What are the recommendations for reconstructing the medial/inferior orbit in cases of fistula in the medial canthal or lacrimal region after trauma or surgery for malignancy?

Reconstruction of the Medial/Inferior Orbit for Fistulas in the Medial Canthal or Lacrimal Region

The optimal approach for reconstructing medial/inferior orbital fistulas after trauma or malignancy surgery requires a staged approach based on timing, with immediate repair for muscle entrapment causing oculocardiac reflex, early repair (within 2 weeks) for symptomatic diplopia with positive forced ductions, and delayed repair for persistent restrictive strabismus. 1

Initial Assessment and Imaging

• CT maxillofacial is the preferred initial imaging modality for suspected medial orbital injuries, providing high-resolution delineation of osseous and soft-tissue structures 1, 2
• MRI may be beneficial as a supplementary study in cases with cranial nerve deficits not fully explained by CT, particularly for evaluating soft tissue involvement 1
• A detailed sensorimotor examination is essential to assess versions, ductions, saccades, pursuit, and alignment in multiple gaze positions 1, 3
• Forced duction and forced generation testing help distinguish restriction from paresis of extraocular muscles 1, 3
• Monitor vital signs for bradycardia or heart block, which may indicate muscle entrapment causing oculocardiac reflex - a potentially life-threatening condition requiring urgent intervention 1, 3

Treatment Algorithm Based on Timing

Immediate Surgical Repair (Emergency)

• Patients with CT evidence of entrapped muscle or periorbital tissue with nonresolving oculocardiac reflex require immediate surgical repair 1
• "White-eyed blow-out fracture" with muscle entrapment and oculocardiac reflex (particularly in children) requires immediate surgical repair 1
• Globe subluxation into the maxillary sinus requires immediate surgical repair 1

Early Surgical Repair (Within 2 Weeks)

• Symptomatic diplopia with positive forced ductions or entrapment on CT with minimal improvement requires early surgical repair 1
• Large floor fractures, hypoglobus, and progressive infraorbital hypoesthesia require early surgical repair 1
• Early enophthalmos or hypoglobus causing facial asymmetry requires early surgical repair 1
• Significant fat or periorbital tissue entrapment can result in permanent strabismus even without muscle entrapment and should be addressed early 1

Delayed Repair (After 2 Weeks)

• Restrictive strabismus and unresolved enophthalmos that persist after initial observation may benefit from delayed repair 1
• In cases without muscle entrapment, waiting 4-6 months after orbital trauma is advised as strabismus may resolve spontaneously 1

Surgical Techniques for Medial Canthal/Lacrimal Fistula Reconstruction

For Post-Traumatic Fistulas

• Primary repair of traumatic injuries to the canalicular system has success rates of 70-82% 4
• Silicone intubation with special attention to the medial canthal tendon is recommended for urgent primary repair of canalicular lacerations 4
• For lacrimal duct trauma, reconstruction using two autostable ("self-retaining") monocanaliculonasal lacrimal tubes has shown good outcomes in both children and adults 5
• Stepwise wound closure respecting the topographic anatomy is mandatory, treating lid and lacrimal ducts as one functional unit 5

For Post-Malignancy Resection Fistulas

• En bloc resection followed by immediate reconstruction is recommended for lacrimal sac tumors 6
• A combined sinus-orbit approach effectively manages lacrimal sac tumors to achieve optimal tumor clearance from the orbit and nasal cavity 6
• Simultaneous reconstruction of bony defects with contoured titanium mesh provides:
  • Fixation anchor for the medial canthal tendon
  • Globe support
  • Supporting platform for the lower eyelid and cheek to minimize midface collapse 6
• For large medial canthal defects involving the lacrimal apparatus, a paramedian forehead flap combined with AlloDerm as a conduit for reconstruction of the medial canthus and lacrimal outflow tract has shown success 7
• Multiple local flaps can be used for large defects extending beyond the medial canthal region:
  • Glabellar flap for the medial canthal defect
  • Upper eyelid myocutaneous advancement flap for upper eyelid defects
  • Cheek rotation flap for lower eyelid defects 8

Complications and Management

• Even with proper repair, strabismus and diplopia can persist in up to 37% of patients postoperatively 1
• A short burst of oral steroids can hasten recovery and help identify strabismus that will persist despite resolution of orbital edema/hematoma 1
• Postoperative radiation for malignant cases may be associated with complications including skin breakdown over reconstruction materials, medial canthal tendon dystopia, and potential fistula formation 6
• Secondary reconstructions of traumatically caused tear-duct system obstructions have varying success rates depending on the microsurgical techniques used 4
• Conjunctivodacryocystorhinostomy with polyethylene or silicone tubes for secondary reconstruction has success rates of 61-72% 4
• Dacryocystorhinostomy for traumatic injuries has shown a success rate of 87.5% 4

Important Considerations

• All life-threatening and vision-threatening conditions must be treated before addressing the strabismus or cosmetic concerns 1
• Serious ocular injury occurs in up to 24% of orbital fractures, emphasizing the need for comprehensive ophthalmologic evaluation 1
• Conservative management options including occlusion, filters, Fresnel prisms, and prism glasses may provide temporary or permanent relief of diplopia in less severe cases 1, 3