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Evaluation of Chamberlain’s and Mcrae’s Lines and Significance in Relation to Skull Base Problems

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Introduction: The odontoid process is the central pillar of craniovertebraljunction. It is assessed by lateral cervical spine and base of skull radiographs which however have diagnostic challenges due to the complexity of the anatomy. Modern-day Computed Tomography (CT) offers excellent bony detail and its ability to reconstruct the acquired CT data into various imaging planes makes the assessment of the cranio-cervical junction easy and more accurate. The standard skull base lines (Chamberlain’s and McRae’s lines) are used in the evaluation of the craniovertebral junction. They help to illustrate the degree of deformity in patients with basilar impression and aid in surgical decisions with regard to decompression, fixation and stabilization. These measurements are also used as guides in the conservative follow up of patients or those who are surgically managed. The Aim of The Study: To evaluate the relationship of the odontoid tip of C2 to the standard skull baselines of Chamberlain’s and McRae’s on computed tomography in symptomatic and asymptomatic patients. Materials and Methods: Reformatted midline sagittal CT images of 150 patients (M-68,F-82) were retrospectively evaluated. The shortest perpendicular distance was measured from the Chamberlain’s and McRae’s baselines for each subject to the odontoid tip. Results: The most common age group in male is 41-50 and female 31-40 years. The mean position of the odontoid process was 2.65 mm below Chamberlain’s line (median 2.7 mm, SD 0.21mm) and 4.6 mm (median 4.6 mm, SD 0.19 mm) below McRae’s line.There was no statistically significant difference in measurements between male and female patients. Conclusion: Imaging of this small structure to reach a specific diagnosis continues to be a challenge for radiologists. Multiplanar imaging with CT allows more detailed evaluation of bony and soft tissue structures. Adequate knowledge of development, complex anatomy, various disease processes, topographic relationships of odontoid with respect to CVJ and craniometry in association with the appropriate clinical background can provide a meaningful diagnosis. These results provide the mean of normal distance from the odontoid process to the standard skull base lines on CT. This study can be used as a base line data to access skull base problems.

Perspectives

Introduction: The odontoid process is the central pillar of craniovertebraljunction. It is assessed by lateral cervical spine and base of skull radiographs which however have diagnostic challenges due to the complexity of the anatomy. Modern-day Computed Tomography (CT) offers excellent bony detail and its ability to reconstruct the acquired CT data into various imaging planes makes the assessment of the cranio-cervical junction easy and more accurate. The standard skull base lines (Chamberlain’s and McRae’s lines) are used in the evaluation of the craniovertebral junction. They help to illustrate the degree of deformity in patients with basilar impression and aid in surgical decisions with regard to decompression, fixation and stabilization. These measurements are also used as guides in the conservative follow up of patients or those who are surgically managed. The Aim of The Study: To evaluate the relationship of the odontoid tip of C2 to the standard skull baselines of Chamberlain’s and McRae’s on computed tomography in symptomatic and asymptomatic patients. Materials and Methods: Reformatted midline sagittal CT images of 150 patients (M-68,F-82) were retrospectively evaluated. The shortest perpendicular distance was measured from the Chamberlain’s and McRae’s baselines for each subject to the odontoid tip. Results: The most common age group in male is 41-50 and female 31-40 years. The mean position of the odontoid process was 2.65 mm below Chamberlain’s line (median 2.7 mm, SD 0.21mm) and 4.6 mm (median 4.6 mm, SD 0.19 mm) below McRae’s line.There was no statistically significant difference in measurements between male and female patients. Conclusion: Imaging of this small structure to reach a specific diagnosis continues to be a challenge for radiologists. Multiplanar imaging with CT allows more detailed evaluation of bony and soft tissue structures. Adequate knowledge of development, complex anatomy, various disease processes, topographic relationships of odontoid with respect to CVJ and craniometry in association with the appropriate clinical background can provide a meaningful diagnosis. These results provide the mean of normal distance from the odontoid process to the standard skull base lines on CT. This study can be used as a base line data to access skull base problems.

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This page is a summary of: CT Evaluation of Chamberlain’s and Mcrae’s Lines and its Significance in Relation to Skull Base Problems at Meenakshi Medical College and Hospital, Indian Journal of Anatomy, January 2018, Red Flower Publication Private, Ltd.,
DOI: 10.21088/ija.2320.0022.7318.4.
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