BASICS

DESCRIPTION

Orbital cellulitis is an acute infection of the soft tissue contained within the orbital space. It typically arises from adjacent sinusitis but can also occur from spreading of a superficial skin infection or dacryocystitis, penetrating trauma, extension of endophthalmitis, or endogenous bacteremia.

EPIDEMIOLOGY

Incidence

Orbital cellulitis has an approximate incidence of 3 to 6/1,000,000. It has a higher incidence in blacks than in whites or (1) Hispanics and is slight more common in men than in women. Finally, it is more common in children than in teenagers and adults.

RISK FACTORS

• Sinusitis

• Periocular trauma

PATHOPHYSIOLOGY

• Upwards of 80% of orbital cellulitis infections are the result of a sinus infection spreading into the orbit, typically from ethmoid sinusitis. This is due to the thin bone separating the two spaces and the valveless veins that drain from the sinus through the orbit en route to the cavernous sinus.

• Fungal infections such as mucormycosis and aspergillosis can cause these infections but are much less common.

ETIOLOGY

• The ethmoid, maxillary, and frontal sinuses surround the orbit. Thus infection in these spaces can potentially spread in to the orbit. The sinus is typically a sterile space but with upper respiratory infections, the sinus drainage can be compromised leading to congestion and infection. In children younger than 9 years, these infections are typically monomicrobial aerobic infections, which respond well to antibiotics alone. By the time patients reach their mid teenage years, and beyond, the infection is more typically a polymicrobial aerobe/anaerobe infection requiring more intense antibiotic therapy and more often surgery.

• Common bacteria include coagulase-negative Staphylococcus species, Streptococcus species, and Staphylococcus aureus, both Methicillin-susceptible Staphylococcus Aureus (MSSA) and Methicillin-resistant Staphylococcus Aureus (MRSA). In addition, pseudomonas species, Moraxella catarrhalis, Eikenella corrodens, and various anaerobes can be the culprit.

• In immunocompromised patients and uncontrolled diabetes, do not overlook the possibility of a fungal infection, such as mucormycosis.

COMMONLY ASSOCIATED CONDITIONS

Bacterial sinusitis, fungal sinusitis, pre-septal cellulitis of eyelid, dacryocystitis, orbital trauma

DIAGNOSIS

HISTORY

Patient presents acutely with increasing edema, erythema, and pain around the eye that has occurred over several hours to several days. Many will have a history of underlying sinus disease, an acute respiratory tract infection, skin infection, or recent trauma. They progress to develop decreased motility with double vision (if the eyelids are not swollen shut).

PHYSICAL EXAM

• Erythema and edema of lids and orbit

• Proptosis

• Decreased vision

• Conjunctival injection and chemosis

• Limitation in ocular motility

• Sluggish pupil with possible afferent pupil defect

• Elevated intraocular pressure

DIAGNOSTIC TESTS & INTERPRETATION

Lab

• CBC with white count

• Culture of any discharge

• Blood cultures may be helpful.

Imaging

Initial approach

CT scan of the orbits

Follow-up & special considerations

• Repeat imaging studies are frowned upon as clinical findings and radiologic findings do not progress and regress at the same pace. Rather, the radiologic findings fade much more slowly and may still show inflammation or edema even though the patient is improving.

• MRI/magnetic resonance venography (MRV) can be obtained if cavernous sinus thrombosis is a concern.

Diagnostic Procedures/Other

CT scan is the gold standard.

DIFFERENTIAL DIAGNOSIS

• Preseptal cellulitis

• Orbital inflammatory syndrome

• Dacryoadenitis

• Metastatic tumor

• Herpes zoster ophthalmicus

TREATMENT

MEDICATION

First Line

Broad-spectrum IV antibiotics that cover gram positive, gram negative, and anaerobes, especially in patients older than 14 years. These include fortified penicillins, third-generation cephalosporins, fluoroquinolones, or a combination of these medications. Intravenous antibiotic choices would include ampicillin sulbactam, ceftriaxone, aminoglycosides, vancomycin, clindamycin, and fluoroquinolones.

Second Line

Steroid therapy is controversial but can be a helpful adjunct to the antibiotics in reducing swelling and congestion in both the orbit and sinus.

ADDITIONAL TREATMENT

General Measures

Typically admit these patients to the hospital for IV antibiotics, close observation, and possibly surgery. Regular examination of the eye 1–4 times per day depending on the severity to ensure that the vision is not being compromised.

Issues for Referral

The nonophthalmologist can manage this in an inpatient setting, but an ophthalmologist should be involved to monitor the status of the orbit and vision. If sinusitis is the underlying source of infection, ENT surgeons should also be involved.

SURGERY/OTHER PROCEDURES

• The primary source of the infection must be treated. Since 60–80% of orbital cellulitis cases arise from sinus disease, sinus surgery should be included with any plan to surgically treat the orbit.

• An orbitotomy should be considered if there is a frank abscess in the orbit, visual compromise exists, there is an atypical infection, or the patient is not responding to intravenous antibiotic therapy after several days.

IN-PATIENT CONSIDERATIONS

Initial Stabilization

Start IV antibiotic therapy as soon as possible but be aware it typically takes 24–48 hours for the patient to stabilize, especially if they are older than 14 years with a polymicrobial infection.

Admission Criteria

Confirmation of orbital cellulitis as a diagnosis should almost always be treated as an inpatient. Patient needs to be observed closely for evidence of significant visual compromise and posterior intracranial spread of the infection.

Nursing

Check vision and pupils at least once a shift. Warm compresses can help with the infection.

Discharge Criteria

Significant improvement of infection with no further acute threat to the vision.

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Patients should receive approximately two full weeks of antibiotic therapy total. Thus they should be discharged home on oral antibiotics or with a peripherally inserted central catheter (PICC) line for continued IV antibiotics when indicated.

Patient Monitoring

• Outpatient follow-up within a week of discharge to ensure that the infection is resolving and the vision is stable.

• If there was an associated sinusitis, follow-up with an ENT surgeon is recommended as well.

DIET

Typically not a concern. However, patients with diabetes should have their glucose control optimized as hyperglycemia promotes infection.

PROGNOSIS

Excellent, with today’s imaging capabilities, antibiotics, and team approach to managing these patients.

COMPLICATIONS

Blindness, cavernous sinus thrombosis, eyelid necrosis, meningitis, brain abscess, sepsis, death

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