Chamberlain's Line Violation in Basilar Invagination Patients Compared with Normal Subjects: A Systematic Literature...

Area of Science:

• Craniocervical junction abnormalities
• Diagnostic imaging in neurology
• Spinal imaging analysis

Background:

• Basilar invagination (BI) is a complex condition affecting the craniocervical junction.
• Accurate diagnosis relies on consistent radiological measurements, particularly the violation of Chamberlain's line.
• Existing literature shows variability in diagnostic criteria for BI using odontoid tip positioning.

Approach:

• Conducted a systematic literature review of 23 studies (13 radiological, 10 clinical) on basilar invagination.
• Analyzed radiological data, primarily from CT and MRI, to assess odontoid tip violation above Chamberlain's line.
• Performed a meta-analysis on 8 studies involving 1233 normal subjects to establish normative values for Chamberlain's line violation (CLV).

Key Points:

• Significant variability exists in reported cutoff values for diagnosing BI using odontoid tip violation.
• The mean measured CLV in patients with BI was 3.95 mm, with a median of 5 mm.
• The meta-analysis of normal subjects revealed a mean CLV of -0.63 mm (dens tip below the line).

Conclusions:

• The diagnostic criteria for basilar invagination based on Chamberlain's line violation are inconsistent across studies.
• A dens violation above Chamberlain's line exceeding 1.18 mm is proposed as a diagnostic threshold for BI.
• This standardized threshold aims to improve diagnostic accuracy, particularly for type B basilar invagination.