title: Twin-like appearance of an unruptured intracerebral anterior communicating artery (ACom) aneurysm in a male sibling of a patient with a ruptured ACom aneurysm.
abstract: Increased risk of intracranial aneurysm rupture with subsequent subarachnoid haemorrhage (SAH) is related to several possible factors, including first-grade familial aneurysms.
  
  
  
  Here we present a case of one ruptured and one unruptured identical twin-like anterior communicating artery (ACom) aneurysm present in two male siblings, without any proven genetic predisposition. According to evidence-based scores, aneurysm rupture risk for the younger (51 years old) sibling (with an unruptured ACom aneurysm) would be low, leaving the decision for either treatment or clinical follow-up to the discretion of the treating physician.
  
  
  
  From a clinical neurosurgical perspective, however, especially since his older brother suffered an aneurysmal SAH at age 57 (i.e. 6 life-years later) from a twin-like-appearing ACom aneurysm, in our opinion rupture seems almost inevitable, thus prompting treatment at an early stage.
authors.affiliation: Department of Neurosurgery, University Hospital Zurich, Frauenklinikstrasse 10, 8091, Zürich, Switzerland. jorn.fierstra@usz.ch.
authors.forename: Jorn
authors.initials: J
authors.lastname: Fierstra
authors.affiliation: Department of Neurosurgery, University Hospital Zurich, Frauenklinikstrasse 10, 8091, Zürich, Switzerland.
authors.forename: Jan Karl
authors.initials: JK
authors.lastname: Burkhardt
authors.affiliation: Department of Neuroradiology, Clinical Neuroscience Center, University of Zurich, University Hospital Zurich, Zürich, Switzerland.
authors.forename: Stamatios
authors.initials: S
authors.lastname: Stamou
authors.affiliation: Department of Neurosurgery, University Hospital Zurich, Frauenklinikstrasse 10, 8091, Zürich, Switzerland.
authors.forename: Luca
authors.initials: L
authors.lastname: Regli
authors.affiliation: Department of Neurosurgery, University Hospital Zurich, Frauenklinikstrasse 10, 8091, Zürich, Switzerland.
authors.forename: Oliver
authors.initials: O
authors.lastname: Bozinov
mesh_terms: D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging* / Q000235:genetics; D020022:Genetic Predisposition to Disease; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D035781:Siblings
keywords: Anterior communicating artery aneurysm; Familial; Rupture risk; Subarachnoid haemorrhage