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 inflamed with the swelling now extending onto her cheek.
Orbital cellulitis is sight-threatening and must be considered whenever there is ever any apparent cellulitis in the eye region.
A patient with orbital cellulitis is often toxic in appearance with a high-grade fever, proptosed eye 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 the case of periorbital cellulitis in 95% of cases, it is from local spread from a scratch, an insect bite or eczema. Occasionally it can arise from pre-existing dacryocystitis.
As the orbit is surrounded by three sets of paranasal sinuses, these are a common source of infection in orbital cellulitis with migration of colonised bacteria. This makes orbital cellulitis more common in teens than younger children, due to a higher incidence of sinusitis. Orbital cellulitis may also arise as a result of 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 gradual onset 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 influenza 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 quite severe. If there is any doubt then it should be treated as the 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 serious and the patient can be quite 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?
Other than the standard full blood exam and cultures, imaging of the orbit and sinuses with CT or MRI is needed to ascertain the presence or absence of an abscess and to aid operative planning.
How is orbital cellulitis treated?
The old surgical adage of ‘if there’s pus about, let it out” holds true and maxillo-facial, 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. Unless it is caught early, orbital cellulitis may lead to blindness due to optic nerve compression, cavernous sinus thrombosis, osteomyelitis, meningitis or a cerebral abscess.
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.
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