Female, 14 years old, with episodes of falling. No evidence of parenchymal edema or mass effect is seen. No focal parenchymal lesions are detected. Diffusion-weighted images are normal. There are no findings to suggest acute intracranial hemorrhage or any abnormal extra-axial fluid collections. The ventricles are normal in size and morphology. The region of the pituitary gland is within normal limits. The cerebellar tonsils descend 3 to 4 mm below the plane of the foramen magnum, but they maintain a round contour and there is little if any significant crowding.
1.No acute intracranial abnormality or other definite findings to account for the patient's symptoms.2.Cerebellar tonsillar ectopia is of uncertain significance