Abstracts

Rationale: To reveal the clinical characteristics of infantile spasms (IS) caused by mitochondrial respiratory chain complex (MRC) defects.Methods: We retrospectively reviewed clinical, neuroradiological and electrophysiological features of 23 IS patients with MRC defects, confirmed by biochemical assay of MRC activities in muscle biopsy. We also analyzed the treatment outcome.Results: 1) Among 23 patients with IS caused by MRC defect, 10 (43.5%) patients were male and 13 (56.5%) were female. Their median age at seizure onset was 6 months (6.0±3.3 month, 10 days – 15 months). 2) Twenty (87.0%) out of 23 patients showed decreased enzyme activities in MRC I, 1 (4.3%) in MRC II, and 2 (8.7%) in MRC IV. 3) Twenty-two (95.7%) out of 23 patients showed abnormal MRI findings. Seventeen patients showed diffuse atrophy of which 1 associated to cerebellar atrophy, 3 to white matter hyperintensity; 5 patients showed signal changes in deep nuclei such as basal ganglia and thalamus; 2 patients had cortical dysplasia. 4) Lactate peak in MR spectroscopy occurred in 10 (45.5%) out of 22 cases. 5) Eight (34.8%) patients showed more than 50% reduction in the frequency of clustering spasms, whereas 13 (56.5%) had no responses to antiepileptic drugs. 6) Seven (43.8%) out of 16 patients who started on ketogenic diet showed more than 50% reduction in seizure frequency, moreover 6 (37.5%) patients had seizure free outcome. 7) Seventeen (73.9%) of the patients receiving the mitochondrial cocktail therapy with coenzyme Q10 and multi-vitamin showed clinical improvement as measured by the caretaker’s global assessment form. Conclusions: MRC defects is one of the important causes of IS and active application of KD and mitochondrial cocktail therapy is effective in significant proportion.