Metabolite changes in normal-appearing gray and white matter are linked with disability in early primary progressive multiple sclerosis.
BACKGROUND
Abnormalities in normal-appearing brain tissues may contribute to disability in primary progressive multiple sclerosis (PPMS), where few lesions are seen on conventional imaging.


OBJECTIVE
To evaluate the mechanisms underlying disease progression in the early phase of PPMS by measuring metabolite concentrations in normal-appearing white matter (NAWM) and cortical gray matter (CGM) and to assess their relationship with clinical outcomes.


METHODS
Case-control study.


METHODS
Tertiary referral hospital. Patients Forty-three consecutive patients within 5 years of onset of PPMS and 44 healthy control subjects.


METHODS
Concentrations of choline-containing compounds, phosphocreatine, myo-inositol, total N-acetyl-aspartate (tNAA), and glutamate-glutamine were estimated using proton magnetic resonance spectroscopic imaging. Brain parenchymal, white matter and gray matter fractions and proton density and gadolinium-enhancing lesion loads were calculated. The Expanded Disability Status Scale and Multiple Sclerosis Functional Composite scores were recorded.


RESULTS
In CGM, concentrations of the tNAA (P<.001) and glutamate-glutamine (P = .005) were lower in patients with PPMS than in controls. In NAWM, myo-inositol levels were higher (P = .002) and tNAA levels were lower (P = .005) in patients with PPMS than in controls. The Expanded Disability Status Scale score correlated with the tNAA concentration in CGM (r = -0.44; P = .03) and with myo-inositol (r = 0.41; P = .01) and glutamate-glutamine concentrations (r = 0.41; P = .01) in NAWM. Proton density lesion load correlated negatively with CGM tNAA concentration and positively with NAWM myo-inositol concentration.


CONCLUSIONS
Metabolite changes, which differ in CGM and NAWM, occur in early PPMS and are linked with disability.
Sastre-Garriga
J
J
Institute of Neurology, London, United Kingdom.
Ingle
G T
GT
Chard
D T
DT
Ramió-Torrentà
Lí
L
McLean
M A
MA
Miller
D H
DH
Thompson
A J
AJ
D000328:Adult; D017668:Age of Onset; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism; D015415:Biomarkers; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology; D002794:Choline / Q000032:analysis / Q000378:metabolism; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D007294:Inositol / Q000032:analysis / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D020528:Multiple Sclerosis, Chronic Progressive / Q000175:diagnosis* / Q000378:metabolism* / Q000503:physiopathology; D009413:Nerve Fibers, Myelinated / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D019581:Neuropil / Q000378:metabolism / Q000473:pathology; D010725:Phosphocreatine / Q000032:analysis / Q000378:metabolism; D011237:Predictive Value of Tests; D012016:Reference Values; D013223:Statistics as Topic
D015415:Biomarkers; D010725:Phosphocreatine; D001224:Aspartic Acid; D018698:Glutamic Acid; D007294:Inositol; C000179:N-acetylaspartate; D002794:Choline