The black eyebrow sign in orbital blowout fracture.

Orbital blowout fractures are frequently associated with intraorbital emphysema. This may be seen on a frontal skull radiograph as a lucent area at the superior side of the orbit, simulating a black eyebrow. Although computed tomography remains the primary imaging modality for assessing patients with clinically obvious blowout fracture, conventional radiography is often the first imaging study performed in cases of orbital trauma. By consequensce, knowledge of the black eyebrow sign is very useful especially to more unexperienced radiologists working at the emergency department.