Conventional MRI findings in hereditary degenerative ataxias: a pictorial review

Abstract

Purpose: Cerebellar ataxias are a large and heterogeneous group of disorders. The evaluation of brain parenchyma via MRI plays a central role in the diagnostic assessment of these conditions, being mandatory to exclude the presence of other underlying causes in determining the clinical phenotype. Once these possible causes are ruled out, the diagnosis is usually researched in the wide range of hereditary or sporadic ataxias.

Methods: We here propose a review of the main clinical and conventional imaging findings of the most common hereditary degenerative ataxias, to help neuroradiologists in the evaluation of these patients.

Results: Hereditary degenerative ataxias are all usually characterized from a neuroimaging standpoint by the presence, in almost all cases, of cerebellar atrophy. Nevertheless, a proper assessment of imaging data, extending beyond the mere evaluation of cerebellar atrophy, evaluating also the pattern of volume loss as well as concomitant MRI signs, is crucial to achieve a proper diagnosis.

Conclusion: The integration of typical neuroradiological characteristics, along with patient's clinical history and laboratory data, could allow the neuroradiologist to identify some conditions and exclude others, addressing the neurologist to the more appropriate genetic testing.

Keywords: Cerebellar ataxia; Conventional MRI; Magnetic resonance imaging.

Fig. 1

Brain MRI scan of a 69-year-old female SCA1 patient. Axial T2-weighted (a) and coronal FLAIR (b) images show a global cerebellar volume loss, along with brainstem atrophy (c–d) and the presence of the “hot cross bun” sign (arrows)

Fig. 2

Imaging findings in a 38-year-old female SCA2 patient. Sagittal (a) and axial (b) multiplanar reconstructions of 3D T1-weighted volume show a global cerebellar volume loss, involving both the vermis and cerebellar hemispheres, along with significant brainstem atrophy, particularly affecting the pons which demonstrates a flattening of its inferior profile (arrows)

Fig. 3

Axial (a, c) and coronal (b) T2-weighted images showing mild cerebellar atrophy, with enlargement of the 4th ventricle (arrow), in a 30-year-old female SCA3 patient

Fig. 4

Brain MRI findings in a 56-year-old female SCA6. In the sagittal T1- (a) and coronal T2- (b) weighted images, it is appreciable a global cerebellar atrophy, with particular involvement of the vermis (arrow) and a relative sparing of the pons

Fig. 5

Neuroradiological findings in a 79-year-old male SCA7 patient. Axial T2- (a) and sagittal T1- (b) weighted sequences demonstrate a global cerebellar, as well as pontine (arrow), atrophy. Along with the infratentorial involvement, a diffuse supratentorial gray matter volume loss is also present (c)

Fig. 6

Brain MRI scan of 43-year-old male SCA8 patient. Coronal T2- (a) and sagittal T1- (b) weighted images show global cerebellar atrophy, with a relative sparing of the pons

Fig. 7

Axial (a) and sagittal (b) multiplanar reconstructions of a 3D T1-weighted volume show the typical brain MRI appearance in FRDA patients, as depicted in this 20-year-old male subject where a preserved cerebellar volume is present

Fig. 8

Brain MRI findings in a 45-year-old female ARSACS patient. A predominant superior vermian atrophy is shown on a sagittal T1-weighted sequence (a, white arrow), along with as a mild T2-weighted hypointensity affecting the transverse pontine fibers (b, black arrows). Parietal (c) and cervical spinal cord (a, arrowheads) atrophy is also evident

Fig. 9

Axial T2- (a) and sagittal T1- (b) weighted images of an 18-year-old male AOA1 patient showing a severe global cerebellar atrophy, with relative sparing of the brainstem

Fig. 10

Coronal T2- (a) and sagittal T1- (b) weighted images of a 25-year-old female AOA2 patient showing a moderate global cerebellar and a relative brainstem sparing

Fig. 11

Imaging finding in a 69-year-old male SPG7 patient. Brain MRI axial (a) and sagittal T2- (b) weighted images show the presence of a mild global cerebellar atrophy, with particular involvement of the vermis (black arrow)

Fig. 12

Neuroradiological findings in a 26-year-old female AT patient. A mild global cerebellar atrophy is shown in both axial (a) and coronal (b) T2-weighted images, while the T2*-weighted sequence allows for the depiction of small punctuate hypointense foci (arrows in c) representing both hemosiderin deposits and telangiectatic vessels

Fig. 13

Brain MRI findings in a 42-year-old male CTX patient. Along with a mild global cerebellar atrophy, it is present gliosis and calcifications of the deep cerebellar WM, extending to the peri-dentate region (arrows), as shown in the axial FLAIR (a), T1-weighted (b), and SWI (c) sequences

Fig. 14

A 36-year-old female SCAR10 patient showing a global cerebellar atrophy, along with a mild T2-weighted hyperintensity affecting both dentate nuclei (black arrows in b)

Fig. 15

Imaging findings in a 55-year-old male patient with FXTAS. Axial T1- (a) and T2- (b) weighted sequences show the presence of a mild global cerebellar atrophy, associated with the typical T2-weighted hyperintensity of the middle cerebellar peduncles (black arrows in b)