Dynamic magnetic resonance imaging evaluation of craniovertebral junction abnormalities

Objectives: To evaluate the role of dynamic magnetic resonance imaging (MRI) in cramovertebral junction (CVJ) abnon-nalities. Materials and Methods: Twenty-five patients with suspected CVJ abnormalities underwent dynamic MRI of the CVJ, and in 20 of these patients, noncontrast computed tomography scan of the CVJ was done. The images were evaluated for atlantoaxial instability (AAI), spinal canal narrowing, cord compression, presence of altered cord signal intensity, and bony abnormalities in neutral, flexion, and extension. Results: Dynamic MRI detected 15 cases of AAI (10 fixed and 5 mobile AAI), 21 patients had varying degrees of spinal canal narrowing. Five patients showed increased narrowing on flexion/ extension. Two patients demonstrated direct cord compression in flexion, whereas in neutral position, only dural compression was seen. One patient had cord compression on extension that was not seen in neutral or flexed position. Conclusion: Dynamic MRI was able to detect cases of cord compression that were not seen in neutral position and was diagnostic in all cases of mobile AAI where mobility at this joint affects the treatment options. Dynamic MRI is extremely useful for evaluating cramovertebral junction abnormalities and, in particular, cord compression.