title: Ruptured Distal Posterior Inferior Cerebellar Artery (PICA) Aneurysms Associated with Cerebellar Arterial Venous Malformations (AVMs): A Case Series and Review of the Literature Demonstrating the Need for Angiographic Evaluation and Feasibility of Endovascular Treatment.
abstract: OBJECTIVE
  The characteristics, diagnosis, and preferred management strategies for distal posterior inferior cerebellar artery (PICA) aneurysms associated with cerebellar arteriovenous malformation (AVMs) are poorly understood. We present a case series with attention to aneurysm angioarchitecture, diagnostic imaging, treatment approaches, and a thorough review of the literature. With this information, we demonstrate a specific anatomical pattern for these aneurysms, an underreported need for conventional digital subtraction angiography (DSA) during evaluation, along with the utility of endovascular treatment with liquid embolic agents.
  
  
  METHODS
  Neurosurgical patients from 2005 to 2016 were reviewed to identify PICA aneurysms along with distal PICA aneurysms. Details of their presentation, imaging studies, associated AVMs and treatment were recorded. A thorough literature search of previous case series and case reports of distal PICA aneurysms with and without associated small cerebellar AVMs was performed with PubMed and Google Scholar.
  
  
  RESULTS
  Thirty-four patients with PICA aneurysms were identified at our institution, 12 of which were in a distal segment. All 12 of these patients underwent DSA as a part of their evaluation. Of the 12 patients with distal PICA aneurysms, 9 presented with subarachnoid hemorrhage and intraventricular hemorrhage. Five of these patients had a small occult cerebellar AVM. All nine patients presenting with a ruptured distal PICA aneurysm had a Fischer grade 4 subarachnoid hemorrhage. Of the five patients with a small occult cerebellar AVM, the AVM nidus was missed on computed tomography angiogram (CTA) interpretation but easily visualized with DSA. CTA followed by DSA with concurrent endovascular treatment was performed in 9 of the 12 patients with distal PICA aneurysms. Two of the 12 patients were treated with microsurgical clip ligation, and one mycotic aneurysm was identified and treated with antibiotics. Parent vessel sacrifice was used distal to the aneurysm in all 5 associated AVM cases with liquid embolic agents as well as AVM embolization in 3 of the 5 cases. Fifty-one well-described case reports of distal PICA aneurysms associated with small cerebellar AVMs have been reported in the literature. A total of 12 well-described case series of distal PICA aneurysms that comment on associated AVMs describe an associated small cerebellar AVM incidence of 4%-50%. In our case series, the incidence of an associated small cerebellar AVM with a distal PICA aneurysm was 42%.
  
  
  CONCLUSIONS
  In cases of distal PICA aneurysms, there is a frequent association of a small cerebellar AVM. In our series, CTA was an inadequate diagnostic study to identify the associated AVM, and DSA was necessary to definitely visualize the AVM nidus. Endovascular treatment of the aneurysm and AVM with the use of liquid embolic agents was a feasible and useful management strategy.
authors: Department of Neurosurgery, University of Colorado, Aurora, Colorado, USA. Electronic address: david.case@ucdenver.edu.
authors: David
authors: D
authors: Case
authors: Department of Neurosurgery, University of Colorado, Aurora, Colorado, USA.
authors: David
authors: D
authors: Kumpe
authors: Department of Neurosurgery, University of Colorado, Aurora, Colorado, USA.
authors: Luis
authors: L
authors: Cava
authors: Department of Neurosurgery, University of Colorado, Aurora, Colorado, USA.
authors: Robert
authors: R
authors: Neumann
authors: Department of Neurosurgery, University of Colorado, Aurora, Colorado, USA.
authors: Andrew
authors: A
authors: White
authors: Department of Neurosurgery, University of Colorado, Aurora, Colorado, USA.
authors: Christopher
authors: C
authors: Roark
authors: Department of Neurosurgery, University of Colorado, Aurora, Colorado, USA.
authors: Joshua
authors: J
authors: Seinfeld
mesh_terms: D000328:Adult; D000368:Aged; D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging / Q000628:therapy*; D002526:Cerebellar Diseases / Q000175:diagnosis / Q000628:therapy*; D003131:Combined Modality Therapy / Q000379:methods; D004621:Embolization, Therapeutic / Q000379:methods*; D057510:Endovascular Procedures / Q000379:methods*; D019317:Evidence-Based Medicine; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000628:therapy*; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis / Q000628:therapy*; D008297:Male; D008875:Middle Aged
keywords: AVMs; Aneurysms; DSA; Distal PICA; PICA; Ruptured aneurysm; SAH