ABSTRACT
The earliest intraoperative guidance systems were developed in the 1980s for neurosurgical procedures. They utilized a stereotactic frame that required fixation of the patient's head during surgery with cranial screws [1]. An articulated mechanical arm or "wand" held a probe, which could be localized in the surgical field by means of electromechanical sensors. A frameless system was eventually
developed [2], which was used for a variety of sinonasal procedures [3-5]. However, many surgeons found this system to be awkward to use and time-consuming [6,7]. In addition, the patient's head still had to be immobilized during surgery. The introduction of wandless and frameless systems in the mid-1990s greatly facilitated the utility of image-guided technology for otolaryngologic surgery [814]. These devices required neither articulated arms nor head immobilization and could be readily adapted for use during commonly performed endoscopic sinus procedures.
