title: Relationship Between Successful Extracranial-Intracranial Bypass Surgeries and Ischemic White Matter Hyperintensities.
abstract: OBJECTIVE
  Few studies have described regression of white matter hyperintensities (WMHs); however, no studies have described their recurrence or fluctuation. Thus, we aimed to study the course of WMHs on fluid-attenuated inversion recovery (FLAIR) magnetic resonance image (MRI) after extracranial-intracranial (EC-IC) bypass surgery and its correlation with the clinical outcome.
  
  
  METHODS
  We enrolled perioperative FLAIR MRIs of 12 patients with WMHs who underwent EC-IC bypass surgeries because of ischemic-vascular stenosis with postoperative improvement of the cerebral blood flow confirmed by (123)I-iodoamphetamine single-photon emission computed tomography. Correlation between WMHs and cerebral blood flow was confirmed by perioperative single-photon emission computed tomography and diffusion-weighted imaging MRI. The WMHs were assessed visually with meticulous volumetric grading. Depending on postoperative changes among different grades, the WMHs course was determined to be improved, fluctuating, worsened, or unchanged. A statistical analysis was performed on the course of WMHs over time.
  
  
  RESULTS
  Imaging analysis was done with FLAIR MRI in 12 patients. The course of WMHs over time was 41.7% improvement, 33.3% fluctuation, 16.7% unchanged, and 8.3% worsening of the deep WMHs. After unilateral bypass surgery, 80% of the improved WMHs occurred bilaterally. Among patients with improved clinical outcomes, 16.7% showed improvement and 33.3% showed fluctuation, whereas in patients with unchanged clinical outcomes, 25% showed improvement of their WMHs on follow-up FLAIR MRIs.
  
  
  CONCLUSIONS
  This study might be considered the first step to find a relationship between successful EC-IC bypass surgeries and the course of ischemic WMHs. It could also open the door for further studies to make more solid conclusions.
authors.affiliation: Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Japan; Department of Neurosurgery, Al-Azhar University Faculty of Medicine-Nasr city, Cairo, Egypt. Electronic address: nagm@shinshu-u.ac.jp.
authors.forename: Alhusain
authors.initials: A
authors.lastname: Nagm
authors.affiliation: Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Tetsuyoshi
authors.initials: T
authors.lastname: Horiuchi
authors.affiliation: Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ito
authors.affiliation: Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Hongo
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000601:surgery*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D049292:Leukoaraiosis / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D017063:Outcome Assessment, Health Care; D015899:Tomography, Emission-Computed, Single-Photon
keywords: Cerebral ischemia; EC-IC bypass; FLAIR MRI; Fluctuation; White matter hyperintensities