Laminar Cortical Necrosis in MELAS Syndrome: MR and Neuropathological Observations

Abstract

Laminar cortical necrosis has been described in many conditions of cellular energy depletion, such as hypoxia and hypoglycemia. In MELAS, a genetic defect in mitochondrial protein synthesis leads to impairment of oxidative phosphorylation, with subsequent insufficient energy production within the cell. Neurons are more vulnerable to energy depletion than glial cells and vascular elements, and among the layers of the cerebral cortex the lower laminae are more vulnerable than the superficial layers.

We studied a child with severe MELAS syndrome two months before death with MR and compared the images to autopsy findings, including macroscopic specimens and light and electron microscopy. The MR images showed an excellent correlation with the neuropathological results and displayed the various degrees of damage to the brain tissue caused by deficient energy production. Acute laminar cortical necrosis was seen as swelling of the cortex with intracortical hyperintense bands in T₂-weighted images. The subacute stage with focal cortical hemorrhage was displayed as hyperintensity of the gyral surface in T₁-weighted and hypointensity in T₂-weighted images, with T₂-hyperintensity and swelling of the rest of the cortex and underlying white matter. Severe cortical atrophy represented the chronic stage.

Key words

Laminar cortical necrosis - MELAS - Mitochondrial disorders