Alternating proptosis. A case report of acute orbital myositis defined by the computerized tomographic scan.

A 27-year-old woman had a two-week course of acute painful right proptosis with ptosis, medial conjunctival injection, and restriction of eye movements--particularly abduction. One month later, a similar remitting painful left proptosis with complete limitation of abduction developed. Computerized tomographic x-ray scanning showed marked contrast enhancement of both medial rectus muscles, documenting the presumptive diagnosis of acute orbital myositis without recourse to invasive diagnostic techniques. Myositis is a common component of idiopathic orbital inflammatory disease (orbital pseudotumor), but awareness of the rare patient with acute inflammation clinically localized to the extraocular muscles will decrease confusion with cranial nerve and cavernous sinus disease.