A device and method of treating an aneurysm in a cranial artery of a patient includes providing a coil delivery system having a bypass catheter with a proximal end portion, a distal end portion, and an intermediate portion. The bypass catheter also includes a bypass lumen extending from the proximal end portion to the distal end portion and a coil delivery lumen that extends from the proximal end portion to a coil delivery opening in a side wall of the bypass catheter. The coil delivery system also includes an embolic coil or multiple coils capable of being deployed separately through the coil delivery opening and electrolytically detached, and at least one balloon disposed about an outer surface of the bypass catheter and capable of substantially preventing blood flow around the outer surface of the bypass catheter when inflated. The system may be used without coil embolization to provide endovascular bypass with segmental vessel occlusion during brain surgery such as craniotomy with clipping of a cerebral aneurysm.
