1H MR spectroscopy in Friedreich's ataxia and ataxia with oculomotor apraxia type 2

Abstract

Background and aim-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.Corresponding author: Isabelle Iltis Center for Magnetic Resonance Research University of Minnesota 2021 6 th St SE Minneapolis, MN 55455 isabelle@cmrr.umn.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Section. Disease-related NeuroscienceResearch highlights 1 H MR Spectroscopy in Friedreich's Ataxia and Ataxia with Oculomotor Apraxia Type 2 •Friedreich's ataxia (FRDA) and ataxia with oculomotor apraxia type 2 (AOA2) are the two most frequent forms of autosomal recessive cerebellar ataxias• Biomarkers of the disease progression are lacking •( 1 H) magnetic resonance spectroscopy (MRS) was used to assess 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• Distinct neurochemical patterns were observed in the two patient populations• In AOA2, total N-acetylaspartate levels in the cerebellum strongly correlated with the FARS score (p < 0.01)• Studies with larger patient populations will determine if the alterations in metabolite levels observed here may be utilized to monitor disease progression and treatment 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). NIH Public AccessResults-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).Conclusion...

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