Orbital Inflammations

Orbital Cellulitis - Eyelid Emergency

Infection posterior to orbital septum. Sight-threatening emergency.

• Etiology:
  • Most common: Ethmoid sinusitis (>90%).
  • Others: Dacryocystitis, dental infection, trauma.
• Key Differentiator from Preseptal:
  • Preseptal: No proptosis, normal vision & eye movements.
• Clinical Triad (📌 POV):
  • Proptosis (painful)
  • Ophthalmoplegia (painful)
  • Vision ↓ (may include RAPD)
• Other Signs: Eyelid edema, erythema, chemosis, fever.
• Diagnosis: CT scan (orbit & sinuses) gold standard.
• Management:
  • Urgent hospital admission.
  • IV broad-spectrum antibiotics (e.g., Vancomycin + Ceftriaxone).
  • Surgical drainage if abscess, no improvement in 24-48 hrs, or vision decline.

⭐ Orbital cellulitis is distinguished from preseptal cellulitis by the presence of proptosis, painful ophthalmoplegia, and/or decreased visual acuity.

Thyroid Eye Disease - Graves' Gaze

• Autoimmune disorder; most common cause of bilateral/unilateral proptosis in adults.
• Associated with Graves' hyperthyroidism; can be euthyroid or hypothyroid.
• Pathophysiology: TSH receptor antibodies (TRAb) stimulate orbital fibroblasts → glycosaminoglycan (GAG) deposition & adipogenesis → extraocular muscle (EOM) & orbital fat expansion.
• Key Gaze-Related Signs:
  • Proptosis (Exophthalmos): Axial, non-pulsatile.
  • Eyelid Retraction (Dalrymple's sign): Staring appearance.
  • Lid Lag on Downgaze (Von Graefe's sign).
  • Restrictive Myopathy: Diplopia, ↑IOP on upgaze/side gaze.
    • 📌 Mnemonic for EOM involvement: "I'M SLOW" (IR → MR → SR → LR → Obliques).
  • Compressive Optic Neuropathy (DON): Risk of vision loss.
• Investigations: TFTs (TSH, T3, T4, TRAb), CT/MRI orbits (fusiform EOM belly enlargement, tendon sparing).
• Management: Control thyroid status. Mild: lubricants. Active moderate-severe: IV corticosteroids, orbital radiotherapy, teprotumumab. Inactive/Stable: orbital decompression, strabismus surgery, eyelid surgery.

⭐ The Inferior Rectus (IR) is the most commonly involved extraocular muscle, leading to restricted elevation and vertical diplopia looking up.

Idiopathic Orbital Inflammation - Enigmatic Eyes

• A.k.a. Orbital Pseudotumor. Idiopathic, non-granulomatous orbital inflammation; diagnosis of exclusion.
• Clinical: Acute unilateral pain, proptosis, diplopia, ↓ vision, eyelid edema, chemosis.
  • Bilateral cases: suspect systemic disease (e.g., GPA, sarcoidosis).
• Types: Myositis (most common), dacryoadenitis, anterior (scleritis/uveitis), apical, diffuse.
• Investigations:
  • CT/MRI: Diffuse infiltration, muscle enlargement (tendons spared vs. TED), lacrimal gland.
  • Biopsy: Rules out malignancy/infection; shows non-specific inflammation.
• Treatment:
  • Corticosteroids (Prednisolone 1-1.5 mg/kg/day): Rapid, dramatic response is characteristic.
  • Radiotherapy for steroid-resistant/dependent cases.
  • Immunosuppressants (methotrexate) for refractory cases.

⭐ Tolosa-Hunt Syndrome: IOI of cavernous sinus/SOF, causing painful ophthalmoplegia.

Other Key Inflammations - Orbital Oddities

• Fungal Infections:
  • Mucormycosis (ROCM): Aggressive. Risk: Diabetes, immunosuppression. Signs: Black eschar, proptosis, ophthalmoplegia. Dx: Biopsy (non-septate hyphae, $90°$ branching). Rx: Amphotericin B, surgery.
  • Aspergillosis: Invasive or allergic forms. Dx: Biopsy (septate hyphae, acute-angle branching).
• Idiopathic Inflammations:
  • Orbital Pseudotumor (IOIS): Painful proptosis, diplopia, restricted motility. Dramatic steroid response.
  • Tolosa-Hunt Syndrome: Painful ophthalmoplegia (CN III, IV, V1, VI). Granulomatous. Steroid responsive.
• Systemic Associations:
  • Sarcoidosis: Dacryoadenitis, uveitis, optic neuropathy.
  • GPA (Wegener's): Proptosis, scleritis, NLD obstruction. c-ANCA+.

⭐ Biopsy finding in Mucormycosis: broad, non-septate hyphae with wide-angle ($90°$) branching, is a key diagnostic feature.

High‑Yield Points - ⚡ Biggest Takeaways

• Orbital cellulitis: Post-septal infection, often from sinusitis; causes proptosis, painful ophthalmoplegia, ↓vision.
• Preseptal cellulitis: Anterior to septum; eyelid swelling, but no proptosis or ophthalmoplegia.
• Thyroid Eye Disease (TED): Most common cause of adult proptosis (uni/bilateral); follow NO SPECS.
• Idiopathic Orbital Inflammation (IOI): Painful proptosis and ophthalmoplegia; diagnosis of exclusion.
• Tolosa-Hunt Syndrome: Inflammation of cavernous sinus/SOF causing painful ophthalmoplegia; responds to steroids.