Case 15 – A 25-year-old man after a motor vehicle accident

A 25-year-old man is brought to the emergency department by ambulance after a motor vehicle accident. The paramedics report that his vehicle, which was not equipped with airbags, hit a telephone pole at a speed of approximately 35 mph. His temperature is 37.0°C (98.6°F), heart rate is 91/min, respiratory rate is 13/min, and blood pressure is 116/78 mm Hg. He is alert and oriented to person and place, but does not recall the date or any of the events leading up to the accident. He also reports that he feels very dizzy whenever he looks up at the ceiling. Examination of the head and neck reveals slight enophthalmos of the left orbit with infraorbital and upper lip anesthesia.

What is the most likely diagnosis?

Orbital fracture. Blowout fractures are the result of blunt trauma to the globe with rapid expansion of the orbital contents and rupture through the bony floor. A blowout fracture can also be the result of a direct blow to the orbital rim.

What is the etiology of this condition?

Facial fractures secondary to motor vehicle and recreational accidents are more common in rural areas, whereas penetrating trauma and assault-related injuries are more common in urban populations. Domestic violence and abuse should always be considered as a possible cause of the injury.

What other symptoms are common in patients with this condition?

Diplopia on upward gaze suggests inferior rectus muscle entrapment, but the etiology may be multifactorial. Infraorbital anesthesia is the result of a contused infraorbital nerve and anesthesia of the maxillary teeth and upper lip is common. Rarely, patients demonstrate enophthalmos, or sunken globe, when a large section of the globe has ruptured. Occasionally, a step-off deformity can be palpated over the intraorbital rim, or subcutaneous emphysema results from fracture into a sinus or nasal antrum.

What tests and/or imaging tools could be used to confirm the diagnosis?

Plain films are useful in the diagnosis of blowout fractures. The “hanging teardrop” sign suggests orbital fat herniating into the maxillary sinus. Once a blowout fracture is suspected, a CT scan of the face with coronal sections can be used to determine the surface area of the broken orbital floor.

What is the most appropriate management for this patient?

All orbital fractures may have repair delayed for 1-2 weeks; however, opinions regarding surgical repair vary among providers. Antibiotics against sinus pathogens are recommended for patients with subcutaneous emphysema.

By Julie Katz, MD, Resident in Anatomic and Clinical Pathology, The Johns Hopkins Hospital; in association with Le TT, Schabelman E, Shivaram A, and Klein J, eds: First Aid Cases for the USMLE Step 2 CK. New York: McGraw-Hill, 2007.