Arachnoid cyst, Chiari malformation, and neck and back pain. Brain: There is inferior extension of the cerebellar tonsils, left greater than right, by approximately 15 mm with a peg-like configuration with crowding of tissue at the foramen magnum that results in impeded CSF flow across the posterior foramen magnum and a relatively small posterior fossa. There is a 7 mm wide extra-axial CSF space medial to the left temporal lobe. There is no evidence of intracranial hemorrhage, mass, or acute infarct. The ventricles and basal cisterns are normal in size and configuration, including a subcentimeter right lateral ventricular xanthogranuloma. There is no midline shift. The major cerebral flow voids are intact. There is mild posterior plagiocephaly. The orbits, paranasal sinuses, and scalp soft tissues are grossly unremarkable.Spine: There is thoracic syringohydromyelia centered at the T7 vertebral body level that measures up to 7 mm in width. There is mild retroflexion of the dens with minimally attenuated adjacent CSF flow. The conus medullaris is positioned at the L1 vertebral body level. The vertebral column alignment is otherwise within normal limits. The vertebral body and disc space heights are preserved. The vertebral bone marrow signal is unremarkable. There is no significant spinal canal stenosis. The paravertebral soft tissues are unremarkable.
1. Findings compatible with Chiari malformation with inferior extension of the cerebellar tonsils, left greater than right, by approximately 15 mm and a thoracic syrinx that measures up to 7 mm in width.2. Mildly retroflexed dens.3. Small medial temporal region arachnoid cyst.