 Again noted are low-lying cerebellar tonsils which extend up to 7 mm below the level of the foramen magnum, although they retain a rounded contour. There is moderate crowding at the level of the foramen magnum. CSF flow imaging appears to have been only obtained during flexion and extension, without neutral positioning as reference. There is slight interval change in morphology of the CSF space caudal to the cerebellar tonsils upon the different positions, more diminutive in the extension position, although overall the tonsillar pathology appears similar.Upon extension, there is biphasic CSF flow along the ventral brainstem cervical cord, although slightly attenuated at the C1-C2 level. Dorsally, minimal biphasic flow is seen along the CSF space just caudal to the cerebellar tonsils, as well as along the dorsal cervical spinal canal with slight attenuation at the C3 level. On flexion, more conspicuous biphasic flow seen ventrally along the cervical spinal canal and to a lesser degree along the ventral brainstem. Dorsally, there is a similar pattern of biphasic CSF flow is described previously, although there is slight improved visualization of the flow including a small component which appears to be located along the fourth ventricular outflow.The cervical spine is in normal alignment, with slight straightening of the normal cervical lordosis. There is mild disc narrowing at C5-C6 and moderate disc narrowing at C6-C7. The vertebral body and disk heights are otherwise well-maintained. No worrisome focal marrow signal abnormality is appreciated. The spinal cord is of normal caliber and signal.Minimal focal disc disease at C6-C7, with a shallow left paracentral disc protrusion flattening the left ventral cord, likely impinging on the left ventral C7 nerve root. There is no significant stenosis. Minimal disc bulges are present from C3-C4 through C5-C6.
1.Redemonstration of crowding at the level the foramen magnum with abnormal caudal extension of the cerebellar tonsils below this level although they remain rounded in morphology. Slight interval change in extent of CSF space caudal to the tonsils at this level upon change in patient positioning from flexion to neutral to extension, with slight decreased extent of the space on extension.2.CSF flow imaging not definitively obtained in the neutral position, although from extension to flexion, biphasic flow actually appears slightly improved both ventrally and dorsally.3.Minimal cervical spondylotic changes, most prominent at C6-C7. There is flattening of the left ventral cord at this level with probable impingement of the left ventral C7 nerve root.