Brain Structure and Degeneration Staging in Friedreich Ataxia: MRI Volumetrics from the ENIGMA-Ataxia Working Group

Harding IH, Chopra S, Arrigoni F, Boesch S, Brunetti A, Cocozza S, Corben LA, Deistung A, Delatycki M, Diciotti S, Dogan I, Evangelisti S, França MC Jr, Göricke SL, Georgiou-Karistianis N, Gramegna LL, Henry PG, Hernandez-Castillo CR, Hutter D, Jahanshad N, Joers JM, Lenglet C, Lodi R, Manners DN, Martinez AR, Martinuzzi A, Marzi C, Mascalchi M, Nachbauer W, Pane C, Peruzzo D, Pisharady PK, Pontillo G, Reetz K, Rezende TJ, Romanzetti S, Saccà F, Scherfler C, Schulz JB, Stefani A, Testa C, Thomopoulos SI, Timmann D, Tirelli S, Tonon C, Vavla M, Egan GF, Thompson PM.; Ann Neurol. 2021 Aug 26. doi: 10.1002/ana.26200. Epub ahead of print. PMID: 34435700. 

The brainstem, dentate nucleus region, and superior and inferior cerebellar peduncles showed greatest reductions in volume relative to controls (Cohen's d = 1.5-2.6). Cerebellar grey matter alterations were most pronounced in lobules I-VI (d = 0.8), while cerebral differences occurred most prominently in precentral gyri (d = 0.6) and corticospinal tracts (d = 1.4). Earlier onset age predicted less volume in the motor cerebellum (rmax = 0.35) and peduncles (rmax = 0.36). Disease duration and severity correlated with volume deficits in the dentate nucleus region, brainstem, and superior/inferior cerebellar peduncles (rmax = -0.49); subgrouping showed these to be robust and early features of FRDA, and strong candidates for further biomarker validation. Cerebral white matter abnormalities, particularly in corticospinal pathways, emerge as intermediate disease features. Cerebellar and cerebral grey matter loss, principally targeting motor and sensory systems, preferentially manifests later in the disease course.