Table 2.

Summary of Neuroimaging Findings in Ataxia

Modality	Major Finding
MRI	SCA1 ROI: ↓cerebellum [42], brainstem [42] VBM: ↓cerebellum [54], brainstem (including midbrain, pons, and medulla) [54], caudate [54], putamen [54], and temporal lobe [54] ↓WM in cerebellar hemispheres [51] ↓GM in cerebellar hemispheres [51], left anterior and posterior cerebellum [48], vermis [51], brainstem [48], right putamen, and pallidum [48] SCA2 ROI: ↓cerebellum [42, 43], brainstem [42, 43] (mesencephalon [43], pons [43], anteroposterior diameter of the pons [43]) VBM: ↓WM in pons [51], middle cerebellar peduncle [51], cerebellar hemispheres [51] ↓GM in cerebellar hemispheres and vermis [51] DTI: ↓fractional anisotropy and mode of anisotropy in the brain stem, cerebellar peduncles, cerebellum, cerebral hemisphere WM, corpus callosum, and thalami [56] SCA3 ROI: ↓cerebellum [46, 47], cerebellar nuclei [44], brainstem [46], vermis [47] volume, spinal core area [60], and spinal cord eccentricity [60] VBM: ↓cerebellum [48, 54], basal ganglia [48], brainstem (including midbrain, pons, and medulla) [48, 54], caudate [54], putamen [54], striatal [48], and temporal lobe [54] ↓GM in cerebellum [52], cerebellar hemispheres [49, 51], brainstem [49, 52], vermis [51], bilateral thalamus [49] ↓GMD in cerebellum [50], brainstem [50], frontal [50], occipital lobes [50], parietal [50], subcortical GM [50], temporal lobes [50] ↓WM in cerebellum [52], cerebellar hemispheres [49], brainstem [52], bilateral thalamus [49] DTI: ↓fractional anisotropy in cerebellum [52], brainstem [52];↑radial diffusivity in cerebellum [52], brainstem [52], frontal lobes [52], temporal lobes [52], thalamus [52] ↓cerebellum [124], anterior lobe [124], left posterior lobe [124], right posterior upper lobe [124] SCA6 ROI: ↓cerebellum [44, 46], cerebellar nuclei [44], brainstem [46], superior vermis [65] VBM: ↓cerebellum [48, 54], basal ganglia [48], brainstem [48, 54], caudate [48] SCA17 ROI: ↓cerebellum [45], vermis, caudate nucleus [45] VBM: ↓cerebellum, limbic system (parahippocampus, cingulate) and parietal precuneus [53] DRPLA ROI: ↓midbrain [55], pontine tegmentum [55], basis pontis [55], cerebellar vermis [55] SIR: ↑cerebral WM [57], thalamus [57], midbrain [57], pontine tegmentum [57], basis pontis [57], inferior olive [57], and cerebellar WM [57] Atrophy of the cerebrum [57], midbrain tegmentum [57], pontine tegmentum [57], basis pontis [57], superior cerebellar peduncle [57], and cerebellum [57]
MRS	SCA1 ↓[Glu] in cerebellar hemisphere [125, 126], pons [125–127], vermis [125, 126] ↓[NAA] in cerebellar hemisphere [42], cerebellar WM [127], pons [42, 127], vermis [125, 127] ↓[NAAG] in cerebellar WM [127], pons [127] ↓[tNAA] in cerebellum [128], cerebellar hemisphere [125, 126], cerebellar WM [127], parietofrontal lobe WM [128], pons [125–127], sensory cortex [128], vermis [125–127], visual cortex [128] ↓Cho/Cr ratio in cerebellar hemisphere [62], basis pontis [61] ↓Glu/Gln ratio in vermis [125] ↓NAA/Cho ratio in cerebellar hemisphere [62] ↓NAA/Cr ratio in cerebellar hemisphere [61, 62], basis pontis [61], vermis [62] ↑[Asc] in vermis [127] ↑[Glc] in vermis [127] ↑[Gln] in cerebellar white matter [127], vermis [125, 126] ↑[mI] in cerebellar hemisphere [125, 126], pons [125–127] ↑[Tau] in cerebellar WM [127] ↑[tCr] in cerebellar hemisphere [125, 126], cerebellar WM [127] ↑[Glc + Tau] in cerebellar hemisphere [125, 126], cerebellar WM [127], vermis [127] SCA2 ↓[Cho] in cerebellum [129], vermis [129] ↓[Glu] in cerebellar hemisphere [126], pons [126], vermis [126] ↓[NAA] in cerebellar hemisphere [42, 63], cerebellum [129], pons [42], vermis [129] ↓[tNAA] in cerebellar hemisphere [126], pons [126], vermis [126] ↓Cho/Cr ratio in cerebellar hemisphere [62], vermis [62] ↓NAA/Cho ratio in cerebellar hemisphere [62], vermis [62] ↓NAA/Cr ratio in cerebellar hemisphere [62], basal ganglia [63], frontal lobes [63], pons [63], vermis [62, 63] ↑[Gln] in cerebellar hemisphere [126], cerebellar WM [127], vermis [126] ↑[GSH] in cerebellar WM [127], vermis [126] ↑[mI] in cerebellar hemisphere [63], cerebellar WM [127], pons [63, 127], vermis [126, 127] ↑[Tau] in cerebellar WM [127], vermis [126, 127] ↑[tCr] in cerebellar hemisphere [126], cerebellar WM [127], pons [126], vermis [126, 127] ↑[Glc + Tau] in cerebellar hemisphere [126], cerebellar WM [127], pons [127], vermis [127] ↑mI/Cr ratio in cerebellar hemispheres [63], basal ganglia [63], frontal lobes [63], pons [63], vermis [63] SCA3 ↓[NAA] in cerebellum [124, 129], pons [127], vermis [124, 129] ↓[NAAG] in cerebellar WM [127] ↓[tNAA] in cerebellar WM [127], vermis [127] ↓NAA/Cho ratio in cerebellar hemisphere [62], dentate nucleus [64], vermis [62, 64] ↓NAA/Cr ratio in cerebellar hemisphere [62], cortex [64], dentate nucleus [64], middle cerebellar peduncle [64], vermis [62, 64] ↑[mI] in pons [127] ↑[Tau] in cerebellar WM [127] ↑[tCr] in cerebellar WM [127] ↑[Glc + Tau] in vermis [127] SCA6 ↓[GABA] in cerebellar WM [127], vermis [127] ↓[NAA] in cerebellum [63, 129], vermis [127, 129] ↓[tNAA] in vermis [127] ↓NAA/Cho ratio in cerebellar hemisphere [62, 65], vermis [62, 65] ↓NAA/Cr ratio in cerebellar hemisphere [62], vermis [62] ↑[Lac] in vermis [126] ↑[mI] in cerebellar hemisphere [126], vermis [126] ↑[Glc + Tau] in cerebellar hemisphere [126], vermis [127] SCA17 ↓NAA/Cho ratio in vermis [62] ↓NAA/Cr ratio in cerebellar hemisphere [62], vermis [62]
fMRI	↓cerebellar cortex [44], cerebellar nuclei [44]
PET	SCA1 [18F]FDG:↓metabolism in cerebellum [68], cerebral cortex [67], cerebellar hemispheres [67], vermis [67], brainstem [67, 68], caudate nucleus [67], putamen [67], thalamus [67], whole brain cortex [67] SCA2 [18F]FDG:↓metabolism in cerebellum [58, 68, 69], anterior-posterior lobe ratio [69], brainstem [68], parietal cortex [68], pons [58], parahippocampal gyrus [58], frontal cortex [58] [11C]dMP:↓Dopamine transporter levels in putamen [68], caudate nucleus [68] SCA3 [18F]FDG:↓metabolism in cerebellum [58, 68], cerebellar hemispheres [70, 71], cerebellar vermis [70], occipital cortex [70, 71], brainstem [68, 70, 71], putamen [68], thalamus [68], parahippocampal gyrus of the limbic system [58], lentiform nucleus [58];↑metabolism in parietal and temporal cortices preclinically [71] [11C]dMP:↓Dopamine transporter levels in putamen [68], caudate nucleus [68] [11C]MP4P:↓thalamus [130] SCA6 [18F]FDG:↓metabolism in cerebellum [58, 68, 69], cerebellar hemispheres [72], anterior-posterior lobe ratio [69], basal ganglia [72], brainstem [72], caudate [72], putamen [68], frontal cortex [58, 72], prefrontal cortex [58], occipital cortex [72], temporal cortex [72];↑temporal cortex [68] SCA17 [18F]FDG:↓metabolism in caudate nucleus [45], putamen [45] [11C]dMP:↓Dopamine transporter levels in caudate nucleus and putamen [45] [11C]Raclopride:↓D2 receptor levels in caudate nucleus and putamen [45]
SPECT	SCA2 [99mTc]TRODAT-1 SPECT:↓striatal DAT binding [73] [123I]β-CTT SPECT:↓striato-cerebellar ratio [131] [123I]IBZM SPECT:↓striato-frontal IBZM binding ratio [131] [123I]FP-CIT SPECT:↓uptake in caudate, putamen [132] SCA3 [99mTc]TRODAT-1 SPECT:↓nigrostriatal ratio [74] [99mTc]HMPAO SPECT:↓perfusion in cerebellar hemispheres [47], inferior [47] and superior [47] frontal lobe [47], lateral temporal lobe [47], parietal lobe [47], vermis [47] [99mTc]ECD SPECT:↓perfusion in bilateral cerebellum [75], vermis [75] [123I]iomazenil SPECT:↓binding in cerebellum [133], cerebral cortex [133], thalamus [133], striatum [133] SCA6 [99mTc]ECD SPECT:↓perfusion in cerebellar hemisphere[76], cerebral vermis[76] SCA17 [99mTc]TRODAT-1 SPECT:↓striatal DAT binding [73]

Asc: ascorbate; Cho: Choline; Cr: Creatine; [¹²³I]β-CIT :

[¹²³I]2β-carbomethoxy-3b-(4-iodophenyl)tropane; [¹¹C]dMP:

[¹¹C]D-threo-methylphenidate; DAT: dopamine transporters; DTI: diffusion tensor imaging; [⁹⁹mTc]ECD: technetium-99m N,N-1,2-ethylene diylbis-L-cysteine diethyl ester dihydrochloride; [¹⁸F]FDG: [¹⁸F]fluorodeoxyglucose; 3D-FD: three-dimensional fractal dimension; fMRI: functional magnetic resonance imaging; [¹²³I]FP-CIT:

[¹²³I]N-fluoropropyl-2b-carbomethoxy-3b-(4-iodophenyl) nortropane ([¹²³I]ioflupane);

GABA: gamma-aminobutyric acid; Glc: glucose; Gln: glutamine; Glu: glutamate; GM: gray matter; GMD: gray matter density; GSH: glutathione; [⁹⁹mTc]HMPAO: technetium-99m hexamethylpropylene amine oxime; [¹²³I]IBZM SPECT:

[¹²³I](S-)-2-hydroxy-3-iodo-6-methoxy-N[(l-ethyl-2-pyrrolidinyl) methyl]-benzamide; [¹²³I]IMZ: [¹²³I]iomazenil; Lac: lactate; mI: myo-Inositol; [¹¹C]MP4P: N-[¹¹C]-methyl piperidine-4-propionate; MRI: magnetic resonance imaging; MRS: magnetic resonance spectroscopy; NAA: N-acetyl aspartate; NAAG: N-acetylaspartylglutamate; PET: positron emission tomography; [¹¹C]RAC: [¹¹C]Raclopride; ROI: region of interest; SIR: signal intensity ratio; SPECT: single photon emission computed tomography; Tau: taurine; tCr: total creatine; tNAA: total N-acetyl aspartate; VBM: voxel-based morphometry; WM: white matter.