[Oculomotor nerve compression on MRI in a 56-year-old man with pituitary apoplexy due to panhypophisitis].

A 56-year-old man noted sudden onset of headache, fever, right pupil-spared oculomotor nerve palsy and consciousness disturbance. Swelling of pituitary with T1 high intensity on brain MRI suggested the diagnosis of pituitary apoplexy. Considering significant decrease of pituitary anterior lobe hormone and central diabetes insipidus, high dose of hydrocortisone was administered. Eight days after onset, consciousness level and headache improved. On day 30, brain MRI revealed the reduction of mass size, and on day 46, photophobia and double vision disappeared. Following the rapid response to steroid and disappearance of pituitary lesion, pituitary apoplexy was probably caused by panhypophisitis. Thin-slice brain MRI confirmed the compression of oculomotor nerve at inlet zone of cavernous sinus, suggesting the mechanism of oculomotor palsy was perfusion impairment of feeding artery.