title: Symptomatic and silent ischemia associated with microsurgical clipping of intracranial aneurysms: evaluation with diffusion-weighted MRI.
abstract: OBJECTIVE
  Silent ischemic events are known to occur during diagnostic and interventional endovascular procedures between 10% and 69% of the time. The occurrence of silent and symptomatic ischemic events in the surgically treated population is not known, although atherosclerotic changes of intracranial vessels or within the aneurysms wall or neck area are seen often during surgery.
  
  
  METHODS
  Patients with unruptured and ruptured intracranial aneurysms treated by microsurgical clipping were prospectively evaluated with MRI using diffusion-weighted imaging sequences before and within 24 hours after surgery. Patients were evaluated clinically before and after surgery. During surgery, the overall and maximal time of temporary occlusion as well as the total number of temporary and finally applied clips was noted. Diffusion-weighted images were analyzed with determination and characterization of diffusion-weighted imaging abnormalities.
  
  
  RESULTS
  Thirty-six patients with 51 aneurysms were included. One symptomatic and 5 silent ischemic lesions were found in 5 patients. This represents a risk of silent ischemia of 9.8% per treated aneurysm and a risk of symptomatic stroke of 2%. The most significant risk factor in increasing order was: age (P<0.05), presence of thrombus (P<0.05), number of final clips applied (P<0.05), number of temporary clips used (P<0.01), total time of temporary clip occlusion (P<0.001), and maximal time of temporary occlusion (P<0.001).
  
  
  CONCLUSIONS
  The risk of silent and symptomatic ischemic events during microsurgical clipping of intracranial aneurysms seems to be low. Microsurgical clipping is safe and should continue to be strongly considered as a treatment option.
authors.affiliation: Department of Neurosurgery, University Hospital Zürich, Frauenklinikstr. 10, 8091 Zürich, Switzerland. nkrayenbuehl@bluewin.ch
authors.forename: Niklaus
authors.initials: N
authors.lastname: Krayenbühl
authors.forename: Eren
authors.initials: E
authors.lastname: Erdem
authors.forename: Minna
authors.initials: M
authors.lastname: Oinas
authors.forename: Ali F
authors.initials: AF
authors.lastname: Krisht
mesh_terms: D000367:Age Factors; D002545:Brain Ischemia / Q000209:etiology* / Q000473:pathology* / Q000503:physiopathology; D002536:Cerebral Arteries / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000601:surgery*; D020767:Intracranial Thrombosis / Q000150:complications; D008297:Male; D008866:Microsurgery / Q000009:adverse effects / Q000295:instrumentation; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000009:adverse effects* / Q000295:instrumentation; D011183:Postoperative Complications / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D012307:Risk Factors; D013525:Surgical Instruments / Q000009:adverse effects; D013997:Time Factors; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures / Q000009:adverse effects* / Q000295:instrumentation