Chamberlain’s line, clivus-canal angle, Welcker’s basal angle, Boogaard’s angle, and foramen magnum angle: a brief review for type B basilar invagination

Abstract

IntroductionType B basilar invagination (BI) is an abnormality of the craniovertebral junction (CVJ).  Since first descriptions occurred in the 18th and 19th centuries BI have gained remarkable clinical and surgical importance.ObjectiveTo describe usual craniometric parameters of assessment of type B BI and to discuss future perspectives of craniometry in the field.MethodsThis is a brief review of the literature on the CVJ parameters used for the BI diagnosis. ResultsAlthough there are several craniometric parameters used in the diagnosis of BI, there are few studies on the validation of these parameters on radiography and volumetric images.  Accuracy studies for Chamberlain’ line, clivus-canal angle, Boogaard’s angle, Welcker’s basal angle, and foramen magnum angle occurred consistently at CT and MRI. Brachycephaly and reduced cranial height are strongly associated with type B BI.ConclusionThe classical parameters of the Chamberlain's line, Boogaard's angle and clivus-canal angle are still important tests for the diagnostic evaluation of type B BI.