Because GDC embolization, unlike a direct surgical procedure, does not require direct mechanical movement in cerebral tissue around an aneurysm, the adjacent brain tissue is less affected. However, it is recognized that perianeurysmal edema appears in rare situations after embolization and leads to the development and deterioration of neurological symptom 1) 2)

1)
Russell SM, Nelson PK, Jafar JJ. Neurological deterioration after coil embolization of a giant basilar apex aneurysm with resolution following parent artery clip ligation. J Neurosurg. 2002;97:705–708.
2)
Iihara K, Murao K, et al. Continued growth of and increased symptoms from a thrombosed giant aneurysm of the vertebral artery after complete endovascular occlusion and trapping: the role of vasa vasorum. J neurosurg. 2003;98:407–413.