Optic nerve trauma with unilateral edema as a result of head injury.

We encountered a patient who suffered a head injury that translated to the optic nerves, leading to dramatic unilateral right optic nerve edema. The decedent was a 20-year-old unsecured passenger in a convertible. The car collided with a pickup truck. The patient survived for 8 h. At autopsy, a comminuted skull fracture involving the right frontal bone including the right orbital plate was found. The right optic nerve measured 1.2 cm in diameter, compared to only 0.4 cm for the left optic nerve. Microscopically, the right optic nerve was markedly edematous, but the nerve fibers and nuclei were viable and intact. The dramatic difference in size between the right and left optic nerves can be attributed to several mechanisms. The survival interval was essential for the asymmetrical swelling to take place. Optic nerve trauma is relatively rare in head injuries, reported to be present in 0.5% of automobile accidents and assaults. Other causes of optic nerve trauma and edema include tumors, osteopetrosis, or reaction to a peripheral hemodialysis shunt.