[Crossed cerebellar diaschisis after brainstem infarction]

Metabolic depression in the cerebellar hemisphere contralateral to supratentorial stroke termed "Crossed Cerebellar Diaschisis" (CCD) was first described by Baron and coworkers and now interpreted as a transneuronal deactivation resulted from loss of excitatory afferent inputs. Among the cerebrocerebellar pathways possibly involved, the corticopontocerebellar pathway is considered to be the most important to induce CCD. According to the hypothesis that CCD results from the destruction of the corticopontocerebellar pathway, any lesion wherever located in the corticopontocerebellar pathway may induce CCD. Little is known, however, about CCD after the brainstem lesion. Our case presented here showed that a brainstem lesion actually induced CCD and that CCD resulted from transneuronal deactivation. An 80-year-old female was admitted to the neurological department of Kasugai City Hospital because of left-sided hemiparesis of sudden onset on March 19, 1989. On admission and 5 days after admission CT scan of the brain was performed, but no stroke lesion was found. Magnetic resonance imaging of the brain disclosed a localized lesion in the right peduncle and tegmentum of the midbrain. Single photon emission computerized tomography of the brain using N-isopropyl-P-(123I) iodoamphetamine (IMP) performed about a month after admission disclosed decreased blood flow in the left hemisphere of the cerebellum compared with the right one and the findings of CCD were observed.