Traumatic aneurysm rupture following a closed head injury is rare. The rupture of a cavernous internal carotid artery (ICA) aneurysm following a head injury presenting as a tentorial subdural hematoma has not been reported in the literature. We discuss a 50-year-old woman with a closed head injury with her initial computed tomography scan showing a tentorial subdural hematoma. Further investigations revealed the presence of a ruptured cavernous ICA aneurysm. We also conducted a literature review of posttraumatic ICA aneurysmal rupture.