case_images: PMC5926209_01
case_images: Preoperative. Nineteen hours after admission. Sagittal T2-weighted MR image (TR 3116.7 TE 102.0) of the CMJ shows 7 mm of tonsillar herniation (arrowhead). The subarachnoid space is absent and the CMJ is indented by the dens (arrow). There is no signal change suggesting acute injury. The reference line indicates the anatomical level of the axial image in figure 2
case_images: SNI-9-88-g002.jpg
case_images: PMC5926209_01_SNI-9-88-g002.jpg
case_images: F1
case_images: Sagittal MRI demonstrated 7 mm of tonsillar descent below the foramen magnum, consistent with CMI [Figure 1].
case_images: Preoperative. Nineteen hours after admission. Axial T2-weighted MR image (TR 5150.0 TE 101.0) shows dorsolateral compression of the medulla (arrows) without evidence of surrounding CSF. There is no signal change identifying acute injury
case_images: SNI-9-88-g003.jpg
case_images: PMC5926209_01_SNI-9-88-g003.jpg
case_images: F2
case_images: Axial MRI showed significant medullary compression, with the right tonsil causing more compression than the left [Figure 2].
case_images: Preoperative. Sixty-one hours post injury. Axial T2-weighted MR image (TR 7200.0 TE 119.6) at the level of the foramen magnum shows hyperintense signal in the medulla in a paramedian location (short arrow) and in the dorsal columns (long arrow). The medulla is compressed by the cerebellar tonsils. The reference line of the inset sagittal image corresponds to the anatomic level of the axial image
case_images: SNI-9-88-g004.jpg
case_images: PMC5926209_01_SNI-9-88-g004.jpg
case_images: F3
case_images: T2-weighted MRI demonstrated hyperintense signal in the pyramids at and below the foramen magnum and in the dorsal columns of the spinal cord [Figures 3 and 4].
case_images: Preoperative. Sixty-one hours post injury. Axial T2-weighted MR image (TR 7200.0 TE 119.6) at the level of the dens shows hyperintense signal in the anterolateral aspect of the rostral cervical spinal cord. The medulla is compressed by the cerebellar tonsils. The reference line of the inset sagittal image corresponds to the anatomic level of the axial image
case_images: SNI-9-88-g005.jpg
case_images: PMC5926209_01_SNI-9-88-g005.jpg
case_images: F4
case_images: T2-weighted MRI demonstrated hyperintense signal in the pyramids at and below the foramen magnum and in the dorsal columns of the spinal cord [Figures 3 and 4].