This is an example of band heterotopia, a malformation of cortical development that is due to arrested neuronal migration. Subcortical band heterotopia is strongly linked with lissencephaly and in the most recent classification system for malformations of cortical development they are grouped together as lissencephaly type I - subcortical band heterotopia spectrum.

Band heterotopia is characterized on CT and MRI as a band of grey matter located deep to, and roughly paralleling, the cortex, with either normal or pachygyric overlying cortex.