Peri-orbital vs orbital cellulitis
6-year-old Chardonnay is brought to the emergency department by her mother. Two or three days ago, she noticed what appeared to be a bite on her daughter’s eyelid. Despite warm compresses, her eyelid has become progressively redder and more swollen, with the swelling extending onto her cheek.
Bottom line
Orbital cellulitis is sight-threatening and must be considered whenever there is any apparent cellulitis in the eye region.
A patient with orbital cellulitis is often toxic in appearance with a high-grade fever, proptosis and pain on eye movements.
Peri-orbital, or pre-septal, cellulitis is much more benign but it can be hard to differentiate between the two and so always err on the side of caution.
What’s the orbital septum?
It’s a continuation of the periosteum around the orbital margin, extending to the tarsal plates of the eyelids.
How might infection get into the orbit?
In 95% of cases, periorbital cellulitis is localised, spread by a scratch, an insect bite, or eczema. Occasionally, it can arise from pre-existing dacryocystitis.
Three sets of paranasal sinuses surround the orbit and are a common source of infection in orbital cellulitis, with colonised bacteria migrating. This makes orbital cellulitis more common in teens than in younger children due to a higher incidence of sinusitis. Orbital cellulitis may also arise due to haematogenous spread from any source of bacteraemia and may occasionally be the result of poor dental hygiene and a periosteal abscess.
How does a patient with peri-orbital cellulitis present?
There is often a gradual onset of unilateral eyelid oedema and erythema that may extend beyond the region of the orbit itself to the cheek and surrounding face. It is often accompanied by a low-grade fever. The eye itself is unaffected.
What organisms are commonly responsible?
Peri-orbital cellulitis may be caused by Staph. aureus, Strep. pneumoniae or occasionally Haemophilus influenzae in the unimmunised.
How is peri-orbital cellulitis treated?
It can be hard to differentiate between orbital and peri-orbital cellulitis, and the consequences of getting it wrong are severe. If there is doubt, it should be treated as more serious orbital cellulitis. Peri-orbital cellulitis responds well to amoxicillin-clavulanate or cephalexin.
How does a patient with orbital cellulitis present?
These infections are much more severe. The patient can be pretty toxic in appearance with a high-grade fever and lid oedema and erythema often confined to the eye socket itself as the infection is behind the orbital septum. As the abscess develops, the eye becomes proptosed, and movements become painful.
What investigations are suggested in the work-up?
In addition to the standard full blood exam and cultures, imaging of the orbit and sinuses with CT or MRI is needed to determine the presence or absence of an abscess and to aid operative planning.
How is orbital cellulitis treated?
The old surgical adage, ‘If there’s pus about, let it out,’ holds true, and maxillofacial, ENT, or ophthalmic surgeons are keen to get these patients to theatre sooner rather than later. Surgical drainage is augmented with high-dose IV antibiotics such as flucloxacillin and ceftriaxone.
What can go wrong if you get the diagnosis wrong?
In the early stages of the disease, it is easy to confuse orbital cellulitis for its less serious cousin, peri-orbital cellulitis. However, unless caught early, orbital cellulitis may lead to blindness due to optic nerve compression, cavernous sinus thrombosis, osteomyelitis, meningitis or a cerebral abscess.
Outcome
Chardonnay was diagnosed with peri-orbital cellulitis secondary to a mosquito bite and was treated with a week-long course of amoxicillin-clavulanate. At a planned review after two days, she showed marked improvement.
References
Gellady AM, Shulman ST, Ayoub EM. Periorbital and orbital cellulitis in children. Pediatrics. 1978 Feb;61(2):272-7.
Malcolm A. Buchanan, Wisam Muen, Peter Heinz, Management of periorbital and orbital cellulitis, Paediatrics and Child Health, Volume 22, Issue 2, February 2012, Pages 72-77
