Radiological approach to basilar invagination type B: Reliability and accuracy

Interobserver and intraobserver reliability of skull base angles measured on magnetic resonance images

BACKGROUND

Determination of platybasia and basilar kyphosis are significant parts of routine cranial magnetic resonance (MR) interpretations. These situations may explain a patient’s symptoms or may be associated with other anomalies.

AIM

To indicate the interobserver and intraobserver reliability of the skull base angles (SBA) (Koenigsberg standard) and modified SBA (mSBA) measurement techniques.

METHODS

In total, 391 patients who had undergone cranial MR imaging were re-assessed regarding the SBA measurements. The SBA and mSBA techniques were used on MR images. Two reviewers independently measured the same angles twice within a 15-day interval, using different monitors. Intraclass correlation coefficient (ICC) was calculated to reveal the intraobserver and interobserver agreements.

RESULTS

There was an excellent agreement between reviewers regarding both angle measurements (ICC was 0.998 for SBA and mSBA). Excellent agreement levels were also observed for intraobserver measurements. ICC was 0.998 for SBA and 0.999 for mSBA for reviewer 1. ICC was 0.997 for SBA and 0.999 for mSBA according to the measurement results of reviewer 2. Higher SBA and mSBA values were observed for females compared to males. There was no correlation between SBA and age for SBA. However, a negative and low-level correlation was observed between mSBA values and age for both reviewers.

CONCLUSION

SBA and mSBA measurements indicated excellent agreement regarding interobserver and intraobserver differences. The study results showed that SBA angles were reliable measurement techniques to be used on MR images.

The role of clivus and atlanto-occipital lateral mass height in basilar invagination with or without atlas occipitalization

Basilar invagination (BI) is a common deformity. This study aimed to quantitatively evaluate the height of clivus and atlanto-occipital lateral mass (LM) in patients with BI with or without atlas occipitalization (AOZ). We evaluated 166 images of patients with BI and of controls. Seventy-one participants were control subjects (group A), 68 had BI with AOZ (group B), and 27 had BI without AOZ (group C). Parameters were defined and measured for comparisons across the groups. Multiple linear regression analysis was used to test the relationship between Chamberlain's line violation (CLV) and the clivus height ratio or atlanto-occipital LM height. Based on the degree of AOZ, the lateral masses in group B were classified as follows: segmentation, incomplete AOZ, complete AOZ. From groups A to C, there was a decreasing trend in the clivus height and clivus height ratio. There was a linear negative correlation between the clivus height ratio and CLV in the three groups. Generally, the atlanto-occipital LM height followed the order of group B < group C < group A. The atlanto-occipital LM height was included only in the equations of groups B. There were no cases of atlantoaxial dislocation (AAD) in group C. There was a decreasing trend in LM height from the segmentation type to the complete AOZ type in group B. BI can be divided into three categories: AOZ causes LM height loss; Clivus height loss; Both clivus and LM height loss. The clivus height ratio was found to play a decisive role in both controls and BI group, while the atlanto-occipital LM height loss caused by AOZ could be a secondary factor in patients with BI and AOZ. AOZ may be a necessary factor for AAD in patients with congenital BI. The degree of AOZ is associated with LM height in group B.

Clinical and Anthropological Analyses of a Case From 19th Century South Africa With a Confluence of Uncommon Cranial Pathological Conditions

This study combines clinical and anthropological analyses to investigate the complex cranial pathology of a South African individual from the 19th century. The cranium was examined macroscopically and radiographically. Conducting a standard differential diagnosis was challenging given the complexity and uncommon nature of the pathology and required drawing on relatively sparse paleopathological and clinical case reports. Multiple conditions were identified including biparietal thinning, basilar invagination, platybasia, and complicated chronic frontal sinusitis, where the intracranial extension of sinus infection may likely have contributed to the individual's death. The authors urge for awareness of these uncommon conditions, as their presence can easily be overlooked or confound skeletal assessments. This clinical study contributes to the authors' understanding of uncommon and poorly described paleopathological diseases and will help to better facilitate their diagnosis in future research. It represents one of the first studies describing such an unusual cooccurrence of uncommon pathologies in an archeological individual.

Basilar invagination: a tilt of the foramen magnum

OBJECTIVES

Congenital basilar invagination (BI) is a craniocervical deformity marked by odontoid prolapse into the skull base. The foramen magnum angle (FMA), which is formed by Chamberlain's line and McRae's line has not been fully studied. The study aimed to investigate the FMA and its relationship with other craniocervical parameters.

METHODS

Participants were divided into controls, type A BI and type B BI. Parameters included Chamberlain line violation (CLV), atlantodental interval, clivus height, clivus anteroposterior dimension, FMA, basal angle, clivo-axial angle, head and neck flexion angle, Boogard's angle, and subaxial cervical spine lordosis angle. Comparision of these parameters among the three groups and correlation analysis between FMA and other parameters was performed. The significance level was set at P<0.05.

RESULTS

A total of 111 controls, 111 type A BI patients, and 62 type B BI patients were enrolled. The FMAs in the control, type A BI, and type B BI groups were 6.21 (3.67,8.71), 22.16±6.61, and 22.39 (17.27, 31.08) °, respectively. Correlation analysis revealed correlations between the FMA and other variables. In the two BI subgroups, FMA was significantly correlated with CLV, clivus height, clivus anteroposterior dimension, basal angle, clivo-axial angle, and Boogard's angle.

CONCLUSION

The FMA in patients with BI was approximately 22° and approximately 6° in controls, indicating that the FM in BI had a greater tilt. As a pathological condition, FMA can reflect the degree of BI. Clivus hypogenesis is a reason for excessive tilt of the FM.