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ORBITAL COMPLICATIONS OF RHINOSINUSITIS By Dr. Firas M. Hassan F.I.B.M.S Otolaryngologist Introduction Complication of rhinosinusitis may be defined as any adverse progression of chronic or acute bacterial infection beyond the paranasal sinuses. — The incidence of rhinosinusitis-related complications has fortunately decreased since the introduction of antibiotics, but they result in devastating consequences if they are not promptly recognized and treated. They are often categorized based on orbital, intracranial, or osseous involvement. In general, computed tomography (CT) is considered ideal for radiographical evaluation of the orbit while magnetic resonance imaging (MRI) is better utilized for the intracranium. Its close proximity to the paranasal sinuses makes the orbit the most commonly involved structure in rhinosinusitis-related complications, encompassing between 60-75% of such events. This is usually attributed to the ethmoid sinuses although the frontal and maxillary sinuses may occasionally contribute to these conditions. The orbit is often the first to experience sequelae of rhinosinusitis in light that the bony lamina papyracea and the fibrous periorbita and orbital septum are the only major anatomic barriers protecting the orbit from direct extension of the inflammatory and infectious changes occurring in the neighboring sinuses. Furthermore, the valveless superior and inferior ophthalmic veins facilitate a relatively unimpeded route for infectious thrombophlebitis to travel past the periorbita and affect the orbital contents. Children tend to experience orbital complications more than the adult population, but they do not always exhibit typical clinical findings suggestive of acute infection such as complaints of pain or a general deterioration, and leukocytosis is found only in approximately half of cases. Individuals younger than seven years of age are usually afflicted solely with orbital manifestations while older children often experience both orbital and intracranial complications. This difference is thought to be related to the age-related sinus development of the frontal sinus. Streptococcus and Staphylococcus species are the more commonly responsible microbial agents involved in pediatric orbital complications, while Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis usually affect adult patients. Chandler devised a classification scheme that categorizes the various forms of rhinosinusitis-related orbital complications in to: 1. Preseptal cellulitis Inflammation does not extend beyond the orbital septum (the site at which the medial orbital periosteal reflection attaches to the medial eyelid at the tarsal plate). 2. Postseptal cellulitis or orbital cellulitis without abscess Inflammation extends into the tissues of the orbit. 3. Subperiosteal abscess There is abscess formation deep to the periosteum of the orbital bones, usually the lamina papyracea. 4. Orbital abscess There is abscess formation within the orbit which has breached the periosteum. 5. Cavernous sinus thrombosis/abscess The inflammatory process has extended through the optic foramen into the cavernous sinus which thromboses and possibly progresses to abscess formation. Despite five distinct processes described with this classification scheme, it is important to appreciate that they are not mutually exclusive and may occur concurrently. Management of Orbital Complications Clinical presentation history of a mild upper respiratory tract infection accompanied or followed by swelling around the eye. It is far more common in children (50 percent under six years) and young adults (76–85 percent under 20). Visual problems may be present if the problem is stage three (subperiosteal abscess) or beyond, and specific enquiries should be made regarding visual acuity and colour vision, problems which might indicate a compromise of optic nerve function. At stage five (cavernous sinus thrombosis), as well as chemosis, periorbital oedema and proptosis, there will be a progressive opthalmoplegia (lateral gaze may be affected first) and visual impairment (possibly resulting in total blindness) due to direct cranial nerve involvement, together with other symptoms including headache and trigeminal parasthesia. These are often bilateral, especially proptosis. Physical examination Clinical endoscopic examination of the nose should be performed to help determine the site and extent of disease. Formal ophthalmological assessment of: o full range of eye movements, o degree of proptosis, o relative afferent pupillary defect, o visual acuity (using a Snellen chart), o colour vision, o inspection of the optic disc should be made. This assessment should be repeated daily where clinically appropriate. Where there is increasing concern, six-hourly monitoring of the full range of eye movements, visual acuity and colour vision should be undertaken in conjunction with regular temperature and pulse measurements. For ongoing monitoring of treatment, the simple regular measurement of temperature should not be forgotten, as any persisting infection may manifest itself as sustained or ‘spiking’ pyrexia. Such a situation would indicate further radiological investigation. Investigations Radiological investigation The main aim of radiological investigation will be to define the extent and site of the disease. If there is full ocular movement and normal vision (including colour vision), no immediate radiological investigation is indicated, unless there are concerns about an intracranial problem also being present. Appropriate investigations should be undertaken to confirm the presence, and site of, a suspected surgically treatable abscess prior to drainage. The investigation of choice is a high definition computed tomography (CT) scan taken in both coronal and axial planes. Haematological investigations The place of haematological investigations is: 1. to help ensure there is no serious underlying disease process such as a leukaemia; 2. to act as an assessment of fitness for surgery; 3. to monitor the patient's response to treatment. Other investigations It will often be helpful to set up blood cultures as soon as possible, preferably prior to, but not at the expense of, antibiotic treatment. Similarly, the culture of any purulent material found in the nose on clinical examination at the time of surgery in the sinuses or from an abscess is important. In patients with a diagnosed complication of rhinosinusitis, urinalysis should be undertaken to detect diabetes mellitus, which might have led to immunocompromise. Treatment Medical tratment Unless an abscess is demonstrated by radiological or other investigation, nonsurgical management of rhinosinusitis complications would usually be the first choice. The exception to this would be when vision was affected by pressure on the optic nerve resulting from surrounding inflammation without abscess formation. The aim of medical management is two-fold: (1) to control and eliminate the disease process directly relating to the complication; (2) to control and eliminate the primary rhinosinusitis. Although antimicrobials will form the mainstay of medical treatment, many clinicians would advocate specific treatment for nasal decongestion with the aim of facilitating resolution of the underlying rhinosinusitis. A typical decongestant regime would be the intranasal administration of ephedrine 0.5 percent drops, two drops six-hourly to the affected side of the nose. However, there is little evidence to support this as an addition to treatment. The selection of antibiotics will usually be made before any information regarding the infecting organism or its sensitivity to antimicrobials is available. The choice of antibiotics, therefore, needs to be of a broad enough spectrum to cover the likely infecting organisms, but at the same time be reasonably selective in order to minimize the development of microbe resistance. Accordingly, a regime of intravenous cephalosporin with metronidazole would be an appropriate first choice. Initially, medical management should be planned for 24 hours, with frequent monitoring of the patient over this period as described above. If there is not a significant clinical improvement in the first 24 hours of medical treatment, surgical intervention should be considered. Additionally, if there is clinical deterioration, then emergency surgical intervention is likely to be appropriate. For orbital complications, intravenous antibiotic administration should continue until clinical improvement is well established and only then should oral treatment be substituted. A good indication of established improvement is the absence of pyrexia for a period of 24 hours combined with a general clinical improvement. There is little good evidence as to how long oral antibiotics should be continued, but a period of 7–14 days would usually be effective. In the case of cavernous sinus thrombosis, the addition of anticoagulation to antibiotic therapy and appropriate surgical drainage of any collection may be beneficial in preventing mortality, but not morbidity. In all instances, the importance of working with and consulting other clinical colleagues should not be overlooked. An appropriate combination of ear, nose and throat (ENT) surgeons, paediatricians, ophthalmologists and neurologists should be involved in the management from the time the patient is admitted to hospital. Surgical treatment The surgical treatment of patients with complications of rhinosinusitis can be conveniently divided into that necessary for the treatment of the rhinosinusitis and that necessary for the treatment of the complication. These are likely to be carried out at the same time, but may involve more than one team of surgeons. Infections with cellulitis alone are likely to settle with conservative treatment, whereas patients with proptosis but normal eye movements and visual acuity are likely to require surgery. Orbital cellulitis is almost always secondary to ethmoid rhinosinusitis, but may occur with frontal rhinosinusitis. Some surgeons suggest that endoscopic ethmoidectomy together with removal of the lamina papyracea and perinasal drainage of the orbital abscess is sufficient treatment. However, unless the surgeon is extremely familiar with endoscopic nasal surgery, it is probably easier and wiser to use an external approach. This has the advantage of allowing an assistant to help keep the operative field clear. If an external approach is used, the conventional Lynch–Howarth approach for an external ethmoidectomy will allow the surgeon to drain the subperiosteal abscess ‘on the way’ to carrying out the definitive ethmoidectomy. Drainage of the abscess can be established using drainage tubes placed to drain either into the nasal cavity (fixing to the septum) or externally through the medial canthal incision. The former, endonasal, siting is likely to result in less cosmetic deformity than leaving an external drain. Although simple drainage of an orbital abscess without any ethmoid surgery (relying on medical treatment to deal with the rhinosinusitis) may be effective, it is probably better to perform both definitive surgery for the rhinosinusitis, as well as surgery for the orbital abscess at the same time. Treatment of specific types of Orbital Complication Preseptal Cellulitis Eyelid edema and erythema is quite noticeable with preseptal cellulitis, but a small eyelid abscess may occasionally be encountered. A key characteristic is the integrity of both extraocular muscle movment and inherent vision. CT images will only reveal diffuse thickening of the eyelids and conjunctiva, all of which should occur superficial to the orbital septum. As such, medical therapy is typically sufficient to adequately treat cases of preseptal cellulitis with the initiation of intravenous antibiotics, application of warm compresses, and elevating the head of the bed. Additionally, facilitating sinus drainage with nasal saline irrigations, decongestants, and mucolytics may provide some benefit. Orbital Cellulitis Progression of the inflammatory changes deep to the orbital septum constitutes orbital cellulitis. While eyelid edema and erythema will also be present, the eye may demonstrate proptosis and chemosis. Some patients may complain of pain or diplopia due to impaired extraocular muscle movement, but the vision itself remains unaffected. Low-attenuation adjacent to the lamina papyracea is often noticed on CT, but a discrete abscess should not be encountered. As with preseptal cellulitis, medical management with antibiotics and nasal drainage is often successful. Clinical reassessment and surgical drainage should be considered if visual acuity is at 20/60 or worse or if there is no improvement or even symptomatic progression within 24 hours. Subperiosteal Abscess This subperiosteal collection typically displaces orbital contents inferiorlylaterally with subsequent exophthalmos. While some may exhibit normal extraocular muscle movement early on, patients will present with proptosis, chemosis, and ophthalmoplegia leading to complaints of orbital pain, diplopia, and reduced visual acuity. Some abscesses may extrude through the eyelid. CT imaging is diagnostically accurate in 86-91%, revealing a rim-enhancing hypodensity adjacent to the lamina papyracea with mass-effect. Acquiring the assistance from the ophthalmologist and pursuing prompt surgical intervention is clearly warranted since drastic visual sequelae may result if this condition is not addressed, especially in the face of progressively worsening vision or extraocular muscle movement or if there is a lack of improvement after 24 hours. There is a small contingent that advocates medical therapy alone may be sufficient in 50-67%, but this notion is usually reserved for children less than four years of age with small abscesses. Ultimately, a combined surgical and medical treatment plan should achieve complete resolution in 95-100% of cases. The chosen surgical approach varies by surgeon but is often set with the goal of removing the lamina papyracea and opening the ethmoid cells to remove the abscess and facilitate sinus drainage. Most prefer an external incision, such as the Lynch incision, along the medial-superior aspect of the orbital rim to provide access to the subperiosteal plane. Antral wash-out can be used as an adjuvant for the external approach. An endoscopic approach may be ideal for more medially located collections, allowing the removal of the lamina papyracea while sparing the patient an external facial incision. Orbital Abscess An abscess formation within the orbital tissues themselves will present with a similar clinical picture as a subperiosteal abscess. Ophthalmoplegia and reduced visual acuity is also present, but the degree of exophthalmos and chemosis is felt to be more severe compared to that experienced with subperiosteal abscesses. A similar rim-enhancing hypodensity is noted on CT, but it is not relegated solely to near the lamina papyracea. In conjunction with draining the responsible paranasal sinuses, incising the periorbita and draining the intraconal abscess with the assistance with ophthalmology is paramount to avoid the significant risk of irreversible blindness. Cavernous Sinus Thrombosis Cavernous sinus thrombosis often manifests with similar signs as an orbital abscess as the inflammatory and infectious process traverses posteriorly from the orbit toward the intracranium. Orbital pain, proptosis, chemosis, ophthalmoplegia, and impaired vision are also present, but the key distinguishing feature is that there is also contralateral involvement. Poor venous enhancement may be noted on CT, but the presence of heterogeneity and increased size of the cavernous sinus on MRI is considered a more confirmatory radiographical finding. Cavernous sinus thrombosis is often associated with meningismus and sepsis, and not surprisingly carries a mortality rate up to 30%. High-dose intravenous antibiotics that can cross the blood-brain barrier and surgical drainage of the paranasal sinuses are clearly warranted, but the use of anticoagulation to prevent thrombus propagation has been highly controversial. Algorithm showing the management of orbital complications References 1. Bailey BJ, Johnson, JT, Newlands SD, eds. Head and Neck Surgery – Otolaryngology, 4th Ed. Philadelphia: Lippincott, 2006:307-11, 406, 493503. 2. Robert Slack nd Richard Sim, Complications of rhinosinusitisr, ScottBrown's Otorhinolaryngology , Head and Neck Surgery , volume 2, 7th edition. Michael Gleeson. 2008, 120: 1539-46. 3. Chandler JR, Langenbrunner DJ, Stevens ER. The pathogenesis of orbital complications in acute sinusitis. Laryngoscope 1970; 80: 1414-28. 4. Herrmann BW, Forsen JW Jr. Simultaneous intracranial and orbital complications of acute rhinosinusitis in children. Int J Pediatr Otorhinolaryngol 2004; 68:619-25. 5. Lanza DC, Kennedy DW. Adult rhinosinusitis defined. Otolaryngol Head Neck Surg 1997; 117:S1-S7. 6. Lee KJ, ed. Essential Otolaryngology - Head and Neck Surgery, 9th Ed. New York: McGraw-Hill, 2008. pp 365-6. 7. Oxford LE, McClay J. Complications of acute sinusitis in children. 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