Causes of neuronal heterotopia other than migration disturbances

A differentiated form of cerebellocortical fragments (case 1) in the white matter or even in the cerebellar dentate nucleus, found in a fetus with trisomy 13, may be due to an auto-transplantation accompanied by a penetrating vessel. A similar condition was observed in the Ammon's horn (case 2) incidentally as a heterotopic tissue fragment of the dentate fascia. Further cause of heterotopia may be speculated as a mechanical separation by a surrounding and developing tissue part in case of organized, differentiated cerebellocortical heterotopia in the white matter (cases 3-5) which were clinically silent. Migration disturbances are not the only cause of neuronal heterotopia since the structure of heterotopia is differentiated and organized by tissue components.