Transvenous approach for the treatment of direct carotid cavernous fistula following Pipeline embolization of cavernous carotid aneurysm: a report of two cases and review of the literature - Lin, L-M; Colby, G P; Jiang, B; Pero, G; Boccardi, E; Coon, A L (J Neurointerv Surg, 2015)