Imaging of Clival Hypoplasia in CHARGE Syndrome and Hypothesis for Development: A Case-Control Study

Morphological Measurement and Anatomical Variations of the Clivus Using Computed Tomography

Objectives The aim of this study was to evaluate the clivus morphology, including fossa navicularis magna (FNM), canalis basilaris medianus (CBM), and craniopharyngeal canal (CC), on computed tomography (CT) images.

Design This is a retrospective study.

Setting Faculty of Dentistry, Department of Dentomaxillofacial Radiology.

Participants The CT images of 500 patients (253 males; 247 females) were evaluated.

Main Outcome Measures The prevalence of FNM, CBM, and CPC; the length, width, and depth of FNM; and CBM types were recorded. Also, a morphological analysis of the clivus (length of the clivus, angle between the clivus and the posterior margin of the foramen magnum, angle between the clivus and the dens axis, and anteroposterior diameter of the foramen magnum) was performed.

Results FNM was identified in 5.4%, CBM in 4%, and CC in 0.8% of the study group. Type 5 CBM was not found. Type 6 was the most common CBM type. There was no significant correlation between the age and gender of patients with FNM. There were significant differences between the clivus length, the angle between the clivus and the dens axis, the anteroposterior diameter of the foramen magnum, and gender. Also, there was a significant difference between the angle between the clivus and the foramen magnum and age.

Conclusions The anatomical variations of the clivus are rare and important for the oral and maxillofacial radiologist to make the differential diagnosis. These anatomical variations should not be confused with pathologic formations. The morphological measurements and anatomical variations of the clivus can be evaluated in detail on CT images.

Association between Brachycephaly, Chiari Malformation, and Basilar Invagination

BACKGROUND

 There is evidence that Chiari malformation (CM) and basilar invagination (BI) are largely due to disproportion between the content and volume of the posterior fossa. A recent study identified an increased association between brachycephaly and BI. In several types of craniosynostosis, the posterior fossa volume is smaller than normal, and this is more pronounced in coronal synostosis. The aim of this study is to evaluate the association between CM and BI.

METHODS

 The cephalic index (CI) measured on magnetic resonance imaging (MRI) from a sample of patients with craniocervical malformation was compared with that of normal subjects.

RESULTS

 The average CI in the craniovertebral junction malformation (CVJM) group was significantly higher in BI patients than in normal subjects. The BI patients also had the highest CI among the whole sample of patients (p = 0.009).

CONCLUSIONS

 In this study, BI patients had the highest CI among patients with CVJM and a significantly higher CI than those in the control group. Our data confirm the association between BI and brachycephaly.

Persistent Trigeminal Artery: A Novel Imaging Finding in CHARGE Syndrome

BACKGROUND AND PURPOSE

Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, Ear abnormalities and deafness (CHARGE) syndrome is an autosomal dominant genetic disorder with evolving clinical diagnostic criteria. Recently, a number of additional anomalies have been described in this syndrome, which may aid in early diagnosis, particularly in incomplete phenotypes or atypical cases. The persistent trigeminal artery is an embryonic carotid-vertebral anastomosis, rarely seen in the healthy population, with a reported prevalence of 0.4%. Because we had observed the persistent trigeminal artery in patients with CHARGE syndrome, this study aimed to explore the prevalence of the persistent trigeminal artery in this syndrome.

MATERIALS AND METHODS

A retrospective study was performed at our tertiary center. MR imaging studies, clinical records, and genetic results were reviewed for patients diagnosed with CHARGE syndrome between 2006 and 2019. The prevalence of the persistent trigeminal artery in patients with CHARGE syndrome was recorded and compared with other established diagnostic criteria.

RESULTS

Twenty-five patients with CHARGE syndrome were included. The persistent trigeminal artery was demonstrated on MR imaging in 14/25 (56%) patients and was seen more frequently than 4 of 9 other established diagnostic criteria in our cohort. When individual major or minor diagnostic criteria were absent, the persistent trigeminal artery was still demonstrated on MR imaging in 52%-67% of these patients with CHARGE syndrome.

CONCLUSIONS

The prevalence of the persistent trigeminal artery in CHARGE syndrome of 56% is higher than that of some other established diagnostic criteria and much higher than that in the general population. The persistent trigeminal artery may be a useful addition to the expanding phenotype of CHARGE syndrome, supplementing other diagnostic criteria. Radiologists should be aware of this novel finding demonstrable on MR imaging.

Rare and de novo coding variants in chromodomain genes in Chiari I malformation

Chiari I malformation (CM1), the displacement of the cerebellum through the foramen magnum into the spinal canal, is one of the most common pediatric neurological conditions. Individuals with CM1 can present with neurological symptoms, including severe headaches and sensory or motor deficits, often as a consequence of brainstem compression or syringomyelia (SM). We conducted whole-exome sequencing (WES) on 668 CM1 probands and 232 family members and performed gene-burden and de novo enrichment analyses. A significant enrichment of rare and de novo non-synonymous variants in chromodomain (CHD) genes was observed among individuals with CM1 (combined p = 2.4 × 10^-10), including 3 de novo loss-of-function variants in CHD8 (LOF enrichment p = 1.9 × 10^-10) and a significant burden of rare transmitted variants in CHD3 (p = 1.8 × 10^-6). Overall, individuals with CM1 were found to have significantly increased head circumference (p = 2.6 × 10^-9), with many harboring CHD rare variants having macrocephaly. Finally, haploinsufficiency for chd8 in zebrafish led to macrocephaly and posterior hindbrain displacement reminiscent of CM1. These results implicate chromodomain genes and excessive brain growth in CM1 pathogenesis.

CHARGE syndrome in the era of molecular diagnosis: Similar outcomes in those without coloboma or choanal atresia

CHARGE syndrome (OMIM 214800) is a condition characterized by multisystem involvement with CHD7 pathogenic mutations leading to disease in the majority of patients. Discovery of the molecular cause of CHARGE unmasked a larger phenotypic spectrum than was previously appreciated. Within our interdisciplinary CHARGE syndrome program, we sought to characterize our CHD7-positive CHARGE cohort without coloboma or choanal atresia, highlighting complications and outcomes. We describe 18 individuals with CHD7-confirmed diagnosis from 15 families. The most sensitive finding in the cohort was temporal bone malformations, present in 13/15 individuals. Individuals had an average of 1.6 major features and 3.3 minor features defined by the Blake et al. guidelines. Despite lack of major features or major malformations, the majority of individuals continued to have difficulties with pneumonia, aspiration, secretion management and motility issues that greatly impacted their lives. Our findings illustrate the need for molecular testing and timely recognition given that the major co-morbidities are frequently experienced by patients with the mildest clinical spectrum of CHARGE syndrome.

The role of clivus length and cranial base flexion angle in basilar invagination and Chiari malformation pathophysiology

BACKGROUND

The craniovertebral junction is an anatomically well-defined transitional zone located between the skull and the cervical spine. Multiple malformations can affect this region with the most prominent being basilar invagination (BI) and Chiari malformation (CM). Despite numerous studies, the origin, pathophysiology, and classification of these pathologies remain controversial. The objective of this study was to evaluate the implication of cranial base flexion angle and clivus length in the development of these conditions.

METHODS

Midline tomography and magnetic resonance imaging of normal subjects and patients diagnosed with BI (types I and II) and Chiari malformation were evaluated. A craniometric study of the skull base was performed. Linear and angular measurements were used for comparisons between groups.

RESULTS

109 images from patients with craniovertebral junction malformation and controls were evaluated. Seventeen had BI-I, 26 had BI-II, 36 had CM, and 30 were normal subjects. Demographic data for the two groups were not significantly different. Craniometric analysis of images revealed a gradation in linear and angular variables from controls to CM, BI-I, and BI-II patients. Clivus length was significantly smaller in BI-II patients compared with other groups, while basal angle was greater. Moderate or strong correlations were noted among all variables analyzed.

CONCLUSION

Data suggest that clivus length and basal angle may play a role in pathophysiology of BI and CM.

Cerebellar Heterotopias: Expanding the Phenotype of Cerebellar Dysgenesis in CHARGE Syndrome

BACKGROUND AND PURPOSE

Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, and Ear abnormalities and deafness (CHARGE) syndrome is a multisystem developmental disorder associated with a number of well-described clinical and imaging findings, including cerebellar hypoplasia. We observed cerebellar heterotopias on MR imaging in 2 patients with CHARGE, confirmed by postmortem examination. We sought to determine the prevalence and define the characteristics of similar findings on MR imaging for a cohort of patients with CHARGE syndrome.

MATERIALS AND METHODS

We performed a retrospective, observational, cross-sectional study to assess the prevalence and characteristic features of cerebellar heterotopias in 35 patients with CHARGE syndrome with available brain MR imaging studies, as well as to evaluate additional features of cerebellar dysgenesis.

RESULTS

Cerebellar heterotopias were identified in 27/35 (77%) patients with CHARGE, characteristic in both location and appearance. Additional features of cerebellar dysgenesis were present in 31/34 evaluable patients (91%), including inferior vermian hypoplasia (90%), anteromedial rotation of the inferior tonsils (90%), and disorganized foliation of the cerebellar hemispheres (74%) or superior vermis (16%).

CONCLUSIONS

Patients with CHARGE syndrome have a high prevalence of characteristic cerebellar heterotopias and disorganized foliation and abnormal cerebellar morphology, thereby expanding the phenotype of cerebellar dysgenesis in this syndrome.