Presentation
Seizures.
Patient Data



















Cerebellar tonsillar herniation with caudal herniation of the obex of the medulla oblongata through the foramen magnum.
No evidence of hydrocephalus or syringohydromyelia.
Normal size and signal intensity of both hippocampi and amagdyla. No evidence of mesial temporal sclerosis.
Case Discussion
Chiari 1.5 malformation, or bulbar variant of Chiari I malformation, is a term used in the literature to describe the combination of cerebellar tonsillar herniation (as seen in Chiari I malformation) along with caudal herniation of some portion of the brainstem (often obex of the medulla oblongata) through the foramen magnum. It is considered a progression of Chiari I malformation.