Mapping anterograde and retrograde degeneration after stroke.

This article focuses on tools to quantify secondary degeneration after stroke and monitor effects of intervention. Researchers monitored in two patients the time course of Wallerian degeneration (WD) of the pyramidal tract following striatocapsular stroke. Diffusion tensor imaging was obtained on three occasions from the subacute into the chronic stage. They found a progressive decrease of the fractional anisotropy (FA) with an increase in mean diffusivity (MD) in the pyramidal tract at the level of the cerebral peduncle, reflecting the changes expected in WD-a progressive disintegration of fibre structure. They found significant increases in MD from 1 month onward, without parallel changes in FA, presumably reflecting a progressive loss of neurons and glial cells.