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Orbital cellulitis (ReelDx)

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49 y/o with swelling and redness around the eye

Patient will present as →  a 49-year-old man presents to the emergency department with a 2-day history of right eye pain, swelling, and decreased vision. On examination, he has proptosis, ophthalmoplegia (paralysis of the extraocular muscles), and chemosis of the right eye. His temperature is 101°F (38.3°C), and blood cultures are pending. A CT scan of the orbits shows evidence of an abscess in the right orbit.

Orbital cellulitis is an infection of the orbital muscles and fat behind the eye (differentiate from periorbital cellulitis, which is only an infection of the skin)

  • Pt will present with decreased extraocular movement, pain with movement of the eye, and proptosis
  • Often associated with untreated sinusitis. It occurs more often in children than adults - ages 7-12 y/o
  • The most common cause of orbital cellulitis is staphylococcus aureus
  • Decreased vision is a rare manifestation of orbital cellulitis
Orbital cellulitis

Involvement of muscles and fat behind the eye

History, clinical exam, and focused assessment of extraocular muscles

  • The imaging modality of choice for the diagnosis of orbital cellulitis is CT with contrast
  • CBC and blood culture may be standard in some settings
RtmaxobitinfectteethCT

A left maxillary sinusitis (dark arrow) and facial/orbital cellulitis (empty arrow)

If orbital cellulitis/abscess is seen on CT requires an ophthalmology evaluation

  • Hospitalization and IV broad-spectrum antibiotics
  • Vancomycin + ceftriaxone/cefotaxime is used in the empiric treatment of orbital cellulitis to cover methicillin-resistant Staphylococcus aureus (MRSA)

Question 1
Which of the following clinical findings differentiates periorbital from orbital cellulitis?
A
erythema
Hint:
See D for explanation
B
fever
Hint:
See D for explanation
C
lid edema
Hint:
See D for explanation
D
worsening pain with eye movements
E
development of a rash on the face
Hint:
See D for explanation
Question 1 Explanation: 
Periorbital cellulits is characterized by warmth, redness, swelling, and tenderness over the affected eye, along with conjunctival injection, eyelid swelling, chemosis, and fever. Orbital cellulitis includes all the symptoms of periorbital (preseptal) cellulitis with the addition of ocular pain and limitation of eye movement. Other physical examination findings may include lid edema, proptosis, marked tenderness to the globe, decreased visual acuity, and pupillary paralysis.
Question 2
The most common organism isolated in periorbital cellulitis in vaccinated children in the absence of trauma is
A
H. influenzae type B
Hint:
Before widespread immunization, Haemophilus influenzae type B was the most common cause secondary to bacteremia (about 80% of cases) and remains so in nonimmunized populations.
B
Streptococcus pneumoniae
C
Moraxella catarrhalis
Hint:
See B for explanation
D
Staphylococcus aureus
Hint:
The most common pathogens associated with external foci (trauma) are Staphylococcus aureus and Streptococcus pyogenes, but these are seldom isolated from the blood
E
Pseudomonas aeruginosa
Hint:
See B for explanation
Question 2 Explanation: 
Periorbital and orbital cellulitis may be caused by trauma (e.g., a wound, an insect bite), an associated infection (e.g., sinusitis), or seeding from bacteremia. Before widespread immunization, Haemophilus influenzae type B was the most common cause secondary to bacteremia (about 80% of cases) and remains so in nonimmunized populations. Streptococcus pneumoniae accounted for most of the remaining 20% of cases. S. pneumoniae is the most likely agent in Haemophilus influenzae type B-vaccinated patients when sinusitis is present. The most common pathogens associated with external foci (trauma) are Staphylococcus aureus and Streptococcus pyogenes, but these are seldom isolated from the blood. In general, a bacterial pathogen is isolated from the blood in < 33% of patients with periorbital cellulitis.
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References: Merck Manual · UpToDate

Orbital disorders (PEARLS) (Prev Lesson)
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