Pneumocephalus. A sign of intracranial involvement in orbital fracture.

Fractures of the orbit resulting from blunt or penetrating injury that involve the paranasal sinuses may tear the dura and allow air to enter the cranial cavity (pneumocephalus). Pneumocephalus is sometimes the only sign of intracranial involvement. It is characteristically delayed in onset and clinically unsuspected, so that routine follow-up roentgenograms of patients with orbitosinus fractures may be the only means of assuring early detection. Roentgenographically, the air may be seen in spidural, subdural subarachnoid, intracerebral, or intraventricular locations. Prophylactic parenterally administered antibiotics may prevent intracranial infection. However, since about 25% of patients still develop meningitis, surgical repair of the dural fistula is often necessary.