Benign episodic bilateral juvenile internal ophthalmoplegia.

A case of benign episodic bilateral juvenile internal ophthalmoplegia in a nine-year-old female is presented. Two separate episodes of sudden onset of bilateral mydriasis and accommodative loss accompanied by headache occurred, without any other physical, neuroophthalmic, or third nerve involvement. Complete resolution occurred over a period of months in both episodes. The differential diagnosis of isolated internal ophthalmoplegia is reviewed, and the episodic unilateral mydriasis syndrome of Hallett and Cogan appears to be similar to the bilateral involvement in the case presented.