Abstract
Increasing prevalence of patients undergoing endoscopic sinus surgery (ESS) makes understanding methods to preventing complications important to otolaryngologists. This commentary details clinical pearls and perioperative strategies that may minimize complications and increase preparedness for appropriate decision making in the event of a complication. Preoperative preparation is an important factor in preventing adverse events in ESS. This includes ensuring the presence of objective radiographic findings before pursuing operative management, both for patients’ safety as well as medicolegal reasons, and providing adequate preoperative patient education. Appreciating variants in skull base and orbital wall anatomy through preoperative imaging is crucial for avoidance of intracranial and orbital complications. The importance of optimal visualization intraoperatively and the appropriate role of CT-guided imaging are also discussed. Finally, strategies for dealing with postoperative sequelae of more common complications are noted. This article represents a brief review for introductory sinus surgeons and is not meant as an all encompassing review.
1
Introduction
The increase in patients undergoing endoscopic sinus surgery (ESS) over the past two decades and accompanying technological innovations necessitate an understanding of inherent risks as well as approaches to prevent complications. Critical intracranial and orbital structures surrounding the paranasal sinuses make adverse events potentially devastating. Several straightforward precautions combined with sound perioperative strategies may prevent complications and ensure preparedness for an appropriate course of action in the case of an unfortunate event, ultimately limiting medicolegal liability and improving patient safety.
2
Preoperative considerations
Adequate preoperative evaluation is crucial for prevention of complications, as understanding variants in patient’s sinonasal anatomy and the extent of disease is necessary to facilitate appropriate decision making. ESS should not be undertaken without radiographic evidence of disease or maximal medical management. If complications were to occur and a patient initiates litigation, it may be nearly impossible to justify the necessity of ESS in such a case. Indeed, the degree of pathology on imaging is the strongest predictive prognostic factor after ESS . For symptomatic patients without radiographic evidence of disease, medical management alone may satisfy the goals of enhancing patient safety while minimizing liability. Utilizing the Lund–Mackay staging assists in CT interpretation in this regard, as a very low score (at or near 0) is less likely to gain maximal benefit from operative management .
Appreciating variants in skull base anatomy is essential to avoid intracranial complications . Length of the lamina lateralis ( Fig. 1 A ), categorized by Keros type , plays an important role in the preoperative review of CT imaging. A type 3 lamina lateralis has a depth of 8–16 mm. While this is found in a smaller percentage of the population, this skull base configuration is most often violated during ESS . In contrast, shorter and smaller lamina lateralis, such as type 1, are less often breached. The majority of patients fall somewhere in between these two extremes, with a Keros type 2 that has a depth between 4 and 7 mm.
Another critical aspect of evaluating skull base anatomy includes disease abutting the skull base. When this is noted on preoperative imaging, ESS surgeons can be more conservative by avoiding complete skeletonization of the skull base . This ensures that if there are skull base defects, direct and aggressive manipulation is kept to a minimum. Additionally, the slope ( Fig. 1 B) of the skull base and the presence of dehiscence ( Fig. 1 C) should be noted on preoperative imaging.
Location of the ethmoidal arteries should be identified on the preoperative CT. Generally, the posterior ethmoidal artery is located intracranially. The anterior ethmoidal artery, however, may be found in the ethmoid sinus mesentery in 20%–40% of cases, and is typically adjacent to the superior oblique muscle ( Fig. 1 D) . If transection is necessary, it is preferable to divide these arteries farther from the orbit to prevent retraction of the cut end of these vessels into the orbit which could lead to a retrobulbar hemorrhage. Dividing these arteries closer to the cribriform leaves a remnant vasculature that can be cauterized even in the case of partial retraction toward the orbit.
Examination of the medial orbital wall anatomy is also important preoperatively. The location of the lacrimal sac and duct and the presence of visible dehiscence of the lamina papyracea should be noted. The relationship of the uncinate process to the medial orbital wall is important. If adequate space exists between the uncinate process and the medial orbital wall, the former can be dissected away using a sickle knife. If the uncinate process, however, is against the medial orbital wall, a frontal sinus probe may be used to gently peel it away from the orbit.
Sinus anatomy variants are important to recognize during review of preoperative imaging. These include variant ethmoid cells such as Haller cells, Onodi cells, and agger nasi cells. Haller cells are found below the orbital floor ( Fig. 2 A ) and should be noted to avoid intraorbital penetration. Agger nasi cells are anteriorly located ethmoid cells ( Fig. 2 B) and may be viewed anterior to the middle turbinate on coronal CT imaging ( Fig. 2 C) . Agger nasi cells are important in deciding optimal approach in surgery involving the frontal recess . Onodi cells are posteriorly located ethmoid air cells, lying directly superior to the sphenoid sinus ( Fig. 2 D). The optic nerve and carotid arteries may be located within or nearby Onodi cells; therefore, identifying whether they are present on preoperative CT is crucial in avoiding serious sequelae associated with injury of these structures .
Thorough discussion with patients of informed consent detailing risks, benefits, and alternatives should be undertaken prior to ESS. This includes meticulous discussion of potential intracranial and intraorbital injuries. Recent analysis of litigation related to iatrogenic orbital injury and cerebrospinal fluid (CSF) leak found that inadequate informed consents played a significant role in initiation of litigation. Factors such as orbital injury, CSF leak, bleeding, infection, and anosmia and hyposmia, should be discussed with patients , and documented in writing on informed consent forms and potentially on an ESS preoperative and postoperative instruction sheets to facilitate patient comprehension.
2
Preoperative considerations
Adequate preoperative evaluation is crucial for prevention of complications, as understanding variants in patient’s sinonasal anatomy and the extent of disease is necessary to facilitate appropriate decision making. ESS should not be undertaken without radiographic evidence of disease or maximal medical management. If complications were to occur and a patient initiates litigation, it may be nearly impossible to justify the necessity of ESS in such a case. Indeed, the degree of pathology on imaging is the strongest predictive prognostic factor after ESS . For symptomatic patients without radiographic evidence of disease, medical management alone may satisfy the goals of enhancing patient safety while minimizing liability. Utilizing the Lund–Mackay staging assists in CT interpretation in this regard, as a very low score (at or near 0) is less likely to gain maximal benefit from operative management .
Appreciating variants in skull base anatomy is essential to avoid intracranial complications . Length of the lamina lateralis ( Fig. 1 A ), categorized by Keros type , plays an important role in the preoperative review of CT imaging. A type 3 lamina lateralis has a depth of 8–16 mm. While this is found in a smaller percentage of the population, this skull base configuration is most often violated during ESS . In contrast, shorter and smaller lamina lateralis, such as type 1, are less often breached. The majority of patients fall somewhere in between these two extremes, with a Keros type 2 that has a depth between 4 and 7 mm.
Another critical aspect of evaluating skull base anatomy includes disease abutting the skull base. When this is noted on preoperative imaging, ESS surgeons can be more conservative by avoiding complete skeletonization of the skull base . This ensures that if there are skull base defects, direct and aggressive manipulation is kept to a minimum. Additionally, the slope ( Fig. 1 B) of the skull base and the presence of dehiscence ( Fig. 1 C) should be noted on preoperative imaging.
Location of the ethmoidal arteries should be identified on the preoperative CT. Generally, the posterior ethmoidal artery is located intracranially. The anterior ethmoidal artery, however, may be found in the ethmoid sinus mesentery in 20%–40% of cases, and is typically adjacent to the superior oblique muscle ( Fig. 1 D) . If transection is necessary, it is preferable to divide these arteries farther from the orbit to prevent retraction of the cut end of these vessels into the orbit which could lead to a retrobulbar hemorrhage. Dividing these arteries closer to the cribriform leaves a remnant vasculature that can be cauterized even in the case of partial retraction toward the orbit.
Examination of the medial orbital wall anatomy is also important preoperatively. The location of the lacrimal sac and duct and the presence of visible dehiscence of the lamina papyracea should be noted. The relationship of the uncinate process to the medial orbital wall is important. If adequate space exists between the uncinate process and the medial orbital wall, the former can be dissected away using a sickle knife. If the uncinate process, however, is against the medial orbital wall, a frontal sinus probe may be used to gently peel it away from the orbit.
Sinus anatomy variants are important to recognize during review of preoperative imaging. These include variant ethmoid cells such as Haller cells, Onodi cells, and agger nasi cells. Haller cells are found below the orbital floor ( Fig. 2 A ) and should be noted to avoid intraorbital penetration. Agger nasi cells are anteriorly located ethmoid cells ( Fig. 2 B) and may be viewed anterior to the middle turbinate on coronal CT imaging ( Fig. 2 C) . Agger nasi cells are important in deciding optimal approach in surgery involving the frontal recess . Onodi cells are posteriorly located ethmoid air cells, lying directly superior to the sphenoid sinus ( Fig. 2 D). The optic nerve and carotid arteries may be located within or nearby Onodi cells; therefore, identifying whether they are present on preoperative CT is crucial in avoiding serious sequelae associated with injury of these structures .
