Orbital Trauma

Orbital Anatomy & Intro - Bones & Beyond

• Bones (7): Pyramidal cavity. Walls:
  • 📌 Mnemonic: "FLEZMS P" (Frontal, Lacrimal, Ethmoid, Zygomatic, Maxillary, Sphenoid, Palatine).
  • Roof: Frontal, Lesser Sphenoid wing.
  • Floor: Maxillary, Zygomatic, Palatine (weakest).
  • Medial: Maxilla, Lacrimal, Ethmoid (lamina papyracea - thinnest), Sphenoid body.
  • Lateral: Zygomatic, Greater Sphenoid wing (strongest).
• Key Openings & Contents:
  • Optic Canal: CN II, Ophthalmic artery.
  • Superior Orbital Fissure (SOF): CN III, IV, V1, VI; Sup. Ophthalmic Vein.
  • Inferior Orbital Fissure (IOF): CN V2, Infraorbital vessels; Inf. Ophthalmic Vein.
• Volume: Approx. 30 ml.

⭐ The orbital floor (maxillary bone) is the most common site for blowout fractures, followed by the medial wall (ethmoid - lamina papyracea).

Orbital Fractures - Walls That Tumble

• Blowout Fracture: Most common; inferior wall (maxillary sinus) > medial wall (ethmoid sinus).
  • Mechanism: Sudden ↑ intraorbital pressure (e.g., fist, ball).
  • Signs: Diplopia (esp. upgaze), enophthalmos, infraorbital anesthesia, orbital emphysema.
  • 📌 "Trapdoor" fracture in children: minimal external signs, significant muscle entrapment.
• Tripod Fracture (Zygomaticomaxillary Complex - ZMC): Involves zygomatic arch, lateral orbital rim/wall, inferior orbital rim/floor.
  • Signs: Facial flattening, trismus, palpable step-offs.
• Le Fort Fractures (II & III): Involve orbital rims/walls as part of larger midface fractures.
  • Le Fort II: Pyramidal; involves nasal bones, maxilla, lacrimal bones, orbital floor/rim.
  • Le Fort III: Craniofacial dysjunction; involves ZMC, nasoethmoidal complex, orbital walls.

⭐ Diplopia on upgaze and infraorbital nerve anesthesia are classic signs of an orbital floor blowout fracture involving the inferior rectus muscle or infraorbital nerve respectively.

Clinical Assessment - Eyes on a Prize

• History: Mechanism (blunt/penetrating), symptoms (pain, ↓vision, diplopia, numbness).
• Examination "EOM & Pupils First":
  • Visual Acuity (VA): Document meticulously.
  • Pupils: Size, reactivity, RAPD (optic nerve damage).
  • Ocular Motility: Diplopia, restricted movements (esp. up/down gaze in blowout), Forced Duction Test (FDT).
  • Globe: Proptosis/Enophthalmos.
  • Palpation: Orbital rim step-off, crepitus, tenderness.
  • Sensation: Infraorbital nerve anesthesia.
  • 📌 Mnemonic (Blowout Signs): "TRAP" - Trapped muscle, Rim step-off, Anesthesia, Peri-orbital changes.
• Imaging:
  • CT Scan (axial & coronal): Gold standard. Shows fractures, muscle entrapment.
  • X-ray (Waters'): "Tear-drop" sign; limited.

⭐ CT scan (axial and coronal views) is the gold standard for diagnosing orbital fractures, detailing bone and soft tissue involvement.

![Image of CT scan showing orbital floor fracture with muscle entrapment]

Orbital Trauma Management - Patch & Proceed

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High‑Yield Points - ⚡ Biggest Takeaways

• Orbital floor blowout fracture is most common, involving maxillary bone; often traps inferior rectus muscle.
• Key signs: diplopia on upgaze, restricted elevation, and infraorbital nerve anesthesia.
• "Teardrop sign" on CT scan signifies herniated orbital contents into maxillary sinus.
• Retrobulbar hemorrhage is an ocular emergency causing proptosis, ↑IOP; requires urgent lateral canthotomy & cantholysis.
• Orbital emphysema (crepitus) indicates fracture communicating with paranasal sinuses.
• Enophthalmos can be a delayed complication due to orbital volume changes or fat atrophy.