Exploring the neurosurgical anatomy of the human insula: a combined and comparative anatomic-radiologic study

The human insula constitutes the invaginated portion of the cerebral cortex and is less well understood than other cortical areas because of its hidden location. Our purpose was to study the neurosurgical anatomy of the human insula via a combined and comparative study of its gross and imaging anatomy.

We totally studied the anatomy of 148 normal insulae in anatomic specimens and radiologic images. We evaluated the number of all insular gyri (short and long), we statistically analyzed our results, and we made comparisons among hemispheres and gender. We also compared the two studies. Finally, we searched in the literature to make comparisons with other authors and to add our experience to the today existing knowledge of the insular anatomy.

We found a significantly greater value of the insular gyri number for males, potential underestimation of the real insular gyri number by MRI and that the classic insular gyri pattern can rarely be absent. The middle short insular gyrus can be indistinguishable more likely on MRIs than during surgery, the long insular gyri are less curved than the short gyri, and finally, the insular perforating vessels usually originate at the inferior insular part.

Deep knowledge of the gross, imaging, and surgical anatomy of the insula is of paramount importance for neurosurgeons dealing with disorders in this area. The male insula is larger (increased gyri pattern) than the female. Moreover, the classic insular gyri pattern can rarely be absent, probably as a normal anatomic variation.