Nagata and Sasaki applied the superior temporal sulcus (STS) approach to treat trigone meningiomas. They suggested that the STS approach was applicable to small trigonal tumors with an acceptable risk of morbidity. However, this approach has several potential risks of postoperative morbidity caused by retraction injury of the superior temporal gyrus or parietal lobe. The possible morbidities associated with the STS approach include damage to : association fibers, the optic radiation, the auditory radiation, the Heschl's Gyrus, and the parietal lobe ¹⁾.