Dizziness and ataxia. The cerebellar tonsils extend up to 7 mm inferior to the foramen magnum and display pointed morphologies. The posterior fossa has a relatively small capacity and there is crowding of the foramen magnum. There is no evidence of intracranial hemorrhage, mass, or acute infarct. The brain parenchyma and pituitary gland appear unremarkable. The ventricles and basal cisterns are normal in size and configuration. There is no midline shift or herniation. The major cerebral flow voids are intact. The orbits are grossly unremarkable. There are findings suggestive of arrested pneumatization of the sphenoid sinuses.
Findings compatible with Chiari I malformation. No evidence of acute intracranial hemorrhage, mass, or acute infarct.