2023. Infants were classified as non-CM-II or CM-II based on the presence of cerebellar displacement. All patients underwent computed tomography (CT) at 0 months of age. Volumetric parameters included intracranial volume (ICV), lateral ventricles volume (LVV), posterior cranial fossa volume (PCFV), cerebellum volume (CBMV), and brainstem volume (BSV). LVV represented supratentorial structures, while PCFV, CBMV, and BSV represented infratentorial structures.

RESULTS

CM-II was diagnosed in 30 infants (57.7%). Correlation analysis revealed significant negative correlations between supratentorial (LVV) and infratentorial volumes (PCFV, CBMV, and BSV), and positive correlations among volumes within the same space(e.g., PCFV, CBMV, and BSV). CM-II infants exhibited significantly larger ICV (p = 0.04) and LVV (p < 0.001), but smaller PCFV (p < 0.001) and CBMV (p < 0.001) than non-CM-II infants. LVV was the best predictor for distinguishing non-CM-II from CM-II (area under the curve = 0.91).

CONCLUSION

This study identified positive correlations within the same space and negative correlations between supratentorial and infratentorial volumes. LVV emerged as a critical indicator of CM-II, reflecting the relationship between reduced infratentorial space and enlarged supratentorial ventricles (hydrocephalus). These findings provide insights into the pathophysiology and clinical implications of CM-II in MMC patients.

Methodology for pediatric head computed tomography image segmentation and volumetric calculation using a tablet computer and stylus pen

PURPOSE

This study presents a MATrix LABoratory (MATLAB)-based methodology for calculating intracranial volumes from head computed tomography (CT) data and compares it with established methods.

METHODS

Regions of interest (ROI) were manually segmented on CT images using a stylus pen, facilitated by mirroring a computer desktop onto a tablet. The volumetric process involved three main steps: (1) calculating the volume of a single voxel, (2) counting the total number of voxels within the segmented ROI, and (3) multiplying this voxel count by the single-voxel volume. This method was applied to 83 pediatric head CT scans from patients with minor head trauma, and the volumetric results were compared with those obtained from OsiriX.

RESULTS

A paired t-test revealed a statistically significant difference (p < 0.001) between volumes obtained with our MATLAB-based method and those from OsiriX, with our method measuring 0.32% higher. However, an unpaired t-test found no statistically significant differences between the volumetric population groups (p = 0.84).

CONCLUSION

The significant difference identified by the paired t-test likely reflects statistical distinctions arising from differences in the calculation methods of the two approaches. Conversely, the unpaired t-test suggests no statistically detectable differences between the volumetric populations. Although this does not imply that the two methods produce identical results, the volumetric populations derived from our method may originate from the same underlying population as those obtained using OsiriX. By taking these points into account, our method has the potential to serve as a valuable tool for volumetric measurements.

Fusion of the occipitomastoidal synchondrosis as a developmental marker in the Sima de los Huesos Crania (Atapuerca, Spain)

The basicranium contains multiple synchondroses potentially informative for estimating the developmental stage of individuals. The basilar synchondrosis has been routinely used for this purpose in bioarchaeological, forensic and paleoanthropological research, and studies carried out in modern human populations have shown a close relationship between the fusion of the occipitomastoidal synchondrosis and developmental processes. This synchondrosis articulates the jugular process of the occipital bone with the jugular surface of the temporal bone. As the process of fusion of the synchondrosis progresses, the jugular surface undergoes a series of alterations whose study allows to establish the state of fusion of the synchondrosis when the individual died. The extraordinary preservation of the jugular surface in a large number of individuals represented in the fossil hominin sample from the middle Pleistocene site of the Sima de los Huesos (SH) has made it possible to carry out the first systematic study to assess the usefulness of occipitomastoidal synchondrosis in the establishment of the state of development in fossil hominins. Our results show that the complete closure of the occipitomastoidal synchondrosis occurred toward the end of the growth period in the SH fossils. This result opens up the possibility of using it to determine the developmental stage of fossil hominins for which no other information is available, such as the state of the dentition or the degree of closure of the basilar synchondrosis. This has allowed us to infer a state of development for three SH crania where it could not previously be established with certainty.

Growth patterns and ratios of posterior cranial fossa structures in the Japanese pediatric population: a study utilizing CT scans

PURPOSE

The changes in the proportion of posterior cranial fossa structures during pediatric development remain unclear. This retrospective study aimed to investigate the growth patterns and ratios of these structures using CT scans.

METHODS

Head CT scans of pediatric patients with minor head trauma from Osaka Women's and Children's Hospital between March 2006 and May 2023 were analyzed. The study segmented the intracranial volume (ICV), posterior cranial fossa volume (PCFV), cerebellum volume (CBMV), and brainstem volume (BSV). Correlation coefficients were calculated among the parameters. Patients aged 0 to 10 years were divided into 15 age-related clusters, and mean and standard deviation values were measured. Growth curves were created by plotting mean values sequentially. Ratios such as PCFV/ICV and (CBMV + BSV)/PCFV were examined. Statistical analyses, including unpaired t tests and logarithmic curve fitting, were performed.

RESULTS

A total of 234 CT scans (97 from females, 115 from infants under 1 year of age) were analyzed. Positive correlations were observed among the parameters, with the strongest between PCFV and CBMV. The growth curves for ICV, PCFV, CBMV, and BSV exhibited a two-phase process, with rapid growth until approximately 4 years of age, followed by stabilization. The ratios PCFV/ICV and (CBMV + BSV)/PCFV showed increasing trends from birth onwards, stabilizing by 4 and 1 years of age, respectively.

CONCLUSION

This study provides insights into the growth patterns and ratios of posterior cranial fossa structures in the pediatric population. The findings demonstrate a two-phase growth process and increasing trends in the examined ratios.

Time course of sutural width during the physiological growth from birth to adulthood: CT quantitative and qualitative evaluations of sutural arches

PURPOSE

We performed a retrospective qualitative and quantitative evaluation of the sutural changes during the physiological growth to define the age-related ossification stages of major and minor skull sutures or synchondroses.

METHODS

A total of 390 healthy subjects, examined for cranio-facial trauma and whose CT scans turned out to be normal, were clustered into homogenous age-matched groups ranged from birth to 90 years. High-resolution CT was used to assess the degree of sutural closure according to a 3-grade scoring system, the sutural pattern, the width, and the density of the gap calculated as the average of two or three ROIs along each suture/synchondrosis.

RESULTS

The identification of a definite pattern depended on the suture's type, the closure degree, and the width of the gap (p < 0.001). The interdigitation process was more intricate for most of vault sutures than the skull base sutures/synchondroses. Closing grades 1, 2, and 3 were associated to an identifiable sutural pattern and the cutoff value of 1.45 mm of the gap width allowed to detect an identifiable sutural pattern with the best combination of sensitivity (97%) and specificity (98%). Age and sutural closing degree were inversely related to gap width while positively related to the gap density (p < 0.001).

CONCLUSION

The sutural ossification is an age-related process, distinctive for each suture, and synchondrosis; it occurs neither according to a predefined order along sutural arches nor following a sequential distribution in the cranial fossae, and some sutures continued their growth process during lifetime.

Morphology of the Occipital Bones and Foramen Magnum Resulting From Premature Minor Suture Fusion in Crouzon Syndrome

To identify skull-base growth patterns in Crouzon syndrome, we hypothesized premature minor suture fusion restricts occipital bone development, secondarily limiting foramen magnum expansion.

Skull-base suture closure degree and cephalometric measurements were retrospectively studied using preoperative computed tomography (CT) scans and multiple linear regression analysis.

Evaluation of multi-institutional CT images and 3D reconstructions from Wake Forest's Craniofacial Imaging Database (WFCID).

Sixty preoperative patients with Crouzon syndrome under 12 years-old were selected from WFCID. The control group included 60 age- and sex-matched patients without craniosynostosis or prior craniofacial surgery.

None.

2D and 3D cephalometric measurements.

3D volumetric evaluation of the basioccipital, exo-occipital, and supraoccipital bones revealed decreased growth in Crouzon syndrome, attributed solely to premature minor suture fusion. Spheno-occipital (β = -398.75; P < .05) and petrous-occipital (β = -727.5; P < .001) suture fusion reduced growth of the basioccipital bone; lambdoid suture (β = -14 723.1; P < .001) and occipitomastoid synchondrosis (β = -16 419.3; P < .001) fusion reduced growth of the supraoccipital bone; and petrous-occipital suture (β = -673.3; P < .001), anterior intraoccipital synchondrosis (β = -368.47; P < .05), and posterior intraoccipital synchondrosis (β = -6261.42; P < .01) fusion reduced growth of the exo-occipital bone. Foramen magnum morphology is restricted in Crouzon syndrome but not directly caused by early suture fusion.

Premature minor suture fusion restricts the volume of developing occipital bones providing a plausible mechanism for observed foramen magnum anomalies.

The foramen magnum in scaphocephaly

PURPOSE

The foramen magnum (FM) presents various alterations in craniosynostoses, such as brachycephaly or Crouzon syndrome. However, to date, no study has been devoted to its morphology and morphometry in scaphocephaly, which is the most common of cranial deformities resulting from premature fusion of cranial sutures.

METHODS

We assessed the morphology and morphometry of FM using preoperative thin-cut CT scans of 107 children with non-syndromic sagittal craniosynostosis aged 1-12 months (mean age 5.38 months). A series of sagittal and transverse dimensions were taken and the FM area was calculated in each case. Obtained data were compared to the age-matched control group of 101 normocephalic children.

RESULTS

Dolichotrematous type of FM was dominant in the scaphocephaly group and observed in 63/107 cases (58.9%). The mean FM area in the scaphocephaly group was 519.64 mm² and was significantly smaller compared to the control group (p = 0.0011). The transverse diameter and anterior sagittal diameter were also significantly smaller (p = 0.0112 and p = 0.0003, respectively).

CONCLUSION

The area of FM in scaphocephaly is smaller compared to normal individuals. This is associated with a significant reduction of the width of FM in children with sagittal craniosynostosis. FM in scaphocephaly is larger than in other reported series of children with brachycephaly or Crouzon syndrome.

Functional and morphological changes in hypoplasic posterior fossa

BACKGROUND

The knowledge of the development and the anatomy of the posterior cranial fossa (PCF) is crucial to define the occurrence and the prognosis of diseases where the surface and/or the volume of PCF is reduced, as several forms of craniosynostosis or Chiari type I malformation (CIM). To understand the functional and morphological changes resulting from such a hypoplasia is mandatory for their correct management. The purpose of this article is to review the pertinent literature to provide an update on this topic.

METHODS

The related and most recent literature addressing the issue of the changes in hypoplasic PCF has been reviewed with particular interest in the studies focusing on the PCF characteristics in craniosynostosis, CIM, and achondroplasia.

RESULTS AND CONCLUSIONS

In craniosynostoses, namely, the syndromic ones, PCF shows different degrees of hypoplasia, according to the different pattern and timing of early suture fusion. Several factors concur to PCF hypoplasia and contribute to the resulting problems (CIM, hydrocephalus), as the fusion of the major and minor sutures of the lambdoid arch, the involvement of the basal synchondroses, and the occlusion of the jugular foramina. The combination of these factors explains the variety of the clinical and radiological phenotypes. In primary CIM, the matter is complicated by the evidence that, in spite of impaired PCF 2D measurements and theories on the mesodermal defect, the PCF volumetry is often comparable to healthy subjects. CIM is revealed by the overcrowding of the foramen magnum that is the result of a cranio-cerebral disproportion (altered PCF brain volume/PCF total volume). Sometimes, this disproportion is evident and can be demonstrated (basilar invagination, real PCF hypoplasia); sometimes, it is not. Some recent genetic observations would suggest that CIM is the result of an excessive growth of the neural tissue rather than a reduced growth of PCF bones. Finally, in achondroplasia, both macrocephaly and reduced 2D and 3D values of PCF occur. Some aspects of this disease remain partially obscure, as the rare incidence of hydrocephalus and syringomyelia and the common occurrence of asymptomatic upper cervical spinal cord damage. On the other hand, the low rate of CIM could be explained on the basis of the reduced area of the foramen magnum, which would prevent the hindbrain herniation.

Study of the growth and shape of the brain and cranial base during the first two years of life

Ontogeny of the cranial base and the brain integrates data on growth, maturation and ontogenetic allometry of these two systems in the course of development. The aim of our work was to study the ontogeny of the cranial base and the brain in order to understand their growth dynamic and shape changes using a traditional morphometric approach in individuals with normal (non-pathological) development.

MATERIEL AND METHOD

Forty-seven infants having been included in the unexpected infant death french protocol were analyzed. Medical imaging (CT and MRI) exams, followed by an autopsy and pathology examination allowed us to include only infants free from brain disease or pathology affecting growth.

RESULTS

Testing of measurement reliability validated 12 distances and 3 angles as well as the positioning of the landmarks that had been used to obtain the distances and the angles. No correlation between sex and the various variables studied was found. However, a correlation was observed between these variables and age, making it possible to propose a growth curve. A medium to strong correlation was found between brain variables and the bone variables of the cranial base, underlining the parallel development of the two systems.

CONCLUSION

Our study, carried out in a rigorously selected population of infants, presents a fundamental approach to the study of ontogenesis.

Posttraumatic Cranial Suture Diastasis in Pediatric Temporal Bone Fractures

OBJECTIVE

Only a handful of case reports exist describing posttraumatic sutural diastasis in the calvarium and none report concurrent temporal bone involvement. We aim to describe diastasis along the temporal bone suture lines in the setting of temporal bone trauma and to identify clinical sequelae.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary Level 1 trauma center.

PATIENTS

Forty-four patients aged 18 and younger who suffered a temporal bone fracture from 2013 to 2018 were identified. Diastasis and diastasis with displacement at the occipitomastoid, lambdoid, sphenosquamosal and petro-occipital sutures, and synchondroses were determined.

MAIN OUTCOME MEASURES

The presence of temporal bone suture and synchondrosal diastasis following temporal bone trauma. Diastasis was defined as sutural separation of a distance greater than 1 mm in comparison to the contralateral side.

RESULTS

Using our diastasis diagnostic criteria, diastasis occurred in 41.5% of temporal bone fractures. Transverse fracture types were significantly associated with diastasis (p ≤ 0.001). Lower Glasgow Coma Scale (GCS) and loss of consciousness (LOC) were associated with the presence of diastasis with displacement and diastasis (p = 0.034 and p = 0.042, respectively). Otic capsule violation was more common in fractures with diastasis but did not reach statistical significance. There were two cases of cerebrospinal fluid otorrhea and three deaths in cases that featured diastasis.

CONCLUSION

Our findings indicate that diastasis is a positive predictor for higher disruptive force injuries and more severe outcomes and complications. Posttraumatic temporal bone suture diastasis may represent a separate clinico-pathologic entity in addition to the usual temporal bone fracture classification types.

Hydrocephalus in infants: the unique biomechanics and why they matter

OBJECT

Hydrocephalus diagnosed prenatally or in infancy differs substantially from hydrocephalus that develops later in life. The purpose of this review is to explore hydrocephalus that begins before skull closure and full development of the brain. Understanding the unique biomechanics of hydrocephalus beginning very early in life is essential to explain two poorly understood and controversial issues. The first is why is endoscopic third ventriculostomy (ETV) less likely to be successful in premature babies and in infants? The second relates to shunt failure in a subset of older patients treated in infancy leading to life-threatening intracranial pressure without increase in ventricular volume.

METHODS

The review will utilize engineering concepts related to ventricular volume regulation to explain the unique nature of hydrocephalus developing in the fetus and infant. Based on these concepts, their application to the treatment of complex issues of hydrocephalus management, and a review of the literature, it is possible to assess treatment strategies specific to the infant or former infant with hydrocephalus-related issues throughout life.

RESULTS

Based on engineering, all hydrocephalus, except in choroid plexus tumors or hyperplasia, relates to restriction of the flow of cerebrospinal fluid (CSF). Hydrocephalus develops when there is a pressure difference from the ventricles and a space exterior to the brain. When the intracranial volume is fixed due to a mature skull, that difference is between the ventricle and the cortical subarachnoid space. Due to the distensibility of the skull, hydrocephalus in infants may develop due to failure of the terminal absorption of CSF. The discussion of specific surgical treatments based on biomechanical concepts discussed here has not been specifically validated by prospective trials. The rare nature of the issues discussed and the need to follow the patients for decades make this quite difficult. A prospective registry would be helpful in the validation of surgical recommendations.

CONCLUSION

The time of first intervention for treatment of hydrocephalus is an important part of the history. Treatment strategies should be based on the assessment of the roll of trans-mantle pressure differences in deciding treatment strategies. Following skull closure distension of the ventricles at the time of shunt failure requires a pressure differential between the ventricles and the cortical subarachnoid space.

Vestiges of Ossified Spheno-occipital Suture in an Elderly Patient With Down Syndrome and Lateral Skull Base Fracture

BACKGROUND/AIM

Down syndrome (DS) patients often show characteristic changes in the skull, e.g. short cranial base. The synchondroses of the skull base have a significant influence on the shape of the skull. The sphenooccipital synchondrosis (SOS) is the last of the basal synchondroses to ossify. This report is about residual ossification of SOS in an elderly patient with DS.

CASE REPORT

The 65-year-old DS patient was polytraumatized by a fall. In the course of treatment, a purulent otitis externa on the right side was diagnosed, which had developed as a result of the fracture of the fossa glenoidalis. Computed tomograms of the skull base showed the fracture of the mandibular condyle, glenoid fossa and vestiges of SOS.

CONCLUSION

The coincidental finding of vestiges of SOS in an elderly patient with DS raises the question of whether cross-sectional skull base images can show differences in the ossification of SOS between DS patients and a normal population.

Role of thyroid hormones in craniofacial development

The development of the craniofacial skeleton relies on complex temporospatial organization of diverse cell types by key signalling molecules. Even minor disruptions to these processes can result in deleterious consequences for the structure and function of the skull. Thyroid hormone deficiency causes delayed craniofacial and tooth development, dysplastic facial features and delayed development of the ossicles in the middle ear. Thyroid hormone excess, by contrast, accelerates development of the skull and, in severe cases, might lead to craniosynostosis with neurological sequelae and facial hypoplasia. The pathogenesis of these important abnormalities remains poorly understood and underinvestigated. The orchestration of craniofacial development and regulation of suture and synchondrosis growth is dependent on several critical signalling pathways. The underlying mechanisms by which these key pathways regulate craniofacial growth and maturation are largely unclear, but studies of single-gene disorders resulting in craniofacial malformations have identified a number of critical signalling molecules and receptors. The craniofacial consequences resulting from gain-of-function and loss-of-function mutations affecting insulin-like growth factor 1, fibroblast growth factor receptor and WNT signalling are similar to the effects of altered thyroid status and mutations affecting thyroid hormone action, suggesting that these critical pathways interact in the regulation of craniofacial development.

The growth of the posterior cranial fossa in FGFR2-induced faciocraniosynostosis: A review

BACKGROUND

The growth of the posterior fossa in syndromic craniostenosis was studied in many papers. However, few studies described the pathophysiological growth mechanisms in non-operated infants with fibroblast growth factor receptor (FGFR) type 2 mutation (Crouzon, Apert or Pfeiffer syndrome), although these are essential to understanding cranial vault expansion and hydrocephalus treatment in these syndromes.

OBJECTIVE

A review of the medical literature was performed, to understand the physiological and pathological growth mechanisms of the posterior fossa in normal infants and infants with craniostenosis related to FGFR2 mutation.

DISCUSSION

Of the various techniques for measuring posterior fossa volume, direct slice-by-slice contouring is the most precise and sensitive. Posterior fossa growth follows a bi-phasic pattern due to opening of the petro-occipital, occipitomastoidal and spheno-occipital sutures. Some studies reported smaller posterior fossae in syndromic craniostenosis, whereas direct contouring studies reported no difference between normal and craniostenotic patients. In Crouzon syndrome, synchondrosis fusion occurs earlier than in normal subjects, and follows a precise pattern. This premature fusion in Crouzon syndrome leads to a stenotic foramen magnum and facial retrusion.

Chiari I Malformation and Basilar Invagination in Fibrous Dysplasia: Prevalence, Mechanisms, and Clinical Implications

Fibrous dysplasia (FD) is a mosaic disorder of benign fibro-osseous lesions, which may be associated with extraskeletal features as part of McCune-Albright syndrome (MAS). Cranial base abnormalities, including Chiari I malformation (CM1), in which the cerebellum extends below the foramen magnum, and secondary basilar invagination (BI), in which the odontoid prolapses into the posterior cranial fossa, are potentially serious complications of metabolic bone disorders. The purpose of this study was to determine the prevalence, natural history, and risk factors for CM1 and BI in patients with FD/MAS, and to determine mechanisms of cranial base deformities. Clinical and radiographic data from subjects in an FD/MAS natural history study were evaluated and compared to normal controls. In 158 patients with craniofacial FD, 10 (6.3%) cases of CM1 and 12 (7.6%) cases of BI were diagnosed. No cranial base abnormalities were identified in 10 control subjects. Craniomorphometric and volumetric analyses identified cranial constriction and cranial settling as the primary mechanisms of cranial base abnormalities, whereas intracranial hypertension was a contributing factor in a minority of subjects. Longitudinal analyses found progression of odontoid position with age, but no progression of tonsillar position. No endocrinopathies were associated with CM1. MAS endocrinopathies associated with BI included hyperthyroidism (odds ratio [OR] 12.0; 95% confidence interval [CI], 2.9 to 55.6; p < 0.01), precocious puberty (OR 5.6; 95% CI, 1.2 to 26.0; p < 0.05), and hypophosphatemia (OR 7.7; 95% CI, 1.9 to 27.0; p < 0.01). Scoliosis was associated with both CM1 (OR 4.8; 95% CI, 1.1 to 22.8; p < 0.05) and BI (OR = infinity; 95% CI, 4.7 to infinity; p < 0.01). This study successfully characterized cranial base abnormalities in FD/MAS and the pathophysiological connection between them. These findings support routine screening for cranial base abnormalities in patients with craniofacial FD, as well as aggressive management of contributory risk factors. © 2018 American Society for Bone and Mineral Research.

Sex-Related Differences in the Developmental Morphology of the Atlas: A Computed Tomography Study

STUDY DESIGN

A retrospective study.

OBJECTIVE

To elucidate sex-related differences in the age at synchondroses closure, the normative size of the atlas, and the ossification patterns of the atlas in Japanese children.

SUMMARY OF BACKGROUND DATA

The atlas develops from three ossification centers during childhood. The anterior and posterior synchondroses, which are separate ossification centers, mimic fracture lines on computed tomography (CT). Sex-related differences of age dependent morphological changes of the atlas in a large sample size have not been reported.

METHODS

This study analyzed data of 688 subjects (449 boys) between 0 and 18 years old who underwent CT examination of the head and/or neck between January 2010 and July 2016. The age at synchondroses closure, anteroposterior outer, inner, and spinal canal widths of the atlas, and variations of the ossification centers were examined.

RESULTS

Anterior synchondroses closed by 10 years in boys and by 7 years in girls. Significant earlier closure of anterior synchondroses was observed in girls than in boys (P < 0.05 at 4 and 5 years old). Posterior synchondrosis closed by 6 years in boys and by 5 years in girls. The outer, inner, and spinal canal widths increased up to 10 to 15 years in both sexes, although all three parameters in girls peaked 3 years earlier than those in boys. All parameters in boys were significantly larger than those in girls, except in the 10- to 12-year-old age category. Two or more ossification centers in the anterior arch were observed in 18.3% subjects, and 6% had midline ossification centers in the posterior arch of the atlas.

CONCLUSION

Distinct sex-related differences in the age at anterior synchondroses closure and the size of the atlas were observed in Japanese children. Knowledge of morphological features of the atlas could help distinguish fractures from synchondroses.

LEVEL OF EVIDENCE

3.