Succinate dehydrogenase (SDH) deficiency is a rare autosomal recessive neurometabolic disorder that causes brain insult, neurodevelopmental delay, exercise intolerance, and cardiomyopathy. A 25-month-old boy was referred to our neurometabolic center due to developmental regression after injecting the influenza vaccine when he was 10 months old. Magnetic resonance imaging (MRI) showed high signal changes in the brain white matter, and magnetic resonance spectroscopy (MRS) detected a high succinate peak at 2.4 parts per million (ppm). The evaluation of urine organic acids showed a significant elevated succinic acid and whole exome sequencing, confirming SDH. Treatment with a mitochondrial cocktail was initiated, and remarkable improvement was observed. SDH deficiency as a treatable neurometabolic disorder should be considered in any patients with developmental disorders, accompanied by hyperintensity in white matter (as similar to leukodystrophia). Further evaluation is recommended since outcomes depend on early diagnosis and treatment.