MRI: Multifocal infarct-like cortical areas in different stages of ischemic evolution, areas that do not conform to any known vascular territory. Initial lesions often occur in the occipital or parietal lobes with eventual involvement of the cerebellum, cerebral cortex, basal ganglia, and thalamus. Lactate levels are often elevated in serum and cerebrospinal fluid. MR spectroscopy may show an elevated lactate peak in affected and even unaffected brain areas. Muscle biopsy shows ragged red fibers. However, genetic evaluation should be done first, which eliminates the need for muscle biopsy in most cases. Diagnosis may be molecular or clinical: * Stroke-like episodes before 40 years old * Encephalopathy with seizures or dementia * Blood lactic acidosis* or ragged red fibers on muscle biopsy Due to mitochondrial heteroplasmy, urine and blood testing is preferable to blood alone. PCR and ARMS-PCR are commonly used, reliable, rapid, and cost-effective techniques for the diagnosis of<unk> .
MELAS syndrome
Bannayan–Riley–Ruvalcaba syndrome
Pashayan syndrome
Fitzsimmons–Guilbert syndrome
Teunissen–Cremers syndrome
Fryns-Aftimos syndrome
Abruzzo–Erickson syndrome
Berk–Tabatznik syndrome