There had n ' t a report about the study on the microsurgical anatomy of this approach in our country and there were rarely found in the data overseas . the development of the neuro - otology has made it possible for the resection of the semicircular with the preservation of hearing . by the use of this skill , the removal range of the petrosal bone could be enlarged . this is called the expanding retrosigmoid approach 在保留听力的条件下将现代神经耳科学的半规管切除新技术和乙状窦后经内耳孔上入路结合起来，将使该手术入路得到扩展，这就是扩大乙状窦后经内耳孔上入路( erssma ) ，对它的显微外科解剖学研究，国内外来见报道。
