 There are postsurgical changes of suboccipital decompression including resection of the posterior arch of C1. There is much improvement in CSF spaces at the foramen magnum with robust biphasic flow now present ventrally and slightly diminished, but interval improved, flow dorsally. There is small fluid collection at the level of the suboccipital craniectomy measuring approximately 9 mm in thickness compatible with a pseudomeningocele. There is prominent enhancement involving the paraspinous soft tissues likely related to granulation tissue, although infection is not excluded and can be considered in the appropriate setting. Enhancement is also noted along the pial surface of the cerebellar tonsils.There is interval decrease in size of previously seen syrinx. Prior exam demonstrated a syrinx extending from the lower medulla into the cervical and thoracic cord with inferior limit at the T11-T12 level based on prior sagittal lumbar MRI images. Note a dedicated prior thoracic spine MRI is not available for comparison. Current study demonstrates significant decrease in extent and caliber of the syrinx which now extends to the mid T11 level. Residual signal abnormality involving the medulla is again evident best seen on the 3-D T2 sequence. There is marked decrease in the caliber of the syrinx; for example at the C6-C7 level, syrinx previously measuring 6.7 mm now measures 2.4 mm in the AP dimension. Previously seen associated cord expansion has now resolved with thinning/volume loss of the cord parenchyma much more apparent.There is mild reversal of normal cervical lordosis. There is also mild thoracic dextroscoliosis. Vertebral body heights are maintained. Disc desiccation at multiple levels are also seen with minimal bulge. Upper cervical spinal canal appears small on a congenital basis. There is also mild C3-C4 and C4-C5 neural foraminal narrowing. Otherwise no high-grade spinal canal or neural foraminal stenosis. There is calvarial thickening including the partially imaged clivus and also evident on outside brain MRI. Finding nonspecific and may be related to dysplasia or endocrinologic abnormality, for example. Dysplastic appearance of the thoracic ribs are also noted which appear slightly widened.
1. Compared to outside MRI, interval postsurgical changes of suboccipital decompression for Chiari I malformation are seen with much improvement in CSF spaces and biphasic flow at the foramen magnum. There is also marked improvement in size and extent of syrinx which extends from the medulla to the lower thoracic cord, as detailed above. There is associated resolution of previously seen cord expansion with volume loss/parenchymal thinning in the cord now more evident.2. Small suboccipital fluid collection likely represents a pseudomeningocele. There is also T2 hyperintensity involving the cerebellar tonsils as well as enhancement along the surface of the cerebellar tonsils which may represent expected postsurgical change. There is also prominent enhancement involving the suboccipital soft tissues which while may also represent postsurgical change/granulation tissue, but raises possibility of infection in the appropriate clinical setting. 3. Thickening of the clivus/partially imaged calvarium as well as mildly dysplastic appearance of the thoracic ribs which are broadened. These findings are nonspecific and may be related to dysplasia or endocrinologic abnormalities for example.