In a biochemical blood test, lactate acidosis is detected due to the accumulation of lactic and pyruvic acids in the blood and liquor, as well as an increase in the content of alanine in the blood. Also, the level of ketone bodies can be increased. In urine, there is an increased excretion of organic acids: lactic, fumaric, etc. The level of carnitine in blood and tissues is often reduced.
EEG results reveal focal signs of epileptic activity. According to MRI data, an expansion of the ventricles of the brain, bilateral brain damage, calcification of the basal ganglia (caudate nucleus, shell, black substance, pale ball) are detected. It is also possible to identify atrophy of the cerebral hemispheres and brain substances.
Morphological examination reveals gross changes in brain substance: symmetrical foci of necrosis, demyelination and spongy degeneration of the brain, mainly of the middle sections, the bridge, subcortical nodes, thalamus, optic nerve. The histological picture includes cystic degeneration of the brain tissue, astrocytic gliosis, death of neurons, an increase in the number of mitochondria in the cells. In skeletal muscles - accumulation of lipid inclusions, a decrease in histochemical response to complexes 1, 4 of the respiratory chain, subarachromolemal accumulation of mitochondria, anomalous mitochondria with disorganization of cristae. The phenomenon of RRF is often not detected.