A 24-year-old man presents to the emergency department after being struck in the face by a baseball during a game. He reports double vision and numbness over his right cheek. Physical examination reveals periorbital ecchymosis and swelling of the right eye. On extraocular movement testing, the patient has difficulty elevating the right eye, and diplopia worsens with upward gaze. Sensation to light touch is decreased over the right upper lip and lateral nose. Visual acuity is intact, and the globe appears intact without evidence of rupture. A CT scan of the face is obtained.
Which of the following findings is most likely present in this patient?
The correct answer is:
A) Decreased sensation in the distribution of the infraorbital nerve
Orbital blowout fractures most commonly involve the orbital floor (maxillary bone) or medial wall (ethmoid bone). Fracture of the orbital floor can injure or compress the infraorbital nerve, a branch of the maxillary division of the trigeminal nerve (V2), leading to numbness over the cheek, upper lip, and lateral nose. Diplopia with upward gaze occurs due to entrapment of the inferior rectus muscle, a classic feature of orbital floor fractures.
Answer choice B: Entrapment of the lateral rectus muscle, is incorrect. Orbital blowout fractures typically involve the inferior rectus muscle, not the lateral rectus. Lateral rectus dysfunction would impair abduction rather than elevation.
Answer choice C: Fracture of the zygomatic arch, is incorrect. A zygomatic arch fracture may cause facial flattening and trismus due to impingement on the temporalis muscle, but it does not explain diplopia with upward gaze or infraorbital numbness.
Answer choice D: Increased intraocular pressure from retrobulbar hematoma, is incorrect. Retrobulbar hematoma is a vision-threatening emergency characterized by proptosis, decreased visual acuity, afferent pupillary defect, and markedly increased intraocular pressure, findings not present in this patient.
Answer choice E: Optic nerve compression at the orbital apex, is incorrect. Optic nerve compression would present with decreased visual acuity, visual field defects, or an afferent pupillary defect, none of which are described here.
Key Learning Point
Orbital blowout fractures commonly involve the orbital floor, leading to inferior rectus muscle entrapment, causing diplopia on upward gaze, and injury to the infraorbital nerve, resulting in decreased sensation over the cheek and upper lip.
