title: Unstable moyamoya disease: clinical features and impact on perioperative ischemic complications.
abstract: OBJECTIVE
  Unstable moyamoya disease, reasonably defined as cases exhibiting either rapid disease progression or repeated ischemic stroke, represents a challenge in the treatment of moyamoya disease. Despite its overall efficacy, direct bypass for such unstable disease remains controversial in terms of safety. This study aims to reveal factors associated with unstable disease and to assess its impact on postoperative silent or symptomatic ischemic lesions.
  
  
  METHODS
  This retrospective cohort study included both pediatric and adult patients with moyamoya disease who had undergone 140 consecutive direct bypass procedures at Kyoto University Hospital. "Unstable moyamoya disease" was defined as either the rapid progression of a steno-occlusive lesion or repeat ischemic stroke, either occurring within 6 months of surgery. The extent of progression was determined through a comparison of the findings between 2 different MR angiography sessions performed before surgery. The clinical variables of the stable and unstable disease groups were compared, and the association between unstable disease and postoperative diffusion-weighted imaging (DWI)-detected lesion was assessed through univariate and multivariate analyses with generalized estimating equations.
  
  
  RESULTS
  Of 134 direct bypass procedures performed after patients had undergone at least 2 sessions of MR angiography, 24 (17.9%) were classified as cases of unstable disease. Age younger than 3 years (p=0.029), underlying disease causing moyamoya syndrome (p=0.049), and radiographic evidence of infarction (p=0.030) were identified as factors associated with unstable disease. Postoperative DWI-defined lesions were detected after 13 of 140 procedures (9.3%), although only 4 lesions (2.9%) could be classified as a permanent complication. The incidence of postoperative DWI-detected lesions in the unstable group was notable at 33.3% (8 of 24). Univariate analysis revealed that unstable disease (p<0.001), underlying disease (p=0.028), and recent stroke (p=0.012) were factors associated with DWI-detected lesions. Unstable disease remained statistically significant after adjustment for covariates in both the primary and sensitivity analyses (primary analysis: OR 6.62 [95% CI 1.79-24.5]; sensitivity analysis: OR 5.36 [95% CI 1.47-19.6]).
  
  
  CONCLUSIONS
  Unstable moyamoya disease, more prevalent in younger patients and those with underlying disease, is a possible risk factor for perioperative ischemic complications. Recognition of unstable moyamoya disease may contribute to an improved surgical result through focused perioperative management based on appropriate surgical risk stratification.
authors.affiliation: Departments of 1 Neurosurgery and.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Funaki
authors.forename: Jun C
authors.initials: JC
authors.lastname: Takahashi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Takagi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kikuchi
authors.forename: Kazumichi
authors.initials: K
authors.lastname: Yoshida
authors.forename: Takafumi
authors.initials: T
authors.lastname: Mitsuhara
authors.forename: Hiroharu
authors.initials: H
authors.lastname: Kataoka
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Okada
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Fushimi
authors.forename: Susumu
authors.initials: S
authors.lastname: Miyamoto
mesh_terms: D000293:Adolescent; D000328:Adult; D002548:Cerebral Revascularization / Q000379:methods*; D002648:Child; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D018810:Magnetic Resonance Angiography; D008297:Male; D009072:Moyamoya Disease / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery*; D015999:Multivariate Analysis; D011183:Postoperative Complications / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology*; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
keywords: ACA = anterior cerebral artery; DWI = diffusion-weighted imaging; GEE = generalized estimating equation; ICA = internal carotid artery; MCA = middle cerebral artery; MRA = MR angiography; PCA = posterior cerebral artery; STA = superficial temporal artery; TIA = transient ischemic attack; cerebral revascularization; intraoperative complication; mRS = modified Rankin Scale; moyamoya disease; rapid progression; vascular disorders