Overview
Definition:
Orbital cellulitis is a serious bacterial infection of the orbital tissues anterior to the orbital septum
Subperiosteal abscess (SPA) is a collection of pus between the periosteum and the orbital bone, often occurring as a complication of orbital cellulitis or sinusitis.
Epidemiology:
Most common in children under 10 years of age, with a bimodal peak in infants and children aged 7-12 years
Often secondary to paranasal sinusitis (ethmoid and maxillary sinuses being most common)
Other predisposing factors include dacryocystitis, periorbital infections, and trauma.
Clinical Significance:
Orbital cellulitis, particularly with SPA, is a medical emergency due to the risk of vision loss from optic nerve compression, central retinal artery occlusion, and spread of infection to the intracranial structures (e.g., cavernous sinus thrombosis, meningitis)
Prompt diagnosis and management are crucial.
Clinical Presentation
Symptoms:
Fever
Severe eye pain
Periorbital swelling and erythema
Eyelid edema and ptosis
Decreased vision
Diplopia
Proptosis (globe displacement)
Reduced extraocular movements (ophthalmoplegia)
Headache
Nasal discharge if associated with sinusitis.
Signs:
Proptosis is a key sign
Marked chemosis (conjunctival edema)
Ophthalmoplegia, often with pain on attempted eye movement
Afferent pupillary defect (APD) may indicate optic nerve compromise
Reduced visual acuity
Palpable mass in the orbit may suggest abscess
Signs of sinusitis may be present.
Diagnostic Criteria:
Diagnosis is primarily clinical, supported by imaging
Clinical triad of fever, proptosis, and ophthalmoplegia is highly suggestive
Imaging (CT or MRI) confirming orbital or subperiosteal fluid collection is definitive for SPA.
Diagnostic Approach
History Taking:
Detailed history of recent upper respiratory tract infection, sinusitis, otitis media, or trauma
Onset and progression of symptoms
Visual acuity changes
Pain characteristics
Any previous episodes
Allergies and medications.
Physical Examination:
Complete ophthalmologic examination: visual acuity, pupillary reactions, extraocular movements, proptosis measurement, assessment for chemosis and eyelid edema
Funduscopic examination to assess for papilledema or optic disc edema
Palpation of orbital rims for tenderness or mass
Examination of the sinuses and ears.
Investigations:
Complete Blood Count (CBC) with differential to assess for leukocytosis
Blood cultures if febrile
Sinus imaging (CT scan orbit with contrast) is the gold standard for diagnosing SPA, identifying abscess location, size, and relationship to orbital structures
MRI may be used for better soft tissue characterization and intracranial extension assessment
Ultrasound of the orbit can be useful in some cases.
Differential Diagnosis:
Preseptal cellulitis (infection anterior to orbital septum, lacks proptosis and ophthalmoplegia)
Orbital pseudotumor
Rhabdomyosarcoma
Orbital cellulitis without SPA
Allergic reactions
Orbital trauma.
Management
Initial Management:
Urgent referral to ophthalmology and ENT
Intravenous antibiotics should be initiated immediately, covering common pathogens (Streptococcus pneumoniae, Haemophilus influenzae type b (Hib) if unvaccinated, Staphylococcus aureus, Streptococcus pyogenes)
Broad-spectrum antibiotics are typically used pending culture results.
Medical Management:
Empirical IV antibiotics targeting Gram-positive and Gram-negative organisms
Initial choices often include a third-generation cephalosporin (e.g., ceftriaxone) or clindamycin, potentially combined with vancomycin if MRSA is suspected
Duration of IV therapy is typically 7-14 days, followed by oral antibiotics for a total course of 2-4 weeks, depending on clinical response.
Surgical Management:
Indications for surgical drainage of a subperiosteal abscess include: 1
Significant vision loss (acuity < 20/50) or rapidly deteriorating vision
2
Significant proptosis causing exposure keratitis or optic nerve compromise
3
Lack of clinical improvement or worsening despite adequate medical management within 24-48 hours
4
Abscess size > 10 mm
5
Abscess involving the orbital apex or threatening the optic nerve
Procedures typically involve endoscopic sinus surgery for drainage or an open orbital approach.
Supportive Care:
Close monitoring of visual acuity, pupillary responses, and proptosis
Pain management
Nasal decongestants and saline irrigations if associated sinusitis
Humidification and artificial tears for exposure keratitis
Nutritional support.
Complications
Early Complications:
Vision loss (optic nerve compression, retinal vascular occlusion, keratitis)
Intracranial extension (meningitis, brain abscess, cavernous sinus thrombosis)
Orbital apex syndrome
Nasolacrimal duct obstruction.
Late Complications:
Strabismus (ophthalmoplegia)
Amblyopia
Orbital scarring and fibrosis
Recurrent infections
Nasal synechiae following endoscopic surgery.
Prevention Strategies:
Prompt and adequate treatment of sinusitis and other antecedent infections
Good vaccination status against Hib
Prompt surgical intervention for SPAs meeting surgical criteria.
Prognosis
Factors Affecting Prognosis:
Severity of vision loss at presentation
Delay in diagnosis and treatment
Development of complications, particularly intracranial spread or optic nerve damage
Promptness and adequacy of surgical drainage if indicated.
Outcomes:
With prompt and appropriate management, including surgical drainage of SPAs when indicated, visual outcomes are generally good
However, permanent vision impairment or loss can occur, especially if diagnosis or treatment is delayed or if optic nerve involvement is severe.
Follow Up:
Regular follow-up with ophthalmology is essential, typically weekly for the first month, then monthly for several months
Monitoring for visual acuity, extraocular movements, proptosis, and any signs of recurrence or late complications
Long-term follow-up may be needed if amblyopia or strabismus develops.
Key Points
Exam Focus:
SPA in children is often secondary to sinusitis
CT scan is crucial for diagnosis and surgical planning
Indications for surgery are primarily vision-threatening or failure to improve medically
Broad-spectrum IV antibiotics are the cornerstone of medical management.
Clinical Pearls:
Always suspect orbital cellulitis in a child with fever and unilateral periorbital swelling
A red, bulging eye with limited movement is an ophthalmologic emergency
Early surgical consultation is vital for SPAs
Differentiate from preseptal cellulitis by checking for proptosis and ophthalmoplegia.
Common Mistakes:
Delaying imaging or surgical intervention in suspected SPAs
Underestimating the severity and potential for rapid deterioration
Inadequate antibiotic coverage
Failure to consider intracranial extension.