title: Motor and premotor cortices in subcortical stroke: proton magnetic resonance spectroscopy measures and arm motor impairment.
abstract: BACKGROUND
  Although functional imaging and neurophysiological approaches reveal alterations in motor and premotor areas after stroke, insights into neurobiological events underlying these alterations are limited in human studies.
  
  
  OBJECTIVE
  We tested whether cerebral metabolites related to neuronal and glial compartments are altered in the hand representation in bilateral motor and premotor areas and correlated with distal and proximal arm motor impairment in hemiparetic persons.
  
  
  METHODS
  In 20 participants at >6 months postonset of a subcortical ischemic stroke and 16 age- and sex-matched healthy controls, the concentrations of N-acetylaspartate and myo-inositol were quantified by proton magnetic resonance spectroscopy. Regions of interest identified by functional magnetic resonance imaging included primary (M1), dorsal premotor (PMd), and supplementary (SMA) motor areas. Relationships between metabolite concentrations and distal (hand) and proximal (shoulder/elbow) motor impairment using Fugl-Meyer Upper Extremity (FMUE) subscores were explored.
  
  
  RESULTS
  N-Acetylaspartate was lower in M1 (P = .04) and SMA (P = .004) and myo-inositol was higher in M1 (P = .003) and PMd (P = .03) in the injured (ipsilesional) hemisphere after stroke compared with the left hemisphere in controls. N-Acetylaspartate in ipsilesional M1 was positively correlated with hand FMUE subscores (P = .04). Significant positive correlations were also found between N-acetylaspartate in ipsilesional M1, PMd, and SMA and in contralesional M1 and shoulder/elbow FMUE subscores (P = .02, .01, .02, and .02, respectively).
  
  
  CONCLUSIONS
  Our preliminary results demonstrated that proton magnetic resonance spectroscopy is a sensitive method to quantify relevant neuronal changes in spared motor cortex after stroke and consequently increase our knowledge of the factors leading from these changes to arm motor impairment.
authors.affiliation: University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Sorin C
authors.initials: SC
authors.lastname: Craciunas
authors.forename: William M
authors.initials: WM
authors.lastname: Brooks
authors.forename: Randolph J
authors.initials: RJ
authors.lastname: Nudo
authors.forename: Elena A
authors.initials: EA
authors.lastname: Popescu
authors.forename: In-Young
authors.initials: IY
authors.lastname: Choi
authors.forename: Phil
authors.initials: P
authors.lastname: Lee
authors.forename: Hung-Wen
authors.initials: HW
authors.lastname: Yeh
authors.forename: Cary R
authors.initials: CR
authors.lastname: Savage
authors.forename: Carmen M
authors.initials: CM
authors.lastname: Cirstea
mesh_terms: D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D005260:Female; D007839:Functional Laterality; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000378:metabolism; D009069:Movement Disorders / Q000209:etiology*; D011522:Protons; D011877:Radionuclide Imaging; D013223:Statistics as Topic; D020521:Stroke / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology*
chemical_list: D011522:Protons; D001224:Aspartic Acid; C000179:N-acetylaspartate
keywords: distal and proximal arm motor impairment; motor and premotor cortices; proton magnetic resonance spectroscopy; subcortical stroke