Indirect carotid–cavernous sinus fistula following mechanical thrombectomy: A case report of a rare iatrogenic injury with progressive presentation

•All of cases reported type A CCFs, and patients were presented with either asymptom from generation of fistula to duration of postoperative follow-up or distinct presentations at once after MT.•Our case reports for the first time a definite type B indirect CCF following MT between meningohypophyseal trunk and CS with progressive presentations.•Spontaneous dural CCFs are inclined to occur in middle-aged or elderly women, especially in postmenopausal women, so age and sex are regarded as background factors of progressing.•The change of drainage route is an immediate cause of progressive presentations.