Table 1
Main Neuroradiological (NR) Characteristics of Brain Imaging (Magnetic Resonance Imaging or Computerized Tomography) in the Spinocerebellar Ataxias (SCAs)
| NR Finding | SCAs |
|---|---|
| Pure cerebellar atrophy | 4, 5S, 6S, 10, 11, 13S, 14S, 15/16V, 18Mi, 19/22Mi, 21Mi, 24Mi,, 25–28, 29S,V, 30–32, 35, 37V, 38, 41Mi,V, 42V, 43Mo,V, 44, 47Mi,V |
| Cerebellar atrophy with other findings | |
| Pontine atrophy | 3, 7, 8S, 13Mo, 34, 40 |
| Olivopontocerebellar atrophy | 1, 2S, 36 |
| Spinal cord atrophy | 3, 7 |
| Cortical atrophy | 2, 3, 12 |
| Pontocerebellar, cortical, and subcortical atrophy | 17 (frontotemporal lobes, basal ganglia), 23S (frontotemporal lobes) |
| Atrophy of the brainstem, superior cerebellar peduncle, and abnormal signals in the brainstem, cerebellum, and thalamus | DRPLA |
| Calcifications of the dentate nuclei | 20Mo |
| “Hot cross bun sign” | 1, 2, 3, 6, 7, 8, 34 |
| Demyelinating lesions on brain MRI | 9 |
| Selective cerebellar atrophy | |
| Cerebellar vermis atrophy and hemosiderin deposits in the mesencephalon. | 45 |
| Posterior area of the vermis and paravermis | 48 |
| No cerebellar atrophy | |
| Generally normal, when present, mild cerebellar atrophy | 46 |
[i] Source: Adapted from references 2,3,62
Abbreviations: V, Main Involvement of Vermis; S, Severe Cerebellar Atrophy; Mi, Mild Cerebellar Atrophy; Mo, Moderate Cerebellar Atrophy;
DRPLA, Dentatorubral-Pallidoluysian Atrophy; SCA, Spinocerebellar Ataxias; NR, Neuroradiological; MRI, Magnetic Resonance Imaging.
Table 2
Main Neuroimaging Modalities Available for Spinocerebellar Ataxias Evaluation
| Modality | Information Afforded | Clinical Utility | Current Availability |
|---|---|---|---|
| CT | Identification of gross brain abnormalities. | Useful to characterize the main partners of atrophy, but not specifically. | Widely available. |
| MRI | Identification of abnormalities with accuracy to gray matter, white matter, and cerebrospinal fluid. | Useful to characterize the main partners of atrophy and signal changes, specifically; more sensitive to subtle alterations. | Available in developed geographic regions. Limited availability in underdeveloped areas. |
| Three-dimensional (3D) true volumetric methods and voxel-based morphometry allow automated segmentation and comparison between groups, in both cross-sectional and longitudinal studies. | Limited to specialized research centers. | ||
| MRS | Identification and interpretation of altered metabolites concentration in specific areas. | Assess physiological function of the observable metabolites and their concentration changes. Specific areas should be assessed. | Limited to specialized centers. |
| fMRI | Analyses of perfusion-induced changes in image contrast, during performance of a task. | Color maps superimposed on morphological images allows visualizing both positive correlation (greater activation during task) and negative correlation (reduced activation during task). | Limited to specialized research centers. |
| FDG-PET | Regional brain glucose metabolism | Downstream marker of neuronal injury and neurodegeneration. Important for presymptomatic evaluation. | Limited to specialized centers. |
Figure 1
The “Hot Cross Bun Sign” or “Cross Sign”, Typical but Not Pathognomonic Sign of Multiple System Atrophy (MSA), Can be Found in the Spinocerebellar Ataxias (SCAs): (A) a case of MSA and (B) SCA 2. Circles – T2 hyperintensity forms a cross on axial images through the pons, representing selective degeneration of pontocerebellar tracts. (A) Axial T2 image shows atrophy in the pons, bilateral middle cerebellar peduncle, and cerebellum. (B) Axial T2 FLAIR image shows severe atrophy in pons and cerebellum. A larger dilatation of the fourth ventricle is also noted.
Figure 2
Spinocerebellar Ataxia 3 (SCA 3): Initial And Advanced Stages of the Disease. Sagittal T1-weighted images of the brain in patient with SCA 3. Brain stem and cerebellum atrophy are clearly visible from the onset of clinical manifestations. With the evolution of the disease, there is an increase mainly in cortical and cerebellar atrophy.
Figure 3
Spinocerebellar Ataxia 10 (SCA 10) Image. Sagittal T1-weighted image of the brain in patient with SCA 10 showing cerebellar atrophy.
Figure 4
Dentatorubral-pallidoluysian atrophy image. A T1-weighted midsagittal image of a patient with DRPLA shows atrophy of the brain stem and cerebellum.