To present a case of idiopathic orbital inflammation (IOI) to expand the differential diagnosis of hemicrania continua.

Hemicrania continua is an indomethacin-responsive primary headache disorder with unilateral headache with or without autonomic features that is a clinical diagnosis of exclusion.

A 64-year-old woman presented with episodes of headache and visual changes beginning two years prior with left temporal and retro-orbital constant, pulsating-like pain.  Two months later, her headache worsened and she developed intermittent left ptosis with ipsilateral lacrimation and rhinorrhea.  She was treated with indomethacin for possible hemicrania continua, with only partial improvement in pain.  One year later, she developed decreased visual acuity with left eye inferonasal field loss and was found to have left parasellar meningeal enhancement.  She was treated with indomethacin and had spontaneous return of vision after one week.  Her symptoms recurred nine months later on the contralateral side with right eye vision loss to finger counting and diplopia on rightward gaze.  Physical examination demonstrated a CN VI palsy and right afferent pupillary deficit.

Repeat MRI head showed right orbital apex enhancement and an otherwise extensive diagnostic evaluation for autoimmune, inflammatory and neoplastic causes was unrevealing.  She was diagnosed with IOI causing a right orbital apex syndrome.  She was treated with high-dose prednisone and had complete resolution of headache with restoration of vision, while continuing to be monitored vigilantly for secondary causes of orbital apex syndrome.