Crossed Cerebellar Diaschisis in a Patient with MELAS Syndrome: A Case Report.

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) is a rare genetic disorder from a spectrum of mitochondrial diseases. Most commonly it presents with stroke-like symptoms, seizures, encephalopathy and myopathy. As it affects predominantly metabolically active organs, it can cause cardiomyopathy, diabetes mellitus, etc. We report a case of a young male patient with genetically proven MELAS who had a history of periodical generalized tonic-clonic seizures and then developed recurrent transient paresthesia of the right extremities, speech disturbance and apraxia. During work-up, an MRI done after a generalized tonic-clonic seizure showed hypoperfusion and edema in right cerebellar hemisphere caused by the contralateral cerebral acute ischemic lesion in left insular cortex which produced initial symptoms. This interesting finding is called crossed cerebellar diaschisis (CCD). CCD is a rare entity which refers to a decrease in metabolism, perfusion, and overall function in a cerebellar hemisphere because of a contralateral cerebral lesion. The disturbance of the function in an area distant from the location of initial brain lesion is possible because the two areas are connected via fiber tracts. This pathology most commonly occurs after ischemic stroke but also after seizures, supratentorial tumors, encephalitis etc. Our patient continued to have recurrent occasional transient paresthesia of the right extremities, but the follow-up MRI showed complete regression of hyperintensities in the left cerebral cortex and edema in right cerebellar hemisphere. In this paper we report co-existence of a rare neuroradiological finding such as CCD, in patient with rare cerebrovascular disease.

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