A 7-year-old boy has a history of intermittent allergy and sinus problems characterized by watery eyes, rhinorrhea, and a feeling of fullness in the front part of his face and nose. One day, the boy's mother notices that he has developed a persistent cough. When she asks him how he feels, he says that his head hurts and that his mouth tastes nasty. A quick check of his temperature indicates that he has a low-grade fever. The boy's mother figures that this is just another allergy-related incident and gives the boy an antihistamine.

The next morning, the boy awakens with a severe headache and is unable to open his right eye. He obviously feels very ill, so his mother immediately takes him to the family pediatrician. The boy's vital signs are normal except for the fever (which is now 39.1ºC). On physical examination, the right eyelids and the area around the right eye are obviously swollen and erythematous. When the lids are retracted, the eye appears to be displaced downward. There is considerable pain on palpation of the eye. When the boy is asked to move the eye, he says that he can't move it very much and that it hurts when he tries to move it. Except for a small quantity of exudate emanating from the eyelids, there are no other remarkable physical findings.

Question 1.1: What is your preliminary diagnosis?

The clinical presentation in this case is quite distinctive. The unusual combination of symptoms (fever, headache, apparent displacement of the eye, and opthalmoplegia-paralysis of the ocular muscles) strongly suggests that the patient has a case of orbital cellulitis. Orbital cellulitis is an acute inflammation of the connective tissue of the eye socket that occurs mostly in children. The inflammation is intraorbital but extraocular. The disease is often associated with acute sinusitis (see below), which is consistent with the patient's history.

Question 1.2: How is the diagnosis confirmed?

Opthalmoplegia and proptosis-forward displacement of the eyeball are the cardinal symptoms of orbital cellulitis. It is often necessary to utilize a specialized measuring device to confirm that proptosis is occurring because the badly swollen eyelids make it hard to recognize by simple visual inspection of the eye. (The downward displacement of the eye in this case hints at proptosis but doesn't necessarily confirm it.) High-resolution CT scans, including axial and coronal views are essential for the confirmation of orbital cellulitis. However, it may be hard to obtain coronal views (which require hyperextension of the next) when dealing with uncooperative children and acutely ill patients. Laboratory tests should include a CBC with differential.

Test Results:

Optical measurements confirm the presence of proptosis. The white blood cell count is >21,000 cells/microliter, and the differential indicates a distinct left shit. CT imaging reveals soft tissue swelling over the right orbit and the eye definitely appears to be displaced forward. The CT imaging also shows that the right ethmoid sinus is almost completely opaque. There are no signs of abscesses in the intraorbital (but extraocular) space or in the brain.

Question 1.3: How do you identify the causative agent?

The best bet is to collect purulent material from the nose with a cotton or alginate swab for Gram stain and culture on both aerobic and anaerobic media. In this, case the exudate emanating from the eyelids should also be Gram stained and cultured. (Needle aspiration of the orbit is contraindicated in cases of orbital cellulitis.) Blood cultures are routinely done prior to administration of antibiotics, but they seldom reveal the causative agent. In this case, Staphylococcus aureus was cultured from both the lid exudate and the nasal specimen. Gram stains of the material revealed numerous Gram-positive cocci in clusters.

Question 1.4: How did the causative agent get to this part of the body?

Orbital cellulitis typically comes about in one of three ways: (1) extension of the infection from the periorbital structures, most often from the paranasal sinuses, but also from the face, globe, or lacrimal sac; (2) direct inoculation of the orbit during trauma or surgery; or (3) via hematogenous spread from bacteremia. In this, case, the causative agent clearly reached the orbit by the first of these routes. The anterior and lateral borders of the ethmoid sinuses form the medial and superior borders of the orbit. The orbit is then separated from the ethmoid sinus by the lamina papyracea, which is literally a paper-thin piece of bone. An infection in the ethmoid sinus can readily break through this very thin piece of bone and enter the orbit.

Question 1.5: How do the major symptoms come about?

One of the cardinal symptoms of orbital cellulitis-proptosis causes the eyeball to become exopthalmic, which means that it protrudes out of the orbit. Exophthalmus develops when swelling and a build up of exudate in the orbit (as a result of inflammation) decrease the size of the orbital cavity and force the eyeball outward and downward. Eye movement then becomes quite limited (opthalmoplegia, the other cardinal symptom of orbital cellulitis) as the muscles controlling eye movement become edematous and stretched. Stretching of the optic nerve in this situation sometimes leads to decreased visual acuity or even complete blindness.

Question 1.6: What other agents cause this disease?

Orbital cellulitis is most often caused by spread of an infection from the ethmoid sinuses (above), in which case the most important causative agents are Streptococcus pneumoniae and other types of streptococci, Staphylococcus aureus (especially in relatively virulent infections like this one), Haemophilus influenzae (especially in children), and a variety of non-spore-forming anaerobes. When orbital cellulitis results from infection of the maxillary sinus (i.e., secondary to a dental infection), the frequent causative agents are organisms that are indigenous to the mouth, including anaerobes like Bacteroides. Orbital cellulitis stemming from dacryocystitis (inflammation of the lacrimal gland) is generally caused by S. aureus, S. pneumoniae, S. pyogenes, or H. influenzae), whereas cases resulting from infections of the soft tissues of the eyelids are most often caused by various staphylococci or S. pyogenes. Fungal orbital cellulitis also occurs and is typically caused by Mucor or Aspergillus species.

Question 1.7: How should you treat this case?

Orbital cellulitis is considered a medical emergency. The patient should be hospitalized as soon as possible. Because this case is associated with acute sinusitis, the treatment of choice is surgical drainage of the ethmoid sinus. This will decompress the orbit and allow the eyeball to return to its usual location. Antibiotic therapy should also be started as quickly as possible. The initial treatment can be selected according to the causative agents that are usually associated with specific sources of infection. In this case, for example, you would start with drugs that are likely to be effective against typical sinus pathogens. The treatment can be adjusted later if the patient does not respond quickly enough or if lab findings regarding the identity and drug susceptibility characteristics of the actual causative agent indicate that a different drug regimen is likely to be more effective.

Question 1.8: When are you most likely to see this disease?

Orbital cellulitis is more common, both nationally and internationally, in the winter months, primarily because of the increased prevalence of sinusitis when the weather is cold. There is no racial predilection for orbital cellulitis, and the frequency of occurrence is essentially the same for males and females. The disease is clearly more common in children than in adults. The median age for children hospitalized with cellulitis is 7 years.

Question 1.9: What complications are possible?

Orbital or intracranial complications may occur. Subperiorbital or orbital abscesses may develop (7-9% of cases) and should be visible in imaging studies. Permanent vision loss may occur from corneal damage secondary to exposure or neurotrophic keratitis, secondary glaucoma, optic neuritis, destruction of intraocular tissues, or other problems. Blindness may also result from elevated intraorbital pressure or direct extension of the optic nerve from the sphenoid sinus. Direct involvement of the ocular motor nerves or the extraocular muscles may result in decreased ocular motility. Intracranial complications include meningitis (2% of cases), cavernous sinus thrombosis (1%), and intracranial, epidural, or subdural abscess formation.

It is primarily because of these potential complications that orbital cellulitis is always considered a medical emergency. Early diagnosis and treatment can effectively prevent most of these problems. Before antibiotics became available, orbital cellulitis had a mortality rate of 17%, and 20% of the survivors were blind in the affected eye.