Makindo Medical Notes

Orbital cellulitis is a serious bacterial infection affecting the tissues within the orbit, posterior to the orbital septum. It is considered a medical emergency due to its potential to cause severe complications, including vision loss, intracranial infections such as meningitis, cavernous sinus thrombosis, and even death. It is most commonly seen in children but can occur at any age.

Aetiology

• Sinusitis: The most common cause, particularly ethmoid sinusitis.
• Trauma: Penetrating injuries, facial lacerations, or insect bites.
• Surgery: Post-operative infections following orbital or sinus procedures.
• Haematogenous spread: Bacteria spreading from distant systemic infections.
• Microorganisms:
  • Streptococcus pneumoniae
  • Haemophilus influenzae type b (especially in children)
  • Staphylococci and streptococci

Pathophysiology

Orbital cellulitis typically arises from the spread of infection from adjacent sinuses, particularly the ethmoid sinus, due to their close anatomical proximity. The infection crosses the thin lamina papyracea, leading to inflammation and swelling in the orbital tissues. This results in increased orbital pressure, which can compromise optic nerve function and blood supply to ocular structures.

Clinical Features

• Swollen, erythematous eyelids.
• Fever and systemic symptoms of infection.
• Conjunctival chemosis (swelling of the conjunctiva).
• Severe orbital pain, particularly with eye movement.
• Proptosis (protrusion of the eyeball).
• Ophthalmoplegia (restricted eye movement).
• Decreased visual acuity or blurred vision.
• Diplopia (double vision).
• History of recent sinus infection, trauma, or surgery.

Complications

• Vision Loss: Due to optic nerve compression or ischaemia.
• Intracranial Spread: Meningitis, cavernous sinus thrombosis, brain abscess.
• Orbital Abscess: Localized collection of pus within the orbit.
• Systemic Sepsis: Spread of infection into the bloodstream.

Investigations

• Blood Tests: Elevated white blood cell count, CRP, and ESR.
• Imaging: CT scan of the orbit and sinuses: To differentiate between orbital cellulitis and preorbital cellulitis, identify abscesses, and evaluate sinus involvement. MRI: In cases of suspected intracranial extension.
• Microbiology: Blood cultures and swabs for Gram stain and culture to identify the causative organism.

Differentials

Feature	Orbital Cellulitis	Preorbital (Preseptal) Cellulitis
Definition	Medical emergency characterized by bacterial infection of tissues posterior to the orbital septum (within the orbit), posing a severe sight- and life-threatening risk.	Localized infection of tissues anterior to the orbital septum; less severe than orbital cellulitis.
Clinical Presentation	Swollen eyelids, fever, chemosis, history of facial laceration, trauma, insect bite, or sinusitis.	Similar to orbital cellulitis but usually confined to the anterior tissues without orbital involvement.
Key Symptoms	Ophthalmoplegia (restricted eye movement). Proptosis (eye bulging). Severe eye pain, especially on movement. Blurred vision or decreased visual acuity. Diplopia (double vision).	Skin erythema, lid oedema, warmth, and tenderness. Ptosis and pyrexia. No proptosis or pain on eye movement. Localised pain and swelling but vision is unaffected.
Common Pathogens	Streptococcus pneumoniae, Haemophilus influenzae type b, staphylococci, or streptococci often linked to trauma or sinusitis.	Same as orbital cellulitis.
Complications	Potential to extend into the skull, causing meningitis, cavernous sinus thrombosis, and blindness.	Extension beyond or into the skull is uncommon.
Imaging	Computed tomography (CT) scan to determine the extent of the infection (preorbital vs. orbital) and exclude complications such as abscess formation.	Same as orbital cellulitis.
Management	Same-day referral to an ophthalmologist. Co-management with ENT specialists. Blood cultures and IV broad-spectrum antibiotics to cover likely pathogens until culture results are available. Requires inpatient care initially.	Same as orbital cellulitis in severe cases. Milder cases may be managed with oral antibiotics and ambulatory care.

Management:requires urgent medical intervention to prevent complications.

• Hospital Admission: All cases of orbital cellulitis should be managed as inpatients.
• Intravenous Antibiotics: Broad-spectrum antibiotics such as:
  • Vancomycin (to cover MRSA).
  • Third-generation cephalosporins (e.g., ceftriaxone) or piperacillin-tazobactam to cover Streptococcus and Haemophilus.
  Therapy is adjusted based on culture results.
• Surgical ENT Intervention: Required for complications such as:
  • Orbital abscess drainage.
  • Sinus surgery to address underlying sinus infection.
• Supportive Care:
  • Analgesia for pain relief.
  • Antipyretics for fever.

Prognosis

With prompt diagnosis and appropriate treatment, most patients recover without significant sequelae. Delayed treatment or severe complications, however, can result in permanent vision loss or even mortality.

Prevention

• Timely treatment of sinus infections and facial trauma.
• Vaccination against Haemophilus influenzae and Streptococcus pneumoniae in children.
• Good hygiene practices to prevent infections.

References

• American Academy of Ophthalmology
• Royal College of Ophthalmologists