MERRF (myoclonus epilepsy with ragged-red fibers) syndrome is a neurological disorder that is characterized by myoclonus, myopathy, peripheral neuropathy, and slow decline in intellectual ability. This mitochondrial syndrome is inherited maternally and most commonly is caused by m.8344A>G mutation in the mtDNA gene, MT-TK which encodes mitochondrial transfer (t)RNA lysine. Here, we present a case of MERRF with unique MRI findings.

MRI brain showed bilateral T2/FLAIR hyperintensity at the medial thalamus, dorsal midbrain, bilateral facial colliculi, dorsal medulla and cervicomedullary junction with no contrast enhancement. Extensive workup, including EMG, LP, and autoimmune workup were negative. Genetic testing was done and revealed mutation (m.8344 A>G) in the MTTK gene which is consistent with MERRF.

MERRF is a mitochondrial disease that usually present with progressive weakness, ataxia, and epilepsy. Usual MRI findings include cerebellar atrophy, increased signal intensity in the periaqueductal gray matter or cerebellar peduncles. Here, we report new pattern of MRI findings in a patient with MERRF that can help in future diagnosis of the disease.