MERRF (Myoclonic Epilepsy with Ragged Red Fibers) is manifested by seizures, cerebellar ataxia, ptosis, intention tremor, myopathy, proximal renal tubular dysfunction, cardiomyopathy, peripheral neuropathy, optic atrophy, deafness, multiple lipomatosis, and eventually dementia.
On imaging patients, in the second decade have increased T2/FLAIR signal along with atrophy of the dorsal midbrain (periaqueductal), cerebellum, and superior cerebellar peduncles. Atrophy is also seen of the cortex, white matter, and basal ganglia of the cerebral hemispheres.