Systems and methods for treating spinal stenosis include endoscopic access devices and bone removal devices used to perform a foraminotomy or other bone removal procedures. Some of the bone removal devices include expandable members which may be used to control the forced exerted and/or position of the bone removal mechanism, and to protect neurovascular structures and other soft tissue structures from the bone removal mechanism. Other bone removal devices include a trephine with a viewing window and a guide wire lumen used to position the trephine at a target tissue site using an anchored wire. The viewing window may be used to monitor structures or tissues adjacent to the target tissue site.