Walsh & Hoyt: Traumatic Myopathies

Trauma is probably the most common cause of isolated extraocular muscle damage. When the injury is not associated with orbital fracture, ocular motor dysfunction may be caused by intramuscular edema and hemorrhage, by muscle laceration, or by avulsion of the muscle origin or insertion. When there is associated orbital fracture, the same mechanisms of injury may occur. In addition, however, the extraocular muscles and surrounding tissue may be injured by bone fragments or become entrapped within the fracture site, producing restriction of ocular motility.