Treatment for Lateral Rectus Muscle Entrapment with Orbital Wall Fracture
Immediate surgical repair is indicated for lateral rectus muscle entrapment with orbital wall fracture, particularly when associated with oculocardiac reflex symptoms or significant diplopia with positive forced ductions. 1
Initial Assessment and Diagnosis
- Vital signs monitoring: Check for bradycardia, heart block, dizziness, nausea, vomiting, or loss of consciousness which may indicate oculocardiac reflex requiring urgent intervention 1
- Imaging: CT scan is preferred over MRI if there's concern about metallic foreign bodies 1
- Clinical examination:
- Forced duction and forced generation testing to distinguish restriction from paresis
- Detailed sensorimotor exam with attention to versions, ductions, and alignment in multiple gaze positions
- Double Maddox rod, Lancaster red-green, or Hess screen tests may be helpful
Treatment Algorithm
Immediate Surgical Repair (Within Hours to Days)
Indicated for:
- Entrapped lateral rectus muscle with nonresolving oculocardiac reflex
- Significant restriction of ocular motility with positive forced ductions
- CT evidence of muscle entrapment
- Globe subluxation into sinus (rare complication) 1
Early Surgical Repair (Within 2 Weeks)
Indicated for:
- Symptomatic diplopia with positive forced ductions or entrapment on CT with minimal improvement
- Significant fat or periorbital tissue entrapment
- Large orbital wall fractures
- Early enophthalmos or hypoglobus causing facial asymmetry 1
Delayed Repair or Observation
- For minimal diplopia (not in primary or downgaze)
- Good ocular motility without significant enophthalmos
- Restrictive strabismus without entrapment may benefit from delayed repair 1
Surgical Considerations
- Muscle recovery: Attempt to recover "lost" muscles whenever possible 1
- Transposition procedures: May be indicated if muscle recovery is impossible or if muscle is severely paretic 1
- Adjustable sutures: Often helpful in these complex cases 1
- Multidisciplinary approach: May require coordination between ophthalmology, oculoplastics, and neurosurgery 1
Medical Management
- Steroids: A short course of oral steroids (such as dexamethasone) can help reduce postoperative swelling and uncover persistent strabismus 2
- Recommended regimen: 8 mg on surgery day, 6 mg on first day after surgery, 4 mg on second day, and 2 mg on third day 2
Post-Treatment Considerations
- Even with repair, strabismus and diplopia may persist (37% of patients have persistent diplopia after orbital blowout fracture repair) 1
- For persistent diplopia, conservative treatments include:
- Occlusion
- Fresnel prisms
- Botulinum toxin injection
- Prism glasses 1
Pitfalls and Caveats
- Missed diagnosis: Muscle entrapment can present with subtle findings or mimic other conditions, leading to delays in diagnosis 3
- "Missing muscle syndrome": When the entrapped muscle is not visible on multiple contiguous CT cuts, this indicates severe entrapment requiring urgent intervention 4
- Muscle avulsion: Consider the possibility of muscle tear or avulsion if orbital tissue entrapment and nerve paresis are excluded as causes of reduced ocular motility 5
- Complete evaluation: Thoroughly review imaging studies for possible muscle injury before surgery 5
- Adhesions: Orbital fat entrapment can be as challenging as muscle entrapment, resulting in fibrotic and adhesion syndromes 1
Remember that the primary goal of treatment is to eliminate diplopia in primary position and downgaze, and to enlarge the field of binocular single vision. More than one strabismus surgery and long-term use of prism glasses may be required in complex cases.