White matter and cortical changes in atypical parkinsonisms: A multimodal quantitative MR study.

OBJECTIVES: To evaluate white matter and cortical changes in patients with parkinsonisms and healthy controls (HC), applying both hypothesis-free and regions of interest (ROI)-based advanced brain MR analyses. METHODS: Twenty-five patients with Progressive Supranuclear Palsy - Richardson's Syndrome (PSP-RS), nine with cerebellar and nine with parkinsonian Multiple System Atrophy variants (MSA-C and MSA-P), forty-seven with Parkinson's Disease (PD) and twenty-seven HC underwent a 1.5 T brain-MR protocol including high-resolution 3D T1-weighted and 25-direction diffusion tensor imaging sequences. We performed cortical and white matter analysis by using vertex-based cortical thickness evaluation and Tract Based Spatial Statistics (TBSS), followed by a ROI-based cortical thickness analysis and probabilistic tractography of cortico-spinal tract (CST), and middle and superior cerebellar peduncles (MCP and SCP). RESULTS: In PSP-RS, both ROIs-based and voxel-wise analyses demonstrated significant thinning of the pre-central cortices and diffuse white matter alterations involving supra- and infratentorial compartments. Along-tract tractography analysis of CST showed a significantly higher MD in PSP-RS vs PD and HC limited to the portion of the tract within the corona radiata. In MSA-C, a predominant involvement of MCPs was evident, while alterations in MCPs in MSA-P and in SCPs in PSP-RS and MSA-C were also present. CONCLUSION: Specific patterns of cortical and white matter changes in atypical parkinsonism patients reflect the neuropathological and clinical features of these disorders. This study shows that quantitative brain MR techniques can detect significant changes that help to elucidate the physiopathology of movement disorders and support their differential diagnosis.

The contribution of cerebellar proton magnetic resonance spectroscopy in the differential diagnosis among parkinsonian syndromes.

INTRODUCTION: The in vivo differential diagnosis between idiopathic Parkinson's disease (PD) and atypical parkinsonian syndromes (PS), such as multiple system atrophy [MSA with a cerebellar (C) and parkinsonian (P) subtype] and progressive supranuclear palsy - Richardson's Syndrome (PSP-RS) is often challenging. Previous brain MR proton spectroscopy ((1)H-MRS) studies showed biochemical alterations in PS, despite results are conflicting. Cerebellum plays a central role in motor control and its alterations has been already demonstrated in atypical PS. The main aim of this study was to evaluate diagnostic accuracy of cerebellar (1)H-MRS in the differential diagnosis between PD and atypical PS. METHODS: We obtained (1)H-MRS spectra from the left cerebellar hemisphere of 57 PS (21 PD, and 36 atypical PS) and 14 unaffected controls by using a 1.5 T GE scanner. N-acetyl-aspartate (NAA)/Creatine (Cr), choline-containing compounds (Cho)/Cr, myoinositol (mI)/Cr, and NAA/mI ratios were calculated. RESULTS: NAA/Cr and NAA/mI ratios were significantly lower (p < 0.01) in atypical PS compared to PD and controls, and in MSA-C compared to PD, MSA-P, PSP-RS and controls. PSP-RS group showed reduced NAA/Cr ratios compared to PD (p < 0.05) and controls (p < 0.05), and reduced NAA/mI compared to controls (p < 0.01). NAA/Cr ratio values higher than 1.016 showed 100% sensitivity and negative predictive value, 62% positive predictive value and 64% specificity in discriminating PD. CONCLUSION: Cerebellar biochemical alterations detected by using (1)H-MRS could represent an adjunctive diagnostic tool to improve the differential diagnosis of PS.

Iodine-123 metaiodobenzylguanidine scintigraphy and iodine-123 ioflupane single photon emission computed tomography in Lewy body diseases: complementary or alternative techniques?

PURPOSE: To compare myocardial sympathetic imaging using (123)I-Metaiodobenzylguanidine (MIBG) scintigraphy and striatal dopaminergic imaging using (123)I-Ioflupane (FP-CIT) single photon emission computed tomography (SPECT) in patients with suspected Lewy body diseases (LBD). METHODS: Ninety-nine patients who performed both methods within 2 months for differential diagnosis between Parkinson's disease (PD) and other parkinsonism (n = 68) or between dementia with Lewy bodies (DLB) and other dementia (n = 31) were enrolled. Sensitivity, specificity, accuracy, positive and negative predictive values of both methods were calculated. RESULTS: For (123) I-MIBG scintigraphy, the overall sensitivity, specificity, accuracy, positive and negative predictive values in LBD were 83%, 79%, 82%, 86%, and 76%, respectively. For (123)I-FP-CIT SPECT, the overall sensitivity, specificity, accuracy, positive and negative predictive values in LBD were 93%, 41%, 73%, 71%, and 80%, respectively. There was a statistically significant difference between these two methods in patients without LBD, but not in patients with LBD. CONCLUSIONS: LBD usually present both myocardial sympathetic and striatal dopaminergic impairments. (123)I-FP-CIT SPECT presents high sensitivity in the diagnosis of LBD; (123)I-MIBG scintigraphy may have a complementary role in differential diagnosis between PD and other parkinsonism. These scintigraphic methods showed similar diagnostic accuracy in differential diagnosis between DLB and other dementia.

Spinocerebellar ataxia type 12 identified in two Italian families may mimic sporadic ataxia.

SCA12 is an autosomal dominant cerebellar ataxia characterized by onset in the fourth decade of life with action tremor of arms and head, mild ataxia, dysmetria, and hyperreflexia. The disease is caused by an expansion of >or=51 CAGs in the 5' region of the brain- specific phosphatase 2 regulatory subunit B-beta isoform (PPP2R2B) gene. SCA12 is very rare, except for a single ethnic group in India. We screened 159 Italian ataxic patients for SCA12 and identified two families that segregated an expanded allele of 57 to 58 CAGs, sharing a common haplotype. The age at onset, phenotype, and variability of symptoms were compatible with known cases. In one family, the disease was apparently sporadic due to possible incomplete penetrance and/or late age at onset. Our data indicate that SCA12 is also present in Italian patients, and its genetic testing should be applied to both sporadic and familial ataxias.

Recent developments in innervation imaging using iodine-123-metaiodobenzylguanidine scintigraphy in Lewy body diseases.

Radiolabeled metaiodobenzylguanidine (MIBG) is an analog of guanethidine and is taken up by the postganglionic presynaptic nerve endings. MIBG uptake in the heart correlates with adrenergic function, which can be reduced in Lewy body diseases. We described the recent developments in innervation imaging using (123)I-MIBG scintigraphy in Lewy body diseases including Parkinson's disease and dementia with Lewy bodies. Particularly, we underlined the role of MIBG scintigraphy in differential diagnosis of movement disorders. As described by recent studies, MIBG scintigraphy is a valuable diagnostic tool for differentiation between Lewy body diseases and parkinsonian syndromes or other movement disorders with parkinsonism. Furthermore, this method may provide a powerful differential diagnostic tool between dementia with Lewy bodies and Alzheimer's disease. We also reported the results of clinical investigations about the correlation between characteristics of Parkinson's disease and myocardial MIBG uptake.