Case Notes
History
51 yo male with acute mental status changes. Patient has previously undergone bone marrow transplant for leukemia 6 years earlierExam
MR flair
Prior Study
Axial pre and post contrast T1-w MR1. Diffuse inflammatory, immune-based disorder with sufficient bilateral cerebellitis to produce grade 1.6/4 obstructive hydrocephalus.
2. Along with the cerebellar inflammatory changes there is also inflammation surrounding the perineurium of multiple cranial nerves consistent with Miller-Fisher syndrome (post inflammatory immune response).
3. There is also thickening of the hypothalamus and pituitary stalk, again likely part of the same post inflammatory immune response affecting the cerebellum and the cranial nerves.
Noncontrast sagittal T1-w MR
1. Usually grade 1.6/4 hydrocephalus would produce a central downward incisural herniation. However, in this case, the degree of cerebellar edema is dominant resulting in a net central transtentorial hernation.
2. The optic chiasm and adjacent hypothalamus and pituitary stalk are thickened likely from the same process affecting the cerebellar hemispheres.