What is the oculocardiac reflex and how is it managed?

The Oculocardiac Reflex: Definition, Pathophysiology, and Management

The oculocardiac reflex is a potentially life-threatening trigeminovagal reflex that causes bradycardia, heart block, or other dysrhythmias when orbital structures are manipulated or compressed, requiring immediate recognition and management to prevent serious cardiovascular complications. 1, 2

Definition and Pathophysiology

• The oculocardiac reflex is a trigeminovagal reflex arc where stimulation of the ophthalmic division of the trigeminal nerve (afferent limb) triggers the vagus nerve (efferent limb), resulting in negative chronotropic effects on the heart 3, 4
• First described in 1908 by Aschner, this reflex manifests as bradycardia, heart block, or other cardiac dysrhythmias when orbital structures are manipulated 3, 5
• The reflex can be triggered by:
  • Traction on extraocular muscles 5
  • Pressure on or within the eyeball 4
  • Orbital trauma with muscle entrapment 1, 2
  • Traction on eyelid muscles (also called blepharocardiac reflex) 4, 6

Clinical Presentation

• Cardiac manifestations:
  • Sinus bradycardia (most common) 3, 5
  • Complete heart block 1
  • Ventricular escape rhythms 3
  • Asystole in severe cases 6, 7
• Associated symptoms:
  • Nausea and vomiting (most common non-cardiac symptom) 7
  • Dizziness 1, 2
  • Loss of consciousness 1, 2
  • Diplopia (in cases of orbital trauma) 7

Risk Factors

• Pediatric patients (more pronounced reflex) 5, 7
• Young adults (median age 22 in trauma cases) 7
• Low body weight 6
• Hypoventilation, hypoxemia, and acidosis (exacerbate the reflex) 5
• Orbital floor fractures (most common fracture pattern triggering the reflex) 7

Diagnosis

• Vital sign monitoring showing bradycardia or dysrhythmia during orbital manipulation 1, 2
• Temporal relationship between orbital stimulation and cardiac changes 4, 6
• In trauma cases, CT imaging to identify:
  • Orbital floor fractures 1, 2
  • Extraocular muscle entrapment 1, 2
  • Periorbital tissue entrapment 1, 2
• Forced duction testing to confirm muscle entrapment 1

Management

Immediate Management

• Immediate cessation of the triggering stimulus (release traction or pressure) 6
• Continuous cardiac monitoring 4, 6
• Establishment of intravenous access 4
• Administration of atropine for persistent bradycardia 4, 5
• Correction of any hypoxemia, hypercarbia, or acidosis 5

Surgical Management

• Immediate surgical repair is indicated for patients with CT evidence of entrapped muscle or periorbital tissue associated with a nonresolving oculocardiac reflex 1, 2
• "White-eyed blow-out fracture" (trap-door fracture with muscle entrapment and oculocardiac reflex, seen primarily in children) requires urgent surgical intervention 1, 2
• Globe subluxation into the maxillary sinus demands immediate surgical repair 1, 2

Preventive Measures

• Gentle surgical technique during orbital and periorbital procedures 6
• Avoidance of excessive traction on extraocular muscles or orbital fat 6
• Preoperative administration of anticholinergic medications (e.g., atropine) in high-risk cases 4, 5
• Retrobulbar block can prevent the reflex in some cases 5

Clinical Significance

• The oculocardiac reflex is particularly important in:
  • Ophthalmic surgery, especially strabismus procedures 5
  • Orbital trauma with muscle entrapment 1, 2, 7
  • Blepharoplasty and other eyelid surgeries 4, 6
• Even with proper repair of orbital fractures, diplopia can persist in up to 37% of patients postoperatively 2
• The reflex is not static and may evolve over a patient's clinical course, requiring ongoing monitoring 7

Prognosis

• Prompt recognition and management typically results in complete resolution of cardiac symptoms 7
• In cases of orbital trauma requiring surgical repair, the oculocardiac reflex usually resolves after decompression of entrapped tissues 1, 2
• For non-urgent cases without persistent oculocardiac reflex, waiting 4-6 months after trauma is advised to ensure stability of misalignment before addressing residual strabismus 1, 2