Angular craniometry in craniocervical junction malformation

Abstract

The craniometric linear dimensions of the posterior fossa have been relatively well studied, but angular craniometry has been poorly studied and may reveal differences in the several types of craniocervical junction malformation. The objectives of this study were to evaluate craniometric angles compared with normal subjects and elucidate the main angular differences among the types of craniocervical junction malformation and the correlation between craniocervical and cervical angles. Angular craniometries were studied using primary cranial angles (basal and Boogard’s) and secondary craniocervical angles (clivus canal and cervical spine lordosis). Patients with basilar invagination had significantly wider basal angles, sharper clivus canal angles, larger Boogard’s angles, and greater cervical lordosis than the Chiari malformation and control groups. The Chiari malformation group does not show significant differences when compared with normal controls. Platybasia occurred only in basilar invagination and is suggested to be more prevalent in type II than in type I. Platybasic patients have a more acute clivus canal angle and show greater cervical lordosis than non-platybasics. The Chiari group does not show significant differences when compared with the control, but the basilar invagination groups had craniometric variables significantly different from normal controls. Hyperlordosis observed in the basilar inavagination group was associated with craniocervical kyphosis conditioned by acute clivus canal angles.

Incidence of basilar invagination in patients with tonsillar herniation ? a case control craniometrical study

“…The presence of platybasia and a smaller clivus length in the tonsillar herniation can favoring an upper displacement of the cervical spine into the cranial base, explaining the higher incidence of BI in the case compared to control group. Different from our findings, Botelho and Ferreira did not find differences in craniometrical measurements performed in Chiari malformation patients and control groups, but BI patients had wider basal angles and sharper clivus canal angles 17 . Of note, for these authors, BI was diagnosed when the tip of the odontoid was at least 5 mm up the Chamberlain's line, possible excluding patients with less severe forms of BI that also would have the diagnosis of CM.…”

Basilar Invagination: cranio-cervical kyphosis rather than prolapse from the upper cervical spine

“…Specific measurements for BI will be pointed 5 . After that, relationship between craniocervical junction kyphosis and cervical lordosis angle will be analyzed 5,7 .…”

“…Basilar invagination (BI) is classically described as a developmental anomaly of the craniovertebral junction in which the odontoid abnormally prolapses into the foramen magnum 3 . BI was recently divided into those associated with craniocervical instability in which odontoid process invaginates inside foramen magnum (Type I Basilar Invagination) and those not associated with instability but with flattened basecranium (Type II Basilar invagination) ( Figure 1) 4,5,6 . Linear and angular craniometric studies helped to clarify pathophysiology of these malformations 5 .…”

“…BI was recently divided into those associated with craniocervical instability in which odontoid process invaginates inside foramen magnum (Type I Basilar Invagination) and those not associated with instability but with flattened basecranium (Type II Basilar invagination) ( Figure 1) 4,5,6 . Linear and angular craniometric studies helped to clarify pathophysiology of these malformations 5 . Craniometric analysis of skull and cervical spine has shown interrelation between craniocervical kyphosis and cervical spine lordosis suggesting some new correlation with potential therapeutic importance 5 .…”

“…Linear and angular craniometric studies helped to clarify pathophysiology of these malformations 5 . Craniometric analysis of skull and cervical spine has shown interrelation between craniocervical kyphosis and cervical spine lordosis suggesting some new correlation with potential therapeutic importance 5 . The objective of this study is to demonstrate the role of craniocervical junction kyphosis in pathophysiology of basilar invagination, confronting with the classic concept of upper cervical spine prolapsed into the skull base.…”