- 1 Disease Entity
- 2 Diagnosis
- 3 Management
- 4 Additional Resources
- 5 References
Disease Entity[edit | edit source]
Orbital cellulitis is an inflammation of the soft tissues of the eye socket behind the orbital septum, a thin tissue which divides the eyelid from the eye socket. Infection isolated anterior to the orbital septum is considered to be preseptal cellulitis. Orbital cellulitis most commonly refers to an acute spread of infection into the eye socket from either the adjacent sinuses, skin or from spread through the blood.
Disease[edit | edit source]
Orbital Cellulitis (ICD-9 #376.01)
Etiology[edit | edit source]
Orbital cellulitis most commonly occurs when bacterial infection spreads from the paranasal sinuses, most often from the ethmoid sinus through the thin lamina papyracea of the medial orbital wall. It can also occur when an eyelid skin infection or an infection in an adjacent area spreads to the orbit or from an infection in the blood system. The drainage of the eyelids, sinuses is largely throughout the orbital venous system:more specifically, through the superior and inferior orbital veins that drain into the cavernous sinus. This venous system is devoid of valves and for this reason infection might spread, in preseptal and orbital cellulitis, into the cavernous sinus causing a sight threatening complication such as cavernous sinus thrombosis.
Risk Factors[edit | edit source]
Risk factors include recent upper respiratory illness, acute or chronic bacterial sinusitis, recent trauma, recent ocular or periocular infection, or systemic infection.
General Pathology[edit | edit source]
The orbital tissues are infiltrated by acute and chronic inflammatory cells and the infectious organisms may be identified on the tissue sections. The organisms are best identified by microbiologic culture. The most common infectious pathogens include gram positive streptococcal and staphylococcal species. In children younger than 9, the infections are typically from one organism; in children older than 9 and in adults, the infections may be polymicrobial with both aerobic and anaerobic bacteria.
The most common pathogens in orbital cellulitis, strep and staph are both gram positive. Streptococcal infections are identified on culture by their formation of pairs or chains. Streptococcal pyogenes (Group A Strep) requires blood agar to grow and exhibits clear (beta) hemolysis on blood agar. Streptococcus such as streptococcus pneumonia produce Green (alpha) hemolysis, or partial reduction of red blood cell hemoglobin. Staphyloccal species show a cluster arrangement on gram stain. Staphylococcus aureus forms a large yellow colony on rich medium in distinction to Staphylococcus epidermidis which forms white colonies. Gram negative rods can be seen in both orbital cellulitis related to trauma and in some older children or adults. Anaerobic bacteria such as peptococcus, peptostreptococcus, bacteroides can be involved in infections extending from sinusitis in adults or older children. Fungal infections with either mucor or aspergillus need to be considered in immunocompromised or diabetic patients; immunocompetent patients may also have fungal infections in rare cases.
Pathophysiology[edit | edit source]
Orbital cellulitis most commonly occurs in the setting of an upper respiratory or sinus infection. The human upper respiratory tract is normally colonized with Strep pneumoniae and infection can occur through several mechanisms. Strep pyogenes infections also occur primarily in the respiratory tract. The complex cell surface of this gram positive organism determines its virulence and ability to invade the surrounding tissue and incite inflammation. Staph aureus infections occur commonly in the skin and spread to the orbit from the skin. Staphylococcal organisms also produce toxins which help to promote their virulence and leads to the inflammatory response seen in these infections. The inflammatory response elicited by all these pathogens plays a major role in tissue destruction in the orbit.
Primary prevention[edit | edit source]
Identifying patients and effectively treating upper respiratory or sinus infections before they evolve into orbital cellulitis is an important aspect of preventing preseptal cellulitis from progressing to orbital cellulitis. Equally important in preventing orbital cellulitis is prompt and appropriate treatment of preseptal skin infections or even odentogenic infections before they spread into the orbit.
Diagnosis[edit | edit source]
The diagnosis of orbital cellulitis is based on clinical examination.The presence of orbital signs such as proptosis, pain with eye movements, ophthalmoloplegia, optic nerve involvement as well as fever and leukocytosis confirm the diagnosis.
History[edit | edit source]
The presence of a painful red eye, with lid edema in a child with a recent upper respiratory infection is the typical presentation of orbital cellulitis. Patient history should also include the presence of headache, orbital pain, double vision, progression of symptoms, recent upper respiratory symptoms (e.g. nasal discharge or stuffiness), pain over sinuses, fever, lethargy, recent periocular trauma or injury, family or health care contacts with MRSA, history of sinus, ear, or facial infections or surgery, recent ocular surgery, pertinent medical conditions, medications currently used, as well as the presence of diabetes mellitus and the immune status of the patient.Specific questions regarding any change in mental status, pain with neck movement, or nausea or vomiting should be asked.
Physical examination[edit | edit source]
The physical examination should include:
- Best-corrected visual acuity(BCVA).Decreased vision might be indicative of optic nerve involvement or could be secondary to severe exposure keratopathy or retinal vein occlusion.
- Color vision assessment to assess the presence of optic nerve involvement.
- Proptosis measurements using Hertel exophthalmometry.
- Visual field assessment via confrontation.
- Assessment of pupillary function with particular attention paid to the presence of a relative afferent pupillary defect(rAPD).
- Ocular motility and presence of pain with eye movements.Also, there might be involvement of the III, IV, and VI cranial nerve in cases of cavernous sinus involvement.
- Orbit exam should include documentation of direction of displacement of globe (a superior subperiosteal abscess will displace the globe inferiorly), resistance to retropulsion on palpation, unilateral or bilateral involvement
- Measurement of intraocular pressure (IOP).
- Slit-lamp biomicroscopy of the anterior segment if possible to look for signs of exposure keratopathy in cases of severe proptosis.
- Dilated fundus exam will exclude or confirm the presence of optic neuropathy or retinal vascular occlusion.
Signs[edit | edit source]
As a preseptal infection progresses into the orbit, the inflammatory signs typically increase with increasing redness and swelling of the eyelid with a secondary ptosis. As the infection worsens, proptosis develops and extraocular motility becomes compromised. When the optic nerve is involved, loss of visual acuity is noted and an afferent pupillary defect can be appreciated. The intraocular pressure often increases and the orbit becomes resistant to retropulsion. The skin can feel warm to the touch and pain can be elicited with either touch or eye movements. Examination of the nose and mouth is also warranted in order to look for any black eschar which would suggest a fungal infection.
Symptoms[edit | edit source]
Systemic symptoms including fever and lethargy may or may not be present. Change in the appearance of the eyelids with redness and swelling is frequently a presenting symptom. Pain, particularly with eye movement, is commonly noted. Double vision may also occur.
Diagnostic procedures[edit | edit source]
Computed tomography (CT)of the orbit is the imaging modality of choice for patients with orbital cellulitis.Most of the time, CT is readily available and will give the clinician information regarding the presence of sinusitis, subperiosteal abscess, stranding of orbital fat, or intracranial involvement. Nevertheless, in cases of mild to moderate orbital cellulitis with no optic nerve involvement, the initial management of the patient remains medical.Imaging is warranted only in cases of poor response to i.v. antibiotics, with progression of orbital signs in order to confirm the presence of complications such as subperiosteal abscess, or intracranial involvement.Although a magnetic resonance imaging(MRI)scan is safer in children since there is no risk of radiation exposure, the long acquisition time and the need for prolonged sedation make CT scan the imaging modality of choice.
Laboratory test[edit | edit source]
Admission to the hospital is warranted in all cases of orbital cellulitis.A complete blood count with differential as well as blood cultures should be ordered.
Differential Diagnosis-[edit | edit source]
The differential diagnosis includes:
- Idiopathic inflammation/specific inflammation (e.g. orbital pseudo tumor, Wegener's disease, sarcoidois)
- Neoplasia (e.g. leukemia, rhabdomyosarcoma, lymphoma, retinoblastoma, metastatic carcinoma)
- Trauma (e.g.retrobulbar hemorrhage, orbital emphysema)
- Systemic diseases (e.g sickle cell disease with bony infarcts and subperiosteal hematomas)
- Endocrine disorders (e.g. thyroid ophthalmopathy)
Management[edit | edit source]
General treatment[edit | edit source]
The management of orbital cellulitis requires admission to the hospital and initiation of broad-spectrum i.v. antibiotics.Blood cultures, nasal, throat swabs, should be undertaken and the antibiotics should be modified based on the results.In infants with orbital cellulitis a 3rd generation cephalosporin is usually initiated such as cefotaxime, ceftriaxone or ceftazidime along with a penicillinase-resistane penicillin.In older children, since sinusitis is most commonly associated with aerobic and anaerobic organisms, clindamycin might be another option. Metronidazole is also being increasingly used in children. As mentioned before, the antibiotic regimen should be modified based on the results of cultures if needed. The child should be followed closely in the hospital setting for progression of orbital signs and development of complications.Once improvement has been documented with 48 hours of intravenous antibiotics, consideration for switching to oral antibiotics may be appropriate.
Medical follow up[edit | edit source]
A multi-disciplinary approach is usually warranted for patients with orbital cellulitis under the care of pediatricians, ENT surgeons, ophthalmologists and infectious disease specialists.
Surgery[edit | edit source]
The prevalence of subperiosteal or orbital abscess complicating an orbital cellulitis approaches 10%. The clinician should suspect the presence of such an entity if there is progression of orbital signs, and /or systemic compromise despot the initiation of appropriate intravenous antibiotics for at least 24-48hours. In these cases, a contrast-enhanced CT scan should be ordered to evaluate the orbit, the paranasal sinuses, and /or the brain. If an orbital abscess is present it should be drained.The management of subperiosteal abscess though remains more controversial since there are cases of resolution with the use of i.v. antibiotics only.As a general recommendation, observation with I.V. antibiotics only is indicated when:
- child under age of 9
- no intracranial involvement
- medial wall abscess of moderate size
- no vision loss
Complications[edit | edit source]
The complications of orbital cellulitis are ominous and include optic neuropathy, retinal vein occlusion, severe exposure keratopathy, cavernous sinus thrombosis, meningitis and death.
Prognosis[edit | edit source]
With prompt recognition and aggressive medical and surgical treatment the prognosis is excellent.
Additional Resources[edit | edit source]
References[edit | edit source]
1.Brook I. Role of methicillin-resistant Staphylococcus aureus in head and neck infections. J Laryngol Otol 2009;123(12):1301-7.
2.Cannon PS, Mc Keag D, Radford R, et al. Our experience using primary oral antibiotics in the management of orbital cellulitis in a tertiary referral centre. Eye (Lond) 2009;23(3):612-5.
3.Fu SY, Su GW, McKinley SH, Yen MT. Cytokine expression in pediatric subperiosteal orbital abscesses. Can J Ophthalmol 2007;42(6):865-9.
4.Garcia GH, Harris GJ. Criteria for nonsurgical management of subperiosteal abscess of the orbit: analysis of outcomes 1988-1998. Ophthalmology 2000;107(8):1454-6; discussion 7-8.
5.Goldstein SM, Shelsta HN. Community-acquired Methicillin-resistant Staphylococcus aureus Periorbital Cellulitis: A Problem Here to Stay. Ophthal Plast Reconstr Surg 2009;25(1):77.
6.Harris GJ. Subperiosteal abscess of the orbit. Age as a factor in the bacteriology and response to treatment. Ophthalmology 1994;101(3):585-95.
7.Harris GJ. Subperiosteal abscess of the orbit: computed tomography and the clinical course. Ophthal Plast Reconstr Surg 1996;12(1):1-8.
8.McKinley SH, Yen MT, Miller AM, Yen KG. Microbiology of pediatric orbital cellulitis. Am J Ophthalmol 2007;144(4):497-501.
9.Miller A, Castanes M, Yen M, et al. Infantile orbital cellulitis. Ophthalmology 2008;115(3):594.
10.Nageswaran S, Woods CR, Benjamin DK, Jr., et al. Orbital cellulitis in children. Pediatr Infect Dis J 2006;25(8):695-9.