 The cerebellar tonsils now extend up to 7 mm inferior to the foramen magnum. In addition, the dens is retroflexed effacing the ventral foramen magnum representing an anatomic cranio-cervical junction variant. Cerebrospinal fluid flow is markedly reduced posterior to the cerebellar tonsils, but is intact anterior to the cord. There is a persistent long-segment linear high T2 signal within the central canal of the spinal cord extending from the level of lower cervical region to the conus medullaris is consistent with syringohydromyelia and is similar in size as on the prior exam, measuring up to 4 mm in maximum cross-section. There is no evidence of spinal canal stenosis within the cervical or thoracic spine. There is loss of the cervical lordosis, but no spondylolisthesis.
Decreased inferior extension of the cerebellar tonsils, but persistent small-caliber diffuse cervicothoracic syringohydromyelia.