Embryological development of the human insula and its implications for the spread and resection of insular gliomas.

The human insular cortex, or the lobus insularis, is considered the developmentally most primitive lobe of the telencephalon. Covered by an overlying cortical lid, the insula has functions that are distinct from yet related to those of the adjacent temporal lobe and deep limbic structures. In the first part of this paper the authors outline the development of the human insula, including the cellular heterogeneity comprising the various parts of the insular lobe. Using the understanding gained from the development of the insula they then address implications of insular development for cortical development and connection as well as for tumorigenesis and tumor spread from the insula to other cortical structures, most notably the temporal lobe. An understanding of cortico-insular development and interconnection allows for both a better understanding of insular pathology and also facilitates planning of resection of cortico-insular gliomas to avoid damage to eloquent structures.