[Clinical and pathological study on early diagnosis of Parkinson's disease and dementia with Lewy bodies]

Dementia with Lewy bodies and Parkinson's disease-dementia: current concepts and controversies

Dementia with Lewy bodies (DLB) and Parkinson's disease-dementia (PDD), although sharing many clinical, neurochemical and morphological features, according to DSM-5, are two entities of major neurocognitive disorders with Lewy bodies of unknown etiology. Despite considerable clinical overlap, their diagnosis is based on an arbitrary distinction between the time of onset of motor and cognitive symptoms: dementia often preceding parkinsonism in DLB and onset of cognitive impairment after onset of motor symptoms in PDD. Both are characterized morphologically by widespread cortical and subcortical α-synuclein/Lewy body plus β-amyloid and tau pathologies. Based on recent publications, including the fourth consensus report of the DLB Consortium, a critical overview is given. The clinical features of DLB and PDD include cognitive impairment, parkinsonism, visual hallucinations, and fluctuating attention. Intravitam PET and post-mortem studies revealed more pronounced cortical atrophy, elevated cortical and limbic Lewy pathologies (with APOE ε4), apart from higher prevalence of Alzheimer pathology in DLB than PDD. These changes may account for earlier onset and greater severity of cognitive defects in DLB, while multitracer PET studies showed no differences in cholinergic and dopaminergic deficits. DLB and PDD sharing genetic, neurochemical, and morphologic factors are likely to represent two subtypes of an α-synuclein-associated disease spectrum (Lewy body diseases), beginning with incidental Lewy body disease-PD-nondemented-PDD-DLB (no parkinsonism)-DLB with Alzheimer's disease (DLB-AD) at the most severe end, although DLB does not begin with PD/PDD and does not always progress to DLB-AD, while others consider them as the same disease. Both DLB and PDD show heterogeneous pathology and neurochemistry, suggesting that they share important common underlying molecular pathogenesis with AD and other proteinopathies. Cognitive impairment is not only induced by α-synuclein-caused neurodegeneration but by multiple regional pathological scores. Recent animal models and human post-mortem studies have provided important insights into the pathophysiology of DLB/PDD showing some differences, e.g., different spreading patterns of α-synuclein pathology, but the basic pathogenic mechanisms leading to the heterogeneity between both disorders deserve further elucidation. In view of the controversies about the nosology and pathogenesis of both syndromes, there remains a pressing need to differentiate them more clearly and to understand the processes leading these synucleinopathies to cause one disorder or the other. Clinical management of both disorders includes cholinesterase inhibitors, other pharmacologic and nonpharmacologic strategies, but these have only a mild symptomatic effect. Currently, no disease-modifying therapies are available.

Reduced MIBG accumulation of the parotid and submandibular glands in idiopathic Parkinson's disease

INTRODUCTION

Alpha-synuclein pathology (ASP) is a characteristic histopathological finding in idiopathic Parkinson's disease (PD). The ASP involves not only the brain but also extracranial structures. In the present study we utilized MIBG scintigraphy to measure the sympathetic innervation of the major salivary glands. We were interested in whether MIBG uptake in the major salivary glands represents a potential biomarker for ASP in PD.

METHODS

We investigated 77 PD patients (age 61 ± 10 years, mean ± SD), while 15 non-PD patients (age 58 ± 15 years) with arterial hypertension, who underwent MIBG scintigraphy to exclude pheochromocytoma, served as age-matched controls. The MIBG uptake of the parotid glands and the submandibular glands was quantified by means of a region of interest technique. The sublingual glands were too small for an exact measurement. We applied Generalized Estimating Equations (GEE) to identify and remove factors which may bias the statistical correlation analysis.

RESULTS

The PD patients showed a significantly lower MIBG uptake in the parotid and submandibular glands than the controls (p < 0.0001). MIBG uptake in the PD patients did not correlate with clinical severity (Hoehn and Yahr stage, motor part of the UPDRS) or disease duration.

CONCLUSION

MIBG uptake in the parotid and submandibular glands might be a candidate biomarker for PD. The missing correlation between MIBG uptake and clinical PD parameters suggests that ASP of the extracranial sympathetic superior cervical ganglion, which innervates the major salivary glands, develops independently from the cerebral dopaminergic nigrostriatal ASP.

Assessment of the efficacy of early phase parameters by (123)I-MIBG dynamic imaging for distinguishing Lewy body-related diseases from Parkinson's syndrome

OBJECTIVE

The aim of this study was to assess the efficacy of early phase washout rate (early WR) and area under the time-activity curve (AUTAC) by (123)I-metaiodobenzylguanidine (MIBG) dynamic chest imaging for distinguishing Lewy body-related diseases (LBRD) from Parkinson's syndrome (PS) and reducing examination time.

METHODS

Sixty-two patients with suspected LBRD who underwent (123)I-MIBG dynamic imaging in early phase were retrospectively selected. The early WR and AUTAC were calculated from (123)I-MIBG dynamic data of the heart. We evaluated the relationships between proposed and conventional parameters by using Spearman's rank correlation coefficient. Differences in parameters between LBRD and PS groups were tested for statistical significance using the Mann-Whitney U test. The diagnostic performance of all parameters for distinguishing LBRD from PS was assessed in terms of receiver operating characteristic (ROC) analysis. Additionally, combination diagnostic performance and concordance rate between early phase parameters and late H/M ratio by kappa statistics were also assessed.

RESULTS

The early WR and AUTAC showed a positive and negative correlation with conventional parameters. Both the early WR and AUTAC of LBRD group were significantly distinguishable from those of the PS group (p < 0.001). Area under the ROC curve of the early WR (0.98) was greater than that of AUTAC (0.91). The diagnostic performance of combination of the early phase parameters was 93 % sensitivity and 100 % specificity. Moreover, the early phase parameters showed excellent agreement with late H/M ratio (k = 0.93).

CONCLUSIONS

The early WR and AUTAC showed high performance for distinguishing LBRD from PS, and the combination diagnosis with early H/M ratio and early WR contribute to improve the diagnostic performance. Thus, these parameters would be useful for reducing the examination time of myocardial (123)I-MIBG scintigraphy to diagnose LBRD.

[Clinical and imaging diagnostics of Parkinson's disease and multiple system atrophy]

The diagnosis of Parkinson's disease (PD) and multiple system atrophy (MSA) is primarily made by clinical symptoms, but might still remain challenging even for experienced neurologists. Neuroradiologic imaging may be a useful tool in the diagnostic work-up, particularly for excluding other diseases, such as normal pressure hydrocephalus, multi-infarct dementia and cerebellar lesions. Nuclear medicine methods can additionally support the diagnosis and differential diagnosis of PD and MSA.

Non-motor extranigral signs and symptoms in Parkinson's disease

Clinical symptoms in Parkinson's disease (PD) comprise both motor and non-motor symptoms. In this disease, synucleinopathic-induced, nigral dopamine deficiency-related dysfunction of the basal ganglia is held responsible for the characteristic levodopa-responsive motor signs and symptoms (bradykinesia, hypokinesia, rigidity), known as parkinsonism and essential for clinical diagnosis in PD, as well as subtle motivational and cognitive dysfunctions. Some motor symptoms, such as tremor and postural instability, and most non-motor symptoms, however, are not fully levodopa-responsive, and suggested to manifest extranigral pathology. These symptoms include autonomic, sleep, sensory and neuropsychiatric symptoms, which in some cases may precede the first signs of motor parkinsonism, closely correlating with the progression of Lewy body pathology in PD. The recognition and treatment of these mostly under-recognized and under-treated symptoms is important, as these symptoms might have more impact on the quality of life in PD patients as compared to motor parkinsonism. On top of this, recognition of these manifestations in the prodromal phase of motor PD is critical to early diagnosis and treatment, as disease-modifying drugs, once identified, should be initiated as soon as possible, preferably in this premotor phase of the disease. On top of this, (non)motor extranigral symptoms in PD might also be of iatrogenic origin, whether directly as indirectly. During conventional, oral, dopaminomimetic treatment, the progressive loss of striatal dopaminergic nerve endings with the loss of cerebral dopamine storage capacity, renders the cerebral dopamine level fully dependent of the plasma levodopa levels, thus changing dopaminergic receptor stimulation from continuous to a more pulsatile pattern. Supposedly due to this process, neuroplastic changes in (sub)cortical dopaminergic pathways might cause therapeutic response fluctuations: motor and nonmotor fluctuations with anxiety- and panic-attacks and/or mood swings, dyskinesias and punding. Finally, dopaminomimetic pharmacotherapy may also induce extranigral non-motor drug-related direct adverse effects, such as impulse control disorders. In this article, non-motor signs and symptoms of extranigral PD-related pathology will be discussed, as well as the (suggested) criteria for diagnosis and treatment. Of course, also the recognition of the signs and symptoms of the prodromal (premotor) phase, suggestive for the presence of the PD, will be discussed. Iatrogenic non-motor symptoms, though, will not be further discussed.

Detection of Lewy body disease in patients with late-onset depression, anxiety and psychotic disorder with myocardial meta-iodobenzylguanidine scintigraphy

PURPOSE

Lewy body disease (LBD) is comprised of a spectrum of diseases that includes Parkinson's disease (PD), PD dementia (PDD) and dementia with LBD (DLBD), an array of dementia, and motor symptoms. Low uptake of myocardial meta-iodobenzylguanidine (MIBG) validates diagnosis of LBD. Psychiatric symptoms sometimes precede atypical Parkinsonian syndromes in LBD. Of 34 patients with low MIBG uptake, late-onset depressive, anxiety, or psychotic symptoms were analyzed in term of clinical profiles.

METHOD

Thirty-four patients were classed into three groups according to three main symptoms, 11 patients with visual hallucination (VH), 13 with depression-anxiety (DA), and 10 with psychosis with cognitive disturbance (PCD). Cutoff values of heart-to-mediastinum (HM) ratio of MIBG were set at 1.78 in early phase or 1.68 in late phase.

RESULTS

Group VH patients showed a trend toward higher age at onset and occipital lobe hypoperfusion. Group DA patients lacked central and core features of DLBD and five of them showed frontal lobe hypoperfusion. Group PCD patients had the highest frequencies of suggestive symptoms and UPDRS scores and showed temporal lobe hypoperfusion. HM ratio was not associated with clinical profiles of three groups. Cognitive function was more severely disturbed in atypical Parkinsonian syndrome cases at an initial visit.

CONCLUSION

Group VH was considered to DLBD, and Group PCD was regarded as PDD or DLBD with early psychotic presentation. Group DA has a possibility of early depression or anxiety disorder of LBD although it lacked DLBD criteria. Atypical Parkinsonian syndromes are associated with cognitive disturbance irrespective of psychiatric profiles.

Diagnostic and Pathophysiological Impact of Myocardial MIBG Scintigraphy in Parkinson's Disease

Myocardial MIBG scintigraphy is established in the diagnosis and differential diagnosis of Parkinson's disease (PD). Numerous studies address the pathophysiological impact of myocardial MIBG scintigraphy: the myocardial MIBG uptake correlates with the clinical phenotype of PD; the background of this phenomenon is unclear. Furthermore MIBG scintigraphy enables to study the extracranial Lewy body type-degeneration. In combination with cerebral dopamine transporter imaging, MIBG scintigraphy allows to correlate cerebral and extracranial Lewy body type-degeneration in PD.

[Clinical and pathological study on early diagnosis of Parkinson's disease and dementia with Lewy bodies]

Cardiac uptake of meta-iodobenzylguanidine (MIBG) is specifically reduced in Lewy body disease (LBD). To see pathological basis of the reduced cardiac uptake of MIBG in LBD, we immunohistichemically examined cardiac tissues from patients with LBD, related movement disorders and Alzheimer's disease (AD). In LBD, cardiac sympathetic denervation occurs, which accounts for the reduced cardiac uptake of MIBG. Patients with LBD have Lewy bodies (LBs) in the nervous system, whereas patients with the other neurodegenerative parkinsonism, parkin-associated Parkinson's disease (PD) and AD and have no LBs. Therefore, cardiac sympathetic denervation is closely related to the presence of LBs in a wide range of neurodegenerative processes. We further investigate how a-synuclein aggregates are involved in degeneration of the cardiac sympathetic nerve in PD. Accumulation of alpha-synuclein aggregates in the distal axons of the cardiac sympathetic nervous system precedes that of neuronal somata or neurites in the paravertebral sympathetic ganglia and that it heralds centripetal degeneration of the cardiac sympathetic nerve in PD. This chronological and dynamic relationship between alpha-synuclein aggregates and degeneration of the cardiac sympathetic nervous system may represent the pathological mechanism underlying a common degenerative process in PD.