(1)H MR spectroscopy in Friedreich's ataxia and ataxia with oculomotor apraxia type 2.
OBJECTIVE
Friedreich's ataxia (FRDA) and ataxia with oculomotor apraxia type 2 (AOA2) are the two most frequent forms of autosomal recessive cerebellar ataxias. However, brain metabolism in these disorders is poorly characterized and biomarkers of the disease progression are lacking. We aimed at assessing the neurochemical profile of the pons, the cerebellar hemisphere and the vermis in patients with FRDA and AOA2 to identify potential biomarkers of these diseases.


METHODS
Short-echo, single-voxel proton ((1)H) magnetic resonance spectroscopy data were acquired from 8 volunteers with FRDA, 9 volunteers with AOA2, and 38 control volunteers at 4T. Disease severity was assessed by the Friedreich's Ataxia Rating Scale (FARS).


RESULTS
Neuronal loss/dysfunction was indicated in the cerebellar vermis and hemispheres in both diseases by lower total N-acetylaspartate levels than controls. The putative gliosis marker myo-inositol was higher than controls in the vermis and pons in AOA2 and in the vermis in FRDA. Total creatine, another potential gliosis marker, was higher in the cerebellar hemispheres in FRDA relative to controls. Higher glutamine in FRDA and lower glutamate in AOA2 than controls were observed in the vermis, indicating different mechanisms possibly leading to altered glutamatergic neurotransmission. In AOA2, total N-acetylaspartate levels in the cerebellum strongly correlated with the FARS score (p<0.01).


CONCLUSIONS
Distinct neurochemical patterns were observed in the two patient populations, warranting further studies with larger patient populations to determine if the alterations in metabolite levels observed here may be utilized to monitor disease progression and treatment.
Iltis
Isabelle
I
Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN 55455, USA. isabelle@cmrr.umn.edu
Hutter
Diane
D
Bushara
Khalaf O
KO
Clark
H Brent
HB
Gross
Myron
M
Eberly
Lynn E
LE
Gomez
Christopher M
CM
Oz
Gülin
G
D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001931:Brain Mapping; D003401:Creatine; D005260:Female; D005621:Friedreich Ataxia / Q000134:cerebrospinal fluid / Q000150:complications / Q000175:diagnosis*; D020234:Gait Ataxia / Q000134:cerebrospinal fluid / Q000150:complications / Q000175:diagnosis*; D018698:Glutamic Acid; D006801:Humans; D007294:Inositol; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D015835:Ocular Motility Disorders / Q000134:cerebrospinal fluid / Q000150:complications / Q000175:diagnosis*; D011522:Protons; D013057:Spectrum Analysis; D013223:Statistics as Topic; D055815:Young Adult
D011522:Protons; D001224:Aspartic Acid; D018698:Glutamic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine