Crossed cerebellar diaschisis
Crossed cerebellar diaschisis (CCD) refers to a depression of blood flow and metabolism affecting the cerebellar hemisphere occurring as a result of a contralateral focal, supratentorial lesion (e.g. infarct, radiation necrosis, following tumor resection).
It is a well-recognized phenomenon following cerebral infarction. The most likely mechanism is thought to be interruption of cortico-ponto-cerebellar connections due to the infarct which then causes deafferentation and transneural metabolic depression of the contralateral cerebellar hemisphere
Imaging has to be interpreted in the correct clinical context.
CT / MRI and CT perfusion
CT perfusion performed during acute stroke may show a contralateral perfusion abnormality in about 20 % of cases 4. CBF and CBV maps show only mild-to-moderate reduction in these parameters, and are never low enough to classify the personal abnormalities as infarcts. There can be volume loss to the contralateral cerebellar hemisphere.
FDG PET shows hypometabolism in affected cerebellar hemisphere 2.