Orbital Inflammations

Orbital Blueprint - Setting the Stage

• Anatomy: Orbit formed by 7 bones. Key landmark: Orbital septum (fibrous sheet dividing anterior/posterior).
• Crucial Spaces (re: Septum):
  • Preseptal: Anterior to septum. Vision, motility typically normal.
  • Postseptal (Orbital): Posterior to septum. High risk: ↓vision, proptosis, ophthalmoplegia.
• Inflammation Types:
  • By Location: Preseptal vs. Postseptal (critical distinction!)
  • By Etiology: Infectious vs. Non-infectious (e.g., TED, IOI/NSOI).

⭐ The orbital septum is the key anatomical boundary; postseptal inflammation implies true orbital involvement and higher urgency.

Infection Invasion - Orbital Alert

• Key Distinction: Location relative to orbital septum.

  • Preseptal Cellulitis (Periorbital): ANTERIOR. Lid swelling, erythema, warmth. NO proptosis, NO ophthalmoplegia, normal vision.
  • Orbital Cellulitis: POSTERIOR. EMERGENCY! Proptosis, painful ophthalmoplegia, ↓ vision, afferent pupillary defect (APD).

• Common Pathogens: S. aureus, Strep. pneumoniae, H. influenzae. Fungi (e.g., Mucor) in immunocompromised.

• Sources: Sinusitis (esp. ethmoid), dacryocystitis, trauma, dental.

• Management Approach:

  

• Complications (Orbital): Optic neuropathy, cavernous sinus thrombosis, intracranial spread. ⚠️ High risk with delayed treatment.

⭐ > In children, ethmoid sinusitis is the most common precursor to orbital cellulitis.

Steroid Squad - Fiery Orbits

• Idiopathic Orbital Inflammatory Disease (IOID) / Orbital Pseudotumor: Non-infectious, non-neoplastic inflammation.
  • Presentation: Acute painful proptosis, diplopia, chemosis, ↓ vision, restricted EOM.
  • Types: Dacryoadenitis, myositis (commonest), scleritis, perineuritis, diffuse.
  • Investigations:
    • CT/MRI: Diffuse inflammation, muscle belly enlargement (tendon sparing vs TED).
    • Biopsy: Rules out lymphoma, vasculitis (GPA), IgG4-RD.

      ⭐ Biopsy is crucial in atypical/recalcitrant IOID to exclude malignancy (lymphoma) or specific inflammations like IgG4-related disease.

  • Treatment:
    • Corticosteroids (oral prednisolone 1-1.5 mg/kg/day); rapid response.
    • Radiotherapy (20-30 Gy) for steroid-resistant/dependent cases.
    • Immunosuppressants (MTX, AZA), Biologics for refractory IOID.
• Tolosa-Hunt Syndrome: IOID of cavernous sinus/SOF. Painful ophthalmoplegia (CN III, IV, VI). Steroid-responsive.
• 📌 S.O.A.P. for IOID: Swelling, Ophthalmoplegia, Acute, Pain.

Graves' Gaze - Thyroid's Fury

• Patho: Autoimmune; TSH-R Abs on orbital fibroblasts → GAGs, adipogenesis, muscle swelling.
• Clinical Features:
  • Proptosis.
  • Lid retraction (Dalrymple's).
  • Diplopia: restrictive myopathy (Muscles: Inf > Med > Sup > Lat - 📌 IMSLO).
  • Compressive Optic Neuropathy (CON): emergency!
  • Exposure keratopathy.
• Signs (NO SPECS):
  • No signs/symptoms.
  • Only signs (lid retraction).
  • Soft tissue (edema, chemosis).
  • Proptosis (>22 mm / >2 mm asymm).
  • EOM involvement (diplopia).
  • Corneal.
  • Sight loss (CON).
• Investigations:
  • TFTs, TRAb.
  • CT/MRI Orbit: EOM belly ↑, tendon sparing.
• Management:
  • Mild: Lubricants, Selenium, stop smoking.
  • Mod-Severe (active): IV Methylprednisolone, Teprotumumab.
  • Inactive: Orbital decompression, strabismus/lid surgery.

⭐ Most common muscle affected in TED is the Inferior Rectus.

High‑Yield Points - ⚡ Biggest Takeaways

• Orbital cellulitis: Post-septal infection, often from ethmoidal sinusitis. Key signs: proptosis, painful ophthalmoplegia, ↓vision.
• Preseptal cellulitis: Anterior to septum. No proptosis, no ophthalmoplegia; normal vision & ocular motility.
• Thyroid Eye Disease (TED): Most common cause of adult proptosis (unilateral/bilateral). Use NO SPECS for staging.
• Idiopathic Orbital Inflammatory Disease (IOID): Painful ophthalmoplegia; a diagnosis of exclusion. Responds dramatically to steroids.
• Tolosa-Hunt Syndrome: Granulomatous inflammation of cavernous sinus/SOF causing painful ophthalmoplegia & cranial neuropathies.