Cranial, craniofacial and skull base surgery

Lesions involving the middle cranial base, its underlying volumes, and the first cervical vertebrae can be adequately managed surgically by means of a series of different approaches. These have the following basic prerequisites: to supply adequate surgical light, to identify and preserve the neurovascular structures adjacent to the lesion, to restore an adequate barrier between the neurocranium and the upper aerodigestive tracts, and to preserve both the functionality and the appearance of the patient. The approaches comprise a heterogeneous set of surgical techniques. No clear classification has yet been established. As a consequence, the terminology used to describe them is often confusing. Despite this complexity, there are basically four ways by which the lesions (of the lateral sectors of the infratemporal fossa and/or the middle cranial base) can be resected: transtemporal, infratemporal, intracranial, and transfacial. These approaches, depending on the size and location of the lesion, may be used jointly resulting in so-called combined approaches. Transmandibular approaches, the main topic of this chapter, tend to merge substantially with each of the four above approaches, although transmandibular means literally an approach involving exposure of the lesion by more or less substantial mobilization of the mandible portions, and consequently a transfacial approach. However, in surgery, when the middle cranial base is entered laterally, it is impossible to obtain complete exposure only by mobilizing the mandible. Therefore, it is necessary to osteotomize and remove other bone structures such as, for example, the zygomatic arch and/or the temporal squama. Therefore, in the literature, approaches that should be indicated as transmandibular, are identified by their authors with the most varied names, sometimes creating confusion. As mentioned above, transmandibular approaches can be classified as single approaches (when the approach obtained by mobilizing the mandible is exclusively transfacial) or as combined approaches (if the lesion is approached by combining mobilization of the mandible with that of other bone structures such as the zygoma or the temporal squama). In addition, approaches can also be categorized as anterior or lateral, depending on whether the initial incision is carried out anteriorly in the mental region or submandibular region or laterally in the preauricular region and extended below along the anterior margin of the sternocleidomastoid muscle.