 There is atlantooccipital assimilation primarily involving the bilateral lateral masses and the occipital condyles. There is crowding of the CSF spaces at the foramen magnum with mildly elongated appearance of the cerebellar tonsils. Measuring from the inferior aspect of the occipital bone, cerebellar tonsillar ectopia measures up to 4 mm, although measuring from the level of the posterior C1 arch which is fused to the occipital bone, cerebellar tonsils do not herniate inferior to it. CSF flow sequence demonstrates focally diminished biphasic flow at the foramen magnum ventrally and dorsally. Atlantodental interval is not well assessed with MRI with appears borderline widened measuring 2 to 3 mm. There is a syrinx in the cervical cord extending from C2 mid dens to the lower C4 level. Syrinx measures up to up to 3 x 4 mm at the mid C3 and upper C4 levels, measured in the AP and transverse dimensions. Vertebral body heights are maintained. There is loss of cervical lordosis. Multilevel degenerative changes are seen including small disc osteophyte complexes at the C3-C4, C5-C6, and C6-C7 levels. There is up to mild spinal canal stenosis and mild to moderate bilateral neural foraminal stenosis at the C5-C6 level. Mild to moderate left and mild right neural foraminal stenosis is present at the C6-C7 level. Spinal canal and neural foramina in the cervical spine are otherwise patent.THORACIC SPINE
1. Atlantooccipital assimilation with mildly elongated cerebellar tonsils extending to the C1 level. There is crowding of the CSF spaces at the foramen magnum with diminished CSF flow.2. Syrinx in the cervical cord extending from the C2 mid dens to the lower C4 level. There is also trace prominence of the central canal in the thoracic cord. Aforementioned findings are compatible with Chiari I.3. No evidence of tethered cord.4. Mild multilevel degenerative changes as detailed above including mild spinal canal stenosis and mild to moderate bilateral neural foraminal stenosis at the C5-C6 level.5. Borderline widening of the atlantodental interval which can be further assessed with dynamic radiographs as clinically indicated.