Utility of multimodal evoked potential study and electroencephalography inmitochondrial encephalomyopathy

We performed electroencephalography (EEG) and multimodal evoked potential ( EP) studies in 16 patients with various forms of mitochondrial encephalomyo pathy (ME). The electrophysiological investigations revealed signs of invol vement of the peripheral and central nervous system (CNS) in 14 patients, w ith a high incidence of visual-EP (VEP) alterations, indicative of visual p athway vulnerability in mitochondrial diseases. No specific pattern of abno rmalities emerged and, in particular, clinical and laboratory findings did not correlate with each other. EP (particularly VEP and electroretinogram) investigations should be part of the diagnostic work-up of patients with mi tochondrial disorders in order to better characterize the clinical picture, disclose involvement of specific sensory systems of the CNS, and assess pa tients with atypical clinical presentations.