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Ocular motility complications after endoscopic sinus surgery with powered cutting instruments M. TARIQ BHATTI, MD, CARLA M. GIANNONI, MD, EILEEN RAYNOR, MD, RAMIN MONSHIZADEH, MD, and LAWRENCE M. LEVINE, MD, Gainesville and Jacksonville, Florida OBJECTIVE: The purpose of this study was to describe 2 unique cases of ocular motility dysfunction after powered endoscopic sinus surgery and identify potential risk factors for extraocular muscle injury. STUDY DESIGN: Interventional case series. RESULTS: Patient 1 developed a restrictive global ophthalmoplegia after inadvertent entry into the medial orbit during powered endoscopic sinus surgery. Patient 2 had complete loss of adduction of the left eye as a result of transection of the medial rectus muscle by a powered cutting instrument. CONCLUSIONS: Despite advances in endoscopic sinus surgery technique and instrumentation, serious ophthalmic complications may still occur. Inadvertent entry into the medial orbital wall can result in ocular motility complications. Furthermore, it is possible that attraction of orbital contents into the tip of a powered cutting instrument may occur without significant entry into the orbital cavity. SIGNIFICANCE: It is important for endoscopic sinus surgeons to be aware of the intimate anatomical relationship between the orbit and sinuses, as well as the potential risks of the current instruments used in endoscopic sinus surgery. (Otolaryngol Head Neck Surg 2001;125:501-9.) Recent refinements in fiberoptic technology have allowed the use of endoscopic surgical techniques within previously inaccessible structures of the body. Endoscopic guided procedures have gained enormous popularity in the field of otolaryngology, particularly in the diagnosis and treatment of paranasal sinus disease.1 Endoscopic sinus surgery (ESS) emphasizes removal of diseased tissue at sites of obstruction in the ostiomeatal complex, thereby reestablishing the natural mucociliary flow and promoting the recovery of viable inflamed mucosa. Since its introduction, ESS has advanced in terms of its clinical indications, techniques, and instrumentation. 1,2 The confined working spaces of the paranasal sinuses, combined with the close relationship to the orbit, cranium, and surrounding neurovascular structures, potentiates the risk for catastrophic complications.1,3,4 Therefore, it is not surprising that ESS is a leading cause of malpractice litigation in otolaryngology.5 Ophthalmic complications after sinus surgery are well known; double vision is one of the more devastating. A review of the English-language literature identified 12 cases of ocular misalignment associated with ESS using conventional, nonpowered instrumentation.6-16 We describe the first 2 cases of ocular motility complications after surgery (PESS) and discuss a novel mechanism of injury. The previously reported cases are reviewed and compared to identify the potential risk factors for extraocular muscle injury. From the Departments of Ophthalmology (Drs Bhatti, Monshizadeh, and Levine), Neurology (Dr Bhatti), Otolaryngology (Dr Giannoni), and Pediatrics (Drs Giannoni and Levine), University of Florida, Gainesville; and the Department of Otolaryngology (Dr Raynor), University of Florida, Jacksonville. Presented as a poster at the Annual Meeting of the American Academy of Otolaryngologists–Head and Neck Surgery, Denver, CO, September 9-14, 2001. Supported in part by an unrestricted departmental grant from Research to Prevent Blindness, Inc. (New York, NY). Reprint requests: M. Tariq Bhatti, MD, Department of Ophthalmology, University of Florida College of Medicine, Box 100284 JHMHSC, Gainesville, FL 32610-0284; e-mail, tbhatti@eye1.eye.ufl.edu. Copyright © 2001 by the American Academy of Otolaryngology– Head and Neck Surgery Foundation, Inc. 0194-5998/2001/$35.00 + 0 23/1/119514 doi:10.1067/mhn.2001.119514 CASE 1 An 11-year-old boy was evaluated for chronic sinusitis and epistaxis. Computed tomography (CT) study of the sinuses revealed a polypoid soft tissue mass within the right nasal cavity with partial involvement of the right maxillary sinus and ostiomeatal complex. With the patient under general anesthesia, an endoscopic middle meatal antrostomy and polypectomy was performed. The right middle turbinate was medialized and the maxillary ostium identified with a probe. During debridement of the uncinate process with a powered cutting instrument, a defect of the lamina paprycea with protrusion of orbital fat into the sinus was noted. No further manipulation was performed and the maxillary sinus was irrigated with normal saline solution. In the immediate postoperative period, right periorbital edema with right upper eyelid ptosis was noted. Manual elevation of the eyelid resulted in the subjective complaint of horizontal binocular diplopia. After a 10-day course of systemic steroids, the periorbital swelling and ptosis improved, however, the double vision persisted. The patient was then referred to the neuro-ophthalmology service for further evaluation. On examination, visual acuity measured 20/25 in both eyes with normal color vision. Pupillary reactions and visual field testing were normal. Exophthalmometry revealed 2 mm of right enophthalmos and deepening of the superior eyelid crease sulcus. Slit lamp examination revealed a right temporal subconjunctival hemorrhage. Motility of the left eye was normal, but the right eye revealed significant limitation in all gazes (Fig 1). Forced duction testing of the globe demonstrated restriction in all directions. The optic nerves and retina were normal. Sensation of the cheek and forehead to touch were intact. CT study of the orbits revealed a defect of the medial orbital wall and fullness of the right medial rectus muscle with adjacent signal abnormality (Fig 2). Magnetic resonance imaging (MRI) confirmed a medial orbital wall defect with abnormal signal extending from the medial to the inferior rectus muscles (Fig 3). No surgical intervention was recommended, and 6 months later the patient continued to have double vision with only slight improvement of motility. Strabismus surgery is being contemplated. CASE 2 A 56-year-old woman complained of pain and pressure over her left eye. Four years previously she had undergone sinus surgery. A CT of the sinuses revealed frontoethmoid sinusitis and a prolonged course of antibiotics did not relieve her symptoms. An office nasal endoscopy verified mucosal thickening of the left osteomeatal complex. A left endoscopic ethmoidectomy, frontal sinusotomy, and maxillary antrostomy was recommended. Intraoperatively, a microdebrider was used to enlarge the frontal recess and maxillary ostia. Resection of the uncinate process and ethmoid cells was also performed. No intraoperative difficulties were reported by the surgeon. However, a large exotropia with the inability to adduct the left eye was noted in the recovery room. CT scan of the orbits revealed bisection of the belly of the medial rectus muscle (Fig 4). Six days later she was referred to the University of Florida strabismus clinic. On examination, visual acuity was 20/30 in both eyes. Pupillary responses and peripheral vision were normal. Slit lamp biomicroscopy was normal in both eyes. Extraocular motility of the right eye was full. The left eye had complete loss of adduction with normal elevation, depression, and abduction. In primary gaze, there was a 90 prism diopter left exotropia (Fig 5A). The patient underwent a left anterior medial orbitotomy in an effort to retrieve the distal end of the medial rectus muscle. The anterior one third of the muscle was found to be attached to the globe, but a search for the distal end led to the discovery of only fine shreds of tissue that could not be brought forward for reattachment to the proximal end. Two weeks later while awaiting strabismus surgery, botulinum toxin was injected into the left lateral rectus muscle to prevent contracture. Four weeks later, a medial transposition of the left inferior and superior recti muscles with injection of botulinum into the left lateral rectus was performed. Postoperatively she did well and 6 months later was free of double vision in primary gaze, requiring only a small vertical and horizontal prism correction, but with limited movement of the left eye (Fig 5B). DISCUSSION Approximately 138,000 endoscopic ethmoidectomies were performed in 1996,13 and currently ESS is the procedure of choice for medically resistant sinusitis. Its usefulness has extended to various diseases of the sinuses, orbit, and skull base.1,2 Increased visualization, superior cosmesis, and decreased postoperative recovery time justify the use of ESS in almost all diseases of the paranasal sinuses. Despite these advantages, the complication rate of ESS remains similar to traditional techniques such as the Caldwell-Luc or intranasal approaches.14 The growing popularity and refinement of ESS techniques has been paralleled by advancements in instrumentation. Initially, grabbing forceps were used to strip away mucosa and extirpate soft tissue, followed by the development of suction forceps.1 In 1994, Setliff and Parsons15 introduced a revolutionary powered cutting instrument termed the “hummer,” also known as the shaver, microresector, or microdebrider. Modified from a preexisting temporomandibular joint instrument, it was introduced for use in ESS to allow precise surgeon control, constant and clear visualization, minimal intraoperative bleeding, and reduced surgical time. The handpiece is constructed of a hollow metal shaft allowing for continuous irrigation-aspiration and a distal blunt end containing a slightly recessed oscillating or rotating blade. The cutting and aspiration rates are adjustable with a variety of tip diameters, angles, and blade designs, allowing for various levels of surgical aggressiveness during tissue removal.16 Complications associated with ESS are well known and the subject of much concern to the endoscopic sinus surgeon.3,4 Ophthalmic injuries during endoscopic or traditional sinus surgery can involve the nasolacrimal system, pupil, optic nerve, orbital vessels, and extraocular muscles or their neurovascular supply. The specific site of injury varies according to the procedure and technique used. Including the present 2 cases, 14 cases of ocular motility complications have been reported during ESS (Table 1). The medial rectus muscle was the most common extraocular muscle injured (11 of 14).6-10,12 Direct injury or laceration of the medial rectus muscle was present in 9 cases. Two cases were caused by entrapment of the muscle within a defect of the medial orbital wall.6 Only 4 cases had concomitant visual loss or orbital hemorrhage.6,9,12 The cases reported in this article shared 2 characteristics. First, a powered cutting instrument was used during ESS and second, the site of entry into the orbit was the medial wall. Despite these similarities, the resultant clinical presentations and mechanisms of injuries were different. In our first patient, forced duction testing during ophthalmologic examination revealed a restrictive process in the orbit. However, it was not confined to the horizontal plane as expected from an isolated medial rectus muscle restriction or entrapment. The limitation of movement in all gazes was more consistent with a “fixed globe.” Such ophthalmoplegia has been previously reported, but in the setting of nonendoscopic sinus surgery complicated by orbital hemorrhage with scarring and adhesions of the extraocular muscles to the surrounding bone and soft tissues.17-19 There was no evidence of an orbital hemorrhage in our patient, therefore simple violation of the lamina paprycea and intraoperative exposure of the orbital fat did not appear to be the only factor in the development of his ophthalmoplegia. We suspect it was caused by the fat adherence syndrome, a result of disruption of Tenon’s capsule leading to decompartmentalization of the extraconal fat promoting adhesions between the periorbita, orbital fat, sclera and extraocular muscles (Fig 6).20 Both MR and CTdemonstrated disruption of the normal fascial planes between the medial orbital wall and eyeball. In addition, the MR showed loss of the normal fat signal in the inferomedial orbit on the conventional T1-weighted images and increased signal on the fat-suppression images suggesting fibrosis. Arguably, a similar scenario could have resulted from an inflammatory foreign body reaction, but no foreign substance was introduced into the orbit at the time of surgery in our patient.21 The mechanism of injury in our second patient was straightforward. The belly of the medial rectus muscle was inadvertently severed, as evidenced by the CT and the intraoperative “chewed up” appearance of the muscle. Radiologically it was difficult to identify the exact site of the medial wall defect, suggesting that the powered cutting instrument did not enter the orbit completely. Such a small defect in the orbital wall could have been inadvertently created by the tip of the instrument or resulted from a pre-existing dehiscence. We hypothesize that the blade of the instrument caught an edge of the medial orbital bone and engaged the medial rectus muscle into its tip, without substantially entering the orbital cavity (Figs 7 and 8). It is important to realize that the medial rectus muscle can be vulnerable to injury in the region of the middle ethmoids due to its close proximity to the orbital wall, or as the result of a congenital or acquired bowing of the wall itself.22 The potential for powered cutting instruments to cut edges of thin bone and engage soft tissues into its blade has been shown experimentally, using cracked egg shells and oyster muscles to simulate the lamina paprycea and soft tissues of the sinuses, respectively.23 Clinically, this mechanism was used to explain a case of subarachnoid hemorrhage as the result of inadvertent aspiration and tearing of the dura during PESS.24 A potential risk factor in this case and in our patient may have been the surgeon- controlled rate of aspiration of the powered cutting instrument. Higher rates increase the efficacy of mucosal clearance but also theoretically increase the risk of attracting and damaging vital paranasal sinus structures. The intention of this article is not to evaluate the optimum treatment of patients with ocular misalignment after ESS. Given the limited number of cases described, the variable clinical presentations, and mechanisms of injury, treatment should be individualized. If an identifiable laceration to a particular muscle is evident, immediate surgical correction by reattachment of the muscle should be attempted.12 In our first case, because the eyes were relatively straight in primary position, strabismus surgery was not offered as an urgent intervention. In our second case, the double vision in primary position was profound with an identifiable site of injury prompting an unsuccessful attempt at retrieval of the distal medial rectus muscle. Eventually, binocular vision was recovered after a medial transposition of the vertical extraocular muscles.Powered cutting instruments are an effective and efficient tool in the armamentarium of the endoscopic sinus surgeon. However, their use should be tempered with the knowledge that iatrogenic defects or natural dehiscences of the thin bones of the orbit may result in injuries to the orbital contents, particularly the extraocular muscles and their surrounding fascial attachments. Great care should be taken when working with powered cutting instruments in the region of the middle ethmoids. A thorough preoperative and intraoperative assessment of the medial wall of the orbit is recommended. Further experimental and clinical studies may help us better understand the dynamics and forces generated by these relatively new powered cutting instruments. REFERENCES 1. Kennedy DW, Senior BA. Endoscopic sinus surgery: a review.Otolaryngol Clin North Am 1997;30:313-30. 2. Davidson TM, Stearns G. Extended indications for endoscopic sinus surgery. Ear Nose Throat J 1994;73:467-74. 3. Stankiewicz JA. Complications of endoscopic sinus surgery and malpractice. In: Stankiewicz J, editor. Advanced endoscopic sinus surgery, 1st ed. St Louis: Mosby; 1995. p. 151-60. 4. Stankiewicz JA. Complications of endoscopic sinus surgery. Otolaryngol Clin North Am 1989;22:749-58. 5. Lund VJ, Wright A, Yiotakis J. Complications and medicolegal aspects of endoscopic sinus surgery. J Royal Soc Med 1997; 90:422-8. 6. Neuhaus RW. Orbital complications secondary to endoscopic sinus surgery. Ophthalmology 1990;97:1512-8. 7. Eitzen JP, Elsas FJ. Strabismus following endoscopic intranasal sinus surgery. J Pediatr Ophthalmol Strabismus 1991; 28:168-70. 8. Maniglia AJ. Fatal and other major complications of endoscopic sinus surgery. Laryngoscope 1991;101:349-54. 9. Corey JP, Bumsted R, Panje W, Namon A. Orbital complications in functional endoscopic sinus surgery. Otolaryngol Head Neck Surg 1993;109:814-20. 10. Penne RB, Flanagan JC, Stefanszyn MA, et al. Ocular motility disorders secondary to sinus surgery. Ophthalmol Plast Reconstr Surg 1993;9:53-61. 11. Carton A, Hislop S. Orbital floor injury with extraocular muscle entrapment following functional endoscopic sinus surgery. Br J Oral Maxillofac Surg 1999;38:82-3. 12. Trotter WL, Kaw P, Meyer DR, et al. Treatment of subtotal medial rectus myectomy complicating functional endoscopic sinus surgery. JAAPOS 2000;4:250-3. 13. Owings MF, Kozak LJ. Ambulatory and inpatient procedures in the United States, 1996. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Health Statistics, (1998) vital and health statistics. Series 13, data from the National Health Survey; no. 139. 14. May M, Levine HL, Mester SJ, et al. Complications of endoscopic sinus surgery: analysis of 2108 patients—incidence and prevention. Laryngoscope 1994;104:1080-3. 15. Setliff RC III, Parsons DS. The “hummer”: new instrumentation for functional endoscopic sinus surgery. Am J Rhinol 1994;8:275-8. 16. Setliff RC. New concepts and use of powered instrument (the “hummer”) for functional endoscopic sinus surgery, In: Stankiewicz J, editor. Advanced endoscopic sinus surgery, 1st ed. St Louis: Mosby; 1995. p. 161-70. 17. Griffiths JD, Smith B. Optic atrophy following Caldwell-Luc procedure. Arch Ophthalmol 1971;86:15-8. 18. Flynn JT, Mitchell KB, Fuller DG, et al. Ocular motility complications following intranasal surgery. Arch Ophthalmol 1979; 97:453-8. 19. Dutton JJ. Orbital complications of paranasal sinus surgery. Ophthalm Plast Reconstr Surg 1986;2:119-27. 20. Wright KW. The fat adherence syndrome and strabismus after retina surgery. Ophthalmology 1986;93:411-5. 21. Moore DF Jr, Grogan JB, Lindsey WH, et al. The myospherulotic potential of water-soluble ointments. Am J Rhinology 1995;9:215-8. 22. Lim JC, Hadfield PJ, Ghiacy S, et al. Medial orbital protrusion: a potentially hazardous anomaly during endoscopic sinus surgery. J Laryngol Otol 1999;113:754-5. 23. Ferguson BJ, DiBiase PA, D’Amico F. Quantitative analysis of microdebriders used in endoscopic sinus surgery. Am J Otolaryngol 1999;20:294-7. 24. Berenholz L, Kessler A, Sarfaty S, et al. Subarachnoid hemorrhage: a complication of endoscopic sinus surgery using powered instrumentation. Otolaryngol Head Neck Surg 1999;121:665-7. Written by: M. Tariq Bhatti, M.D. http://www.duke.edu/ |
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