Isolated Oculomotor Nerve Palsy Following Minor Head Trauma : Case Illustration and Literature Review
A 36-year-old woman with no past medical history was admitted to hospital after slipping on the ice. The patient did not lose consciousness, but she immediately noted drooping of her right eyelid and double vision when she elevated the lid. There was a 3 cm laceration wound on the chin and some abrasions over the neck and the central region of her face ().\nThe right pupil was fixed and dilated, and there was complete right ptosis. The patient could not elevate, depress, or adduct the right eye, but the eye intorted on attempted downgaze (). The right pupil measured 5 mm in diameter and was sluggish reactive to light. Ophthalmologic tests of vision and intraocular pressure were within normal ranges in both eyes. Further physical and neurological examinations were normal. Skull X-rays and orbital computed tomography (CT) scans immediately after the accident failed to show fractures. MRI and MR angiography of the brain did not reveal any pathology on admission (). Contrast-enhanced spoiled gradient-recalled (SPGR) MR sequences with multiplanar reconstruction (MPR) was subsequently performed to produce high-resolution images of the cisternal portions of the cranial nerves. The 3D MR studies indicated a slightly rough-shaped ON near the the posterior petroclinoid ligament (PCL), but no nerve enhancement (). The patient's history, along with the ophthalmologic symptoms and the radiologic findings strongly suggested the diagnosis of an isolated lesion in the course of the ON without further damage in the right oculomotor nucleus.\nShe was then treated with oral prednisone in a tapering dose over several weeks. MPR of contrast-enhanced 3D MRI taken 2 weeks after the event clearly demonstrated strong enhancement and enlargement over the whole length of the right ON (). At the time of follow-up two months after trauma, her ptosis slightly improved. Three months later, ptosis was completely resolved, and there was some restoration of ocular motion in the direction of adduction. Follow-up MRI 6 months post-injury showed complete resolution of the enhancement and swelling of the right ON (). Nine months after the injury, the patient still suffered from symptomatic glare and blurred vision for near objects, although complete recovery of diplopia was seen. Four months later, spontaneous improvement of pupillary dilatation was observed, and ophthalmology examination also revealed no paralysis of accommodation.