Recurrent pain attacks in a 3-year-old patient with myoclonus epilepsy associated with ragged-red fibers (MERRF): a single-photon emission computed tomographic (SPECT) and electrophysiological study.

We reported a 3-year-old girl with myoclonus epilepsy associated with ragged-red fibers (MERRF) who was afflicted with recurrent pain attacks and allodynia on the right side of the body. Although magnetic resonance imaging showed normal intensity in the thalamus, single-photon emission computed tomography (SPECT) revealed hypoperfusion in the thalamus. Somatosensory evoked potentials showed delayed early cortical responses, particularly on right median nerve stimulation. The parenteral administration of cytochrome c with flavin mononucleotide and thiamine diphosphate abolished the intolerable pain. This clinical improvement was objectively supported by the results of SPECT and neurophysiological findings. These observations suggested that a dysfunction of the thalamus was responsible for her pain and that cytochrome c therapy was of benefit for this symptom.