Two-way crossed cerebellar diaschisis in a clinically isolated syndrome suggestive of multiple sclerosis.

The term diaschisis refers to a neural dysfunction manifesting in anatomically intact, but functionally related, brain regions distant from a primary lesion. Here we report the diaschisis phenomenon as a consequence of a first demyelinating event in the middle and superior cerebellar peduncles in both the ipsilateral cerebellar hemisphere and in the contralateral thalamus and cerebral cortex (two-way crossed cerebellar diaschisis), resulting in the simultaneous disruption of the afferent cortico-ponto-cerebellar pathway and the efferent cerebellar-thalamo-cortical pathway. The use of 18F-FDG-PET could help clarifying in vivo the distant pathophysiological effect of focal lesions in inflammatory diseases such as multiple sclerosis.