Neuronal Compensation and Plasticity in the Brains of Children with Remote Periventricular Leukomalacia.

[Purpose] Our previous studies revealed oligodendroglial regeneration around the necrosis of periventricular leukomalacia (PVL). This report describes neuronal compensation and plasticity in the cortex and white matter of PVL brains. [Subjects and Method] An immunohistochemical study was performed on 15 human brains with PVL, using an antibody for PGP9.5, which is expressed predominantly in differentiating neurons. We semiquantitatively evaluated the expression of PGP9.5 in the cerebral cortex and white matter and compared it with that of age-matched controls. [Results] In the white matter, there was an increase of immunoreactivity beside the necrotic lesions of focal type PVL, but there was often a decrease in widespread or diffuse type PVL. In the cortex, close to necrotic lesions, the immunoreactivity was decreased in pyramidal cells of the 3rd and 5th cortical layers, but was increased in granular cells of the 2nd and 4th cortical layers. [Conclusion] The characteristic increase of axons around PVL in the white matter and granular neurons in the cortex close to PVL suggest neuronal compensation for injured axons and plasticity for the transneuronally degenerated pyramidal neurons. [ABSTRACT FROM AUTHOR]