19
Ophthalmologic Complications
of Endoscopic Sinus Surgery
Successful endoscopic sinus surgery requires a thorough knowledge of the area. The intimate anatomical relations between the orbit and ethmoid sinus is of paramount importance in the management of paranasal sinus disease. Vital structures supporting visual function pass adjacent to nasal and sinus passages with little more then mucosal lining and the thin bony lamina separating them. These barriers may be breached by inflammatory reactions, neoplastic processes, or trauma. Because of the importance of the orbit and its contents and this relationship, this chapter discusses the anatomy of the region and the potential complications and their management.
The ethmoid is an unpaired midline bone situated between the orbits. In the coronal view, the central portion of the ethmoid is shaped like a cross. The vertical arm is formed by the nasal septum inferiorly and the crista galli superiorly. On either side, the horizontal arm forms the cribriform plate and fovea ethmoidalis. Suspended from the horizontal arms are the pneumatized ethmoid sinus labyrinth.1
The lateral wall of each labyrinth is composed of the lamina papyracea separating the air cells from the orbit. Along the orbital surface of the lamina papyracea lie the medial rectus muscles and above it the superior oblique muscle. In the posterior orbit, the optic nerve passes close to the lamina papyracea adjacent to the posterior ethmoid air cells. Bansberg et al2 found that 8% of the posterior ethmoid sinus air cells override the ipsilateral sphenoid sinus and are juxtaposed to the optic nerve on the medial side and that the intracanalicular optic nerve is at risk during extirpation of these air cells. In addition, the optic nerve is relatively fixed in position as it enters the bony optic nerve canal at the orbital apex. Therefore, the optic nerve cannot easily be pushed aside and escape direct mechanical injury from surgical instruments introduced into the area. Surgical trauma to the vascular supply of the optic nerve may result in ischemic optic neuropathy.
The medial wall of the ethmoid labyrinth is formed by the thin lamina of the bone surrounding each air cell. The uppermost air cells are capped by the orbital process of the frontal bone forming the roof or fovea ethmoidalis.
The middle turbinate is suspended from each horizontal ethmoid arm. Anteriorly, the origin of the turbinate separates the cribriform plate medially from the fovea ethmoidalis laterally. The anterior and posterior ethmoid arteries arise from the ophthalmic artery as it courses through the superior medial orbit. The vessels pass through the foramina within the frontal ethmoid suture lines at the upper edge of the lamina papyracea. The ethmoid arteries pass across the superior ethmoid sinus, enter the anterior cranial fossa, and pass into the nose just below the cribriform plate. Injury to the ethmoid arteries as they penetrate the periorbita is the major cause of orbital hemorrhage during ethmoid sinus surgery.
Anteriorly, the lacrimal fossa and sac lie in the medial orbit between the anterior and posterior lacrimal crests. The most anterior ethmoid air cells lie anterior to the middle turbinate and may invade the lacrimal bone and frontal process of the maxillary bone. Intranasally, the lacrimal fossa and canal are situated behind the thin vertical ridge of bone just anterior to the tip of the middle turbinate, the membranous portion of the middle meatus and bulla ethmoidalis. The bony nasal lacrimal canal passes within the frontal process of the maxillary bone and along the medial antral wall, exiting into the inferior meatus near the junction of the anterior and middle thirds of the inferior turbinate. The canal is accessible to damage from surgery in the medial antral wall or the most anterior ethmoid air cells.
Preoperative evaluation is important in preventing complications. Patients should be screened for potential risk of hemorrhage. Appropriate laboratory studies, including prothrombin time, partial thromboplastin time, platelet count, and bleeding time, are required in the presence of a history of bleeding disorders. All aspirin, ibuprofen, and other drug products that impair clotting should be discontinued at least 2 weeks before surgery. Medical problems such as hypertension and diabetes should be controlled. Preoperative CT scans should be reviewed for the presence of possible dehiscence in the lamina papyracea, as well as for study of the architecture of the ethmoidal labyrinth, the orbits, and their contents.
A screening history for eye disease as well as documentation of visual acuity and extraocular motility is most helpful. At the time of surgery, the eyes should not be covered or draped so that the globe may be palpated. This may be helpful in identifying defects in the lamina papyracea.
PEARL
For the patient having surgery under general anesthesia, the eyes are taped closed with a small strip of ½-inch hypoallergenic tape. The globe is palpated prior to injecting any local anesthesia and starting the surgery. This gives the surgeon a baseline to the tension of the orbit. The globe is palpated periodically during surgery and at the conclusion.
Traditional ethmoidectomy and sinus surgery are relatively safe procedures, but major and fatal complications may occur. In 1000 intranasal ethmoidectomies, Freedman and Kern3 report a low incidence of complications (2.8%), most of them of a minor type. In 1990, Friedman and Katsantonis4 also reported a low incidence of complication secondary to intranasal ethmoidectomies, (2.08% minor, 0.94% major). Intracranial and orbital complications are rare.
In 1987, Stankiewicz5 reported his experience with endonasal sinus surgery and indicated a complication rate of 28% in 90 patients (17% in 150 ethmoidectomies). In 1989, Stankiewicz6,7 again discussed complication rates in 3000 ethmoidectomies performed in 180 patients. His overall complication rate had dropped to 9.3%. Most complications were minor. However, two cases had cerebrospinal fluid leaks, and one case of temporary blindness occurred. The author credits the low incidence of complications in the latter group of patients to experience.
Schaefer et al8 reported an incidence of 14% minor complications and 0% major. In 458 procedures, Levine9 had 8.3% minor complications and 0.7% major. Most major complications reported are CSF leaks.
In a study by May et al,10 the incidence of complications of endoscopic sinus surgery in 2108 patients was compared with complications in 11 other series of patients grouped together (2583 total) and with a series of patients who underwent traditional endonasal sinus surgery (2110 total). The overall incidence of major complications in all three groups were not statistically different. There was, however, a statistically significant difference in the incidence of orbital complications. Retrobulbar hematoma was significantly higher for traditional sinus surgery (0.47%) compared with endoscopic sinus surgery (0.05% May et al, 0.12% other ESS). It is possible that the higher incidence of this complication associated with traditional surgery is due to the greater extent of surgery for more advanced disease based on touch rather than direct visualization in the posterior ethmoid compartment with greater risk of posterior penetration.
The incidences of minor complications were significantly different for the three groups. The most common minor complication was orbital violation that occurred most frequently during the time of uncinectomy as was manifested as ecchymosis, emphysema, or was asymptomatic.
Table 19–1 lists the reported complications found in this study.
Minor |
Temporary, requiring no treatment Subcutaneous periorbital emphysema Periorbital ecchymosis (preseptal) Dental or lip pain or numbness Temporary, corrected with treatment Bronchial asthma Adhesions (symptomatic) Epistaxis requiring packing Infection: -frontal, maxillary, sphenoid sinus Permanent and not correctable (present beyond 1 year) Dental or lip pain or numbness Loss of smell |
Major |
Corrected with treatment Orbital hematoma (postseptal) Loss of vision Diplopia Ephiphora (requiring dacryocystorhinostomy) Carotid artery injury Hemorrhage requiring transfusion Cerebrospinal fluid leak Meningitis Brain abscess Focal brain hemorrhage Permanent despite treatment Death Blindness Diplopia Stroke Central nervous system deficit |
If the visual function is intact, ice compresses, elevation of the head of the bed, and close observation are indicated in the recovery room. If the visual function is compromised, intranasal packing must be removed. This will decrease intraocular and intraorbital pressure by allowing orbit hemorrhagic soft tissue to prolapse through the medial wall defect into the previous space occupied by the intranasal packing. In addition, the lateral canthotomy with lysis of the superior-inferior canthal tendon should be performed. The released lateral canthal tendon will allow forward displacement of the eyelids and globes with a subsequent decrease in intraocular and intraorbital pressure. This frequently leads to a rapid recovery of visual acuity and reversal of the previous afferent pupil defect. If the visual function continues to be compromised, blunt orbital dissection may release entrapped air or blood under high pressure for the orbital soft tissues. Frequently these maneuvers can be quickly accomplished with local anesthesia at the bedside in the recovery room in those patients who have lost vision after endoscopic sinus surgery. To control continued active bleeding or persistent decreased vision, further orbital surgery is indicated in the operating room. This may include an orbital apex decompression by further removal of the medial orbital wall and orbital floor with inspection of the intranasal space to control bleeding.
PEARL
An endoscopic orbital decompression is performed. Clots are suctioned from the nasal and sinus cavity. A fracture is made in the lamina papyracea, and the lamina papyracea is removed in an “eggshell” fashion using a Freer elevator. The bone is removed superiorly to the orbital roof and inferiorly to the infraorbital nerve. If necessary, incisions are made in the periorbital to decompress the globe.
