White matter hyperintensities in patients with multiple system atrophy

Cerebral Small Vessel Disease Is Associated with Motor, Cognitive, and Emotional Dysfunction in Multiple System Atrophy

BACKGROUND

Cerebral small vessel disease (CSVD) has not been systematically studied in patients with multiple system atrophy (MSA).

OBJECTIVE

We sought to explore whether MSA patients suffer from a heavier CSVD burden relative to healthy individuals and whether CSVD has a relationship with motor, cognitive, and emotional dysfunction in patients with MSA.

METHODS

This study consecutively recruited 190 MSA patients and 190 matched healthy controls whose overall CSVD burden and single CSVD imaging markers (including white matter hyperintensity (WMH), microbleeds, lacunes, and enlarged perivascular spaces (EPVS)) were measured. Of the MSA patients, 118 completed multi-dimensional outcome assessments. Spearman's correlations and multivariable linear regressions were performed.

RESULTS

We observed a greater burden of overall CSVD, WMH, and EPVS in MSA patients compared with controls, but not for microbleeds and lacunes. Motor dysfunction and cognitive impairment were significantly worse in subjects with severe CSVD than those with none-to-mild CSVD. In patients with MSA, the severity of CSVD burden was positively associated with motor impairments as measured by the Unified Multiple System Atrophy Rating Scale-II (β= 2.430, p = 0.039) and Scale for the Assessment and Rating of Ataxia (β= 1.882, p = 0.015). Of CSVD imaging markers, different associations with MSA outcomes were displayed. WMH was associated with motor, cognitive, and emotional deficits, while the EPVS in the centrum semiovale, basal ganglia, and hippocampus regions was correlated only with motor severity, anxiety, and cognition, respectively. Similar findings were noted in MSA-cerebellar and MSA-parkinsonian patients.

CONCLUSIONS

Concomitant CSVD may be correlated with worse multi-dimensional dysfunction in patients with MSA.

Abnormal circadian blood pressure regulation and cognitive impairment in α-synucleinopathies

Circadian blood pressure (BP) rhythm is important for the maintenance of healthy daily life, and its disruption is associated with poor outcomes. Cardiovascular autonomic failure is often observed in older populations but has a greater impact on neurodegenerative disorders such as α-synucleinopathies. These BP abnormalities include orthostatic hypotension (OH), supine hypertension (SH), and a loss of nocturnal BP fall. OH not only causes falls or syncope but is also related to cognitive impairment in α-synucleinopathies. For example, OH doubles or triples the risk for the development of cognitive impairment in Parkinson's disease (PD). The diffuse central and peripheral neuropathology of α-synuclein may contribute to both OH and cognitive impairment. Moreover, repeated cerebral hypoperfusion in OH is thought to be related to cerebrovascular and neuronal damage, which may cause cognitive impairment. SH, which often coexists with OH, is also associated with cognitive impairment through cerebrovascular damage, such as white matter lesions and cerebral microbleeds. The reverse-dipping (riser) pattern on ambulatory BP monitoring is commonly observed in PD (∼56%), regardless of disease duration and severity. It is also related to cognitive impairment and more pronounced when coexisting with OH. These abnormal circadian BP profiles may be synergistically associated with cognitive impairment and poor outcomes in α-synucleinopathies. Although evidence for aggressive control of BP dysregulation improving cognitive impairment and outcomes is limited, regular BP monitoring appears to be important for total management of α-synucleinopathies.

Neuroimaging cerebrovascular biomarkers in Parkinson's disease

BACKGROUND AND PURPOSE

The cardiovascular risk in Parkinson's disease (PD) remains uncertain and controversial. Some studies suggest PD patients present an increased risk of cerebrovascular disease. We aimed to study the prevalence of neuroimaging cerebrovascular biomarkers in PD patients compared to controls, using an accurate and complete magnetic resonance (MR) imaging evaluation.

MATERIAL AND METHODS

Neuroimaging sub-study within a larger cross-sectional case-control study. An enriched subgroup of PD patients (≤10 years since diagnosis) with at least a moderate cardiovascular mortality risk based on a Systematic COronary Risk Evaluation (SCORE) was compared to community-based controls regarding neuroimaging biomarkers. Patients underwent a high-resolution T1-weighted MR imaging sequence at 3.0 T to visualize neuromelanin. A 3D SWI FFE, sagittal 3D T1-weighted, axial FLAIR and diffusion-weighted image sequences were obtained.

RESULTS

The study included 47 patients, 24 with PD and 23 controls. PD patients presented a reduced area and signal intensity of the substantia nigra and locus coeruleus on neuromelanin-sensitive MR. The median SCORE was 5% in both groups. No significant differences regarding white matter hyperintensities (OR 4.84, 95% CI 0.50, 47.06), lacunes (OR 0.43, 95% CI 0.07, 2.63), microbleeds (OR 0.64, 95% CI 0.13, 3.26), or infarcts (0.95, 95% CI 0.12, 7.41) was found. The frequency of these neuroimaging biomarkers was very low in both groups.

CONCLUSION

The present study does not support an increased prevalence of neuroimaging cerebrovascular biomarkers in PD patients.

White Matter Hyperintensities Mediate Impact of Dysautonomia on Cognition in Parkinson's Disease

Background

Patients with Parkinson's disease (PD) present with a broad spectrum of nonmotor features including autonomic disorders. More severe autonomic dysfunction in PD is associated with increased cognitive deficits. The presence of cerebral small-vessel disease, measured by T2-weighted magnetic resonance imaging white matter hyperintensity (WMH) burden, is also observed in patients with PD with faster cognitive decline.

Objective

To investigate whether baseline orthostatic hypotension and autonomic dysfunction in early-stage PD affect later cognitive decline via mediation through cerebral small-vessel disease.

Methods

De novo PD patients (N = 365) and age-matched controls (N = 174) with baseline T2-weighted/ fluid-attenuated inversion recovery scans were selected from the Parkinson's Progression Markers Initiative. WMHs were automatically segmented. Mediation analysis was used to assess whether WMH load mediates the effect of orthostatic hypotension and autonomic dysfunction (measured by Scales for Outcomes in Parkinson's Disease-Autonomic) on future cognitive decline (measured by Montreal Cognitive Assessment) in an average of 4 years of follow-up.

Results

Mediation analysis supported the existence of a full mediation of WMHs on the effect of diastolic orthostatic hypotension in patients with PD and future cognitive decline (average causal mediation effect: ab = -0.032, 95% confidence interval = -0.064 to -0.01, P = 0.01). There was also a partial mediation for overall autonomic dysfunction (ab = -0.027, 95% confidence interval = -0.054 to 0.00, P = 0.02).

Conclusions

WMHs fully mediate the effect of diastolic orthostatic hypotension and partially mediate the effect of autonomic dysregulation on future cognitive decline in patients with PD. Our findings support the hypothesis that autonomic dysfunction in early clinical stages predisposes the brain to WMHs through dysregulation of the blood flow in the small vessels. This in turn increases the risk of future cognitive impairment in early PD.

The impact of supine hypertension on target organ damage and survival in patients with synucleinopathies and neurogenic orthostatic hypotension

INTRODUCTION

In addition to neurogenic orthostatic hypotension (nOH), patients with synucleinopathies frequently have hypertension when supine. The long-term consequences of both abnormalities are difficult to disentangle. We aimed to determine if supine hypertension is associated with target organ damage and worse survival in patients with nOH.

METHODS

Patients with nOH due to multiple system atrophy (MSA), Parkinson disease (PD), or pure autonomic failure (PAF) were classified into those with or without supine hypertension (systolic BP of at least 140 mmHg or diastolic BP of at least 90 mmHg). Organ damage was assessed by measuring cerebral white matter hyperintensities (WMH), left ventricular hypertrophy (LVH), and renal function. We prospectively followed patients for 30 months (range: 12-66 months) and recorded incident cardiovascular events and all-cause mortality.

RESULTS

Fifty-seven patients (35 with probable MSA, 14 with PD and 8 with PAF) completed all evaluations. In addition to nOH (average fall 35 ± 21/17 ± 14 mmHg, systolic/diastolic, mean ± SD), 38 patients (67%) had supine hypertension (systolic BP > 140 mmHg). Compared to those without hypertension, patients with hypertension had higher blood urea nitrogen levels (P = 0.005), lower estimated glomerular filtration rate (P = 0.008), higher prevalence of LVH (P = 0.040), and higher WMH volume (P = 0.019). Longitudinal follow-up of patients for over 2 years (27.1 ± 14.5 months) showed that supine hypertension was independently associated with earlier incidence of cardiovascular events and death (HR = 0.25; P = 0.039).

CONCLUSIONS

Supine hypertension in patients with nOH was associated with an increased risk for target organ damage, cardiovascular events, and premature death. Defining management strategies and safe blood pressure ranges in patients with nOH remains an important research question.

Role of Magnetic Resonance Imaging in the Diagnosis of Multiple System Atrophy

Background

Multiple system atrophy (MSA) is a rapidly progressing neurodegenerative disorder without effective disease-modifying therapies. Because of a lack of reliable diagnostic biomarkers, there has been increasing interest in using magnetic resonance imaging (MRI) to improve the diagnostic accuracy of MSA.

Methods

This review summarizes recent literatures on the role of MRI in the diagnosis of MSA.

Results

Several MRI abnormalities on conventional MRI already are included in the current diagnostic criteria for MSA. Other features on conventional MRI are also used to make a diagnosis of MSA or to rule out alternative diagnoses. On the other hand, some of the MRI findings that were previously considered suggestive of a diagnosis of MSA are now being challenged, because it turned out that they were not as specific to MSA as previously thought. More advanced MRI modalities, including susceptibility-weighted imaging, diffusion-weighted imaging, diffusion tensor imaging, voxel-based morphometry, and cortical thickness analysis, are now used to study the changes in the brains of patients with MSA. Furthermore, studies have produced promising results demonstrating the use of MRI as a tool for monitoring and assessing disease progression in MSA.

Conclusions

MRI is useful and indispensable in the diagnosis of MSA and also possibly for monitoring disease progression. In this regard, well-designed, long-term, prospective studies on large numbers of patients are needed.

Cerebral autoregulation and white matter lesions in Parkinson's disease and multiple system atrophy

Cerebral autoregulation is a complex homeostatic process which ensures constant brain blood supply, despite continuous blood pressure fluctuations. Recent evidence suggests that in Parkinson's disease (PD) and multiple system atrophy (MSA) this process is maintained in a broadened range of blood pressure values, consistent with an adaptive mechanism to increase tolerance to orthostatic hypotension. In PD and MSA orthostatic hypotension may be accompanied by supine hypertension which has been recently linked with cerebral white matter lesions in these conditions. We hypothesize that cerebral autoregulation adaptation to chronic orthostatic hypotension may be directly related with an increase susceptibility to hypertensive peaks. Evaluation of cerebral autoregulatory behavior may thus represent a novel approach to simultaneously target orthostatic symptoms and silent end-organ damage in alpha-synucleinopathies, with a beneficial impact on cerebrovascular and cognitive outcome.

Diagnosing and treating neurogenic orthostatic hypotension in primary care

In response to a change in posture from supine or sitting to standing, autonomic reflexes normally maintain blood pressure (BP) by selective increases in arteriovenous resistance and by increased cardiac output, ensuring continued perfusion of the central nervous system. In neurogenic orthostatic hypotension (NOH), inadequate vasoconstriction and cardiac output cause BP to drop excessively, resulting in inadequate perfusion, with predictable symptoms such as dizziness, lightheadedness and falls. The condition may represent a central failure of baroreceptor signals to modulate cardiovascular function, a peripheral failure of norepinephrine release from cardiovascular sympathetic nerve endings, or both. Symptomatic patients may benefit from both non-pharmacologic and pharmacologic interventions. Among the latter, two pressor agents have been approved by the US Food and Drug Administration: the sympathomimetic prodrug midodrine, approved in 1996 for symptomatic orthostatic hypotension, and the norepinephrine prodrug droxidopa, approved in 2014, which is indicated for the treatment of symptomatic neurogenic orthostatic hypotension caused by primary autonomic failure (Parkinson's disease, multiple system atrophy and pure autonomic failure). A wide variety of off-label options also have been described (e.g. the synthetic mineralocorticoid fludrocortisone). Because pressor agents may promote supine hypertension, NOH management requires monitoring of supine BP and also lifestyle measures to minimize supine BP increases (e.g. head-of-bed elevation). However, NOH has been associated with cognitive impairment and increases a patient's risk of syncope and falls, with the potential for serious consequences. Hence, concerns about supine hypertension - for which the long-term prognosis in patients with NOH is yet to be established - must sometimes be balanced by the need to address a patient's immediate risks.

Cardiovascular complications in patients with autonomic failure

Patients with autonomic failure are characterized by orthostatic hypotension, supine hypertension, high blood pressure variability, blunted heart rate variability, and often have a "non-dipping" or "reverse dipping" pattern on 24-h ambulatory blood pressure monitoring. These alterations may lead to cardiovascular and cerebrovascular changes, similar to the target organ damage found in hypertension. Often patients with autonomic failure are on treatment with anti-hypotensive drugs, which may worsen supine hypertension. The aim of this review is to summarize the evidence for cardiac, vascular, renal, and cerebrovascular damage in patients with autonomic failure.

Concomitant pathologies among a spectrum of parkinsonian disorders

INTRODUCTION

Many clinicopathological studies do not specify the presence of other pathologies located within the brain, so disease heterogeneity may be under appreciated.

OBJECTIVE

The purpose of this study was to determine the frequencies of concomitant pathologies among parkinsonian disorders.

METHODS

Data from the Arizona Study of Aging and Neurodegenerative Disorders (AZSAND), an ongoing longitudinal clinical-neuropathological study, was used to analyze concomitant pathologies, including Alzheimer's disease (AD), argyrophilic grains (Arg), cerebral amyloid angiopathy (CAA), cerebral white matter rarefaction (CWMR) and overlap of each parkinsonian disorder in clinico-pathologically defined Parkinson's disease (PD; N = 140), dementia with Lewy bodies (DLB; N = 90), progressive supranuclear palsy (PSP; N = 64), multiple system atrophy (MSA; N = 6), corticobasal degeneration (CBD; N = 7); and normal elderly (controls; N = 166).

RESULTS

Of the neuropathologically-confirmed PD cases, 38% had a concomitant diagnosis of AD, 9% PSP, 25% Arg, 44% CWMR, and 24% CAA. For DLB, 89% had AD, 1% PSP, 21% Arg, 51% CWMR, and 50% CAA. For PSP cases, 36% had AD, 20% PD, 1% DLB, 44% Arg, 52% CWMR and 25% CAA. Similar heterogeneity was seen for MSA and CBD cases. Many cases had more than one of the above additional diagnoses.

CONCLUSIONS

These data demonstrate a great deal of concomitant pathologies among different types of parkinsonian disorders; this may help explain the heterogeneity of clinical findings.

Orthostatic and supine blood pressures are associated with white matter hyperintensities in Parkinson disease

BACKGROUND AND PURPOSE

Several reports on the elderly population have suggested that orthostatic hypotension is associated with white matter hyperintensities (WMH); however, little information is available on patients with Parkinson's disease (PD).

METHODS

We analyzed the association blood pressure profiles during tilt table testing with WMH scores in 117 patients with PD. WMH were rated using the semiquantitative visual rating system proposed by Scheltens et al.

RESULTS

The presence of orthostatic hypotension was associated with increasing tendency of WMH score and the blood pressure changes during tilting and supine blood pressure were positively correlated with increasing WMH score.

CONCLUSIONS

This finding indicates that hemodynamic changes associated with orthostatic hypotension may be associated with white matter changes in patients with PD.

The potential prognostic role of cardiovascular autonomic failure in α-synucleinopathies

Cardiovascular autonomic failure is the second most common dysautonomic feature of α-synucleinopathies and has significant impact on daily activities and quality of life. Here we provide a systematic review of cardiovascular autonomic failure in α-synucleinopathies, emphasizing its impact on cognitive functions and disease outcomes. Articles spanning the period between January 1985 and April 2012 were identified from the PubMed database using a keyword-based search. Epidemiological studies highlight the negative prognostic effect of cardiovascular autonomic failure on cardiovascular and cerebrovascular outcomes and overall mortality in all α-synucleinopathies. Altered cerebral perfusion, vascular pressure stress, and related disruption of the blood-brain barrier may also contribute to the white matter hyperintensities and cognitive dysfunction frequently found in patients affected by neurocardiovascular instability. These findings support the hypothesis that cardiovascular autonomic failure may play a negative prognostic role in α-synucleinopathies and suggest that precocious screening and therapeutic management of cardiovascular autonomic failure may positively impact disease course.