Computer-tomographic investigations in malformations of the occipito-cervical junction

CT evaluation of Chamberlain's, McGregor's, and McRae's skull-base lines

AIM

To evaluate the mean distance from the odontoid process of C2 to the standard skull-base lines (Chamberlain's, McGregor's, and McRae's lines) on computed tomography (CT) imaging. To compare these measurements to previously documented plain radiograph and magnetic resonance imaging (MRI) measurements.

MATERIALS AND METHODS

Reformatted midline sagittal CT images of 150 adults were retrospectively evaluated. The shortest perpendicular distance was measured from the Chamberlain's, McGregor's and McRae's baselines for each subject to the odontoid tip. Statistical analysis was performed to compare the CT data with the previously obtained MRI and plain film data.

RESULTS

The mean position of the odontoid process was 1.4mm below Chamberlain's line (median 1.2 mm, SD 2.4 mm), 0.8 mm (median 0.9 mm, SD 3 mm) below McGregor's line and 5 mm (median 5 mm, SD 1.8 mm) below McRae's line. There is no significant difference between male and female results (p>0.05) or between these CT and previous MRI measurements (p>0.05).

CONCLUSION

These results provide the mean and range of normal distance from the odontoid process to the most frequently used skull-base lines on the current population on CT.

Atlanto-axial dislocation in rheumatoid arthritis--diagnostic and therapeutic aspects

Symptoms, signs and neuroradiological findings of 15 cases with atlanto-axial dislocation (AAD) due to rheumatoid arthritis are presented. CT of the craniocervical region revealed the exact anatomical relationships between the dens, the subarachnoid space and the brain stem, especially after intrathecal contrast medium injection and different positions of the head. From the results of operative procedures to reduce AAD it was concluded that early diagnosis and treatment of AAD leads to prompt relief of painful symptoms within 3 months and protects from neurological deterioration.