Presentation
Intermittent neck pain with vertigo.
Patient Data
The MRI sequences demonstrate:
caudal descent of the cerebellar tonsils through the foramen magnum, located 12 mm below the McRae line on sagittal sequences
associated caudal herniation of the medulla oblongata
associated syrinx of the cervical cord at C6-7 level
central disc protrusion at C5-6 and C6-7 levels
Case Discussion
MRI features of Chiari 1.5 malformation with syrinx of the cervical spinal cord.
Chiari 1.5 malformation is defined as a 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.