 The cerebellar tonsils descend below the level of the foramen magnum by at least 5 mm depending on the level of measurement. There is, however, only mild crowding in the posterior fossa and the CSF spaces appear patent. There are no masses, mass effect or midline shift. There is no abnormal enhancement within the brain. The pituitary gland is normal in size. There is no evidence for intracranial hemorrhage or acute cerebral, brainstem or cerebellar infarction. No diffusion-weighted abnormalities are identified. The ventricles and sulci are normal in size. There are no extraaxial fluid collections or subdural hematomas. Flow voids are present within the major vessels indicating patency. The paranasal sinuses and mastoid air cells are clear.
1.Cerebellar tonsils descending below the level of the foramen magnum compatible with a Chiari I malformation. Clinical correlation is recommended to determine whether this may be related to the patient's symptoms.2.No additional abnormalities noted to explain the patient's headache.