MAGNETIC RESONANCE IN THE DIAGNOSIS OF THE MOST COMMON FORMS OF SPINOCEREBELLAR ATAXIA
Abstract
Spinocerebellar ataxias (SCAs) are a heterogeneous group of autosomal dominant ataxias characterized by dominantly progressive evolution of the cerebellar syndrome and other extracerebellar symptoms and signs. Today there are approximately 40 genetic SCAs and this review aims to the describe the clinical picture and magnetic resonance imaging (MRI) findings of the most common SCA subtypes in Europe and Serbia. This is a group of polyglutamine diseases caused by mutations resulting from the expansion of the CAG repeats and accompanied by the loss of neural volume mainly of the cerebellum and the spinal cord. Magnetic resonance has a vital role in the diagnosis because it excludes structural damage as one of the potential causes of ataxia. In addition to this, the loss of volume as demonstrated by MRI serves as a biomarker which helps to monitor the natural progression of different subtypes of the disease. Typical findings in these MRI scans include cortico-cerebellar atrophy, spinal cord atrophy, olivopontocerebellar atrophy and different combinations of the said atrophies. Unfortunately, there are no distinct pathognomonic MRI signs or combinations of signs to facilitate diagnosis. There are, however, similarities in the MRI findings of some of the SCA subtypes, especially at disease onset. The ability to differentiate one pattern of atrophy from another and observing other clinical characteristics can have an important role can be of significant help in the diagnostic process.
References
1. Reetz K, Costa AS, Mirzazade S, Lehmann A, Juzek A, Rakowicz M, et al. Genotype-specific patterns of atrophy progression are more sensitive than clinical decline in SCA1, SCA3 and SCA6. Brain. 2013;136:905–17.
2. Hara D, Maki F, Tanaka S, Sasaki R, Hasegawa Y. MRI-based cerebellar volume measurements correlate with the International Cooperative Ataxia Rating Scale score in patients with spinocerebellar degeneration or multiple system atrophy. Cerebellum Ataxias. 2016 Aug 17;3:14.
3. Meira AT, Arruda WO, Ono SE, de Carvalho Neto A, Raskin S, Camargo CHF, et al. Neuroradiological Findings in the Spinocerebellar Ataxias. Tremor and Other Hyperkinetic Movements. 2019;9
4. Nibbeling, E.A.R.; Duarri, A.; Verschuuren-Bemelmans, C.C.; Fokkens, M.R.; Karjalainen, J.M.; Smeets, C.J.L.M. et al. Exome sequencing and network analysis identifies shared mechanisms underlying spinocerebellar ataxia. Brain 2017, 140, 2860–2878.
5. Dragašević NT, Culjković B, Klein C, Ristić A, Keckarević M, Topisirović I et al. Frequency analysis and clinical characterization of different types of spinocerebellar ataxia in Serbian patients. Mov Disord. 2006 Feb;21(2):187-91.
6. Pedroso JL, Barsottini OG (2013) Spinal cord atrophy in spinocerebellar ataxia type 1. Arq Neuropsiquiatr 71(12):977.
7. Mandelli ML, De Simone T, Minati L, Bruzzone MG, Mariotti C, Fancellu R, et al. Diffusion tensor imaging of spinocerebellar ataxias types 1 and 2. AJNR Am J Neuroradiol. 2007 Nov-Dec;28(10):1996-2000.
8. Martins CR Jr, Martinez ARM, de Rezende TJR, Branco LMT, Pedroso JL, Barsottini OGP et al. Spinal Cord Damage in Spinocerebellar Ataxia Type 1. Cerebellum. 2017 Aug;16(4):792-796.
9. Velázquez-Pérez LC, Rodríguez-Labrada R, Fernandez-Ruiz J. Spinocerebellar Ataxia Type 2: Clinicogenetic Aspects, Mechanistic Insights, and Management Approaches. Front Neurol. 2017 Sep 11;8:472.
10. Peng L, Peng Y, Chen Z, Wang C, Long Z, Peng H, et al. The progression rate of spinocerebellar ataxia type 3 varies with disease stage. J Transl Med. 2022 May 14;20(1):226.
11. Eichler L, Bellenberg B, Hahn HK, Köster O, Schöls L, Lukas C. Quantitative assessment of brain stem and cerebellar atrophy in spinocerebellar ataxia types 3 and 6: impact on clinical status. AJNR Am J Neuroradiol 2011;32:890–7.
12. Lukas C, Hahn HK, Bellenberg B, Hellwig K, Globas C, Schimrigk SK, et al. Spinal cord atrophy in spinocerebellar ataxia type 3 and 6 : impact on clinical disability. J Neurol. 2008 Aug;255(8):1244-9.
13. Benton CS, de Silva R, Rutledge SL, Bohlega S, Ashizawa T, Zoghbi HY (1998) Molecular and clinical studies in SCA-7 define a broad clinical spectrum and the infantile phenotype. Neurology 51(4):1081–1086.
14. Hugosson T, Gränse L, Ponjavic V, Andréasson S. Macular dysfunction and morphology in spinocerebellar ataxia type 7 (SCA 7). Ophthalmic Genet. 2009 Mar;30(1):1-6.
15. lbuquerque MV, Pedroso JL, Braga Neto P, Barsottini OG. Phenotype variability and early onset ataxia symptoms in spinocerebellar ataxia type 7: comparison and correlation with other spinocerebellar ataxias. Arq Neuropsiquiatr. 2015 Jan;73(1):18-21.
16. Lebre AS, Brice A. Spinocerebellar ataxia 7 (SCA 7). Cytogenet Genome Res. 2003;100(1-4):154-63.
17. Alcauter S, Barrios FA, Díaz R, Fernández-Ruiz J. Gray and white matter alterations in spinocerebellar ataxia type 7: an in vivo DTI and VBM study. Neuroimage. 2011 Mar 1;55(1):1-7.
18. Nakamura K, Jeong SY, Uchihara T, Anno M, Nagashima K, Nagashima T, et al. SCA 17, a novel autosomal dominant cerebellar ataxia caused by an expanded polyglutamine in TATA-binding protein. Hum Mol Genet. 2001 Jul 1;10(14):1441-8.
19. Döhlinger S, Hauser TK, Borkert J, Luft AR, Schulz JB. Magnetic resonance imaging in spinocerebellar ataxias. Cerebellum. 2008;7(2):204-14.