Supplementary Material for: Occult Brain Arteriovenous Malformation Superimposed on a Pial Arteriovenous Fistula: Case Report

<b><i>Introduction:</i></b> Pial arteriovenous fistulas are characterized by an abnormal connection between an intracranial artery and vein without an intervening nidus. Their predominant symptoms largely arise from mass effect, shunting, or hemorrhage. Most conservatively managed cases progress to death, but endovascular and/or surgical intervention is often successful. <b><i>Case Presentation:</i></b> We present the unique case of a 15-year-old girl with spontaneous intracranial hemorrhage from a single-vessel arteriovenous fistula. Although preoperative imaging failed to show a distinct nidus, intraoperative indocyanine green angiography performed after successful clipping of the primary fistulous site revealed residual shunting from a peri-lesional arteriovenous malformation. <b><i>Discussion/Conclusion:</i></b> This case demonstrates the importance of intraoperative imaging and meticulous circumferential inspection of these lesions to detect residual vascular shunting.

**引言**：软脑膜动静脉瘘（pial arteriovenous fistulas）的特征为颅内动脉与静脉之间存在异常直接交通，无中间血管巢。其主要症状多由占位效应、分流或出血引发。多数接受保守治疗的患者病情会进展至死亡，但血管内及/或外科手术干预常可获得成功。
**病例报告**：本文报告一例特殊病例：一名15岁女性因单支血管动静脉瘘引发自发性颅内出血。尽管术前影像学检查未发现明确的血管巢，但在成功夹闭原发瘘口后实施的术中吲哚菁绿血管造影（indocyanine green angiography）显示，病灶周围动静脉畸形（arteriovenous malformation）仍存在残余分流。
**讨论与结论**：本病例凸显了术中影像学检查及对这类病变进行细致环周检视对于发现残余血管分流的重要性。