Diagnosis: Orbital floor fracture
This is a case of left orbital floor fracture with herniation of the inferior rectus muscle. Orbital fractures are most commonly the result of trauma with the orbital floor being most susceptible to fracture given it is the thinnest bone of the orbit. As the orbital floor makes up the roof of the maxillary sinus, inferior rectus often can herniate into the maxillary sinus. Sometimes the muscle can become entrapped or tethered within the fracture, particularly if it is narrow, causing inability to supraduct the affected eye and diplopia on upgaze. Entrapment warrants an emergent consult to ophthalmology. Limited upgaze and can also be present with herniation of inferior rectus in cases of large orbital floor fractures.
Bradycardia, nausea, and vomiting can all be signs of inferior rectus entrapment due to associated stimulation of oculocardiac reflex in this situation. The afferent limb of this pathway is CN V and these have been found to be associated with stretch receptors in periorbital tissues and muscles. This pathway leads to the CNS, where the efferent limb is CN X, and acts to slow the heart rate via vagal stimulation of the SA node. Nausea and vomiting have been found to be associated with vagal stimulation in patients, and therefore can be a sequelae of this reflex. In patients with orbital fracture and bradycardia, there should be a high index of suspicion for muscle entraopment.
Another complication of orbital fracture is enophthalmos, or posterior displacement of the eye, as seen in the second image of the case. Additionally, as the inferior orbital neurovascular bundle courses within the thin bony orbital floor it is highly susceptible to injury in the case of an orbital floor fracture, resulting in numbness of the skin inferior to the orbit.
Initial management of orbital floor fracture requires evaluation to determine severity of the presentation and to rule out other ocular trauma such as orbital compartment syndrome and open globe injury. Entrapment of an extraocular muscle may cause permanent tissue damage if not addressed urgently. Corticosteroids can be administered in those with swelling and limitation of extraocular movements while prophylactic antibiotics to cover sinus pathogens are recommended, However, clinical evidence for these treatment options is limited. Patient’s are also advised to avoid nose blowing to prevent orbital emphysema (air in the orbit).
In the absence of entrapment surgical repair is not urgent. Surgical repair of the orbital floor is indicated if diplopia persists after swelling is resolved, and can also be considered in cases of persistent enophthalmos. The decision to do so is not made until at least 2 weeks following the injury to allow for resolution of swelling, with which diplopia also often resolved.
References and Additional Resources:
2. Dunville LM, Sood G, Kramer J. Oculocardiac Reflex. In: StatPearls. StatPearls Publishing; 2021.
3. Long J, Tann T. Orbital trauma. Ophthalmol Clin North Am 2002; 15:2493
4. Brady SM, McMann MA, Mazzoli RA, et al. The diagnosis and management of orbital blowout fractures: update 2001. Am J Emerg Med 2001; 19:147
5. Jatla KK, Enzenauer RW. Orbital fractures: a review of current literature. Curr Surg 2004; 61:25.
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