Orbital Inflammations

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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).

Orbital Anatomy Cross-Section

⭐ 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:

    Chandler's Classification of Orbital Inflammations

  • 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.

Axial and coronal CT showing orbital myositis

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). CT/MRI of Graves orbitopathy
  • 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.

Practice Questions: Orbital Inflammations

Test your understanding with these related questions

A young girl with a previous history of repeated pain over the medial canthus and chronic use of decongestants now presents with intense chills, rigors, and diplopia on lateral gaze. Examination shows an optic disc that is congested. The most likely diagnosis would be:

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Flashcards: Orbital Inflammations

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Anterior blepharitis is most commonly caused by _____

TAP TO REVEAL ANSWER

Anterior blepharitis is most commonly caused by _____

staphylococcus

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