Frontal sinus surgery has remained a frustrating and dangerous endeavor for many surgeons despite continued advances in instrumentation and surgical techniques. Partly to blame is the relatively inaccessible location of the frontal recess, posterior and cephalad to the anterior insertion of the middle turbinate, hiding away from the surgeon's direct line of vision. Moreover, multiple anterior ethmoid cells may occupy the frontal recess during the embryologic development of the frontal sinus, as early forming ethmoid sinusoids invade and pneumatize the frontal bone to form the frontal sinus . The variable size and location of these air cells contribute to the numerous patterns of the frontal sinus outflow pathway that is actually a potential space amongst the surface of these frontal recess cells, leading to the internal frontal sinus ostium. The remote location and anatomic complexity of the frontal recess along with its close proximity to the lamina papyracea and anterior skull base, led Lothrop  to state that an intranasal approach for frontal sinus drainage was too dangerous to perform. Instead, he described an external approach, which consisted of external ethmoidectomy to enlarge the nasofrontal drainage pathway. This included removal of the frontal sinus floors that were connected through a large nasal septectomy, and bilateral removal of the lacrimal bone and portion of the lamina papyracea that caused medial orbital fat collapse,with later stenosis of the newly created nasofrontal outflow communication. The development of the external osteoplastic flap procedure  with or without frontal sinus obliteration in the 1940s-1960s eliminated the need for a nasofrontal communication and quickly became the standard of care.However, failure rates averaged 10% in early reports [2, 10] and more recently,Weber et al.  reported frontal mucoceles seen by magnetic resonance imaging in 9.4% of the patients approximately 2 years after osteoplastic frontal sinus obliteration. The introduction of the nasal endoscope and endoscopic sinus surgery techniques allowed for better visualization of the frontal recess during surgery and provided an alternative to the open techniques for the surgical treatment of frontal sinus disease. Furthermore, endoscopic frontal surgery precisely addresses the exact location of chronic frontal sinus disease, which involves obstruction of the frontal sinus outflow pathway, in comparison to the open mucosal destructive procedures. Despite all endoscopic technique and instrumentation advances, the frontal sinus continues to remain challenging for many otolaryngologists, with the extent of surgery performed in the frontal recess being constantly debated in the literature. Excessive mucosal damage during endoscopic surgery can lead to scarring with obstruction of frontal drainage, and resection of the middle turbinate can lead to lateralization of the turbinate and obstruction of the frontal recess, as reported by Kuhn et al. . As endoscopic advances continued, the Lothrop procedure was revisited as an alternative to the open destructive techniques. Draf in 1991 described removal of the frontal sinus floor bilaterally using endoscopic and microscopic techniques, and classified the extent of surgery in the frontal recess . Close et al. in 1994 reported their results with 11 patients, and soon thereafter a series of reports established the legitimacy of the procedure with successful long-term surgical outcomes  (Table 25.1). [table presented] In the process, the procedure was renamed to accurately reflect the location and extent of surgery. The endoscopic modified Lothrop procedure offers several distinct advantages over open techniques and is slowly displacing the osteoplastic flap approach as the procedure of choice in persistent frontal disease after failure of medical therapy and more conservative endoscopic surgery. [table presented].
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