title: Is NAA reduction in normal contralateral cerebral tissue in stroke patients dependent on underlying risk factors?
abstract: OBJECTIVE
  This retrospective study investigated the dependence of N-acetyl aspartate (NAA) ratios on risk factors for cerebral vasculopathy such as sex, age, hypertension, diabetes mellitus, carotid stenosis, and dyslipidaemia, which may have affected brain vessels and induced metabolic brain abnormalities prior to stroke. We hypothesise that in stroke patients metabolic alterations in the apparently normal contralateral brain are dependent on the presence or not of such risk factors.
  
  
  METHODS
  Fifty nine patients (31 male, 28 female: 58.8+/-16.1 years old) with cortical middle cerebral artery (MCA) territory infarction were included. Long echo time chemical shift imaging spectroscopy was carried out on a Siemens 1.5 T Magnetom Vision scanner using a multi-voxel PRESS technique. Metabolite ratios (NAA/choline, NAA/creatine, lactate/choline, etc) were studied using uni- and multivariate analyses with respect to common risk factors. The influence of age, stroke lesion size, and time since stroke was studied using a linear regression approach.
  
  
  RESULTS
  Age, sex, and hypertension all appeared to individually influence metabolite ratios, although only hypertension was significant after multivariate analysis. In both basal ganglia and periventricular white matter regions in apparently normal contralateral brain, the NAA/choline ratio was significantly lower in hypertensive (1.37+/-0.16 and 1.50+/-0.19, respectively) than in normotensive patients (1.72+/-0.19 and 1.85+/-0.15, respectively).
  
  
  CONCLUSIONS
  Regarding MCA infarction, contralateral tissue remote from the lesion behaves abnormally in the presence of hypertension, the NAA ratios in hypertensive patients being significantly lower. These data suggest that hypertension may compromise the use of contralateral tissue data as a reference for comparison with ischaemic tissue.
authors.affiliation: Department of Magnetic Rsonance Spectroscopy, University Hospital of Dijon, France. pwalker@u-bourgogne.fr
authors.forename: P M
authors.initials: PM
authors.lastname: Walker
authors.forename: D
authors.initials: D
authors.lastname: Ben Salem
authors.forename: M
authors.initials: M
authors.lastname: Giroud
authors.forename: F
authors.initials: F
authors.lastname: Brunotte
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001921:Brain / Q000503:physiopathology*; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D004292:Dominance, Cerebral / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D020244:Infarction, Middle Cerebral Artery / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D019344:Lactic Acid / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D012016:Reference Values; D012189:Retrospective Studies; D012307:Risk Factors; D013223:Statistics as Topic
chemical_list: D001224:Aspartic Acid; D019344:Lactic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline