Abstracts

Rationale: Anatomically, it is known that the commissural tracts of the temporal lobe are the anterior commissure and the dorsal hippocampal commissure. However, the detailed anatomy of the dorsal hippocampal commissure has not been well described, in addition, Diffusion Tensor Imaging (DTI) studies have not been specifically performed on this tract, and its relation with the temporal lobe seizures is not well understood. Our objective was to describe the microanatomy of the dorsal hippocampal commissure using a white matter dissection technique and relate it to the DTI findings and the clinical presentation of the seizures.Methods: We dissected 5 previously frozen, formalin-fixed human brains (10 hemispheres) under the operating microscope using a fiber dissection technique. We also gathered information on 3T MRI DTI studies of healthy individuals and related it to our anatomical study.Results: The dorsal hippocampal commissure connects both hippocampi as an extension of their tails, traveling attached to the antero-inferior part of the splenium of the corpus callosum. This commissure can be recognized in the DTI studies and is related to the spreading of mesial temporal seizures. Conclusions: We describe this white matter tract pathway and discuss the functional anatomy and the clinical implications in temporal lobe seizures.