Optochiasmal arachnoiditis following cotton wrapping of anterior communicating artery aneurysm treated by surgical removal of granuloma

We report the case of a 50 year old female who presented with visual disturbance due to optochiasmal arachnoiditis and foreign body granuloma 9 months after cotton wrapping for ruptured anterior communicating artery (AcomA) aneurysm. Magnetic resonance imaging (MRI) revealed enhanced mass lesion around AcomA complex and hyperintense signal on optic chiasm and right optic tract by fluid-attenuated inversion recovery image. Despite the repeated steroid pulse therapy, she deteriorated and MRI showed expansion of the granulomatous lesion over 5 months. Surgical removal of foreign body granuloma resulted in marked improvement of visual disturbance as well as of the MRI findings. We conclude that the use of cotton sheet close to the optic nerve should be avoided, and that surgical removal of the granuloma would be the optimal choice especially for the patient in whom steroid therapy fails to improve clinical symptoms.