Patient 1
50 year old gentleman, a known old CVA patient presented with acute onset right sided weakness. Emergency CT was done to rule out reinfarction.
Findings
- Large intracerebral fresh hemorrhage is seen in the left supratentorial parenchyma. Old ischemic changes seen in right cerebral hemisphere.
- Asymmetric subtle hypoattenuation is seen involving the right superior and middle cerebellar peduncles extending into the right cerebellar while matter.Â
Patient 2
75 year old gentleman, developed acute onset slurring of speech and right sided weakness. Urgent CT brain was done. He was beyond the window period.
Findings
- Loss of grey white matter differentiation with hypoattenuation of the left gangliocapsule consistent with acute non hemorrhagic ischemic insult.
- Asymmetric hypoattenuation of right cerebellar white matter. Overlying grey matter appears normal.


Some striking questions these imaging findings raise are:
- Both patients had no clinical presentation with respect to the posterior fossa findings. They presented for clear clinical manifestations pertaining to supratentorial changes.
- These changes did not progress in follow up studies to be florid cerebellar infarctions. In one patient it disappeared, while the other it remained as it is.
Key points
- Crossed cerebellar diaschisis has been described from the mid 80s, documented in functional imaging studies as decreased metabolic activity in the contralateral posterior fossa due to a supratentorial pathology.
- It occurs secondary to involvement of the ponto cerebellar fibres and an associated arterial vasoconstriction.
- Sometimes they can result in infarction as well.
- So next time you do see a cerebral hemispheric infarction, go right down to assess the brain stem and contralateral cerebellum. You might just notice this not so uncommon phenomenon.
Read more
- Pantano, P., et al. “Crossed cerebellar diaschisis.” Brain 109.4 (1986): 677-694.
- Broich, Karl, et al. “Crossed cerebello-cerebral diaschisis in a patient with cerebellar infarction.” Neuroscience letters 83.1 (1987): 7-12.
- Infeld, Bernard, et al. “Crossed cerebellar diaschisis and brain recovery after stroke.” Stroke 26.1 (1995): 90-95.
- Yamada, Hiroki, et al. “Crossed cerebellar diaschisis: assessment with dynamic susceptibility contrast MR imaging.” Radiology 210.2 (1999): 558-562.
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