IGS has proven most useful in cases involving revision sinus surgery [27, 28], cases involving extensive disease (e.g., extensive sinonasal polyposis), difficult or distorted anatomy (e.g., Onodi cells, narrowed pathways), difficult-to-approach anatomic locations including the frontal and sphenoid sinuses, cases with cerebrospinal fluid (CSF) rhinorrhea, and cases involving benign and malignant sinonasal neoplasms. It has also been enormously beneficial in the growing field of endoscopic skull base surgery [29].

Frontal sinus surgery has traditionally been a challenge for the endoscopic sinus surgeon because it requires using angled telescopes and instruments to visualize and operate within the sinus. The particular challenge of working at unnatural angles to identify the frontal sinus has been the cause of many surgeons’ angst because the skull base, anterior ethmoid artery, and intracranial contents are in such close proximity. IGS now allows the sinus surgeon to identify and work within the frontal sinus with much greater flexibility. In the case of difficult-to-reach frontal sinus disease, Zacharek et al. proposed image-guided trephination as a viable alternative to osteoplastic flap with or without obliteration [30]. In addition, when osteoplastic frontal sinusotomy is considered, IGS has been suggested as a valuable addition to maximize exposure without increasing morbidity [31–34]. Sindwani and Metson reported a series of 24 patients between 1992 and 2003 that demonstrated, for the first time, a reduced complication rate with the use of IGS in frontal sinus obliteration surgery [35].

The sphenoid sinus is commonly thought of as the most dangerous sinus in which to operate due to its close relation to crucial anatomic structures including the carotid artery, intracranial contents, and optic nerve. It is also a gateway to many important intracranial anatomic locations. IGS has greatly improved the ability for surgeons to access the sphenoid sinuses safely and to approach tumors involving areas that previously required craniotomies but now are accessible via a transsphenoidal approach. Otori et al. [36] described the transsphenoidal approach for removal of a pituitary lesion and concluded that this was particularly helpful in patients with narrowed sinonasal anatomy.

As the boundaries are pushed with regard to what is acceptable in endoscopic treatment of intracranial lesions, IGS becomes more and more of a necessity for these complicated transsphenoidal approaches. This route allows midline access and visibility to the suprasellar, retrosellar, and parasellar space while eliminating the large risk of brain retraction and makes possible to treat transsphenoidally a variety of midline skull base and parasellar lesions traditionally approached transcranially. In the hands of experienced otolaryngologists and neurosurgeons, lesions involving the cavernous sinus and posterior fossa are accessible via the transsphenoidal approach [37–39].

IGS has proven to be of great value in the surgical approach to the orbit [40]. White et al. [41] described a transnasal approach with IGS for the drainage of periorbital abscesses. Batra and Lanza [42] described orbital exenteration using the endoscopic image-guided approach which they found helped preserve the ophthalmic artery, thus decreasing bleeding, helping to preserve the eyelid, and helping to preserve the superior and lateral periosteum which facilitate mucosal coverage of the exenterated space. Murchison et al. [43] have recently described the transnasal removal of lesions within the orbital apex, which customarily require orbitotomy and craniotomy approaches.

The embryological development of the sinuses leads to distinctive challenges for the pediatric otolaryngologist when dealing with sinonasal disease processes. With sinus development and maturation not completed until late into the second decade, the surgeon must be aware of the unique anatomy involved in pediatric sinus surgery. With this in mind, IGS is a valuable resource to help guide the pediatric surgeon dealing with sinonasal disease.

Due to the relative scarcity of sinonasal surgery in the pediatric population compared to the adult population, there have been no specific studies looking specifically at the safety or efficacy of IGS systems in this age group [44]; however, there are several reports on the use of IGS within the pediatric population, both for common sinonasal processes and for specific disease processes unique to the pediatric population. Postec et al. [45] reviewed their experience with IGS in over 30 patients and discussed its value in assisting with revision cases, polyp removal in children with cystic fibrosis, patients with restenosis of choanal atresia, patients with juvenile nasopharyngeal fibroma, and patients requiring tumor biopsy. Parikh et al. [46] reviewed the largest series of pediatric patients, with 33 patients on whom image-guided sinus surgery was used. Image guidance was only used for advanced sinonasal procedures where there was an anatomic abnormality or disease that extended to the sphenoid sinus, frontal sinus, orbit, or skull base. The most common indications were chronic and acute rhinosinusitis, followed by juvenile nasopharyngeal angiofibroma, and allergic fungal sinusitis, and they had no reported complications with IGS. There have been several other reports [41, 47–49] describing use of image guidance within the pediatric population for cases involving difficult anatomic locations such as the skull base and petrous apex or complicated disease processes including cholesterol granuloma, juvenile nasopharyngeal angiofibroma, and periorbital abscess.

The true measurement of any new technology within the medical domain is its ability to improve patient outcomes, decrease complications, and increase postoperative satisfaction. Several retrospective case series have reported lower rates of complications using image guidance systems [23, 28, 35, 50], although this reached statistical significance in only the study performed by Fried et al. [23], who performed a retrospective study on 97 patients and found a significant decrease in complications in the IGS group. In a prospective study performed by Javer and Genoway [51], patients treated with image-guided ESS were compared to non-image-guided ESS. A 31-item questionnaire regarding short-term quality of life measures was used by the authors. They found a significant trend indicating greater quality of life improvement in the short term in the image-guided group relative to the non-image-guided group.

There is some controversy regarding the advantage of using IGS. Tabaee et al. [52] did not demonstrate a difference in overall intraoperative or postoperative complication rates, rates of revision procedures, or postoperative SNOT-20 scores. That review did find a higher incidence of intraoperative CSF leaks in the non-IGS group; however, another review by Tabaee et al. [53] did not find a significant improvement in the rates of successful closure of leaks with IGS. In addition, IGS was found to increase operative time by 15–30 min per surgery and cost on average 500 dollars more per case, with the additional cost involving cases where disposable handpieces and headsets were utilized. IGS has also been associated with higher intraoperative bleeding and minor headset-related complications [23, 54].

While IGS has certain drawbacks, it is universally accepted as a valuable resource for the practice of sinus surgeon. Smith et al. [55] performed a review of the literature regarding image guidance surgery. They noted that, due to the low number of major complications, a controlled trial would have to involve thousands of patients to attain sufficient power. Additionally, they argue that given the availability of this technology—which may confer safety benefits—randomization of patients away from this technology is “not practical, ethical, or feasible.” They conclude that among authors, there is universal agreement that image guidance systems represent a tool that has the potential to assist ESS surgeons but is no substitute for intimate understanding of each patient’s anatomy.