Bilateral symptomatic large cavernous carotid artery aneurysms treated by extracranial-intracranial bypass with parent artery occlusion.

Bilateral large cavernous sinus internal carotid aneurysms (CCAs) occur very rarely. While the choice of treatment method is important, the timing of contralateral side treatment is equally important. We herein report the case of a 72-year-old woman who presented with progressive bilateral visual impairment and was treated by two-stage. First, the left CCAs had been treated, and the aneurysm was thrombosed, but her left visual acuity did not recover; the right CCA was becoming larger 2 years later, and her right visual acuity began worsening. The right CCAs was treated by almost same method. Her right visual acuity improved compared with the second preoperative findings. Our case findings suggest the importance of considering the appropriate timing to avoid symptom aggravation in patients with bilateral CCAs.