Differences in cerebellar perfusion between Parkinson's disease and multiple system atrophy

Cerebellar blood perfusion is a diagnostic, but not a prognostic, marker for parkinsonian-dominant type multiple system atrophy

INTRODUCTION

Multiple system atrophy (MSA) is clinically characterized by various neurological symptoms. According to the diagnostic criteria, MSA is classified into parkinsonian-dominant type (MSA-P) or cerebellar ataxia-dominant type (MSA-C) based on the predominant signs displayed. Recently, N-isopropyl-p-[123I] iodoamphetamine (123I-IMP) single-photon emission computed tomography (SPECT), a radiological examination evaluating brain perfusion, has been successful in detecting cerebellar hypoperfusion in MSA-P patients, demonstrating its utility in the early detection of cerebellar dysfunction. In this study, we further explored whether this cerebellar hypoperfusion impacts the clinical features of MSA-P, whether it is observable in patients without cerebellar symptoms, and, most importantly, whether it influences the prognosis of MSA-P.

METHODS

We conducted a retrospective analysis of 88 MSA patients who were admitted to our department for the last fifteen years. Clinical data were collected, and cerebellar perfusion was examined using 123I-IMP SPECT. This analysis includes the application of the three-dimensional stereotactic surface projection (3D-SSP) technique and Z-score.

RESULTS

Cerebellar perfusion decreased in MSA-P patients without cerebellar ataxia, compared to healthy individuals (p = 0.0017). The Receiver Operating Characteristic (ROC) curve demonstrated a moderate ability to distinguish MSA-P patients without cerebellar ataxia (MSA-Pp) from healthy controls (AUC = 0.6832). Among MSA-Pp, those exhibiting cerebellar hypoperfusion showed relatively improved neurological prognosis, although the difference was not statistically significant when compared to those with normal cerebellar perfusion.

CONCLUSION

Assessing cerebellar perfusion through IMP-SPECT proves valuable in detecting subclinical cerebellar dysfunction in MSA-Pp. Importantly, cerebellar hypoperfusion does not correlate with a poorer neurological prognosis.

Magnetic Resonance Imaging and Nuclear Imaging of Parkinsonian Disorders: Where do we go from here?

Parkinsonian disorders are a heterogeneous group of incurable neurodegenerative diseases that significantly reduce quality of life and constitute a substantial economic burden. Nuclear imaging (NI) and magnetic resonance imaging (MRI) have played and continue to play a key role in research aimed at understanding and monitoring these disorders. MRI is cheaper, more accessible, nonirradiating, and better at measuring biological structures and hemodynamics than NI. NI, on the other hand, can track molecular processes, which may be crucial for the development of efficient diseasemodifying therapies. Given the strengths and weaknesses of NI and MRI, how can they best be applied to Parkinsonism research going forward? This review aims to examine the effectiveness of NI and MRI in three areas of Parkinsonism research (differential diagnosis, prodromal disease identification, and disease monitoring) to highlight where they can be most impactful. Based on the available literature, MRI can assist with differential diagnosis, prodromal disease identification, and disease monitoring as well as NI. However, more work is needed, to confirm the value of MRI for monitoring prodromal disease and predicting phenoconversion. Although NI can complement or be a substitute for MRI in all the areas covered in this review, we believe that its most meaningful impact will emerge once reliable Parkinsonian proteinopathy tracers become available. Future work in tracer development and high-field imaging will continue to influence the landscape for NI and MRI.

Neuropathological features of levodopa-responsive parkinsonism in multiple system atrophy: an autopsy case report and comparative neuropathological study

Background

In typical patients with multiple system atrophy with predominant parkinsonism (MSA-P) levodopa is ineffective. However, there are some of these patients who respond well to levodopa treatment. Levodopa efficacy in MSA-P patients is thought to be related to the degree of putaminal damage, but the pathological causation between the putaminal involvement and levodopa efficacy has not been established in detail.

Objective

This study aimed to evaluate the neuropathological features of the nigrostriatal dopaminergic system in a "levodopa-responsive" MSA-P patient in comparison with "levodopa-unresponsive" conventional MSA-P patients.

Materials and methods

Clinicopathological findings were assessed in a 53-year-old Japanese man with MSA who presented with asymmetric parkinsonism, levodopa response, and later wearing-off phenomenon. During autopsy, the nigrostriatal pathology of presynaptic and postsynaptic dopaminergic receptor density and α-synuclein status were investigated. The other two patients with MSA-P were examined using the same pathological protocol.

Results

Four years after the onset, the patient died of sudden cardiopulmonary arrest. On autopsy, numerous α-synuclein-positive glial cytoplasmic inclusions in the basal ganglia, pons, and cerebellum were identified. The number of neurons in the putamen and immunoreactivity for dopamine receptors were well-preserved. In contrast, significant neuronal loss and decreased dopamine receptor immunoreactivity in the putamen were observed in the "levodopa-unresponsive" MSA-P control patients. These putaminal pathology results were consistent with the findings of premortem magnetic resonance imaging (MRI). All three patients similarly exhibited severe neuronal loss in the substantia nigra and decreased immunoreactivity for dopamine transporter.

Conclusion

Levodopa responsiveness in patients with MSA-P may be corroborated by the normal putamen on MRI and the preserved postsynaptic nigrostriatal dopaminergic system on pathological examination. The results presented in this study may provide a rationale for continuation of levodopa treatment in patients diagnosed with MSA-P.

The Use of Cerebellar Hypoperfusion Assessment in the Differential Diagnosis of Multiple System Atrophy with Parkinsonism and Progressive Supranuclear Palsy-Parkinsonism Predominant

The differential diagnosis of MSA-P and PSP-P remains a difficult issue in clinical practice due to their overlapping clinical manifestation and the lack of tools enabling a definite diagnosis ante-mortem. This paper describes the usefulness of SPECT HMPAO in MSA-P and PSP-P differentiation through the analysis of cerebellar perfusion of small ROIs. Thirty-one patients were included in the study—20 with MSA-P and 11 with PSP-P; the analysis performed indicated that the most significant difference in perfusion was observed in the anterior quadrangular lobule (H IV and V) on the left side (p < 0.0026). High differences in the median perfusion between the groups were also observed in a few other regions, with p < 0.05, but higher than premised p = 0.0026 (the Bonferroni correction was used in the statistical analysis). The assessment of the perfusion may be interpreted as a promising method of additional examination of atypical parkinsonisms with overlapping clinical manifestation, as in the case of PSP-P and MSA-P. The results obtained suggest that the interpretation of the differences in perfusion of the cerebellum should be made by evaluating the subregions of the cerebellum rather than the hemispheres. Further research is required.

The Cerebellum Is a Common Key for Visuospatial Execution and Attention in Parkinson's Disease

Cognitive decline affects the clinical course in patients with Parkinson's disease (PD) and contributes to a poor prognosis. However, little is known about the underlying network-level abnormalities associated with each cognitive domain. We aimed to identify the networks related to each cognitive domain in PD using resting-state functional magnetic resonance imaging (MRI). Forty patients with PD and 15 normal controls were enrolled. All subjects underwent MRI and the Mini-Mental State Examination. Furthermore, the cognitive function of patients with PD was assessed using the Montreal Cognitive Assessment (MoCA). We used independent component analysis of the resting-state functional MRI for functional segmentation, followed by reconstruction to identify each domain-related network, to predict scores in PD using multiple regression models. Six networks were identified, as follows: the visuospatial-executive-domain-related network (R² = 0.54, p < 0.001), naming-domain-related network (R² = 0.39, p < 0.001), attention-domain-related network (R² = 0.86, p < 0.001), language-domain-related network (R² = 0.64, p < 0.001), abstraction-related network (R² = 0.10, p < 0.05), and orientation-domain-related network (R² = 0.64, p < 0.001). Cerebellar lobule VII was involved in the visuospatial-executive-domain-related and attention-domain-related networks. These two domains are involved in the first three listed nonamnestic cognitive impairment in the diagnostic criteria for PD with dementia (PDD). Furthermore, Brodmann area 10 contributed most frequently to each domain-related network. Collectively, these findings suggest that cerebellar lobule VII may play a key role in cognitive impairment in nonamnestic types of PDD.

The Role of Frontal Assessment Battery and Frontal Lobe Single-Photon Emission Computed Tomography in the Differential Diagnosis of Progressive Supranuclear Palsy Variants and Corticobasal Syndrome-A Pilot Study

Progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) are clinical syndromes classified as atypical parkinsonism. Due to their overlapping symptomatology, recent research shows the necessity of finding new methods of examination of these clinical entities. PSP is a heterogenic disease. PSP Richardson-Steele Syndrome (PSP-RS) and parkinsonism predominant (PSP-P) are the most common clinical variants of progressive supranuclear palsy syndrome. The different clinical course and life expectancy of PSP-RS and PSP-P stress the need of efficient examination in the early stages. The aim of the study was to evaluate the possible feasibility of the combined use of frontal assessment battery (FAB) and single-photon emission computed tomography (SPECT) in the differentiation of PSP-RS, PSP-P, and CBS. The findings show that FAB may be interpreted as a possible supplementary tool in the differential diagnosis of PSP-P and PSP-RS. The differences in SPECT are less pronounced. The study does not show any advantages of performing combined frontal SPECT and FAB in the differential examination of PSP and CBS. Moreover, PSP-RS and CBS, in a detailed evaluation of the frontal lobe, do not show any significant differences. This is a relatively small study which, however, highlights the relevant features of clinical examination of these rare entities.

Discriminative pattern of reduced cerebral blood flow in Parkinson's disease and Parkinsonism-Plus syndrome: an ASL-MRI study

Background

Accurate identification of Parkinson’s disease (PD) and Parkinsonism-Plus syndrome (PPS), especially in the early stage of the disease, is very important. The purpose of this study was to investigate the discriminative spatial pattern of cerebral blood flow (CBF) between patients with PD and PPS.

Methods

Arterial spin labeling (ASL) perfusion-weighted imaging was performed in 20 patients with PD (mean age 56.35 ± 7.56 years), 16 patients with PPS (mean age 59.62 ± 6.89 years), and 17 healthy controls (HCs, mean age 54.17 ± 6.58 years). Voxel-wise comparison of the CBF was performed among PD, PPS, and HC groups. The receiver operating characteristic (ROC) curve was used to evaluate the performance of CBF in discriminating between PD and PPS. The relationship between CBF and non-motor neuropsychological scores was assessed by correlation analysis.

Results

PD group showed a significantly decreased CBF in the right cerebelum_crus2, the left middle frontal gyrus (MFG), the triangle inferior frontal gyrus (IFG_Tri), the left frontal medial orbital gyrus (FG_Med_Orb) and the left caudate nucleus (CN) compared with the HC group (P < 0.05). Besides the above regions, the left supplementary motor area (SMA), the right thalamus had decreased CBF in the PPS group compared with the HC group (P < 0.05). PPS group had lower CBF value in the left MFG, the left IFG_Tri, the left CN, the left SMA, and the right thalamus compared with the PD group (P < 0.05). CBFs in left IFG_Tri, the left CN, the left SMA, and the right thalamus had moderate to high capacity in discriminating between PD and PPS patients (AUC 0.719–0.831). The CBF was positively correlated with the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores in PD patients, while positively correlated with the MMSE, Hamilton Anxiety Scale (HAMA), Hamilton Depression Scale (HAMD) scores in PPS patients (P < 0.05).

Conclusion

PD and PPS patients have certain discriminative patterns of reduced CBFs, which can be used as a surrogate marker for differential diagnosis.