[Isolated traumatic oculomotor nerve palsy caused by minor head trauma].

Isolated traumatic oculomotor nerve palsy caused by minor head trauma is extremely rare. We report a case of this condition. A 65-year-old woman was transferred to our hospital after minor head injury. Initial examination of her right eye revealed a dilated pupil. The result of computed tomography, magnetic resonance imaging, and magnetic resonance angiography of the brain were normal. An examination conducted 6 hours after the accident, examination demonstrated right ptosis, and another conducted 20 hours after the accident, she demonstrated partial limitation of adduction, supraduction, and infraduction of the right eye. Constructive interference in steady-state magnetic resonance imaging demonstrated a slightly rough-shaped oculomotor nerve near the posterior petroclinoid ligament. After 8 months of the accident, the ptosis and limited eye movement were resolved. However, the right dilation of the right pupil persisted. Our case suggests that even minor head trauma can cause isolated oculomotor palsy, and that the posterior petroclinoid ligament is a candidate structure for causing oculomotor nerve palsy without intracranial hemorrhage and skull fracture.