Wallerian degeneration (WaD) is the process of antegrade degeneration of the axons and their accompanying myelin sheaths following proximal axonal or neuronal cell body lesions. It may result following neuronal loss due to cerebral infarction, trauma, necrosis, focal demyelination or hemorrhage.

It is seen as a contiguous tract of gliosis leading from an region of cortical or subcortical of neuronal injury towards the deep cerebral structures, along the expected topographical course of the involved white matter tract.