[Overview and Pitfalls of the Extended Trans:Nasal Endoscopic Approach].

The extended endoscopic endonasal approach(EEA)has been expanding in recent years with the development of instruments and surgical techniques. Basically, sela, extradural, and intranasal lesions such as pituitary tumor, craniopharyngioma, chordoma, chondrosarcoma, and cholesterol granuloma are indicated. Intradural lesions or lesions that extend laterally or downward to the craniocervical junction are more difficult to operate. In addition, cases of hard tumor with calcification of the tumor, cases in which the tumor involves important blood vessels, re-operative cases, and cases after radiotherapy are also difficult cases and should be considered preoperatively. In recent years, we have been trying to keep the nasal structures as much as possible without removing nasal structure, but in cases where the tumor has invaded and destroyed the nasal structures, extended EEA is necessary. The anatomy of the extended EEA is complicated and not common among neurosurgeons. In this chapter, we present the basic anatomy and surgical cases to be understood in extended EEA and explain the pitfalls.