CEREBELLAR DIASCHISIS IN PONTINE INFARCTIONS - A REPORT OF 5 CASES

We evaluate regional cerebral and cerebellar perfusion to prove the oc currence and follow the persistence of crossed cerebellar diaschisis i n infratentorial pontine infarction. Six consecutive patients exhibiti ng mild hemiparetic symptoms or a heavy feeling in the head (mean age 65 years; four women, two men) and diagnosed as having pontine infarct ion by magnetic resonance imaging were subjected to evaluation, Lesion s due to infarction were located at the upper basis pontis in five par tients and the upper tegmentum pontis in one, and medially at the para median portion in four and laterally in two. Regional cerebral and cer ebellar perfusion was evaluated semiquantitatively by iodine-123 N-iso propyl-p-iodoamphetamine (IMP) single-photon emission tomography (SPET ); this was done during the acute stage in five cases (mean time after onset: 0.7 months) and during the chronic stage in three (mean time a fter onset: 14.8 months). Four patients had two examinations during th eir clinical courses. For semiquantitative evaluation of perfusion, an asymmetry index was calculated for each region of interest, set symme trically in regions of the cerebral cortex and cerebellum in both hemi spheres. Significant asymmetry (P<0.01) in cerebellar perfusion, which was reduced in the contralateral (n=4) or ipsilateral (n=1) cerebella r hemisphere, was demonstrated semiquantitatively in four cases during the acute stage and in one during the chronic stage, as compared with normal controls (n=5, mean age 61 years). This asymmetry continued to the chronic stage (6.5 and 33.0 months) in two cases, while no patien t showed any significant asymmetries in cerebral perfusion in any regi on of interest in either SPET study. The pontine lesion may damage the pyramidal tract and corticocerebellar pathway, and interruption of th e cerebrocerebellar pontine circuits may be regarded as the cause of t he crossed cerebellar diaschisis observed in five of the six reported patients with pontine infarction.