title: Reduced thalamic N-acetylaspartate in idiopathic normal pressure hydrocephalus: a controlled 1H-magnetic resonance spectroscopy study of frontal deep white matter and the thalamus using absolute quantification.
abstract: BACKGROUND
  Patients with idiopathic normal pressure hydrocephalus (INPH) frequently have a reduction in cerebral blood flow in the subcortical frontal lobe/basal ganglia/thalamic areas. With magnetic resonance spectroscopy, the metabolism in the brain can be examined. The aim of this study was to investigate if there was a compromised metabolism in the thalamus and in the subcortical frontal areas in INPH patients. This was done by measuring total creatine, myo-inositol, total choline, N-acetylaspartate (NAA), total N-acetylaspartate (tNA), glutamate and lactate levels. A comparison was made with healthy individuals (HI).
  
  
  METHODS
  16 patients (nine males, seven females, mean age 74 years, range 49-83) diagnosed as INPH and 15 HI (nine males, six females, mean age 74 years, range 62-89) were examined. (1)H magnetic resonance spectroscopy (1.5 T, point-resolved spectroscopy, echo time/relaxation time 30/3000 ms, volume of interest 2.5-3 ml) was performed in frontal deep white matter and in the thalamus. Absolute quantification with internal water as a reference was used.
  
  
  RESULTS
  INPH patients had lower NAA (p=0.02) and lower tNA (p=0.05) concentrations in the thalamus compared with HI. NAA and tNA in the frontal deep white matter did not differ between patients and HI. The absolute metabolic concentrations of total creatine, myo-inositol total choline, tNA, lactate and Cr ratios in frontal deep white matter and in the thalamus were similar in INPH patients and HI.
  
  
  CONCLUSIONS
  Reduced thalamic NAA and tNA in INPH patients suggest a compromised metabolic neuronal function in these regions. Thus, the thalamus might have an important role in the pathogenesis of INPH.
authors.affiliation: Department of Clinical and Experimental Medicine, Division of Neuroscience, Linköping University, Linköping, Sweden. fredrik.lundin@lio.se
authors.forename: F
authors.initials: F
authors.lastname: Lundin
authors.forename: A
authors.initials: A
authors.lastname: Tisell
authors.forename: O
authors.initials: O
authors.lastname: Dahlqvist Leinhard
authors.forename: M
authors.initials: M
authors.lastname: Tullberg
authors.forename: C
authors.initials: C
authors.lastname: Wikkelsö
authors.forename: P
authors.initials: P
authors.lastname: Lundberg
authors.forename: G
authors.initials: G
authors.lastname: Leijon
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001479:Basal Ganglia / Q000378:metabolism; D002561:Cerebrovascular Disorders / Q000150:complications / Q000453:epidemiology; D003071:Cognition / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000737:chemistry / Q000378:metabolism*; D020233:Gait Disorders, Neurologic / Q000378:metabolism; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000378:metabolism* / Q000503:physiopathology / Q000523:psychology; D007091:Image Processing, Computer-Assisted; D007427:Intracranial Pressure / Q000502:physiology; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000378:metabolism; D009460:Neurologic Examination; D009483:Neuropsychological Tests; D004856:Postural Balance / Q000502:physiology; D012044:Regression Analysis; D013788:Thalamus / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate