A Technical Guide for Fiber Tract Dissection of the Internal Capsule.

Abstract

Dissection of white fibers is important in identifying detailed neuroanatomical relationships. With tractrography it is possible to transport and apply this knowledge in a practical way to treat many diseases involving the white matter. The Klingler method, subsequently disseminated by Türe with slight modifications was used. We review some historical aspects of white fibers and provide a guide for dissection of the internal capsule. The removal of gray matter allowed us to obtain a view of the white matter. We removed all U-shaped fibers to expose the insular cortex. The cortex of the insular lobe was removed, which exposed the extreme capsule. The removal of the claustrum exposed the external capsule, which covers the lentiform nucleus, specifically the putamen. During dissection, removing some fibers of the external capsule produced windows in which the putamen could be medially visualized. Since the internal capsule lies medial to the lentiform nucleus, it was necessary to remove the nucleus in order to expose the internal capsule. We identified five regions of the internal capsule: the anterior limb, genu, posterior limb, and sublenticular and retrolenticular parts. Finally, we determined that the fibers of the corona radiata condense into the internal capsule at the level of the superior border of the lentiform nucleus. Knowledge gained with the cadaveric fiber dissection technique can be applied in microsurgical practice and can be used to evaluate the surgical treatment for different tumors and vascular malformations.