A patient sustains a direct blow to the periorbital region. Examination reveals enophthalmos, diplopia on upward gaze, restriction of elevation, and hypesthesia of the ipsilateral cheek. CT orbit shows a fracture of the orbital floor. The specific sign of entrapment neuro-vagal reaction that warrants immediate surgical consultation even without significant enophthalmos in pediatric patients is:

• A Presence of more than 2 cm² of herniated orbital fat on CT
• B The oculocardiac reflex with bradycardia and nausea due to inferior rectus entrapment ✓
• C Reduction of visual acuity by two or more lines
• D Diplopia in primary position persisting beyond 72 hours

Explanation

Pediatric orbital blow-out fractures can present as 'trapdoor' fractures — the highly elastic pediatric orbital floor springs back after fracture, trapping the inferior rectus muscle without much fat herniation (hence minimal enophthalmos on CT). The trapped muscle triggers the oculocardiac reflex (afferent: ophthalmic V1 via Gasserian ganglion; efferent: vagus nerve), causing bradycardia, nausea, and syncope — a 'white-eyed blow-out' presentation. This oculovagal response indicates significant entrapment and is an indication for URGENT surgical release (within 24-48 hours) to prevent ischemic damage to the inferior rectus muscle.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.