[Basic Concept of Skull Base Reconstructive Surgery].

In most cases of anterior cranial fossa defects, the cranial cavity and the nasal cavity are connected, and it is necessary to reconstruct the skull base in a narrow sense to separate both cavities. If the surgical purpose is only separation, reconstruction with a pedicled local flap is often possible. As other surgical purposes such as the reconstruction of surrounding tissues are added, the transplanted tissue volume becomes insufficient, and free tissue transfer is required. In the case of a defect in the middle cranial fossa, the cranial cavity is not always connected with the nasal cavity because it is far from the nasal cavity and oral cavity. In this case, it is skull base reconstruction in a broad sense whose purpose is other than separation. There are many factors such as facial soft tissue augmentation and facial nerve reconstruction as the surgical purpose, and the more the purposes, the more likely it is that free tissue transfer will be required. In patients with anterior and middle cranial fossa defects, both cavities are connected and the resected tissue volume is large, so free tissue transfer is selected in most cases, except for a few benign diseases.