Iatrogenic Intracranial Aneurysm After External Ventricular Drain Placement: Traumatic or Mycotic Origin? Case Report and Literature Review

BACKGROUND: Intracranial iatrogenic aneurysms (IIAs) developing after external ventricular drain (EVD) placement or removal have been only rarely reported. Most of these reports assumed a traumatic etiology; however, some have demonstrated an inflammatory origin. We have presented the case of an IIA that developed after an EVD had been inserted to treat acute hydrocephalus secondary to a ruptured arteriovenous malformation. We also performed a literature review and discussed how these IIAs might have an inflammatory rather than a traumatic etiology and how they might lie behind some of the cases of idiopathic hemorrhage observed after EVD manipulation. CASE DESCRIPTION: A 48-year-old woman had presented with acute hydrocephalus secondary to bleeding from a vermian arteriovenous malformation. The EVD inserted for hydrocephalus management required several revisions because of malfunction. Four weeks later, a diagnostic arteriogram had incidentally revealed the existence of a 5-mm aneurysm in an anterior branch of the right callosomarginal artery, coincidental to the EVD trajectory. The patient underwent emergent endovascular treatment of the aneurysm, with complete occlusion and no complications deriving from the procedure. CONCLUSIONS: IIAs associated with EVD placement or removal have been described as a rare complication of the procedure. Despite the scarce number of cases reported and the lack of histological examinations, common features such as a distal location, an incidental diagnosis, and a benign clinical course might suggest a mycotic or inflammatory origin rather than a traumatic etiology. Considering the high volume of EVDs placed annually, this complication might be more frequent than reported. Further studies investigating the association of risk factors for inflammatory aneurysms and hemorrhage incidence after EVD could provide information on this intriguing topic.